Effect of culture conditions on the production of ligninolytic enzymes by white rot fungi Phanerochaete chrysosporium (ATCC 20696) and separation of its lignin peroxidase

Enzymatic diversity of filamentous fungi isolated from forest soil incremented by sugar cane solid waste

Fungi are natural degraders of organic matter which can produce enzymes for many industrial and biotechnological applications. In this context, crude enzymatic extracts of fungal isolates were evaluated regarding their hydrolytic and ligninolytic abilities. The fungal strains were isolated from soil samples from Atlantic Rain Forest Park incremented with sugar cane biomass (filter cake), which allowed the selection of efficient lignocellulolytic enzymes. A total of 190 fungi were isolated and evaluated by endocellulase screenings. Thirteen fungi were selected about their hydrolytic and ligninolytic abilities. Among them, three isolates showed xylanolytic activity. Eleven of the isolates were selected by their cellulolytic abilities. Proteolytic enzymes were also detected for three fungi, allowing the classification as metalloprotease and serine protease. The isolates SPZPF3_47 (Mucor sp.), SPZPF1_129 (Byssochlamys nivea) and SPZPF1_141 (Paecilomyces saturatus) were selected for further investigation on their lignin peroxidase abilities. K_M, V_max and k_cat apparent for lignin peroxidases were also determined. The strain of Mucor sp. (SPZPF3_47) was highlighted since this fungal genus was not well described about its isolation in the adopted conditions in our study, and showing ligninolytic abilities.

Biodelignification of lignocellulose using ligninolytic enzymes from white-rot fungi

Lignocellulose is the most abundant biomass available on earth, including wood and agricultural wastes such as rice straw, corn cobs, and oil palm empty bunches. The biopolymer content in lignocellulose has a great potential as feedstock for producing industrial raw materials such as glucose, sorbitol, xylose, xylitol, and other pharmaceutical excipients. Currently, scientists and governments agree that the enzymatic delignification method is an environmentally friendly green method to be applied. This review attempts to explain the proper preparation of the enzymes laccase, lignin peroxidase, and manganese peroxidase, as well as the important factors influencing their activity. The recent applications of the enzymes for detoxification of hazardous substances, proper enzyme immobilization technique, and future prospect combination with DESs extraction of lignin are also discussed.

Renewable Biomass Utilization: A Way Forward to Establish Sustainable Chemical and Processing Industries

Lignocellulosic biomass feedstocks are promising alternatives to fossil fuels for meeting raw material needs of processing industries and helping transit from a linear to a circular economy and thereby meet the global sustainability criteria. The sugar platform route in the biochemical conversion process is one of the promising and extensively studied methods, which consists of four major conversion steps: pretreatment, hydrolysis, fermentation, and product purification. Each of these conversion steps has multiple challenges. Among them, the challenges associated with the pretreatment are the most significant for the overall process because this is the most expensive step in the sugar platform route and it significantly affects the efficiency of all subsequent steps on the sustainable valorization of each biomass component. However, the development of a universal pretreatment method to cater to all types of feedstock is nearly impossible due to the substantial variations in compositions and structures of biopolymers among these feedstocks. In this review, we have discussed some promising pretreatment methods, their processing and chemicals requirements, and the effect of biomass composition on deconstruction efficiencies. In addition, the global biomass resources availability and process intensification ideas for the lignocellulosic-based chemical industry have been discussed from a circularity and sustainability standpoint.

Rhamnolipid-assisted mycoremediation of polycyclic aromatic hydrocarbons by Trametes hirsuta coupled with enhanced ligninolytic enzyme production

The present study deals with the development of a wood assisted fungal system (WAFS) from wood chips using Trametes hirsuta to remove polycyclic aromatic hydrocarbons (PAHs) in BRW. The WAFS exhibited a 1.4-fold higher ligninolytic enzyme production than free fungi in the effluent. Further, to understand PAHs bioremediation by T. hirsuta, biodegradation along with biosorption were studied in model PAHs, phenanthrene (Phe) and benzo (a) pyrene (BaP), in the presence of synthesized rhamnolipids. The WAFS mineralized up to an average of 91.26% Phe and 87.72 % BaP along with biosorption of 12.35% Phe and 18.36 % BaP within 12 days. Thus, the addition of rhamnolipids showed 1.2-fold enhanced biodegradation. However, rhamnolipid concentrations beyond 50 ppm reduced the degradation efficiency of WAFS. Moreover, the degradation capability of total aromatic hydrocarbon (TAH) in biorefinery wastewater by WAFS is 1.8-fold higher than that of free fungi, which confirms the effectiveness of the system. Implications: Simultaneous application of white-rot fungus along with surfactant into a pollutant environment affects the microenvironment of the fungus and reduces the production of their degradative enzymes. In addition, the requirement of periodical supplement of external nutrient in the real-time matrix for the growth of white rot fungi may trigger competitive growth of indigenous microorganisms. Considering this glitch, the current work utilizes the carpenter waste for the strategical develop a wood assisted fungal system to protect the microenvironment of the fungi in the presence of rhamnolipids and contribute to their survival in real time matrix, with enhanced PAHs degradation efficiency.

