1
|
Raimi AR, Ezeokoli OT, Adeleke RA. Soil nutrient management influences diversity, community association and functional structure of rhizosphere bacteriome under vegetable crop production. Front Microbiol 2023; 14:1229873. [PMID: 37840710 PMCID: PMC10568080 DOI: 10.3389/fmicb.2023.1229873] [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] [Received: 05/27/2023] [Accepted: 09/01/2023] [Indexed: 10/17/2023] Open
Abstract
Introduction Rhizosphere bacterial communities play a crucial role in promoting plant and soil ecosystem health and productivity. They also have great potential as key indicators of soil health in agroecosystems. Various environmental factors affect soil parameters, which have been demonstrated to influence soil microbial growth and activities. Thus, this study investigated how rhizosphere bacterial community structure and functions are affected by agronomic practices such as organic and conventional fertiliser application and plant species types. Methods Rhizosphere soil of vegetable crops cultivated under organic and conventional fertilisers in different farms was analysed using high-throughput sequencing of the 16S rRNA gene and co-occurrence network pattern among bacterial species. The functional structure was analysed with PICRUSt2 pipeline. Results Overall, rhizosphere bacterial communities varied in response to fertiliser type, with soil physicochemical parameters, including NH4, PO4, pH and moisture content largely driving the variations across the farms. Organic farms had a higher diversity richness and more unique amplicon sequence variants than conventional farms. Bacterial community structure in multivariate space was highly differentiated across the farms and between organic and conventional farms. Co-occurrence network patterns showed community segmentation for both farms, with keystone taxa more prevalent in organic than conventional farms. Discussion Module hub composition and identity varied, signifying differences in keystone taxa across the farms and positive correlations between changes in microbial composition and ecosystem functions. The organic farms comprised functionally versatile communities characterised by plant growth-promoting keystone genera, such as Agromyces, Bacillus and Nocardioides. The results revealed that organic fertilisers support high functional diversity and stronger interactions within the rhizosphere bacterial community. This study provided useful information about the overall changes in soil microbial dynamics and how the changes influence ecosystem functioning under different soil nutrient management and agronomic practices.
Collapse
|
2
|
Tang J, Yao J, Pan D, Huang J, Wang J, Li QX, Dong F, Wu X. Characterization and catalytic mechanism of a direct demethylsulfide hydrolase for catabolism of the methylthiol-s-triazine prometryn. JOURNAL OF HAZARDOUS MATERIALS 2023; 446:130708. [PMID: 36608577 DOI: 10.1016/j.jhazmat.2022.130708] [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: 10/26/2022] [Revised: 12/12/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
Demethylthio is one of the most important ways for microorganisms to metabolize triazine herbicides. Previous studies have found that the initial reaction of prometryn catabolism in Leucobacter triazinivorans JW-1 was the hydroxylation of its methylthio group, however, the corresponding functional enzyme was not yet clear. In this study, the gene proA was responsible for the initial step of prometryn catabolism from the strain JW-1 was cloned and expressed, and the purified amidohydrolases ProA have the ability to transform prometryn to 2-hydroxypropazine and methanethiol. The optimized reaction temperature and pH of ProA were 45 °C and 7.0, respectively, and the kinetic constants Km and Vmax of ProA for the catalysis of prometryn were 32.6 μM and 0.09 μmol/min/mg, respectively. Molecular docking analyses revealed that different catalysis efficiency of ProA and TrzN (Nocardioides sp. C190) for prometryn and atrazine was due to non-covalent changes in amino acid residues. Our findings provide new insights into the understanding of s-triazine catabolism at the molecular level.
Collapse
Affiliation(s)
- Jun Tang
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China
| | - Jinjin Yao
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China
| | - Dandan Pan
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China
| | - Junwei Huang
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China
| | - Jie Wang
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China
| | - Qing X Li
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, 1955 East-West Road, Honolulu, HI 96822, USA
| | - Fengshou Dong
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiangwei Wu
- College of Resources and Environment, Anhui Agricultural University, Key Laboratory of Agri-food Safety of Anhui Province, Hefei 230036, China.
