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Castaño JD, El Khoury IV, Goering J, Evans JE, Zhang J. Unlocking the distinctive enzymatic functions of the early plant biomass deconstructive genes in a brown rot fungus by cell-free protein expression. Appl Environ Microbiol 2024; 90:e0012224. [PMID: 38567954 PMCID: PMC11205865 DOI: 10.1128/aem.00122-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 03/10/2024] [Indexed: 05/22/2024] Open
Abstract
Saprotrophic fungi that cause brown rot of woody biomass evolved a distinctive mechanism that relies on reactive oxygen species (ROS) to kick-start lignocellulosic polymers' deconstruction. These ROS agents are generated at incipient decay stages through a series of redox relays that shuttle electrons from fungus's central metabolism to extracellular Fenton chemistry. A list of genes has been suggested encoding the enzyme catalysts of the redox processes involved in ROS's function. However, navigating the functions of the encoded enzymes has been challenging due to the lack of a rapid method for protein synthesis. Here, we employed cell-free expression system to synthesize four redox or degradative enzymes, which were identified, by transcriptomic data, as conserved players of the ROS oxidation phase across brown rot fungal species. All four enzymes were successfully expressed and showed activities that enable confident assignment of function, namely, benzoquinone reductase (BQR), ferric reductase, α-L-arabinofuranosidase (ABF), and heme-thiolate peroxidase (HTP). Detailed analysis of their catalytic features within the context of brown rot environments allowed us to interpret their roles during ROS-driven wood decomposition. Specifically, we validated the functions of BQR as the driver redox enzyme of Fenton cycles and reconstructed its interactions with the co-occurring HTP or laccase and ABF. Taken together, this research demonstrated that the cell-free expression platform is adequate for synthesizing functional fungal enzymes and provided an alternative route for the rapid characterization of fungal proteins, escalating our understanding of the distinctive biocatalyst system for plant biomass conversion.IMPORTANCEBrown rot fungi are efficient wood decomposers in nature, and their unique degradative systems harbor untapped catalysts pursued by the biorefinery and bioremediation industries. While the use of "omics" platforms has recently uncovered the key "oxidative-hydrolytic" mechanisms that allow these fungi to attack lignocellulose, individual protein characterization is lagging behind due to the lack of a robust method for rapid synthesis of crucial fungal enzymes. This work delves into the studies of biochemical functions of brown rot enzymes using a rapid, cell-free expression platform, which allowed the successful depictions of enzymes' catalytic features, their interactions with Fenton chemistry, and their roles played during the incipient stage of brown rot when fungus sets off the reactive oxygen species for oxidative degradation. We expect this research could illuminate cell-free protein expression system's use to fulfill the increasing need for functional studies of fungal enzymes, advancing the discoveries of novel biomass-converting catalysts.
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Affiliation(s)
- Jesus D. Castaño
- Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
| | - Irina V. El Khoury
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Joshua Goering
- Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
| | - James E. Evans
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, USA
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Jiwei Zhang
- Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
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Bankole PO, Omoni VT, Tennison-Omovoh CA, Adebajo SO, Mulla SI. Enhanced removal of dibutyl phthalate in a laccase-mediator system: Optimized process parameters, kinetics, and environmental impact. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 348:119227. [PMID: 37820431 DOI: 10.1016/j.jenvman.2023.119227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/02/2023] [Accepted: 10/02/2023] [Indexed: 10/13/2023]
Abstract
The persistence and recalcitrance of endocrine-disrupting chemicals (EDCs) in the environment have raised momentous concerns due to their carcinogenic, teratogenic, genotoxic, and cytotoxic effects on humans, animals, and plants. Unarguably, dibutyl phthalate (DBP) is one of the most ubiquitous EDCs because of its bioavailability in water, soil, and atmosphere. This study aims to investigate the efficiency of Agaricus bisporus laccase in the degradation of dibutyl phthalate (DBP) in laccase-mediator system. Here, enhanced removal efficiency was recorded during DBP degradation in laccase-mediator systems than in reaction medium containing laccase only. About 98.85% of 30 mg L-1 DBP was efficiently removed in a medium containing 1.3 U mL-1, 0.045 mM Syringaldehyde (SYR) at incubation temperature 30 aC and pH 5 within 24 h. This finding was further corroborated by the synergistic interplay of the optimal parameters in the laccase-SYR system done using response surface methodology (Box-Behnken Design). Furthermore, the addition of 1.5 mM of metal ions in the laccase-SYR system further promoted the enhanced removal of DBP in the following order: Cr3+> Pb2+> Ca2+> Al3+>Zn2+ > Cu2+. A significant decrease in DBP degradation was observed at higher concentrations of metal ions above 1.5 mM due to the inhibition of laccase active sites. The coefficient of correlation (R2 = 0.9885) recorded in the Lineweaver bulk plot affirmed that the removal efficiencies are highly dependent on DBP concentration in the laccase-SYR system. The Gas-Chromatography Mass Spectrometry (GC-MS) analyses affirmed that the ortho-cleavage due to hydrolysis of DBP in the reaction system led to the formation of two metabolic degradation products (MBP and PA). The phytotoxicity assessment affirmed the detoxified status of DBP after treatment with significant improvement (90 and 91%) in the growth of Lens culinaris and Sorghum bicolor. This is the first report on DBP degradation in the laccase-SYR reaction system, underscoring the unique, eco-friendly, economical, and promising alternative to known conventional methods.
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Affiliation(s)
- Paul Olusegun Bankole
- Department of Pure and Applied Botany, College of Biosciences, Federal University of Agriculture P.M.B. 2240 Abeokuta, Ogun State, Nigeria; Environmental Microbiology Group, Institute of Water Research, University of Granada, Calle Ramón y Cajal 4, E-18071 Granada, Spain.
| | | | | | - Seun Owolabi Adebajo
- Department of Microbiology, College of Biosciences, Federal University of Agriculture P.M.B. 2240 Abeokuta, Ogun State, Nigeria
| | - Sikandar Imamsab Mulla
- Department of Biochemistry, School of Applied Sciences, REVA University, Bangalore 560064, India; Division of Biotechnology, Jeonbuk National University, Iksan 54596, Republic of Korea
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Mori T, Terashima T, Matsumura M, Tsuruta K, Dohra H, Kawagishi H, Hirai H. Construction of white-rot fungal-bacterial consortia with improved ligninolytic properties and stable bacterial community structure. ISME COMMUNICATIONS 2023; 3:61. [PMID: 37349534 PMCID: PMC10287725 DOI: 10.1038/s43705-023-00270-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/05/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023]
Abstract
It is believed that wood-rot fungi change their wood decay activities due to influences from co-existing bacterial communities; however, it is difficult to elucidate experimentally the interaction mechanisms in fungal-bacterial consortia because the bacterial community structure is quite unstable and readily changes. Indeed, the wood decay properties of fungal-bacterial consortia consisting of a white-rot fungus Phanerochaete sordida YK-624 and a natural bacterial community changed dramatically during several sub-cultivations on wood. Therefore, development of a sub-cultivation method that imparts stability to the bacterial community structure and fungal phenotype was attempted. The adopted method using agar medium enabled maintenance of fungal phenotypes relating to wood decay and the bacterial community even through dozens of repetitive sub-cultures. Some bacterial metabolic pathways identified based on gene predictions were screened as candidates involved in P. sordida-bacterial interactions. In particular, pathways related to prenyl naphthoquinone biosynthesis appeared to be involved in an interaction that promotes higher lignin degradation selectivity by the consortia, as naphthoquinone derivatives induced phenol-oxidizing activity. Based on these results, it is expected that detailed analyses of the relationship between the wood-degrading properties of white-rot fungal-bacterial consortia and bacterial community structures will be feasible using the sub-cultivation method developed in this study.
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Affiliation(s)
- Toshio Mori
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
- Research Institute for Mushroom Science, Shizuoka University, 836 Ohya, Suruga‑ku, Shizuoka, 422‑8529, Japan.
| | - Taiki Terashima
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Masaki Matsumura
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Koudai Tsuruta
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Hideo Dohra
- Research Institute for Mushroom Science, Shizuoka University, 836 Ohya, Suruga‑ku, Shizuoka, 422‑8529, Japan
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga‑ku, Shizuoka, 422‑8529, Japan
- Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Hirokazu Kawagishi
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
- Research Institute for Mushroom Science, Shizuoka University, 836 Ohya, Suruga‑ku, Shizuoka, 422‑8529, Japan
| | - Hirofumi Hirai
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
- Research Institute for Mushroom Science, Shizuoka University, 836 Ohya, Suruga‑ku, Shizuoka, 422‑8529, Japan
- Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
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Jofré-Fernández I, Matus-Baeza F, Merino-Guzmán C. White-rot fungi scavenge reactive oxygen species, which drives pH-dependent exo-enzymatic mechanisms and promotes CO 2 efflux. Front Microbiol 2023; 14:1148750. [PMID: 37362943 PMCID: PMC10285405 DOI: 10.3389/fmicb.2023.1148750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/20/2023] [Indexed: 06/28/2023] Open
Abstract
Soil organic matter (SOM) decomposition mechanisms in rainforest ecosystems are governed by biotic and abiotic procedures which depend on available oxygen in the soil. White-rot fungi (WRF) play an important role in the primary decomposition of SOM via enzymatic mechanisms (biotic mechanism), which are linked to abiotic oxidative reactions (e.g., Fenton reaction), where both processes are dependent on reactive oxygen species (ROS) and soil pH variation, which has yet been studied. In humid temperate forest soils, we hypothesize that soil pH is a determining factor that regulates the production and consumption of ROS during biotic and abiotic SOM decomposition. Three soils from different parent materials and WRF inoculum were considered for this study: granitic (Nahuelbuta, Schizophyllum commune), metamorphic (Alerce Costero, Stereum hirsutum), and volcanic-allophanic (Puyehue, Galerina patagonica). CO2 fluxes, lignin peroxidase, manganese peroxidase, and dye-decolorizing peroxidase levels were all determined. Likewise, the production of superoxide anion (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH) were assessed in soils microcosms after 36 days of anaerobic incubation with WRF inoculum and induced Fenton reaction under pH variations ranging from 2.5 to 5.1. ROS significantly increased biotic and abiotic CO2 emissions in all tested soils, according to the findings. The highest values (217.45 mg C kg-1) were found during the anaerobic incubation of sterilized and inoculated soils with WRF at a natural pH of 4.5. At pH 4.0, the lowest levels of C mineralization (82 mg C kg-1) were found in Nahuelbuta soil. Enzyme activities showed different trends as pH changed. The Fenton reaction consumed more H2O2 between pH 3 and 4, but less between pH 4.5 and 2.5. The mechanisms that oxidized SOM are extremely sensitive to variations in soil pH and the stability of oxidant radical and non-radical compounds, according to our findings.
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Affiliation(s)
- Ignacio Jofré-Fernández
- Scientific and Technological Bioresource Nucleus (BIOREN), Universidad de La Frontera, Temuco, Chile
- Laboratory of Geomicrobiology, Department of Chemical Sciences and Natural Resources, Universidad de La Frontera, Temuco, Chile
- Network for Extreme Environmental Research (NEXER), Universidad de La Frontera, Temuco, Chile
| | - Francisco Matus-Baeza
- Laboratory of Conservation and Dynamics of Volcanic Soils, Department of Chemical Sciences and Natural Resources, Universidad de La Frontera, Temuco, Chile
- Network for Extreme Environmental Research (NEXER), Universidad de La Frontera, Temuco, Chile
| | - Carolina Merino-Guzmán
- Laboratory of Geomicrobiology, Department of Chemical Sciences and Natural Resources, Universidad de La Frontera, Temuco, Chile
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Markowska-Szczupak A, Paszkiewicz O, Yoshiiri K, Wang K, Kowalska E. Can photocatalysis help in the fight against COVID-19 pandemic? CURRENT OPINION IN GREEN AND SUSTAINABLE CHEMISTRY 2023; 40:100769. [PMID: 36846296 PMCID: PMC9942773 DOI: 10.1016/j.cogsc.2023.100769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 01/21/2023] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
Mould fungi are serious threats to humans and animals (allergen) and might be the main cause of COVID-19-associated pulmonary aspergillosis. The common methods of disinfection are not highly effective against fungi due to the high resistance of fungal spores. Recently, photocatalysis has attracted significant attention towards antimicrobial action. Outstanding properties of titania photocatalysts have already been used in many areas, e.g., for building materials, air conditioner filters, and air purifiers. Here, the efficiency of photocatalytic methods to remove fungi and bacteria (risk factors for Severe Acute Respiratory Syndrome Coronavirus 2 co-infection) is presented. Based on the relevant literature and own experience, there is no doubt that photocatalysis might help in the fight against microorganisms, and thus prevent the severity of COVID-19 pandemic.