A proposed stepwise screening framework for the selection of polycyclic aromatic hydrocarbon (PAH)-degrading white rot fungi

This study suggests a simple three-step screening protocol for the selection of white rot fungi (WRF) capable of degrading polycyclic aromatic hydrocarbons (PAHs), which combines easily applicable bioassay techniques, and verifies that protocol by evaluating the PAH degradation activity, ligninolytic enzyme secretion, and relevant gene expressions of the selected PAH-degraders. Using 120 fungal strains, a sequence of bioassay techniques was applied: Bavendamm's reaction (Step 1), remazol brilliant blue R (RBBR) decolorization (Step 2); assays for tolerance to four mixed PAHs-phenanthrene, anthracene, fluoranthene, and pyrene (Step 3). This stepwise protocol selected 14 PAH-degrading WRF, including Microporus vernicipes, Peniophora incarnata, Perenniporia subacida, Phanerochaete sordida, Phlebia acerina, and Phlebia radiata. Of these, P. incarnata exhibited the highest PAH degradative activity, ranging from 40 to > 90%, which was related to the time-variable secretions of three extracellular ligninolytic enzymes: laccase, manganese-dependent peroxidase (MnP) and lignin peroxidase (LiP). Laccase and MnP production by P. incarnata tended to be greater in the early stages of PAH degradation, whereas its LiP production became intensified with decreasing laccase and MnP production. Pilc1 and pimp1 genes encoding laccase and MnP were expressed, indicating the occurrence of extracellular enzyme-driven biodegradation of PAH by the fungal strains.

Lignin peroxidase mediated silver nanoparticle synthesis in Acinetobacter sp

Metals present in environment render the bacteria to attain certain resistance machinery to survive, one of which is transformation of metal ions to nano forms. Various enzymes and proteins have been suggested to play significant role in synthesis of silver nanoparticles (AgNPs) in bacteria. In present study, we have purified lignin peroxidase from secreted enzyme extract of Acinetobacter sp. employing diethyl aminoethyl cellulose ion exchange and Biogel P-150 gel filtration column chromatography. The purified fraction has a specific activity of 1.571 U/mg with substrate n-propanol and 6.5-fold purification. The tetrameric enzyme, with molecular weight of 99 kDa, consisted of dimers of two polypetides of 23.9 and 24.6 kDa as revealed by native and SDS-PAGE. On exposure to purified enzyme, spherical polydispersed AgNPs of ~ 50 nm were obtained as observed under transmission electron microscope. Optimum activity of the purified enzyme was obtained at pH 2 and 60 °C with n-propanol as substrate. This is the first report describing the reduction of extracellular silver ions by lignin peroxidase purified from Acinetobacter sp.

Physiological Peculiarities of Lignin-Modifying Enzyme Production by the White-Rot Basidiomycete Coriolopsis gallica Strain BCC 142

Sixteen white-rot Basidiomycota isolates were screened for production of lignin-modifying enzymes (LME) in glycerol- and mandarin peel-containing media. In the synthetic medium, Cerrena unicolor strains were the only high laccase (Lac) (3.2–9.4 U/mL) and manganese peroxidase (MnP) (0.56–1.64 U/mL) producers while one isolate Coriolopsis gallica was the only lignin peroxidase (LiP) (0.07 U/mL) producer. Addition of mandarin peels to the synthetic medium promoted Lac production either due to an increase in fungal biomass (Funalia trogii, Trametes hirsuta, and T. versicolor) or enhancement of enzyme production (C. unicolor, Merulius tremellosus, Phlebia radiata, Trametes ochracea). Mandarin peels favored enhanced MnP and LiP secretion by the majority of the tested fungi. The ability of LiP activity production by C. gallica, C. unicolor, F. trogii, T. ochracea, and T. zonatus in the medium containing mandarin-peels was reported for the first time. Several factors, such as supplementation of the nutrient medium with a variety of lignocellulosic materials, nitrogen source or surfactant (Tween 80, Triton X-100) significantly influenced production of LME by a novel strain of C. gallica. Moreover, C. gallica was found to be a promising LME producer with a potential for an easy scale up cultivation in a bioreactor and high enzyme yields (Lac-9.4 U/mL, MnP-0.31 U/mL, LiP-0.45 U/mL).