| |
Collapse
|
3
|
Mawang CI, Azman AS, Fuad ASM, Ahamad M. Actinobacteria: An eco-friendly and promising technology for the bioaugmentation of contaminants. BIOTECHNOLOGY REPORTS (AMSTERDAM, NETHERLANDS) 2021; 32:e00679. [PMID: 34660214 PMCID: PMC8503819 DOI: 10.1016/j.btre.2021.e00679] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 08/05/2021] [Accepted: 09/20/2021] [Indexed: 11/17/2022]
Abstract
Over the past two decades, various eco-friendly approaches utilizing microbial species to clean up contaminated environments have surfaced. In this aspect, actinobacteria have demonstrated their potential in contaminant degradation. The members of actinobacteria phylum exhibits a cosmopolitan distribution, which means that they can be found widely in both aquatic and terrestrial ecosystems. Actinobacteria play important ecological roles in the environment, such as degrading complex polymers, recycling compounds, and producing bioactive molecules. Hence, using actinobacteria to clean up contaminants is an attractive method in the field of biotechnology. This can be achieved through the green technology of bioaugmentation, whereby the degradative capacity of contaminated areas can be greatly improved through the introduction of specific microorganisms. This review describes actinobacteria as an eco-friendly and a promising technology for the bioaugmentation of contaminants, with focus on pesticides and heavy metals.
Collapse
Affiliation(s)
- Christina-Injan Mawang
- Acarology Unit, Infectious Disease Research Centre, Institute for Medical Research, Ministry of Health Malaysia, National Institutes of Health Complex, Setia Alam, Shah Alam, Selangor, 40170, Malaysia
| | - Adzzie-Shazleen Azman
- School of Science, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor, 47500, Malaysia
| | - Aalina-Sakiinah Mohd Fuad
- Department of Biomedical Science, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia Kuantan Campus, Jalan Sultan Ahmad Shah, Bandar Indera Mahkota, Kuantan, Pahang 25200, Malaysia
| | - Mariana Ahamad
- Acarology Unit, Infectious Disease Research Centre, Institute for Medical Research, Ministry of Health Malaysia, National Institutes of Health Complex, Setia Alam, Shah Alam, Selangor, 40170, Malaysia
| |
Collapse
|
4
|
Hexachlorobenzene Monooxygenase Substrate Selectivity and Catalysis: Structural and Biochemical Insights. Appl Environ Microbiol 2020; 87:AEM.01965-20. [PMID: 33097503 DOI: 10.1128/aem.01965-20] [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: 08/10/2020] [Accepted: 10/14/2020] [Indexed: 01/14/2023] Open
Abstract
Hexachlorobenzene (HCB), as one of the persistent organic pollutants (POPs) and a possible human carcinogen, is especially resistant to biodegradation. In this study, HcbA1A3, a distinct flavin-N5-peroxide-utilizing enzyme and the sole known naturally occurring aerobic HCB dechlorinase, was biochemically characterized. Its apparent preference for HCB in binding affinity revealed that HcbA1 could oxidize only HCB rather than less-chlorinated benzenes such as pentachlorobenzene and tetrachlorobenzenes. In addition, the crystal structure of HcbA1 and its complex with flavin mononucleotide (FMN) were resolved, revealing HcbA1 to be a new member of the bacterial luciferase-like family. A much smaller substrate-binding pocket of HcbA1 than is seen with its close homologues suggests a requirement of limited space for catalysis. In the active center, Tyr362 and Asp315 are necessary in maintaining the normal conformation of HcbA1, while Arg311, Arg314, Phe10, Val59, and Met12 are pivotal for the substrate affinity. They are supposed to place HCB at a productive orientation through multiple interactions. His17, with its close contact with the site of oxidation of HCB, probably fixes the target chlorine atom and stabilizes reaction intermediates. The enzymatic characteristics and crystal structures reported here provide new insights into the substrate specificity and catalytic mechanism of HcbA1, which paves the way for its rational engineering and application in the bioremediation of HCB-polluted environments.IMPORTANCE As an endocrine disrupter and possible carcinogen to human beings, hexachlorobenzene (HCB) is especially resistant to biodegradation, largely due to difficulty in its dechlorination. The lack of knowledge of HCB dechlorinases limits their application in bioremediation. Recently, an HCB monooxygenase, HcbA1A3, representing the only naturally occurring aerobic HCB dechlorinase known so far, was reported. Here, we report its biochemical and structural characterization, providing new insights into its substrate selectivity and catalytic mechanism. This research also increases our understanding of HCB dechlorinases and flavin-N5-peroxide-utilizing enzymes.