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Affiliation(s)
- Agata Markowska-Szczupak
- Department of Chemical and Process Engineering, West Pomeranian University of Technology in Szczecin, Piastow 42, 71-065 Szczecin, Poland
| | - Oliwia Paszkiewicz
- Department of Chemical and Process Engineering, West Pomeranian University of Technology in Szczecin, Piastow 42, 71-065 Szczecin, Poland
| | - Kenta Yoshiiri
- Institute for Catalysis (ICAT), Hokkaido University, N21, W10, 001-0021 Sapporo, Japan
- Graduate School of Environmental Science, Hokkaido University, N10, W5, 060-0810 Sapporo, Japan
| | - Kunlei Wang
- Institute for Catalysis (ICAT), Hokkaido University, N21, W10, 001-0021 Sapporo, Japan
| | - Ewa Kowalska
- Institute for Catalysis (ICAT), Hokkaido University, N21, W10, 001-0021 Sapporo, Japan
- Graduate School of Environmental Science, Hokkaido University, N10, W5, 060-0810 Sapporo, Japan
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
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Lu X, Zhao Y, Li F, Liu P. Active polysaccharides from Lentinula edodes and Pleurotus ostreatus by addition of corn straw and xylosma sawdust through solid-state fermentation. Int J Biol Macromol 2023; 228:647-658. [PMID: 36584775 DOI: 10.1016/j.ijbiomac.2022.12.264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/07/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
In this study, Lentinula edodes and Pleurotus ostreatus were selected as representatives to explore the effects of corn straw and xylosma sawdust on the production and activity of polysaccharides by edible fungi during solid-state fermentation. The results clearly indicated that the addition of lignocellulose could promote the polysaccharide content compared to the control group. Meanwhile, the hydroxyl radical scavenging activity of polysaccharides reached the maximum when the glucose concentration was 1.5 %, and among them, the xylosma sawdust groups for two fungi (L. edodes-32.37 %, P. ostreatus-25.86 %) both performed better than corn straw groups (L. edodes-24.96 %, P. ostreatus-20.80 %). In addition, structural characterization and degradation mode analysis were carried out. The results showed that the structure of the xylosma had a stronger destruction than corn straw. The activities of lignocellulolytic enzymes such as carboxymethyl cellulase, filter paper enzyme, β-glucosidase and xylanase increased rapidly in the early stage of fermentation, which could degrade the cellulose and hemicellulose as raw materials for the synthesis of active polysaccharides.
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Affiliation(s)
- Xiaohong Lu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yuanyuan Zhao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Fei Li
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Ping Liu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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7
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A Laccase Gene Reporting System That Enables Genetic Manipulations in a Brown Rot Wood Decomposer Fungus Gloeophyllum trabeum. Microbiol Spectr 2023; 11:e0424622. [PMID: 36651769 PMCID: PMC9927100 DOI: 10.1128/spectrum.04246-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Brown rot fungi are primary decomposers of wood and litter in northern forests. Relative to other microbes, these fungi have evolved distinct mechanisms that rapidly depolymerize and metabolize cellulose and hemicellulose without digesting the more recalcitrant lignin. Its efficient degradative system has therefore attracted considerable attention for the development of sustainable biomass conversion technologies. However, there has been a significant lack of genetic tools in brown rot species by which to manipulate genes for both mechanistic studies and engineering applications. To advance brown rot genetic studies, we provided a gene-reporting system that can facilitate genetic manipulations in a model fungus Gloeophyllum trabeum. We first optimized a transformation procedure in G. trabeum, and then transformed the fungus into a constitutive laccase producer with a well-studied white rot laccases gene (from Trametes versicolor). With this, we built a gene reporting system based on laccase gene's expression and its rapid assay using an 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) indicator dye. The laccase reporter system was validated robust enough to allow us to test the effects of donor DNA's formats, protoplast viability, and gene regulatory elements on transformation efficiencies. Going forward, we anticipate the toolset provided in this work would expedite phenotyping studies and genetic engineering of brown rot species. IMPORTANCE One of the most ubiquitous types of decomposers in nature, brown rot fungi, has lacked robust genetic tools by which to manipulate genes and understand its biology. Brown rot fungi are primary decomposers in northern forests helping recycle the encased carbons in trees back to ecosystem. Relative to other microbes, these fungi employ distinctive mechanisms to disrupt and consume the lignified polysaccharides in wood. Its decay mechanism allows fast, selective carbohydrate catabolization, but without digesting lignin-a barren component that produces least energy trade back for fungal metabolisms. Thus, its efficient degradative system provides a great platform for developing sustainable biotechnologies for biomass conversions. However, progress has been hampered by the lack genetic tools facilitating mechanistic studies and engineering applications. Here, the laccase reporter system provides a genetic toolset for genetic manipulations in brown rot species, which we expect would advance relevant genetic studies for discovering and harnessing the unique fungal degradative mechanisms.
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Chen S, Davaritouchaee M. Nature-inspired pretreatment of lignocellulose - Perspective and development. BIORESOURCE TECHNOLOGY 2023; 369:128456. [PMID: 36503090 DOI: 10.1016/j.biortech.2022.128456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
As sustainability gains increasing importance in addition to cost-effectiveness as a criterion for evaluating engineering systems and practices, biological processes for lignocellulose pretreatment have attracted growing attention. Biological systems such as white and brown rot fungi and wood-consuming insects offer fascinating examples of processes and systems built by nature to effectively deconstruct plant cell walls under environmentally benign and energy-conservative environments. Research in the last decade has resulted in new knowledge that advanced the understanding of these systems, provided additional insights into these systems' functional mechanisms, and demonstrated various applications of these processes. The new knowledge and insights enable the adoption of a nature-inspired strategy aiming at developing technologies that are informed by the biological systems but superior to them by overcoming the inherent weakness of the natural systems. This review discusses the nature-inspired perspective and summarizes related advancements, including the evolution from biological systems to nature-inspired processes, the features of biological pretreatment mechanisms, the development of nature-inspired pretreatment processes, and future perspective. This work aims to highlight a different strategy in the research and development of novel lignocellulose pretreatment processes and offer some food for thought.
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Affiliation(s)
- Shulin Chen
- Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA.
| | - Maryam Davaritouchaee
- Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA
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Davaritouchaee M, Mosleh I, Dadmohammadi Y, Abbaspourrad A. One-Step Oxidation of Orange Peel Waste to Carbon Feedstock for Bacterial Production of Polyhydroxybutyrate. Polymers (Basel) 2023; 15:polym15030697. [PMID: 36771998 PMCID: PMC9920450 DOI: 10.3390/polym15030697] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/25/2023] [Accepted: 01/28/2023] [Indexed: 01/31/2023] Open
Abstract
Orange peels are an abundant food waste stream that can be converted into useful products, such as polyhydroxyalkanoates (PHAs). Limonene, however, is a key barrier to building a successful biopolymer synthesis from orange peels as it inhibits microbial growth. We designed a one-pot oxidation system that releases the sugars from orange peels while eliminating limonene through superoxide (O2• -) generated from potassium superoxide (KO2). The optimum conditions were found to be treatment with 0.05 M KO2 for 1 h, where 55% of the sugars present in orange peels were released and recovered. The orange peel sugars were then used, directly, as a carbon source for polyhydroxybutyrate (PHB) production by engineered Escherichia coli. Cell growth was improved in the presence of the orange peel liquor with 3 w/v% exhibiting 90-100% cell viability. The bacterial production of PHB using orange peel liquor led to 1.7-3.0 g/L cell dry weight and 136-393 mg (8-13 w/w%) ultra-high molecular weight PHB content (Mw of ~1900 kDa) during a 24 to 96 h fermentation period. The comprehensive thermal characterization of the isolated PHBs revealed polymeric properties similar to PHBs resulting from pure glucose or fructose. Our one-pot oxidation process for liberating sugars and eliminating inhibitory compounds is an efficient and easy method to release sugars from orange peels and eliminate limonene, or residual limonene post limonene extraction, and shows great promise for extracting sugars from other complex biomass materials.
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Sun R, Cao Z, Wen X, Ma L, Zhou Y, Li J, Fu M, Zhu P, Li K, Li Q. Quinone redox cycling drives lignocellulose depolymerization and degradation in composting environments based on metagenomics analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 856:159009. [PMID: 36162579 DOI: 10.1016/j.scitotenv.2022.159009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
In this study, the effect of Fe3+ on the quinone redox cycling driving lignocellulosic degradation in composting systems was investigated. The results showed that the degradation rates of cellulose, hemicellulose, and lignin were higher in the experimental group (CT) with Fe2(SO4)3 addition than in the blank group (CK) (CT, 52.55 %, 45.14 %, 56.98 %; CK, 49.63 %, 37.34 %, 52.3 %). Changes in the abundance of key enzymes for quinone reduction (AA3_1, AA3_2, AA6) and the structural succession of microbial communities were analyzed by metagenomic analysis. Among them, Fe2(SO4)3 had the most significant effect on AA3_2, with an approximately 8-fold increase in abundance compared to the beginning of composting. The dominant phylum in the composting process was Actinobacteria. In conclusion, the addition of Fe2(SO4)3 contributed to the quinone redox cycling and effectively improved the degradation rate of lignocellulose in composting.
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Affiliation(s)
- Ru Sun
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Ziyi Cao
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Xiaoli Wen
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Liangcai Ma
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Yucheng Zhou
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Jixuan Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Mengxin Fu
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Pengfei Zhu
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Kecheng Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
| | - Qunliang Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China.
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Li K, Wang Y, Li X, Huang Y, Niu Q, Meng Q, Yang H, Li Q. In-situ generation of H 2O 2 by zero valent iron to control depolymerization of lignocellulose in composting niche. CHEMOSPHERE 2022; 302:134908. [PMID: 35551932 DOI: 10.1016/j.chemosphere.2022.134908] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 04/23/2022] [Accepted: 05/07/2022] [Indexed: 06/15/2023]
Abstract
Lignocellulosic degradation is a bottleneck of bioconversion during the composting process. In-situ generation of H2O2 in the composting system was an ideal method for efficiently promoting lignocellulase degradation, and zero valent iron (ZVI) was concerned because it can generate H2O2 by reducing dissolved oxygen. This study focused on the effects of ZVI treatment on lignocellulose degradation, microbial communities, and carbohydrate-active enzymes (CAZymes) genes during composting. Its results indicated that ZVI increased H2O2 content during composting, accompanied by the formation of •OH. The degradation rates of lignin, cellulose and hemicellulose in ZVI group (20.77%, 30.35% and 44.7%) were significantly higher than in CK group (17.01%, 26.12% and 38.5%). Metagenomic analysis showed that ZVI induced microbial growth that favored lignocellulose degradation, which increased the abundance of Actinobacteria and Firmicutes but reduced Proteobacteria. At the genus level, the abundance of Thermomonospora, Streptomyces, and Bacillus significantly increased. In addition, glycoside hydrolases and auxiliary activities were important CAZymes families of lignocellulose degradation, and their abundance was higher in the ZVI group. Redundancy analysis showed that the increased H2O2 and •OH content was a critical factor in improving lignocellulose degradation. Overall, H2O2 as a co-substrate enhanced the enzymatic efficiency, •OH unspecifically attacked lignocellulose, and the increase in functional microbial abundance was the main reason for promoting lignocellulose degradation in composting.
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Affiliation(s)
- Kecheng Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Yiwu Wang
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Xiaolan Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Yite Huang
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Qiuqi Niu
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Qingran Meng
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Hongxiang Yang
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Qunliang Li
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China.
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12
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Meyer UN, Tischer A, Freitag M, Klaus VH, Kleinebecker T, Oelmann Y, Kandeler E, Hölzel N, Hamer U. Enzyme kinetics inform about mechanistic changes in tea litter decomposition across gradients in land-use intensity in Central German grasslands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 836:155748. [PMID: 35526633 DOI: 10.1016/j.scitotenv.2022.155748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 06/14/2023]
Abstract
Grassland ecosystems provide important ecosystem services such as nutrient cycling and primary production that are affected by land-use intensity. To assess the effects of land-use intensity, operational and sensitive ecological indicators that integrate effects of grassland management on ecosystem processes such as organic matter turnover are needed. Here, we investigated the suitability of measuring the mass loss of standardized tea litter together with extracellular enzyme kinetics as a proxy of litter decomposition in the topsoil of grasslands along a well-defined land-use intensity gradient (fertilization, mowing, grazing) in Central Germany. Tea bags containing either green tea (high-quality litter) or rooibos tea (low-quality litter) were buried in 5 cm soil depth. Litter mass loss was measured after three (early-stage decomposition) and 12 months (mid-stage decomposition). Based on the fluorescence measurement of the reaction product 4-methylumbelliferone, Michaelis-Menten enzyme kinetics (Vmax: potential maximum rate of activity; Km: substrate affinity) of five hydrolases involved in the carbon (C)-, nitrogen (N)- and phosphorus (P)-cycle (β-glucosidase (BG), cellobiohydrolase (CBH), cellotriohydrolase (CTH), 1,4-β-N-acetylglucosaminidase (NAG), and phosphatase (PH)) were determined in tea litter bags and in the surrounding soil. The land-use intensity index (LUI), summarizing fertilization, mowing, grazing, and in particular the frequency of mowing were identified as important drivers of early-stage tea litter decomposition. Mid-stage decomposition was influenced by grazing intensity. The higher the potential activity of all measured C-, N- and P-targeting enzymes, the higher was the decomposition of both tea litters in the early-phase. During mid-stage decomposition, individual enzyme parameters (Vmax of CTH and PH, Km of CBH) became more important. The tea bag method proved to be a suitable indicator which allows an easy and cost-effective assessment of land-use intensity effects on decay processes in manged grasslands. In combination with enzyme kinetics it is an appealing approach to identify mechanisms driving litter break down.