Simple screening protocol for identification of potential mycoremediation tools for the elimination of polycyclic aromatic hydrocarbons and phenols from hyperalkalophile industrial effluents

A number of fungal strains belonging to the ascomycota, basidiomycota and zygomycota genera were subjected to an in vitro screening regime to assess their ligninolytic activity potential, with a view to their potential use in mycoremediation-based strategies to remove phenolic compounds and polycyclic aromatic hydrocarbons (PAHs) from industrial wastewaters. All six basidiomycetes completely decolorized remazol brilliant blue R (RBBR), while also testing positive in both the guaiacol and gallic acid tests indicating good levels of lignolytic activity. All the fungi were capable of tolerating phenanthrene, benzo-α- pyrene, phenol and p-chlorophenol in agar medium at levels of 10 ppm. Six of the fungal strains, Pseudogymnoascus sp., Aspergillus caesiellus, Trametes hirsuta IBB 450, Phanerochate chrysosporium ATCC 787, Pleurotus ostreatus MTCC 1804 and Cadophora sp. produced both laccase and Mn peroxidase activity in the ranges of 200-560 U/L and 6-152 U/L, respectively, in liquid media under nitrogen limiting conditions. The levels of adsorption of the phenolic and PAHs were negligible with 99% biodegradation being observed in the case of benzo-α-pyrene, phenol and p-chlorophenol. The aforementioned six fungal strains were also found to be able to effectively treat highly alkaline industrial wastewater (pH 12.4). When this wastewater was supplemented with 0.1 mM glucose, all of the tested fungi, apart from A. caesiellus, displayed the capacity to remove both the phenolic and PAH compounds. Based on their biodegradative capacity we found T. hirsuta IBB 450 and Pseudogymnoascus sp., to have the greatest potential for further use in mycoremediation based strategies to treat wastestreams containing phenolics and PAHs.

Decolorizing an anthraquinone dye by Phlebia brevispora: Intra-species characterization

Remazol brilliant blue R (RBBR) is an anthraquinone dye derived from anthracene that is decolorized by a white rot fungus, Phlebia brevispora. Interestingly, P. brevispora produces two phenomena of yellowish and pinkish colors during the degradation of RBBR. Here, we characterized the decolorization of RBBR by P. brevispora. The fungus was significantly different between the two colors via UV spectrophotometry, and the morphology of the hyphae observed in the respective color culture was also entirely different. Moreover, both of the two ligninolytic enzymes, laccase and manganese-dependent peroxidase (MnP), were remarkably stimulated in the yellowish culture at the beginning of the decolorization. It is possible that the RBBR decolorizing mechanism might be primarily related to the amount of laccase and MnP produced in the yellowish culture. Thus, the decolorized color may be rapidly estimated at initial period of incubation. In addition, GeneFishing technology revealed that two genes were differentially expressed in yellowish culture.

Enhanced removal of PAHs by Peniophora incarnata and ascertainment of its novel ligninolytic enzyme genes

The hazardous effects of the PAHs should be managed by removal using white rot fungal ligninolytic enzymes. The white rot fungus Peniophora incarnataKUC8836 was stimulated to produce ligninolytic enzymes in a liquid medium by the addition of four substances: 0.5 g L(-1) Tween 80, 70 mg L(-1) CuSO4·5H2O, 10 mg L(-1) MnSO4·H2O, and 0.3 g L(-1) veratryl alcohol. The experiments were carried out in two different media: basal salt and 2% malt extract (ME) liquid medium. Under the experimental conditions, both laccase and manganese-dependent peroxidase (MnP) demonstrated with the highest activities in 2% ME liquid medium following the addition of Tween 80. The biodegradation of anthracene and pyrene was significantly enhanced by the induced ligninolytic enzymes when Tween 80 was added. Tween 80 is a viable co-substrate for P. incarnata, as it enhances the ability of P. incarnata to manage effective biodegradation of PAHs. Most of all, the novel laccase and MnP genes ascertained in this study, showed that the genes were involved in the production of ligninolytic enzymes from P. incarnataKUC8836.