Collapse
|
5
|
Kiyota H. Synthetic studies of biologically active natural products contributing to pesticide development. JOURNAL OF PESTICIDE SCIENCE 2020; 45:177-183. [PMID: 32913421 PMCID: PMC7453299 DOI: 10.1584/jpestics.j20-03] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
Natural product research, including total synthesis, is becoming increasingly important for the discovery of pesticide seeds and leads. Synthetic studies of biologically active compounds such as antibiotics (enacyloxins, polynactin, pamamycins, spirofungin A and B, glutarimides and antimycins), phytopathogenic toxins (pyricuol, pyriculariol, tabtoxinine-β-lactam, gigantenone, phomenone and phaseolinone), marine derived products (pteroenone, β-D-Asp-Gly, didemniselinolipid B, cortistatin A, sanctolide A and gizzerosine), POPs (dieldrin, endosulfan, HCB), plant hormones (abscisic acid and jasmonic acid), insect pheromones (endo-brevicomin etc.), especially using a variety of biotransformation are described.
Collapse
Affiliation(s)
- Hiromasa Kiyota
- Grad. Sch. Environmental & Life Science, Okayama University, 1–1–1 Tsushima-Naka, Kita, Okayama 700–8530, Japan
| |
Collapse
|
6
|
Rhizosphere Soil Microbial Properties on Tetraena mongolica in the Arid and Semi-Arid Regions, China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17145142. [PMID: 32708726 PMCID: PMC7400279 DOI: 10.3390/ijerph17145142] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 12/02/2022]
Abstract
Tetraena mongolica is a rare and endangered species unique to China. The total number and density of Tetraena mongolica shrubs in desertification areas have experienced a sharp decrease with increases in coal mining activities. However, available information on the T. mongolica rhizosphere soil quality and microbial properties is scarce. Here, we investigated the effect of coal mining on the soil bacterial community and its response to the soil environment in the T. mongolica region. The results showed that the closer to the coal mining area, the lower the vegetation coverage and species diversity. The electrical conductivity (EC) in the contaminated area increased, while the total nitrogen (TN), available phosphorus (AP), available potassium (AK), and soil organic carbon (SOC) decreased. The activity of NAG, sucrose, β-glucosidase, and alkaline phosphatase further decreased. In addition, the mining area could alter the soil’s bacterial abundance and diversity. The organic pollutant degradation bacteria such as Sphingomonas, Gemmatimonas, Nocardioides, and Gaiella were enriched in the soil, and the carbon-nitrogen cycle was changed. Canonical correspondence analysis (CCA) and Pearson’s correlation coefficients showed that the change in the bacterial community structure was mainly caused by environmental factors such as water content (SWC) and EC. Taken together, these results suggested that open pit mining led to the salinization of the soil, reduction the soil nutrient content and enzyme activity, shifting the rhizosphere soil microbial community structure, and altering the carbon-nitrogen cycle, and the soil quality declined and the growth of T. mongolica was affected in the end. Therefore, the development of green coal mining technology is of great significance to protect the growth of T. mongolica.
Collapse
|
7
|
Takagi K. Study on the biodegradation of persistent organic pollutants (POPs). JOURNAL OF PESTICIDE SCIENCE 2020; 45:119-123. [PMID: 32508519 PMCID: PMC7251198 DOI: 10.1584/jpestics.j19-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/18/2020] [Indexed: 05/30/2023]
Abstract
The use of organochlorine pesticides, such as dichlorodiphenyltrichloroethane (DDT) and benzene hexachloride (BHC), have contributed substantially to the increase and stable supply of food production post-World War II. However, they have also become a major source of pollution on a global scale due to their persistence in the environment, high bioconcentration, toxicity, and their long-distance mobility. Although the use and production of these pesticides were banned over 45 years ago, they still present a risk to human health and ecosystems, and pose a threat to food safety. These pesticides were designated as persistent organic pollutants (POPs) by the Stockholm Convention in 2001, which urged the industry to reduce or eliminate them globally. The authors of this study have been involved in the research and development of bioaugmentation soil remediation technology to reduce the risk of environmental and crop contamination originating from POPs. In this paper, these studies are summarized, from basic studies (1, 2, 3) to an applied study (4), as follows: (1) use of the soil-charcoal perfusion method to explore POP-degrading bacteria, (2) bacteriological characteristics, metabolic pathways and dechlorination genes of the hexaclorobenzene (HCB)-mineralizing bacterial strain PD653, (3) characteristics and metabolic pathways of the dieldrin-degrading bacterial strain KSF27, and (4) application of these degrading bacteria for remediation of POPs-contaminated soil.
Collapse
Affiliation(s)
- Kazuhiro Takagi
- Institute for Agro-Environmental Sciences, NARO, 3–1–3 Kannodai, Tsukuba-Shi, Ibaraki 305–8604, Japan
| |
Collapse
|