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Affiliation(s)
- Ulf-Niklas Meyer
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Alexander Tischer
- Department of Soil Science, Friedrich-Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Martin Freitag
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Valentin H Klaus
- Insitute of Agricultural Sciences, Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 2, 8092 Zürich, Switzerland
| | - Till Kleinebecker
- Institute for Landscape Ecology and Resource Management, Giessen University, Heinrich-Buff-Ring 26-32, 35392 Gießen, Germany
| | - Yvonne Oelmann
- Geoecology, Department of Geosciences, University of Tübingen, Rümelinstr. 19-23, 72070 Tübingen, Germany
| | - Ellen Kandeler
- Institute of Soil Science and Land Evaluation, Department of Soil Biology, University of Hohenheim, Emil Wolff Str. 27, 70599 Stuttgart, Germany
| | - Norbert Hölzel
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany
| | - Ute Hamer
- Institute of Landscape Ecology, University of Münster, Heisenbergstraße 2, 48149 Münster, Germany.
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13
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Stenholm Å, Hedeland M, Pettersson CE. Neomycin removal using the white rot fungus Trametes versicolor. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2022; 57:436-447. [PMID: 35583106 DOI: 10.1080/10934529.2022.2072644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
The presence of antibiotic resistance genes in wastewater treatment plants (WWTPs), and in river and lake recipients show the need to develop new antibiotic removal strategies. The aminoglycoside antibiotic class is of special concern since the chemical structure of these compounds limits the choices of removal technologies. The experimental design included fungal mediated in vivo and in vitro experiments. The experiments were performed in Erlenmeyer flasks under non-sterile conditions. In the study, the role of the laccase redox mediator 4-hydroxy benzoic acid (HBA) in the removal of neomycin was investigated. The specific objective of the study was to conclude whether it is possible to use the white rot fungus (WRF) Trametes versicolor to biodegrade neomycin. It was shown that it is feasible to remove 34% neomycin in vitro (excluding living fungal cells) by laccase-HBA mediated extracellular biodegradation. In the in vivo experiments, polyurethane foam (PUF) was used as supporting material to immobilize fungal mycelia on. The presence of living fungal cells facilitated a removal of approximately 80% neomycin in the absence of HBA. Using liquid chromatography-high resolution-mass spectrometry, it was possible to tentatively identify oxidation products of neomycin hydrolysates. The results in this study open up the possibility to implement a pretreatment plant (PTP) aimed for neomycin removal.
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Affiliation(s)
- Åke Stenholm
- Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry, Uppsala University, Uppsala, Sweden
- Cytiva AB, Uppsala, Sweden
| | - Mikael Hedeland
- Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry, Uppsala University, Uppsala, Sweden
| | - Curt E Pettersson
- Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry, Uppsala University, Uppsala, Sweden
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14
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Capturing an Early Gene Induction Event during Wood Decay by the Brown Rot Fungus Rhodonia placenta. Appl Environ Microbiol 2022; 88:e0018822. [PMID: 35348388 PMCID: PMC9040566 DOI: 10.1128/aem.00188-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brown rot fungi dominate wood decomposition in coniferous forests, and their carbohydrate-selective mechanisms are of commercial interest. Brown rot was recently described as a two-step, sequential mechanism orchestrated by fungi using differentially expressed genes (DEGs) and consisting of oxidation via reactive oxygen species (ROS) followed by enzymatic saccharification. There have been indications, however, that the initial oxidation step itself might require induction. To capture this early gene regulation event, here, we integrated fine-scale cryosectioning with whole-transcriptome sequencing to dissect gene expression at the single-hyphal-cell scale (tens of micrometers). This improved the spatial resolution 50-fold, relative to previous work, and we were able to capture the activity of the first 100 μm of hyphal front growth by Rhodonia placenta in aspen wood. This early decay period was dominated by delayed gene expression patterns as the fungus ramped up its mechanism. These delayed DEGs included many genes implicated in ROS pathways (lignocellulose oxidation [LOX]) that were previously and incorrectly assumed to be constitutively expressed. These delayed DEGs, which include those with and without predicted functions, also create a focused subset of target genes for functional genomics. However, this delayed pattern was not universal, with a few genes being upregulated immediately at the hyphal front. Most notably, this included a gene commonly implicated in hydroquinone and iron redox cycling: benzoquinone reductase. IMPORTANCE Earth's aboveground terrestrial biomass is primarily wood, and fungi dominate wood decomposition. Here, we studied these fungal pathways in a common "brown rot"-type fungus, Rhodonia placenta, that selectively extracts sugars from carbohydrates embedded within wood lignin. Using a space-for-time design to map fungal gene expression at the extreme hyphal front in wood, we made two discoveries. First, we found that many genes long assumed to be "on" (constitutively expressed) from the very beginning of decay were instead "off" before being upregulated, when mapped (via transcriptome sequencing [RNA-seq]) at a high resolution. Second, we found that the gene encoding benzoquinone reductase was "on" in incipient decay and quickly downregulated, implying a key role in "kick-starting" brown rot.
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15
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Fenton-Mediated Chlorophenol Degradation by Iron-Reducing Compounds Isolated from Endophytic Fungi in Atacama Puna Plateau Lecanicillium ATA01. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8040147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Low-molecular-mass iron-reducing compounds (IRCs) were produced by entomopathogenic endophytic fungi Lecanicillium sp. ATA01 in liquid cultures. The extracellular hydrophilic extract contained three IRCs formed by peptides, iron and phenolate structures with molecular masses of 1207, 567 and 550 Da. These compounds were able to chelate and mediate the reduction of Fe+3 to Fe+2 and oxidized recalcitrant lignin-model substrates such as veratryl alcohol (VA), 2,6-dimethoxyphenol (DMP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) with or without hydrogen peroxide. Besides, IRCs can promote the degradation of chlorophenols. The maximal degradation of p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol was conducted at optimal degradation conditions for IRCs (pH 3.5, iron 100 mM, and H2O2 10 mM). Furthermore, Fenton-like reactions using the synthetic iron chelates DTPA and EDTA and free Fe+2 and Fe+3 were also carried out in order to compare with the reaction mediated by IRCs. The ferric IRCs displayed the ability to enhance the hydroxylation of chlorophenols as a part of a degradation mechanism of the IRC-assisted Fenton reaction. The complexed iron was more efficient than free iron in the Fenton-like reaction, and between them, the fungal chelates were more efficient than the synthetic mill chelates.
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Mattila H, Österman-Udd J, Mali T, Lundell T. Basidiomycota Fungi and ROS: Genomic Perspective on Key Enzymes Involved in Generation and Mitigation of Reactive Oxygen Species. FRONTIERS IN FUNGAL BIOLOGY 2022; 3:837605. [PMID: 37746164 PMCID: PMC10512322 DOI: 10.3389/ffunb.2022.837605] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/21/2022] [Indexed: 09/26/2023]
Abstract
Our review includes a genomic survey of a multitude of reactive oxygen species (ROS) related intra- and extracellular enzymes and proteins among fungi of Basidiomycota, following their taxonomic classification within the systematic classes and orders, and focusing on different fungal lifestyles (saprobic, symbiotic, pathogenic). Intra- and extracellular ROS metabolism-involved enzymes (49 different protein families, summing 4170 protein models) were searched as protein encoding genes among 63 genomes selected according to current taxonomy. Extracellular and intracellular ROS metabolism and mechanisms in Basidiomycota are illustrated in detail. In brief, it may be concluded that differences between the set of extracellular enzymes activated by ROS, especially by H2O2, and involved in generation of H2O2, follow the differences in fungal lifestyles. The wood and plant biomass degrading white-rot fungi and the litter-decomposing species of Agaricomycetes contain the highest counts for genes encoding various extracellular peroxidases, mono- and peroxygenases, and oxidases. These findings further confirm the necessity of the multigene families of various extracellular oxidoreductases for efficient and complete degradation of wood lignocelluloses by fungi. High variations in the sizes of the extracellular ROS-involved gene families were found, however, among species with mycorrhizal symbiotic lifestyle. In addition, there are some differences among the sets of intracellular thiol-mediation involving proteins, and existence of enzyme mechanisms for quenching of intracellular H2O2 and ROS. In animal- and plant-pathogenic species, extracellular ROS enzymes are absent or rare. In these fungi, intracellular peroxidases are seemingly in minor role than in the independent saprobic, filamentous species of Basidiomycota. Noteworthy is that our genomic survey and review of the literature point to that there are differences both in generation of extracellular ROS as well as in mechanisms of response to oxidative stress and mitigation of ROS between fungi of Basidiomycota and Ascomycota.
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Affiliation(s)
| | | | | | - Taina Lundell
- Department of Microbiology, Faculty of Agriculture and Forestry, Viikki Campus, University of Helsinki, Helsinki, Finland
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17
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Zhang J, Meng Markillie L, Mitchell HD, Gaffrey MJ, Orr G, Schilling JS. Distinctive carbon repression effects in the carbohydrate-selective wood decay fungus Rhodonia placenta. Fungal Genet Biol 2022; 159:103673. [PMID: 35150839 DOI: 10.1016/j.fgb.2022.103673] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 01/29/2022] [Accepted: 02/06/2022] [Indexed: 11/19/2022]
Abstract
Brown rot fungi dominate the carbon degradation of northern terrestrial conifers. These fungi adapted unique genetic inventories to degrade lignocellulose and to rapidly release a large quantity of carbohydrates for fungal catabolism. We know that brown rot involves "two-step" gene regulation to delay most hydrolytic enzyme expression until after harsh oxidative pretreatments. This implies the crucial role of concise gene regulation to brown rot efficacy, but the underlying regulatory mechanisms remain uncharacterized. Here, using the combined transcriptomic and enzyme analyses we investigated the roles of carbon catabolites in controlling gene expression in model brown rot fungus Rhodonia placenta. We identified co-regulated gene regulons as shared transcriptional responses to no-carbon controls, glucose, cellobiose, or aspen wood (Populus sp.). We found that cellobiose, a common inducing catabolite for fungi, induced expression of main chain-cleaving cellulases in GH5 and GH12 families (cellobiose vs. no-carbon > 4-fold, Padj < 0.05), whereas complex aspen was a universal inducer for Carbohydrate Active Enzymes (CAZymes) expression. Importantly, we observed the attenuated glucose-mediated repression effects on cellulases expression, but not on hemicellulases and lignin oxidoreductases, suggesting fungi might have adapted diverged regulatory routes to boost cellulase production for the fast carbohydrate release. Using carbon regulons, we further predicted the cis- and trans-regulatory elements and assembled a network model of the distinctive regulatory machinery of brown rot. These results offer mechanistic insights into the energy efficiency traits of a common group of decomposer fungi with enormous influence on the carbon cycle.
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Affiliation(s)
- Jiwei Zhang
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, MN, United States.
| | - Lye Meng Markillie
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States
| | - Hugh D Mitchell
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States
| | - Matthew J Gaffrey
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States
| | - Galya Orr
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States
| | - Jonathan S Schilling
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN, United States.
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18
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Fungi Occurring in Norway Spruce Wood Decayed by Heterobasidion parviporum in Puszcza Borecka Stands (Northeastern Poland). FORESTS 2022. [DOI: 10.3390/f13020229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
In many spruce stands, trees are frequently attacked by the pathogen Heterobasidion parviporum, albeit without visible symptoms in the crown. In the present work, the results of the presence of stem rot, assessed by PICUS Sonic Tomography, and the fungal biota on trees and stumps in eight plots in the Puszcza Borecka Forest are described. The plots were located in stands on original forest soil (4) and on post-agricultural soil (4), where around a stump with H. parviporum symptoms (signs of internal rot and basidiocarps), 30 trees were selected and examined for internal rot. Wood samples were collected from two selected trees for fungal molecular analysis. A total of 79 fungal taxa were found, including 57 taxa in plots on post-agricultural soil and 45 on forest soil. There were 395 fungal records on stumps and 22 records on trees, therein, from the inner parts of felled trunks. Significant differences in the Chao-1 diversity index indicate that the origin of the soil—post-agricultural or forest soil—influenced the alpha diversity of the fungal communities in the forests studied. The values of the Shannon and Simpson indices show that the two communities were similar in terms of species numbers. The presence of basidiomata of H. parviporum and two species of Armillaria (mainly A. cepistipes) in samples on all plots is striking, although Armillaria spp. was detected more frequently. Most of the species identified were typical saprotrophs, although rare species were also found, such as Entoloma byssisedum, Onnia tomentosa, Physisporinus vitreus, Postia ptychogaster, and Ramaria apiculata. The presence of H. parviporum in the inner woody parts was confirmed by PCR analysis, and decay was detected even up to a stem height of 6 m. Armillaria was the dominant genus in the studied stands, and H. parviporum plays a significant and underestimated role in heartwood decay of old spruce trees in Puszcza Borecka Forest.