Carotene-degrading activities from Bjerkandera adusta possess an application in detergent industries

Four extracellular enzymes, a versatile peroxidase, a manganese peroxidase, a dye-decolorizing peroxidase and a lignin peroxidase were discovered in liquid cultures of the basidiomycete Bjerkandera adusta. All of them cleaved β-carotene effectively. Expression was enhanced in the presence of β-carotene or Coomassie Brilliant Blue and peaked after 7-9 days. The monomeric proteins were purified by ion exchange and size exclusion chromatography and exhibited molecular masses of 41, 43, 51 and 43 kDa, respectively. The coding sequences showed homologies from 61 to 89 % to peroxidases from other basidiomycetes. The novel enzymes retained strong activity even in the absence of hydrogen peroxide and at alkaline pH. De-staining of fabrics using detergent-tolerant enzymes may help to save the most important bio-resources, energy and water, in washing processes and led to green processes in textile cleaning.

Anthraquinone dyes decolorization capacity of anamorphic Bjerkandera adusta CCBAS 930 strain and its HRP-like negative mutants

Cultures of the anamorphic fungus Bjerkandera adusta CCBAS 930 decolorizing, in stationary cultures, 0.01 % solutions of carminic acid and Poly R-478, were characterised by a strong increase in the activity of the horseradish peroxidase (HRP-like) and manganese-dependent peroxidase (MnP) at a low activity of lignin peroxidase. Genotypically modified mutants of B. adusta CCBAS 930: 930-5 and 930-14, with total or partial loss of decolorization capabilities relative to anthraquinonic dyes, showed inhibition of the activity of HRP-like peroxidase and MnP. Whereas, compared to the parental strain, in the mutant cultures there was an increase in the activity of lignin peroxidase and laccase. The paper presents a discussion of the role of the studied enzymatic activities in the process of decolorization of anthraquinonic dyes by the strain B. adusta CCBAS 930.

Biotechnological procedures to select white rot fungi for the degradation of PAHs

White rot fungi are essential in forest ecology and are deeply involved in wood decomposition and the biodegradation of various xenobiotics. The fungal ligninolytic enzymes involved in these processes have recently become the focus of much attention for their possible biotechnological applications. Successful bioremediation requires the selection of species with desirable characteristics. In this study, 150 taxonomically and physiologically diverse white rot fungi, including 55 species, were investigated for their performance in a variety of biotechnological procedures, such as dye decolorization, gallic acid reaction, ligninolytic enzymes, and tolerance to four PAHs, phenanthrene, anthracene, fluoranthene, and pyrene. Among these fungi, six isolates showed the highest (>90%) tolerance to both individual PAH and mixed PAHs. And six isolates oxidized gallic acid with dark brown color and they rapidly decolorized RBBR within ten days. These fungi revealed various profiles when evaluated for their biotechnological performance to compare the capability of degradation of PAHs between two groups selected. As the results demonstrated the six best species selected from gallic acid more greatly degraded four PAHs than the other isolates selected via tolerance test. It provided that gallic acid reaction test can be performed to rank the fungi by their ability to degrade the PAHs. Most of all, Peniophora incarnata KUC8836 and Phlebia brevispora KUC9033 significantly degraded the four PAHs and can be considered prime candidates for the degradation of xenobiotic compounds in environmental settings.

Fungal laccase, manganese peroxidase and lignin peroxidase: gene expression and regulation

Extensive research efforts have been dedicated to characterizing expression of laccases and peroxidases and their regulation in numerous fungal species. Much attention has been brought to these enzymes broad substrate specificity resulting in oxidation of a variety of organic compounds which brings about possibilities of their utilization in biotechnological and environmental applications. Research attempts have resulted in increased production of both laccases and peroxidases by the aid of heterologous and homologous expression. Through analysis of promoter regions, protein expression patterns and culture conditions manipulations it was possible to compare and identify common pathways of these enzymes' production and secretion. Although laccase and peroxidase proteins have been crystallized and thoroughly analyzed, there are still a lot of questions remaining about their evolutionary origin and the physiological functions. This review describes the present understanding of promoter sequences and correlation between the observed regulatory effects on laccase, manganese peroxidase and lignin peroxidase genes transcript levels and the presence of specific response elements.