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19
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Xiong BJ, Dusny C, Wang L, Appel J, Lindstaedt K, Schlosser D, Harms H, Wick LY. Illuminate the hidden: in vivo mapping of microscale pH in the mycosphere using a novel whole-cell biosensor. ISME COMMUNICATIONS 2021; 1:75. [PMID: 36765263 PMCID: PMC9723660 DOI: 10.1038/s43705-021-00075-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 11/02/2021] [Accepted: 11/15/2021] [Indexed: 01/07/2023]
Abstract
The pH of an environment is both a driver and the result of diversity and functioning of microbial habitats such as the area affected by fungal hyphae (mycosphere). Here we used a novel pH-sensitive bioreporter, Synechocystis sp. PCC6803_peripHlu, and ratiometric fluorescence microscopy, to spatially and temporally resolve the mycosphere pH at the micrometre scale. Hyphae of the basidiomycete Coprionopsis cinerea were allowed to overgrow immobilised and homogeneously embedded pH bioreporters in an agarose microcosm. Signals of >700 individual cells in an area of 0.4 × 0.8 mm were observed over time and used to create highly resolved (3 × 3 µm) pH maps using geostatistical approaches. C. cinerea changed the pH of the agarose from 6.9 to ca. 5.0 after 48 h with hyphal tips modifying pH in their vicinity up to 1.8 mm. pH mapping revealed distinct microscale spatial variability and temporally stable gradients between pH 4.4 and 5.8 over distances of ≈20 µm. This is the first in vivo mapping of a mycosphere pH landscape at the microscale. It underpins the previously hypothesised establishment of pH gradients serving to create spatially distinct mycosphere reaction zones.
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Affiliation(s)
- Bi-Jing Xiong
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany
| | - Christian Dusny
- Department of Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany
| | - Lin Wang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Jens Appel
- Department of Biology, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 5, 24118, Kiel, Germany
| | - Kristin Lindstaedt
- Department of Solar Materials, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany
| | - Dietmar Schlosser
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany
| | - Hauke Harms
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany
| | - Lukas Y Wick
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraβe 15, 04318, Leipzig, Germany.
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Role of quinone reductases in extracellular redox cycling in lichenized ascomycetes. Fungal Biol 2021; 125:879-885. [PMID: 34649674 DOI: 10.1016/j.funbio.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/25/2021] [Accepted: 06/01/2021] [Indexed: 11/24/2022]
Abstract
Our previous work showed that many lichenized Ascomycetes can generate hydroxyl radicals using quinone-based extracellular redox cycling. During cycling, hydroquinones must be formed and subsequently regenerated from quinones using a quinone reductase (QR). However, we also showed that no simple correlation exists between QR activity and rates of hydroxyl radical formation. To further investigate the role of QR in hydroxyl radical formation, three model lichen species, Leptogium furfuraceum, Lasallia pustulata and Peltigera membranacea were selected for further investigation. All possessed QR activity and could metabolize quinones, and both Leptogium furfuraceum and Lasallia pustulata actively produced hydroxyl radicals. By contrast, P. membranacea produced almost no hydroxyl radicals, and although the lichen readily metabolized quinones, no hydroquinone production was detected. Peltigera had laccase (LAC) activity that was c. 50 times higher than in the other two species, suggesting that LAC rapidly oxidizes the hydroquinones, preventing radical formation deriving from auto-oxidation. It appears that in some lichens hydroxyl radical formation is blocked by the presence of high redox enzyme activity. QR from P. didactyla was studied further and found to display similar properties to the enzyme from free-living fungi, although it possessed an unusually high molecular mass (c. 62 kDa).
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21
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Stenholm Å, Backlund A, Holmström S, Backlund M, Hedeland M, Fransson P. Survival and growth of saprotrophic and mycorrhizal fungi in recalcitrant amine, amide and ammonium containing media. PLoS One 2021; 16:e0244910. [PMID: 34469447 PMCID: PMC8409640 DOI: 10.1371/journal.pone.0244910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/15/2021] [Indexed: 11/21/2022] Open
Abstract
The elimination of hazardous compounds in chemical wastes can be a complex and technically demanding task. In the search for environmental-friendly technologies, fungal mediated remediation and removal procedures are of concern. In this study, we investigated whether there are fungal species that can survive and grow on solely amine-containing compounds. One compound containing a primary amine group; 2-diethylaminoethanol, one compound with a primary amide group; 2,6-dichlorobenzamide (BAM), and a third compound containing a quaternary ammonium group; N3-trimethyl(2-oxiranyl)methanaminium chloride, were selected. The choice of these compounds was motivated by their excessive use in large scale manufacturing of protein separation media (2-diethylaminoethanol and the quaternary amine). 2,6-dichlorobenzamide, the degradation product of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), was chosen since it is an extremely recalcitrant compound. Utilising part of the large fungal diversity in Northern European forests, a screening study using 48 fungal isolates from 42 fungal species, including saprotrophic and mycorrhizal fungi, was performed to test for growth responses to the chosen compounds. The ericoid (ERM) mycorrhizal fungus Rhizoscyphus ericae showed the best overall growth on 2-diethylaminoethanol and BAM in the 1-20 g L-1 concentration range, with a 35-fold and 4.5-fold increase in biomass, respectively. For N3-trimethyl(2-oxiranyl)methanaminium chloride, the peak growth occurred at 1 g L-1. In a second experiment, including three of the most promising fungi (Laccaria laccata, Hygrophorus camarophyllus and Rhizoscyphus ericae) from the screening experiment, a simulated process water containing 1.9% (w/v) 2-diethylaminoethanol and 0.8% (w/v) N3-trimethyl(2-oxiranyl)methanaminium chloride was used. Laccaria laccata showed the best biomass increase (380%) relative to a control, while the accumulation for Rhizoscyphus ericae and Hygrophorus camarophyllus were 292% and 136% respectively, indicating that mycorrhizal fungi can use amine- and amide-containing substrates as nutrients. These results show the potential of certain fungal species to be used in alternative green wastewater treatment procedures.
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Affiliation(s)
- Åke Stenholm
- Cytiva, Uppsala, Sweden
- Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Anders Backlund
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - Maria Backlund
- SLU Artdatabanken, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Mikael Hedeland
- Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Petra Fransson
- Uppsala BioCenter, Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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22
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Abstract
Brown rot fungi release massive amounts of carbon from forest deadwood, particularly at high latitudes. These fungi degrade wood by generating small reactive oxygen species (ROS) to loosen lignocellulose, to then selectively remove carbohydrates. The ROS mechanism has long been considered the key adaptation defining brown rot wood decomposition, but recently, we found preliminary evidence that fungal glycoside hydrolases (GHs) implicated in early cell wall loosening might have been adapted to tolerate ROS stress and to synergize with ROS to loosen woody lignocellulose. In the current study, we found more specifically that side chain hemicellulases that help in the early deconstruction of the lignocellulosic complex are significantly more tolerant of ROS in the brown rot fungus Rhodonia placenta than in a white rot fungus (Trametes versicolor) and a soft rot fungus (Trichoderma reesei). Using proteomics to understand the extent of tolerance, we found that significant oxidation of secreted R. placenta proteins exposed to ROS was less than half of the oxidation observed for T. versicolor or T. reesei. The principal oxidative modifications observed in all cases were monooxidation and dioxidation/trioxidation (mainly in methionine and tryptophan residues), some of which were critical for enzyme activity. At the peptide level, we found that GHs in R. placenta were the least ROS affected among our tested fungi. These results confirm and describe underlying mechanisms of tolerance in early-secreted brown rot fungal hemicellulases. These enzymatic adaptations may have been as important as nonenzymatic ROS pathway adaptations in brown rot fungal evolution.
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Najibi Ilkhechi N, Mozammel M, Yari Khosroushahi A. Antifungal effects of ZnO, TiO 2 and ZnO-TiO 2 nanostructures on Aspergillus flavus. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 176:104869. [PMID: 34119214 DOI: 10.1016/j.pestbp.2021.104869] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Abstract
This study aimed to synthesis ZnO, TiO2, and ZnO-TiO2 (ratio weight of 1/1 for Zn/Ti) nanoparticles using zinc acetate and titanium isopropoxide through the sol-gel method. Physicochemical and morphological characterization and antifungal properties evaluation like minimum inhibition concentration (MIC) and minimum fungicide concentration (MFC) of nanopowders were investigated against A.flavus in vitro. All synthesized nanoparticles (50 μg/ml) showed fungal growth inhibition, while ZnO-TiO2 showed higher antifungal activity against A. flavus than pure TiO2 and ZnO. TiO2 and ZnO-TiO2 (300 μg/ml) inhibited 100% of spur production. Pure ZnO and TiO2 showed pyramidal and spherical shapes, respectively, whereas ZnO-TiO2 nanopowders illustrated both spherical and pyramidal shapes with grown particles on the surface. Based on our findings, a low concentration (150 μg/ml) of ZnO-TiO2 showed higher ROS production and oxidative stress induction, thus the fungicide effect as compared to alone TiO2 and ZnO. In conclusion, ZnO-TiO2 nanostructure can be utilized as a useful antifungal compound, but more studies need to be performed to understand the antifungal mechanism of the nanoparticles rather than ROS inducing apoptosis.
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Affiliation(s)
| | - Mahdi Mozammel
- Faculty of Material Engineering, Sahand University of Technology, Tabriz, Iran.
| | - Ahmad Yari Khosroushahi
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Medical Nanotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
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24
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Umezawa K, Itakura S. Influence of carbon source on wood decay-associated gene expression in sequential hyphal zones of the brown rot fungus Gloeophyllum trabeum. Biosci Biotechnol Biochem 2021; 85:1782-1788. [PMID: 33942872 DOI: 10.1093/bbb/zbab080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 04/27/2021] [Indexed: 11/12/2022]
Abstract
Brown rot fungi show a two-step wood degradation mechanism comprising oxidative radical-based and enzymatic saccharification systems. Recent studies have demonstrated that the brown rot fungus Rhodonia placenta expresses oxidoreductase genes ahead of glycoside hydrolase genes and spatially protects the saccharification enzymes from oxidative damage of the oxidoreductase reactions. This study aimed to assess the generality of the spatial gene regulation of these genes in other brown rot fungi and examine the effects of carbon source on the gene regulation. Gene expression analysis was performed on 14 oxidoreductase and glycoside hydrolase genes in the brown rot fungus Gloeophyllum trabeum, directionally grown on wood, sawdust-agar, and glucose-agar wafers. In G. trabeum, both oxidoreductase and glycoside hydrolase genes were expressed at higher levels in sections behind the wafers. The upregulation of glycoside hydrolase genes was significantly higher in woody substrates than in glucose, whereas the oxidoreductase gene expression was not affected by substrates.
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Affiliation(s)
- Kiwamu Umezawa
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Shuji Itakura
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, Nara, Japan
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25
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Li F, Zhao H, Shao R, Zhang X, Yu H. Enhanced Fenton Reaction for Xenobiotic Compounds and Lignin Degradation Fueled by Quinone Redox Cycling by Lytic Polysaccharide Monooxygenases. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:7104-7114. [PMID: 34130454 DOI: 10.1021/acs.jafc.1c01684] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Fenton reaction is considered to be of great significance in the initial attack of lignocellulose in wood-decaying fungi. Quinone redox cycling is the main way to induce the Fenton reaction in fungi. We show that lytic polysaccharide monooxygenases (LPMOs), through LPMO-catalyzed oxidation of hydroquinone, can efficiently cooperate with glucose dehydrogenase (GDH) to achieve quinone redox cycling. The LPMO/GDH system can enhance Fe3+-reducing activity, H2O2 production, and hydroxyl radical generation, resulting in a fueled Fenton reaction. The system-generated hydroxyl radicals exhibited a strong capacity to decolorize different synthetic dyes and degrade lignin. Our results reveal a potentially critical connection between LPMOs and the Fenton reaction, suggesting that LPMOs could be involved in xenobiotic compound and lignin degradation in fungi. This new role of LPMOs may be exploited for application in biorefineries.
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Affiliation(s)
- Fei Li
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Honglu Zhao
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ruijian Shao
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaoyu Zhang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hongbo Yu
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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26
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Neubauer D, Kolmakova O, Woodhouse J, Taube R, Mangelsdorf K, Gladyshev M, Premke K, Grossart HP. Zooplankton carcasses stimulate microbial turnover of allochthonous particulate organic matter. THE ISME JOURNAL 2021; 15:1735-1750. [PMID: 33462364 PMCID: PMC8163850 DOI: 10.1038/s41396-020-00883-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023]
Abstract
Carbon turnover in aquatic environments is dependent on biochemical properties of organic matter (OM) and its degradability by the surrounding microbial community. Non-additive interactive effects represent a mechanism where the degradation of biochemically persistent OM is stimulated by the provision of bioavailable OM to the degrading microbial community. Whilst this is well established in terrestrial systems, whether it occurs in aquatic ecosystems remains subject to debate. We hypothesised that OM from zooplankton carcasses can stimulate the degradation of biochemically persistent leaf material, and that this effect is influenced by the daphnia:leaf OM ratio and the complexity of the degrading microbial community. Fresh Daphnia magna carcasses and 13C-labelled maize leaves (Zea mays) were incubated at different ratios (1:1, 1:3 and 1:5) alongside either a complex microbial community (<50 µm) or solely bacteria (<0.8 µm). 13C stable-isotope measurements of CO2 analyses were combined with phospholipid fatty acids (PLFA) analysis and DNA sequencing to link metabolic activities, biomass and taxonomic composition of the microbial community. Our experiments indicated a significantly higher respiration of leaf-derived C when daphnia-derived OM was most abundant (i.e. daphnia:leaf OM ratio of 1:1). This process was stronger in a complex microbial community, including eukaryotic microorganisms, than a solely bacterial community. We concluded that non-additive interactive effects were a function of increased C-N chemodiversity and microbial complexity, with the highest net respiration to be expected when chemodiversity is high and the degrading community complex. This study indicates that identifying the interactions and processes of OM degradation is one important key for a deeper understanding of aquatic and thus global carbon cycle.
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Affiliation(s)
- Darshan Neubauer
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, 16775, Stechlin, Germany.
- Institute of Biochemistry and Biology, Potsdam University, 14476, Potsdam, Germany.
| | - Olesya Kolmakova
- Institute of Biophysics SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Krasnoyarsk, Russia
- Siberian Federal University, Institute of Fundamental Biology and Biotechnology, Krasnoyarsk, Russia
| | - Jason Woodhouse
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, 16775, Stechlin, Germany
| | - Robert Taube
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, 16775, Stechlin, Germany
- Institute of Biochemistry and Biology, Potsdam University, 14476, Potsdam, Germany
| | - Kai Mangelsdorf
- GFZ German Research Centre -for Geosciences, Helmholtz Centre Potsdam, Section 3.2 Organic Geochemistry, 14473, Potsdam, Germany
| | - Michail Gladyshev
- Institute of Biophysics SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Krasnoyarsk, Russia
- Siberian Federal University, Institute of Fundamental Biology and Biotechnology, Krasnoyarsk, Russia
| | - Katrin Premke
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Chemical Analytics and Biogeochemistry, Müggelseedamm 310, 12587, Berlin, Germany
| | - Hans-Peter Grossart
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Department of Experimental Limnology, 16775, Stechlin, Germany.
- Institute of Biochemistry and Biology, Potsdam University, 14476, Potsdam, Germany.
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27
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Hervé V, Simon A, Randevoson F, Cailleau G, Rajoelison G, Razakamanarivo H, Bindschedler S, Verrecchia E, Junier P. Functional Diversity of the Litter-Associated Fungi from an Oxalate-Carbonate Pathway Ecosystem in Madagascar. Microorganisms 2021; 9:microorganisms9050985. [PMID: 34062900 PMCID: PMC8147286 DOI: 10.3390/microorganisms9050985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022] Open
Abstract
The oxalate-carbonate pathway (OCP) is a biogeochemical process linking oxalate oxidation and carbonate precipitation. Currently, this pathway is described as a tripartite association involving oxalogenic plants, oxalogenic fungi, and oxalotrophic bacteria. While the OCP has recently received increasing interest given its potential for capturing carbon in soils, there are still many unknowns, especially regarding the taxonomic and functional diversity of the fungi involved in this pathway. To fill this gap, we described an active OCP site in Madagascar, under the influence of the oxalogenic tree Tamarindus indica, and isolated, identified, and characterized 50 fungal strains from the leaf litter. The fungal diversity encompassed three phyla, namely Mucoromycota, Ascomycota, and Basidiomycota, and 23 genera. Using various media, we further investigated their functional potential. Most of the fungal strains produced siderophores and presented proteolytic activities. The majority were also able to decompose cellulose and xylan, but only a few were able to solubilize inorganic phosphate. Regarding oxalate metabolism, several strains were able to produce calcium oxalate crystals while others decomposed calcium oxalate. These results challenge the current view of the OCP by indicating that fungi are both oxalate producers and degraders. Moreover, they strengthen the importance of the role of fungi in C, N, Ca, and Fe cycles.
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Affiliation(s)
- Vincent Hervé
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; (A.S.); (G.C.); (S.B.); (P.J.)
- Laboratory of Biogeosciences, Institute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, Switzerland; (F.R.); (E.V.)
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Correspondence: ; Tel.: +49-6421178122
| | - Anaële Simon
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; (A.S.); (G.C.); (S.B.); (P.J.)
| | - Finaritra Randevoson
- Laboratory of Biogeosciences, Institute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, Switzerland; (F.R.); (E.V.)
| | - Guillaume Cailleau
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; (A.S.); (G.C.); (S.B.); (P.J.)
- Laboratory of Biogeosciences, Institute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, Switzerland; (F.R.); (E.V.)
| | - Gabrielle Rajoelison
- Ecole Supérieure des Sciences Agronomiques, Université d’Antananarivo, Antananarivo 101, Madagascar;
| | | | - Saskia Bindschedler
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; (A.S.); (G.C.); (S.B.); (P.J.)
| | - Eric Verrecchia
- Laboratory of Biogeosciences, Institute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, Switzerland; (F.R.); (E.V.)
| | - Pilar Junier
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland; (A.S.); (G.C.); (S.B.); (P.J.)
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28
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Venkatesagowda B, Dekker RFH. Microbial demethylation of lignin: Evidence of enzymes participating in the removal of methyl/methoxyl groups. Enzyme Microb Technol 2021; 147:109780. [PMID: 33992403 DOI: 10.1016/j.enzmictec.2021.109780] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 02/27/2021] [Accepted: 03/11/2021] [Indexed: 11/30/2022]
Abstract
Lignin is an abundant natural plant aromatic biopolymer containing various functional groups that can be exploited for activating lignin for potential commercial applications. Applications are hindered due to the presence of a high content of methyl/methoxyl groups that affects reactiveness. Various chemical and enzymatic approaches have been investigated to increase the functionality in transforming lignin. Among these is demethylation/demethoxylation, which increases the potential numbers of vicinal hydroxyl groups for applications as phenol-formaldehyde resins. Although the chemical route to lignin demethylation is well-studied, the biological route is still poorly explored. Bacteria and fungi have the ability to demethylate lignin and lignin-related compounds. Considering that appropriate microorganisms possess the biochemical machinery to demethylate lignin by cleaving O-methyl groups liberating methanol, and modify lignin by increasing the vicinal diol content that allows lignin to substitute for phenol in organic polymer syntheses. Certain bacteria through the actions of specific O-demethylases can modify various lignin-related compounds generating vicinal diols and liberating methanol or formaldehyde as end-products. The enzymes include: cytochrome P450-aryl-O-demethylase, monooxygenase, veratrate 3-O-demethylase, DDVA O-demethylase (LigX; lignin-related biphenyl 5,5'-dehydrodivanillate (DDVA)), vanillate O-demethylase, syringate O-demethylase, and tetrahydrofolate-dependent-O-demethylase. Although, the fungal counterparts have not been investigated in depth as in bacteria, O-demethylases, nevertheless, have been reported in demethylating various lignin substrates providing evidence of a fungal enzyme system. Few fungi appear to have the ability to secrete O-demethylases. The fungi can mediate lignin demethylation enzymatically (laccase, lignin peroxidase, manganese peroxidase, O-demethylase), or non-enzymatically in brown-rot fungi through the Fenton reaction. This review discusses details on the aspects of microbial (bacterial and fungal) demethylation of lignins and lignin-model compounds and provides evidence of enzymes identified as specific O-demethylases involved in demethylation.
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Affiliation(s)
- Balaji Venkatesagowda
- Biorefining Research Institute, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada.
| | - Robert F H Dekker
- Biorefining Research Institute, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada; Universidade Tecnológica Federal do Paraná, Programa de Pós-Graduação em Engenharia Ambiental, Câmpus Londrina, CEP: 86036-370, Londrina, PR, Brazil.
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29
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Balasubramaniam B, Prateek, Ranjan S, Saraf M, Kar P, Singh SP, Thakur VK, Singh A, Gupta RK. Antibacterial and Antiviral Functional Materials: Chemistry and Biological Activity toward Tackling COVID-19-like Pandemics. ACS Pharmacol Transl Sci 2021; 4:8-54. [PMID: 33615160 PMCID: PMC7784665 DOI: 10.1021/acsptsci.0c00174] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Indexed: 12/12/2022]
Abstract
The ongoing worldwide pandemic due to COVID-19 has created awareness toward ensuring best practices to avoid the spread of microorganisms. In this regard, the research on creating a surface which destroys or inhibits the adherence of microbial/viral entities has gained renewed interest. Although many research reports are available on the antibacterial materials or coatings, there is a relatively small amount of data available on the use of antiviral materials. However, with more research geared toward this area, new information is being added to the literature every day. The combination of antibacterial and antiviral chemical entities represents a potentially path-breaking intervention to mitigate the spread of disease-causing agents. In this review, we have surveyed antibacterial and antiviral materials of various classes such as small-molecule organics, synthetic and biodegradable polymers, silver, TiO2, and copper-derived chemicals. The surface protection mechanisms of the materials against the pathogen colonies are discussed in detail, which highlights the key differences that could determine the parameters that would govern the future development of advanced antibacterial and antiviral materials and surfaces.
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Affiliation(s)
| | - Prateek
- Department
of Chemical Engineering, Indian Institute
of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Sudhir Ranjan
- Department
of Chemical Engineering, Indian Institute
of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Mohit Saraf
- Department
of Chemical Engineering, Indian Institute
of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Prasenjit Kar
- Department
of Chemical Engineering, Indian Institute
of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Surya Pratap Singh
- Department
of Chemistry, Indian Institute of Technology
Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Vijay Kumar Thakur
- Biorefining
and Advanced Materials Research Center, Scotland’s Rural College (SRUC), Kings Buildings, West Mains Road, Edinburgh EH9 3JG, United Kingdom
| | - Anand Singh
- Department
of Chemistry, Indian Institute of Technology
Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Raju Kumar Gupta
- Department
of Chemical Engineering, Indian Institute
of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
- Center
for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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30
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Vos AM, Bleichrodt R, Herman KC, Ohm RA, Scholtmeijer K, Schmitt H, Lugones LG, Wösten HAB. Cycling in degradation of organic polymers and uptake of nutrients by a litter-degrading fungus. Environ Microbiol 2021; 23:224-238. [PMID: 33140552 PMCID: PMC7894533 DOI: 10.1111/1462-2920.15297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 11/30/2022]
Abstract
Wood and litter degrading fungi are the main decomposers of lignocellulose and thus play a key role in carbon cycling in nature. Here, we provide evidence for a novel lignocellulose degradation strategy employed by the litter degrading fungus Agaricus bisporus (known as the white button mushroom). Fusion of hyphae allows this fungus to synchronize the activity of its mycelium over large distances (50 cm). The synchronized activity has a 13-h interval that increases to 20 h before becoming irregular and it is associated with a 3.5-fold increase in respiration, while compost temperature increases up to 2°C. Transcriptomic analysis of this burst-like phenomenon supports a cyclic degradation of lignin, deconstruction of (hemi-) cellulose and microbial cell wall polymers, and uptake of degradation products during vegetative growth of A. bisporus. Cycling in expression of the ligninolytic system, of enzymes involved in saccharification, and of proteins involved in nutrient uptake is proposed to provide an efficient way for degradation of substrates such as litter.