Effect of soya lecithin on the enzymatic system of the white-rot fungi Anthracophyllum discolor

The present work optimized the initial pH of the medium and the incubation temperature for ligninolytic enzymes produced by the white-rot fungus Anthracophyllum discolor. Additionally, the effect of soya lecithin on mycelial growth and the production of ligninolytic enzymes in static batch cultures were evaluated. The critical micelle concentration of soya lecithin was also studied by conductivity. The effects of the initial pH (3, 4, and 5) and incubation temperature (20, 25, and 30°C) on different enzymatic activities revealed that the optimum conditions to maximize ligninolytic activity were 26°C and pH 5.5 for laccase and manganese peroxidase (MnP) and 30°C and pH 5.5 for manganese-independent peroxidase (MiP). Under these culture conditions, the maximum enzyme production was 10.16, 484.46, and 112.50 U L(-1) for laccase, MnP, and manganese-independent peroxidase MiP, respectively. During the study of the effect of soya lecithin on A. discolor, we found that the increase in soya lecithin concentration from 0 to 10 g L(-1) caused an increase in mycelial growth. On the other hand, in the presence of soya lecithin, A. discolor produced mainly MnP, which reached a maximum concentration of 30.64 ± 4.61 U L(-1) after 25 days of incubation with 1 g L(-1) of the surfactant. The other enzymes were produced but to a lesser extent. The enzymatic activity of A. discolor was decreased when Tween 80 was used as a surfactant. The critical micelle concentration of soya lecithin calculated in our study was 0.61 g L(-1).

Effects of different wavelengths of light on lignin peroxidase production by the white-rot fungi Phanerochaete chrysosporium grown in submerged cultures

In this study, the effects of different wavelengths of light (UV, blue, green, yellow, red) and white light on lignin peroxidase (LiP), protein, biomass and exo-polysaccharide production and glucose uptake by Phanerochaete chrysosporium BKM-F-1767 were determined. The experiments were conducted under aerated (CS) and oxygenated (RS) culture conditions. The results showed that only green light significantly increased maximum LiP production (by 20% and 27% in CS and RS cultures respectively). Green light also increased biomass production in oxygenated cultures (RS). Blue and UV light both significantly reduced maximum LiP activity. Yellow, red and white lights had mixed effects on culture properties. This is the first time that the effects of different wavelengths of light on lignin peroxidase production and other culture properties have been investigated. The novel findings may be important in improving the yield of lignin modifying enzymes for biomass conversion processes and understanding their regulation.

Degrading ability of oligocyclic aromates by Phanerochaete sordida selected via screening of white rot fungi

Seventy-nine white rot strains were screened to determine if they had the potential for use in the degradation of oligocyclic aromates (PAHs) by measuring their dye-decoloration rate. Fourteen strains that were selected based on their dye-decoloration rate were then evaluated for the ability to tolerate various levels of PAHs spiked in agar medium. The ability of white rot fungi to degrade 3- or 4-ring PAHs (anthracene, phenanthrene, fluoranthene, pyrene) was determined. Two strains of Phanerochaete sordida (KUC8369, KUC8370) were possible PAHs degraders, degrading a significantly greater amount of phenanthrene and fluoranthene than the culture collection strain P. chrysosporium (a known PAHs degrader). The production of manganese peroxidase, the only extracellular ligninolytic enzyme detected during the cultivation, was evaluated.

Physiological regulation of laccase and manganese peroxidase production by white-rot Basidiomycetes

This review integrates recent literature and our own data on the physiology of laccase and manganese peroxidase synthesis, focusing on the common characteristics and unique properties of individual fungi as well as on several approaches providing enhanced enzyme secretion. Firstly, the enzyme yield is species-dependent and strain-dependent and selection of new organisms with tremendous synthesis of these enzymes is possible. For example, in screening program the laccase activity of tested basidiomycetes varied from 0.5Uml(-1) to 75Uml(-1). Secondly, the carbon source and lignocellulosic substrate play a crucial role in enzyme production. Thus, laccase activity of Pseudotrametes gibbosa varied from 0.3Uml(-1) (Avicel) to 13.7Uml(-1) (lactose), while the substitution of wheat bran with walnut pericarp increased Cerrena unicolor manganese peroxidase yield from 0.7Uml(-1) to 8.3Uml(-1). Thirdly, aromatic compounds regulate the ligninolytic enzyme synthesis although their effect is very specific depending on fungi physiological peculiarities. 2,4,6-trinitrotoluene (TNT) supplemented to the medium at appropriate concentration significantly accelerated C. unicolor laccase production and 4-fold increased laccase specific activity. Fourthly, co-cultivation of appropriate fungi shows considerable promise as a strategy to highly enhance the enzyme production. For example, pairing of C. unicolor and Phellinus robustus 2-fold increased the total laccase yield.