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Affiliation(s)
- Aurin M. Vos
- Microbiology, Department of BiologyUtrecht UniversityUtrechtthe Netherlands
- Wageningen Plant ResearchWageningen URWageningenthe Netherlands
| | | | - Koen C. Herman
- Microbiology, Department of BiologyUtrecht UniversityUtrechtthe Netherlands
| | - Robin A. Ohm
- Microbiology, Department of BiologyUtrecht UniversityUtrechtthe Netherlands
| | - Karin Scholtmeijer
- Plant BreedingWageningen University and ResearchWageningenthe Netherlands
| | - Heike Schmitt
- Institute for Risk Assessment SciencesUtrecht UniversityUtrechtthe Netherlands
| | - Luis G. Lugones
- Microbiology, Department of BiologyUtrecht UniversityUtrechtthe Netherlands
| | - Han A. B. Wösten
- Microbiology, Department of BiologyUtrecht UniversityUtrechtthe Netherlands
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Transcriptome analysis of the brown rot fungus Gloeophyllum trabeum during lignocellulose degradation. PLoS One 2020; 15:e0243984. [PMID: 33315957 PMCID: PMC7735643 DOI: 10.1371/journal.pone.0243984] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/01/2020] [Indexed: 11/24/2022] Open
Abstract
Brown rot fungi have great potential in biorefinery wood conversion systems because they are the primary wood decomposers in coniferous forests and have an efficient lignocellulose degrading system. Their initial wood degradation mechanism is thought to consist of an oxidative radical-based system that acts sequentially with an enzymatic saccharification system, but the complete molecular mechanism of this system has not yet been elucidated. Some studies have shown that wood degradation mechanisms of brown rot fungi have diversity in their substrate selectivity. Gloeophyllum trabeum, one of the most studied brown rot species, has broad substrate selectivity and even can degrade some grasses. However, the basis for this broad substrate specificity is poorly understood. In this study, we performed RNA-seq analyses on G. trabeum grown on media containing glucose, cellulose, or Japanese cedar (Cryptomeria japonica) as the sole carbon source. Comparison to the gene expression on glucose, 1,129 genes were upregulated on cellulose and 1,516 genes were upregulated on cedar. Carbohydrate Active enZyme (CAZyme) genes upregulated on cellulose and cedar media by G. trabeum included glycoside hyrolase family 12 (GH12), GH131, carbohydrate esterase family 1 (CE1), auxiliary activities family 3 subfamily 1 (AA3_1), AA3_2, AA3_4 and AA9, which is a newly reported expression pattern for brown rot fungi. The upregulation of both terpene synthase and cytochrome P450 genes on cedar media suggests the potential importance of these gene products in the production of secondary metabolites associated with the chelator-mediated Fenton reaction. These results provide new insights into the inherent wood degradation mechanism of G. trabeum and the diversity of brown rot mechanisms.
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Croitoru C, Roata IC. Ionic Liquids as Antifungal Agents for Wood Preservation. Molecules 2020; 25:E4289. [PMID: 32962068 PMCID: PMC7570619 DOI: 10.3390/molecules25184289] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/19/2022] Open
Abstract
Ionic liquids represent a class of highly versatile organic compounds used extensively in the last decade for lignocellulose biomass fractionation and dissolution, as well as property modifiers for wood materials. This review is dedicated to the use of ionic liquids as antifungal agents for wood preservation. Wood preservation against fungal attack represents a relatively new domain of application for ionic liquids, emerging in the late 1990s. Comparing to other application domains of ionic liquids, this particular one has been relatively little researched. Ionic liquids may be promising as wood preservatives due to their ability to swell wood, which translates into better penetration ability and fixation into the bulk of the wood material than other conventional antifungal agents, avoiding leaching over time. The antifungal character of ionic liquids depends on the nature of their alkyl-substituted cation, on the size and position of their substituents, and of their anion. It pertains to a large variety of wood-colonizing fungi, both Basidiomycetes and Fungiimperfecti.
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Affiliation(s)
- Catalin Croitoru
- Materials Engineering and Welding Department, Transilvania University of Brasov, Eroilor 29 Blvd., 500039 Brasov, Romania
| | - Ionut Claudiu Roata
- Materials Engineering and Welding Department, Transilvania University of Brasov, Eroilor 29 Blvd., 500039 Brasov, Romania
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33
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Effect of nanobubble water on anaerobic methane production from lignin. RESEARCH ON CHEMICAL INTERMEDIATES 2020. [DOI: 10.1007/s11164-020-04250-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Hörandl E, Hadacek F. Oxygen, life forms, and the evolution of sexes in multicellular eukaryotes. Heredity (Edinb) 2020; 125:1-14. [PMID: 32415185 PMCID: PMC7413252 DOI: 10.1038/s41437-020-0317-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 04/26/2020] [Accepted: 04/26/2020] [Indexed: 12/27/2022] Open
Abstract
The evolutionary advantage of different sexual systems in multicellular eukaryotes is still not well understood, because the differentiation into male and female individuals halves offspring production compared with asexuality. Here we propose that various physiological adaptations to oxidative stress could have forged sessility versus motility, and consequently the evolution of sexual systems in multicellular animals, plants, and fungi. Photosynthesis causes substantial amounts of oxidative stress in photoautotrophic plants and, likewise, oxidative chemistry of polymer breakdown, cellulose and lignin, for saprotrophic fungi. In both cases, its extent precludes motility, an additional source of oxidative stress. Sessile life form and the lack of neuronal systems, however, limit options for mate recognition and adult sexual selection, resulting in inefficient mate-searching systems. Hence, sessility requires that all individuals can produce offspring, which is achieved by hermaphroditism in plants and/or by multiple mating types in fungi. In animals, motility requires neuronal systems, and muscle activity, both of which are highly sensitive to oxidative damage. As a consequence, motility has evolved in animals as heterotrophic organisms that (1) are not photosynthetically active, and (2) are not primary decomposers. Adaptations to motility provide prerequisites for an active mating behavior and efficient mate-searching systems. These benefits compensate for the "cost of males", and may explain the early evolution of sex chromosomes in metazoans. We conclude that different sexual systems evolved under the indirect physiological constraints of lifestyles.
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Affiliation(s)
- Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants, University of Goettingen, Göttingen, Germany.
| | - Franz Hadacek
- Department of Plant Biochemistry, University of Goettingen, Göttingen, Germany
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35
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Synergy effect of peroxidase enzymes and Fenton reactions greatly increase the anaerobic oxidation of soil organic matter. Sci Rep 2020; 10:11289. [PMID: 32647197 PMCID: PMC7347925 DOI: 10.1038/s41598-020-67953-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 06/15/2020] [Indexed: 11/22/2022] Open
Abstract
In temperate rainforest soils of southern Chile (38 °S), there are high rates of soil organic carbon (SOC) mineralization under oxygen (O2) limitation. We study the combined effects of Fenton reactions and the activity of two enzymes manganese peroxidase (MnP) and lignin peroxidase (LiP), which was hypothesised potentiate SOC mineralization under anoxic conditions leading to carbon dioxide (CO2) release. Both mechanisms produce free radicals when competing for SOC oxidation in the absence of microorganisms. We quantify the CO2 release by induced Fenton reactions in combination with MnP and LiP under aerobic and anaerobic conditions (20 °C, 36 h) in temperate rainforest soils. CO2 levels released by Fenton reactions and enzyme activity were eight times higher than those released by Fenton reaction and peroxidase enzymes in individual treatment. Approximately 31% of the CO2 released under aerobic soil incubation was found to be abiotic (sterilized), while 69% was biotic (non-sterilized soils), and respective values of 17% and 83% were recorded under anaerobic conditions. The relative fluorescence intensity clearly shows ·OH radicals production from Fenton reactions. In conclusion, levels of MnP and LiP coupled with Fenton reactions strongly increase SOC mineralization under long periods of O2 limitation in temperate rainforest soils.
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Stenholm Å, Hedeland M, Arvidsson T, Pettersson CE. Removal of nonylphenol polyethoxylates by adsorption on polyurethane foam and biodegradation using immobilized Trametes versicolor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 724:138159. [PMID: 32408441 DOI: 10.1016/j.scitotenv.2020.138159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 03/22/2020] [Accepted: 03/22/2020] [Indexed: 05/20/2023]
Abstract
Nonylphenol polyethoxylates (NPEOs) are banned in EU due to their endocrine disrupting properties. In a proof of concept study including continuous reactor lab-scale experiments, polyurethane foam (PUF)-immobilized Trametes versicolor was used to reduce the concentration levels of these compounds in an acidic nutrient solution over an 18-day period. Biodegradation and adsorption were identified as the major removal principles. A 90% removal was achieved by solely biodegradation in an experimental setup in which steady state conditions occurred, including NPEO-saturated glass and PUF surfaces. Biotransformation products containing mono- and di-ethoxylated nonylphenol, nonylphenol (NP1EO, NP2EO, NP) and nonylphenol polyethoxy carboxylates (NPECs) were tentatively identified. The maximum static NPEO adsorption capacity of PUF (determined with Erlenmeyer flask experiment) was calculated to 106 mg g-1, and the adsorption was described by the Langmuir isotherm equation. The corresponding maximum dynamic adsorption capacity (determined by continuous reactor experiment) was 100 mg g-1. These findings show that PUF is an excellent adsorbent to NPEOs. Therefore, PUF can either be used as a stand-alone adsorbent to NPEOs or as an immobilizing agent for Trametes versicolor through which a highly efficient biodegradation of these potentially harmful compounds can be achieved. The findings can be of importance in the search for alternative methods to remove NPEOs in process effluents.
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Affiliation(s)
- Åke Stenholm
- Analytical Pharmaceutical Chemistry, Uppsala University, BMC Box 574, SE-751 23 Uppsala, Sweden; GE Healthcare Bio-Sciences AB, Björkgatan 30, SE-751 84 Uppsala, Sweden.
| | - Mikael Hedeland
- Analytical Pharmaceutical Chemistry, Uppsala University, BMC Box 574, SE-751 23 Uppsala, Sweden
| | - Torbjörn Arvidsson
- Analytical Pharmaceutical Chemistry, Uppsala University, BMC Box 574, SE-751 23 Uppsala, Sweden; Medical Products Agency, Box 26, SE-751 03 Uppsala, Sweden
| | - Curt E Pettersson
- Analytical Pharmaceutical Chemistry, Uppsala University, BMC Box 574, SE-751 23 Uppsala, Sweden
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Hall SJ, Huang W, Timokhin VI, Hammel KE. Lignin lags, leads, or limits the decomposition of litter and soil organic carbon. Ecology 2020; 101:e03113. [PMID: 32506475 DOI: 10.1002/ecy.3113] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 05/11/2020] [Accepted: 05/22/2020] [Indexed: 11/07/2022]
Abstract
Lignin's role in litter and soil organic carbon (SOC) decomposition remains contentious. Lignin decomposition was traditionally thought to increase during midstage litter decomposition, when cellulose occlusion by lignin began to limit mass loss. Alternatively, lignin decomposition could be greatest in fresh litter as a consequence of co-metabolism, and lignin might decompose faster than bulk SOC. To test these competing hypotheses, we incubated 10 forest soils with C4 grass litter (amended with 13 C-labeled or unlabeled lignin) over 2 yr and measured soil respiration and its isotope composition. Early lignin decomposition was greatest in 5 of 10 soils, consistent with the co-metabolism hypothesis. However, lignin decomposition peaked 6-24 months later in the other five soils, consistent with the substrate-limitation hypothesis; these soils were highly acidic. Rates of lignin, litter, and SOC decomposition tended to converge over time. Cumulative lignin decomposition was never greater than SOC decomposition; lignin decomposition was significantly lower than SOC decomposition in six soils. Net nitrogen mineralization predicted lignin decomposition ratios relative to litter and SOC. Although the onset of lignin decomposition can indeed be rapid, lignin still presents a likely bottleneck in litter and SOC decomposition, meriting a reconsideration of lignin's role in modern decomposition paradigms.
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Affiliation(s)
- Steven J Hall
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50011, USA
| | - Wenjuan Huang
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50011, USA
| | - Vitaliy I Timokhin
- Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, 53706, USA
| | - Kenneth E Hammel
- U.S. Forest Products Laboratory, Madison, Wisconsin, 53726, USA.,Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, 53706, USA
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Iron-mediated organic matter decomposition in humid soils can counteract protection. Nat Commun 2020; 11:2255. [PMID: 32382079 PMCID: PMC7206102 DOI: 10.1038/s41467-020-16071-5] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 04/13/2020] [Indexed: 11/26/2022] Open
Abstract
Soil organic matter (SOM) is correlated with reactive iron (Fe) in humid soils, but Fe also promotes SOM decomposition when oxygen (O2) becomes limited. Here we quantify Fe-mediated OM protection vs. decomposition by adding 13C dissolved organic matter (DOM) and 57FeII to soil slurries incubated under static or fluctuating O2. We find Fe uniformly protects OM only under static oxic conditions, and only when Fe and DOM are added together: de novo reactive FeIII phases suppress DOM and SOM mineralization by 35 and 47%, respectively. Conversely, adding 57FeII alone increases SOM mineralization by 8% following oxidation to 57FeIII. Under O2 limitation, de novo reactive 57FeIII phases are preferentially reduced, increasing anaerobic mineralization of DOM and SOM by 74% and 32‒41%, respectively. Periodic O2 limitation is common in humid soils, so Fe does not intrinsically protect OM; rather reactive Fe phases require their own physiochemical protection to contribute to OM persistence. Reactive iron minerals protect vast amounts of terrestrial carbon from decomposition and release as CO2. Here the authors show that reactive iron alone does not provide sufficient protection except under strict oxic conditions—instead, iron itself promotes carbon decomposition.
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Hermosilla E, Schalchli H, Diez MC. Biodegradation inducers to enhance wheat straw pretreatment by Gloeophyllum trabeum to second-generation ethanol production. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:8467-8480. [PMID: 31902077 DOI: 10.1007/s11356-019-07460-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
The native state of lignocellulosic biomass is highly resistant to enzymatic hydrolysis and the fermentation process of biofuel production. Brown-rot fungi use an extracellular Fenton system to degrade lignocellulosic biomass in the initial stages of decay. In this work, the combined effects of Mn2+, Fe2+, and NO3- inducers were evaluated based on the activities of hydrolytic enzymes and Fe3+ reduction as well as the catechol-type compound production during wheat straw pretreatment by the brown-rot fungus Gloeophyllum trabeum. Weight loss and chemical changes were evaluated to establish the culture conditions for stimulating wheat straw degradation using a central composite design. The results showed that weight loss and the Fe3+-reducing activity were promoted at the highest concentrations of Fe2+. A positive effect on catechol compound production by the addition of Mn2+ and NO3- was observed. Cellulase activity was increased at the highest concentration of NO3-. The multiple optimizations of G. trabeum culture conditions in wheat straw resulted in 11.3% weight loss and 0.47 total crystallinity index at 0.24 M NO3-, 0.95 mM Fe2+, and 0.85 mM Mn2+ after 40 days. The wheat straw pretreatment by G. trabeum for 10 days increased glucose recovery. The results indicated that the wheat straw pretreatment using G. trabeum with biodegradation inducers could be a complementary step to physicochemical pretreatment of lignocellulosic biomass for production of second-generation ethanol.
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Affiliation(s)
- Edward Hermosilla
- Doctoral Program in Sciences of Natural Resources, Universidad de La Frontera, Temuco, Chile
- Biotechnological Research Center Applied to the Environment (CIBAMA-BIOREN), Universidad de La Frontera, Temuco, Chile
| | - Heidi Schalchli
- Biotechnological Research Center Applied to the Environment (CIBAMA-BIOREN), Universidad de La Frontera, Temuco, Chile
- Chemical Engineering Department, Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile
| | - María Cristina Diez
- Biotechnological Research Center Applied to the Environment (CIBAMA-BIOREN), Universidad de La Frontera, Temuco, Chile.
- Chemical Engineering Department, Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile.
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Liu J, Zhu Y, Wang C, Goodell B, Esker AR. Chelator-mediated biomimetic degradation of cellulose and chitin. Int J Biol Macromol 2020; 153:433-440. [PMID: 32109470 DOI: 10.1016/j.ijbiomac.2020.02.262] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/18/2020] [Accepted: 02/23/2020] [Indexed: 01/26/2023]
Abstract
Non-enzymatic degradation of wood via a chelator-mediated Fenton (CMF) system is the primary method for initial attack in brown rot fungal decomposition of wood, the most common type of fungal degradation of terrestrial carbon biomass on the planet. In this study, the degradation of thin films of cellulose and chitin by a CMF system was investigated and compared to enzymatic hydrolysis. The kinetics of the rapid cellulose and chitin deconstruction and the morphologies of the degraded cellulose and chitin surfaces were studied by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM), respectively. The QCM-D results quantitatively indicated that ~90 wt% of the regenerated cellulose or chitin was capable of being deconstructed by CMF action alone. While enzymatic degradation was consistent with stripping of layers from the surface of the cellulose or chitin films, the CMF process exhibited a pronounced two stage process with a rapid initial depolymerization throughout the films. The initial degradation rates for both model surfaces by the CMF system were faster than enzyme action. This research suggests that the CMF process should be applicable for the deconstruction of a wide variety of polysaccharides over Fenton chemistry alone.
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Affiliation(s)
- Jianzhao Liu
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, United States
| | - Yuan Zhu
- College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China
| | - Chao Wang
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, United States
| | - Barry Goodell
- Department of Microbiology, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Alan R Esker
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, United States.
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Abstract
Fungi dominate the turnover of wood, Earth’s largest pool of aboveground terrestrial carbon. Fungi first evolved this capacity by degrading lignin to access and hydrolyze embedded carbohydrates (white rot). Multiple lineages, however, adapted faster reactive oxygen species (ROS) pretreatments to loosen lignocellulose and selectively extract sugars (brown rot). This brown rot “shortcut” often coincided with losses (>60%) of conventional lignocellulolytic genes, implying that ROS adaptations supplanted conventional pathways. We used comparative transcriptomics to further pursue brown rot adaptations, which illuminated the clear temporal expression shift of ROS genes, as well as the shift toward synthesizing more GHs in brown rot relative to white rot. These imply that gene regulatory shifts, not simply ROS innovations, were key to brown rot fungal evolution. These results not only reveal an important biological shift among these unique fungi, but they may also illuminate a trait that restricts brown rot fungi to certain ecological niches. Fungi dominate the recycling of carbon sequestered in woody biomass. This process of organic turnover was first evolved among “white rot” fungi that degrade lignin to access carbohydrates and later evolved multiple times toward more efficient strategies to selectively target carbohydrates—“brown rot.” The brown rot adaption was often explained by mechanisms to deploy reactive oxygen species (ROS) to oxidatively attack wood structures. However, its genetic basis remains unclear, especially in the context of gene contractions of conventional carbohydrate-active enzymes (CAZYs) relative to white rot ancestors. Here, we hypothesized that these apparent gains in brown rot efficiency despite gene losses were due, in part, to upregulation of the retained genes. We applied comparative transcriptomics to multiple species of both rot types grown across a wood wafer to create a gradient of progressive decay and to enable tracking temporal gene expression. Dozens of “decay-stage-dependent” ortho-genes were isolated, narrowing a pool of candidate genes with time-dependent regulation unique to brown rot fungi. A broad comparison of the expression timing of CAZY families indicated a temporal regulatory shift of lignocellulose-oxidizing genes toward early stages in brown rot compared to white rot, enabling the segregation of oxidative treatment ahead of hydrolysis. These key brown rot ROS-generating genes with iron ion binding functions were isolated. Moreover, transcription energy was shifted to be invested on the retained GHs in brown rot fungi to strengthen carbohydrate conversion. Collectively, these results support the hypothesis that gene regulation shifts played a pivotal role in brown rot adaptation.
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Kremer JL, Melo GP, Marinello PC, Bordini HP, Rossaneis AC, Sábio LR, Cecchini R, Cecchini AL, Verri WA, Luiz RC. Citral prevents UVB-induced skin carcinogenesis in hairless mice. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2019; 198:111565. [DOI: 10.1016/j.jphotobiol.2019.111565] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/24/2019] [Accepted: 07/20/2019] [Indexed: 02/06/2023]
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Jambon I, Thijs S, Torres-Farradá G, Rineau F, Weyens N, Carleer R, Samyn P, Vangronsveld J. Fenton-Mediated Biodegradation of Chlorendic Acid - A Highly Chlorinated Organic Pollutant - By Fungi Isolated From a Polluted Site. Front Microbiol 2019; 10:1892. [PMID: 31474967 PMCID: PMC6702520 DOI: 10.3389/fmicb.2019.01892] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/31/2019] [Indexed: 11/13/2022] Open
Abstract
Chlorendic acid is a recalcitrant, highly chlorinated organic pollutant for which no microbial degrader has yet been identified. To address this knowledge gap, fungi were isolated from bulk soil, rhizosphere, and roots of the common bent (Agrostis capillaris) and the hybrid poplar [Populus deltoides × (Populus trichocarpa × P. deltoides) cv. Grimminge], both of which grow on a chlorendic acid polluted site in Belgium. Isolates were taxonomically identified and phenotypically screened for chlorendic acid degradation. Several fungal isolates could degrade chlorendic acid in liquid media up to 45%. The chlorendic acid degrading fungal isolates produced higher levels of hydroxyl radicals when exposed to the pollutant when compared to non-exposed controls, suggesting that the oxidative degradation of chlorendic acid occurs through production of Fenton-mediated hydroxyl radicals. In addition, the isolated Ascomycete Penicillium sp. 1D-2a degraded 58% of the original chlorendic acid concentration in the soil after 28 days. This study demonstrates that the presence of fungi in a chlorendic acid polluted soil can degrade this highly chlorinated organic pollutant. These results indicate that recalcitrant, seemingly non-biologically degradable organic pollutants, such as chlorendic acid, can be remediated by using bioremediation, which opens new perspectives for in situ bioremediation.
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Affiliation(s)
- Inge Jambon
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - Sofie Thijs
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - Giselle Torres-Farradá
- Department of Microbiology and Virology, Faculty of Biology, University of Havana, La Habana, Cuba
| | - François Rineau
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - Nele Weyens
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - Robert Carleer
- Institute for Materials Research, Hasselt University, Diepenbeek, Belgium
| | - Pieter Samyn
- Institute for Materials Research, Hasselt University, Diepenbeek, Belgium
| | - Jaco Vangronsveld
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
- Department of Plant Physiology, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Lublin, Poland
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Lee JG, Yoon HY, Cha JY, Kim WY, Kim PJ, Jeon JR. Artificial humification of lignin architecture: Top-down and bottom-up approaches. Biotechnol Adv 2019; 37:107416. [PMID: 31323257 DOI: 10.1016/j.biotechadv.2019.107416] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 05/10/2019] [Accepted: 07/14/2019] [Indexed: 11/16/2022]
Abstract
Humic substances readily identifiable in the environment are involved in several biotic and abiotic reactions affecting carbon turnover, soil fertility, plant nutrition and stimulation, xenobiotic transformation and microbial respiration. Inspired by natural roles of humic substances, several applications of these substances, including crop stimulants, redox mediators, anti-oxidants, human medicines, environmental remediation and fish feeding, have been developed. The annual market for humic substances has grown rapidly for these reasons and due to eco-conscious features, but there is a limited supply of natural coal-related resources such as lignite and leonardite from which humic substances are extracted in bulk. The structural similarity between humic substances and lignin suggests that lignocellulosic refinery resulting in lignin residues as a by-product could be a potential candidate for a bulk source of humic-like substances, but structural differences between the two polymeric materials indicate that additional transformation procedures allowing lignin architecture to fully mimic commercial humic substances are required. In this review, we introduce the emerging concept of artificial humification of lignin-related materials as a promising strategy for lignin valorization. First, the core structural features of humic substances and the relationship between these features and the physicochemical properties, natural functions and versatile applications of the substances are described. In particular, the mechanism by which humic substances stimulate the growth of plants and hence can improve crop productivity is highlighted. Second, top-down and bottom-up transformation pathways for scalable humification of small lignin-derived phenols, technical lignins and lignin-containing plant residues are described in detail. Finally, future directions are suggested for research and development of artificial lignin humification to achieve alternative ways of producing customized analogues of humic substances.
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Affiliation(s)
- Jeong Gu Lee
- Division of Applied Life Science (BK21Plus), Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Ho Young Yoon
- Department of Agricultural Chemistry and Food Science & Technology, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Joon-Yung Cha
- Division of Applied Life Science (BK21Plus), Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Woe-Yeon Kim
- Division of Applied Life Science (BK21Plus), Gyeongsang National University, Jinju 52828, Republic of Korea; Department of Agricultural Chemistry and Food Science & Technology, Gyeongsang National University, Jinju 52828, Republic of Korea; PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea; RILS, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Pil Joo Kim
- Division of Applied Life Science (BK21Plus), Gyeongsang National University, Jinju 52828, Republic of Korea; Department of Agricultural Chemistry and Food Science & Technology, Gyeongsang National University, Jinju 52828, Republic of Korea; IALS, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Jong-Rok Jeon
- Department of Agricultural Chemistry and Food Science & Technology, Gyeongsang National University, Jinju 52828, Republic of Korea; IALS, Gyeongsang National University, Jinju 52828, Republic of Korea.
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Huang W, Hammel KE, Hao J, Thompson A, Timokhin VI, Hall SJ. Enrichment of Lignin-Derived Carbon in Mineral-Associated Soil Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:7522-7531. [PMID: 31177774 DOI: 10.1021/acs.est.9b01834] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A modern paradigm of soil organic matter proposes that persistent carbon (C) derives primarily from microbial residues interacting with minerals, challenging older ideas that lignin moieties contribute to soil C because of inherent recalcitrance. We proposed that aspects of these old and new paradigms can be partially reconciled by considering interactions between lignin decomposition products and redox-sensitive iron (Fe) minerals. An Fe-rich tropical soil (with C4 litter and either 13C-labeled or unlabeled lignin) was pretreated with different durations of anaerobiosis (0-12 days) and incubated aerobically for 317 days. Only 5.7 ± 0.2% of lignin 13C was mineralized to CO2 versus 51.2 ± 0.4% of litter C. More added lignin-derived C (48.2 ± 0.9%) than bulk litter-derived C (30.6 ± 0.7%) was retained in mineral-associated organic matter (MAOM; density >1.8 g cm-3), and 12.2 ± 0.3% of lignin-derived C vs 6.4 ± 0.1% of litter C accrued in clay-sized (<2 μm) MAOM. Longer anaerobic pretreatments increased added lignin-derived C associated with Fe, according to extractions and nanoscale secondary ion mass spectrometry (NanoSIMS). Microbial residues are important, but lignin-derived C may also contribute disproportionately to MAOM relative to bulk litter-derived C, especially following redox-sensitive biogeochemical interactions.
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Affiliation(s)
- Wenjuan Huang
- Department of Ecology, Evolution, and Organismal Biology , Iowa State University , Ames , Iowa 50011 , United States
- Key laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden , Chinese Academy of Sciences , Guangzhou 510650 , China
| | - Kenneth E Hammel
- US Forest Products Laboratory , Madison , Wisconsin 53726 , United States
- Department of Bacteriology , University of Wisconsin , Madison , Wisconsin 53706 , United States
| | - Jialong Hao
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics , Chinese Academy of Sciences , Beijing 100029 , China
| | - Aaron Thompson
- Department of Crop and Soil Sciences , The University of Georgia , Athens , Georgia 30602 , United States
| | - Vitaliy I Timokhin
- University of Wisconsin , Wisconsin Energy Institute, DOE Great Lakes Bioenergy Research Center , Madison , Wisconsin 53706 , United States
| | - Steven J Hall
- Department of Ecology, Evolution, and Organismal Biology , Iowa State University , Ames , Iowa 50011 , United States
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Venkatesagowda B. Enzymatic demethylation of lignin for potential biobased polymer applications. FUNGAL BIOL REV 2019. [DOI: 10.1016/j.fbr.2019.06.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Simultaneous bioconversion of lignocellulosic residues and oxodegradable polyethylene by Pleurotus ostreatus for biochar production, enriched with phosphate solubilizing bacteria for agricultural use. PLoS One 2019; 14:e0217100. [PMID: 31095642 PMCID: PMC6521990 DOI: 10.1371/journal.pone.0217100] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/03/2019] [Indexed: 11/23/2022] Open
Abstract
A simultaneous treatment of lignocellulosic biomass (LCB) and low density oxodegradable polyethylene (LDPEoxo) was carried-out using Pleurotus ostreatus at microcosm scale to obtain biotransformed plastic and oxidized lignocellulosic biomass. This product was used as raw matter (RM) to produce biochar enriched with phosphate solubilizing bacteria (PSB). Biochar potential as biofertilizer was evaluated in Allium cepa culture at greenhouse scale. Experiments including lignocellulosic mix and LDPEoxo were performed for 75 days in microcosm. Biotransformation progress was performed by monitoring total organic carbon (TOC), CO2 production, laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) enzymatic activities. Physical LDPEoxo changes were assessed by atomic force microscopy (AFM), scanning electron microscopy (SEM) and static contact angle (SCA) and chemical changes by Fourier transform infrared spectroscopy (FTIR). Results revealed P. ostreatus was capable of LCB and LDPEoxo biotransformation, obtaining 41% total organic carbon (TOC) removal with CO2 production of 2,323 mg Kg-1 and enzyme activities of 169,438 UKg-1, 5,535 UKg-1 and 5,267 UKg-1 for LiP, MnP and Lac, respectively. Regarding LDPEoxo, SCA was decreased by 84%, with an increase in signals at 1,076 cm-1 and 3,271 cm-1, corresponding to C-O and CO-H bonds. A decrease in signals was observed related to material degradation at 2,928 cm-1, 2,848 cm-1, agreeing with CH2 asymmetrical and symmetrical stretching, respectively. PSB enriched biochar favored A. cepa plant growth during the five-week evaluation period. To the best of our knowledge, this is the first report of an in vitro circular production model, where P. ostreatus was employed at a microcosmos level to bioconvert LCB and LDPEoxo residues from the agroindustrial sector, followed by thermoconversion to produce an enriched biochar with PSB to be used as a biofertilizer to grow A. cepa at greenhouse scale.
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Castaño JD, Zhang J, Anderson CE, Schilling JS. Oxidative Damage Control during Decay of Wood by Brown Rot Fungus Using Oxygen Radicals. Appl Environ Microbiol 2018; 84:e01937-18. [PMID: 30194102 PMCID: PMC6210117 DOI: 10.1128/aem.01937-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/04/2018] [Indexed: 02/07/2023] Open
Abstract
Brown rot wood-degrading fungi deploy reactive oxygen species (ROS) to loosen plant cell walls and enable selective polysaccharide extraction. These ROS, including Fenton-generated hydroxyl radicals (HO˙), react with little specificity and risk damaging hyphae and secreted enzymes. Recently, it was shown that brown rot fungi reduce this risk, in part, by differentially expressing genes involved in HO˙ generation ahead of those coding carbohydrate-active enzymes (CAZYs). However, there are notable exceptions to this pattern, and we hypothesized that brown rot fungi would require additional extracellular mechanisms to limit ROS damage. To assess this, we grew Postia placenta directionally on wood wafers to spatially segregate early from later decay stages. Extracellular HO˙ production (avoidance) and quenching (suppression) capacities among the stages were analyzed, along with the ability of secreted CAZYs to maintain activity postoxidation (tolerance). First, we found that H2O2 and Fe2+ concentrations in the extracellular environment were conducive to HO˙ production in early (H2O2:Fe2+ ratio 2:1) but not later (ratio 1:131) stages of decay. Second, we found that ABTS radical cation quenching (antioxidant capacity) was higher in later decay stages, coincident with higher fungal phenolic concentrations. Third, by surveying enzyme activities before/after exposure to Fenton-generated HO˙, we found that CAZYs secreted early, amid HO˙, were more tolerant of oxidative stress than those expressed later and were more tolerant than homologs in the model CAZY producer Trichoderma reesei Collectively, this indicates that P. placenta uses avoidance, suppression, and tolerance mechanisms, extracellularly, to complement intracellular differential expression, enabling this brown rot fungus to use ROS to degrade wood.IMPORTANCE Wood is one of the largest pools of carbon on Earth, and its decomposition is dominated in most systems by fungi. Wood-degrading fungi specialize in extracting sugars bound within lignin, either by removing lignin first (white rot) or by using Fenton-generated reactive oxygen species (ROS) to "loosen" wood cell walls, enabling selective sugar extraction (brown rot). Although white rot lignin-degrading pathways are well characterized, there are many uncertainties in brown rot fungal mechanisms. Our study addressed a key uncertainty in how brown rot fungi deploy ROS without damaging themselves or the enzymes they secrete. In addition to revealing differentially expressed genes to promote ROS generation only in early decay, our study revealed three spatial control mechanisms to avoid/tolerate ROS: (i) constraining Fenton reactant concentrations (H2O2, Fe2+), (ii) quenching ROS via antioxidants, and (iii) secreting ROS-tolerant enzymes. These results not only offer insight into natural decomposition pathways but also generate targets for biotechnological development.
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Affiliation(s)
- Jesus D Castaño
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
| | - Jiwei Zhang
- Department of Plant & Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA
| | - Claire E Anderson
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
| | - Jonathan S Schilling
- Department of Plant & Microbial Biology, University of Minnesota, Saint Paul, Minnesota, USA
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Feng J, Xu X, Wu J, Zhang Q, Zhang D, Li Q, Long C, Chen Q, Chen J, Cheng X. Inhibited enzyme activities in soil macroaggregates contribute to enhanced soil carbon sequestration under afforestation in central China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:653-661. [PMID: 29870941 DOI: 10.1016/j.scitotenv.2018.05.332] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/21/2018] [Accepted: 05/26/2018] [Indexed: 06/08/2023]
Abstract
The fate of soil organic carbon (SOC) sequestered by afforestation is crucial for the mitigation of the anthropogenic climate change but remains largely unclear. This lack of knowledge is particularly true for SOC turnover driven by enzyme activity. Here we measured hydrolase (including β-glucosidase, α-glucosidase, cellobiohydrolase and xylanase) and oxidase (including polyphenol oxidase and peroxidase) activities in soil aggregates following 30-year afforestation in central China. We also analyzed the relationships of enzyme activities with SOC concentrations, soil C:nitrogen (N) ratios and δ13C values of soil organic pool (removing any carbonates by acid hydrolysis) and stable pool (NaOCl-resistant). Afforestation significantly enhanced soil β-glucosidase, α-glucosidase and xylanase activities in bulk soil, as well as SOC concentrations in bulk soil and all aggregate fractions compared to those in the open area and cropland. In particular, the woodland increased SOC concentration in >2000 μm macroaggregates by 4.2- and 3.2-fold, compared to the open area and cropland, respectively. Soil hydrolase activities were generally lower but SOC concentrations were higher in >2000 μm macroaggregates compared with those in other aggregate fractions following afforestation. Hydrolase activities were negatively correlated with SOC and C:N ratios in soil aggregate fractions following afforestation. Results of structural equation modeling indicated that the increasingly inhibited hydrolase activities with increasing soil aggregate size indirectly promoted SOC sequestration following afforestation. In addition, both hydrolase and oxidase were positively correlated with δ13C values in the stable pool of the afforested soils, confirming the essential role of enzymes for SOC turnover in soil aggregates following afforestation. Overall, our results highlight the importance of unevenly distributed enzyme activities among soil aggregates in regulating SOC sequestration following afforestation.
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Affiliation(s)
- Jiao Feng
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Xia Xu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Junjun Wu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Qian Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 10039, China
| | - Dandan Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 10039, China
| | - Qianxi Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Chunyan Long
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 10039, China
| | - Qiong Chen
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 10039, China
| | - Jingwen Chen
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 10039, China
| | - Xiaoli Cheng
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China.
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Ćilerdžić J, Galić M, Ivanović Ž, Brčeski I, Vukojević J, Stajić M. Stimulation of Wood Degradation by Daedaleopsis confragosa and D. tricolor. Appl Biochem Biotechnol 2018; 187:1371-1383. [PMID: 30229433 DOI: 10.1007/s12010-018-2884-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/09/2018] [Indexed: 11/25/2022]
Abstract
Biological pretreatment of the lignocellulosic residues, in which white-rot fungi have a crucial role, has many advantages compared to the chemical, physical, and physico-chemical methods of delignification and therefore attracts increasing scientific attention. Regarding the fact that properties and capacities of the ligninolytic enzymes of Daedaleopsis spp. are still unknown, the aim of this study was to research how nitrogen sources and inducers affect the potential of Daedaleopsis confragosa and Daedaleopsis tricolor to degrade cherry sawdust. NH4NO3, (NH4)2SO4, and peptone were tested as nitrogen sources, while veratryl alcohol, p-anisidine, vanillic acid, and phenylmethylsulfonyl fluoride were the studied inducers. As Mn-dependent peroxidase and laccase were the leader enzymes and cherry sawdust/peptone medium the best stimulator of their activities, the effect of inducers on delignification potential of these species was studied during fermentation of that substrate. Veratryl alcohol was the best stimulator of laccase and phenylmethylsulfonyl fluoride of Mn-dependent peroxidase activity (27,610.0 and 1338.4 U/L, respectively). These inducers also increased cherry sawdust delignification selectivity, particularly in D. tricolor in the presence of phenylmethylsulfonyl fluoride (lignin:hemicellulose:cellulose = 32.1%:0.9%:11.7%). Owing to the presented results, studied species could have an important role in the phase of lignocellulose pretreatment in various biotechnological processes.
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Affiliation(s)
- Jasmina Ćilerdžić
- Faculty of Biology, University of Belgrade, Takovska 43, Belgrade, 11000, Serbia.
| | - Milica Galić
- Faculty of Biology, University of Belgrade, Takovska 43, Belgrade, 11000, Serbia
| | - Žarko Ivanović
- Institute for Plant Protection and Environment, Teodora Drajzera 9, Belgrade, 11000, Serbia
| | - Ilija Brčeski
- Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, Belgrade, 11000, Serbia
| | - Jelena Vukojević
- Faculty of Biology, University of Belgrade, Takovska 43, Belgrade, 11000, Serbia
| | - Mirjana Stajić
- Faculty of Biology, University of Belgrade, Takovska 43, Belgrade, 11000, Serbia
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