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Frontiers in Microbiology 2021Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its... (Review)
Review
Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its widespread presence in soil, sediment, and aquatic environments, which poses a threat to non-target crops, animals, humans, and ecosystems. Therefore, the removal of DUR from contaminated environments has been a hot topic for researchers in recent decades. Bioremediation seldom leaves harmful intermediate metabolites and is emerging as the most effective and eco-friendly strategy for removing DUR from the environment. Microorganisms, such as bacteria, fungi, and actinomycetes, can use DUR as their sole source of carbon. Some of them have been isolated, including organisms from the bacterial genera , , , , , , and and fungal genera , , , , , , and A number of studies have investigated the toxicity and fate of DUR, its degradation pathways and metabolites, and DUR-degrading hydrolases and related genes. However, few reviews have focused on the microbial degradation and biochemical mechanisms of DUR. The common microbial degradation pathway for DUR is transformation to 3,4-dichloroaniline, which is then metabolized through two different metabolic pathways: dehalogenation and hydroxylation, the products of which are further degraded cooperative metabolism. Microbial degradation hydrolases, including PuhA, PuhB, LibA, HylA, Phh, Mhh, and LahB, provide new knowledge about the underlying pathways governing DUR metabolism. The present review summarizes the state-of-the-art knowledge regarding (1) the environmental occurrence and toxicity of DUR, (2) newly isolated and identified DUR-degrading microbes and their enzymes/genes, and (3) the bioremediation of DUR in soil and water environments. This review further updates the recent knowledge on bioremediation strategies with a focus on the metabolic pathways and molecular mechanisms involved in the bioremediation of DUR.
PubMed: 34475856
DOI: 10.3389/fmicb.2021.686509 -
Frontiers in Microbiology 2020Disease suppressive soils with specific suppression of soil-borne pathogens and parasites have been long studied and are most often of microbiological origin. As for the... (Review)
Review
Disease suppressive soils with specific suppression of soil-borne pathogens and parasites have been long studied and are most often of microbiological origin. As for the plant-parasitic nematodes (PPN), which represent a huge threat to agricultural crops and which successfully defy many conventional control methods, soil progression from conducive to suppressive state is accompanied by the enrichment of specific antagonistic microbial consortia. However, a few microbial groups have come to the fore in diminishing PPN in disease suppressive soils using culture-dependent methods. Studies with cultured strains resulted in understanding the mechanisms by which nematodes are antagonized by microorganisms. Recent culture-independent studies on the microbiome associated with soil, plant roots, and PPN contributed to a better understanding of the functional potential of disease suppressive microbial cohort. Plant root exudation is an important pathway determining host-microbe communication and plays a key role in selection and enrichment of a specific set of microbial antagonists in the rhizosphere as first line of defense against crop pathogens or parasites. Root exudates comprising primary metabolites such as amino acids, sugars, organic acids, and secondary metabolites can also cause modifications in the nematode surface and subsequently affect microbial attachment. A positive interaction between hosts and their beneficial root microbiota is correlated with a low nematode performance on the host. In this review, we first summarized the historical records of nematode-suppressive soils and then focused on more recent studies in this aspect, emphasizing the advances in studying nematode-microbe interactions over time. We highlighted nematode biocontrol mechanisms, especially parasitism, induced systemic resistance, and volatile organic compounds using microbial consortia, or bacterial strains of the genera , , , , , , and , or fungal isolates of , , , , , , , and . We discussed the importance of root exudates in plant communication with PPN and soil microorganisms, emphasizing their role in microbial attachment to the nematode surface and subsequent events of nematode parasitism. Comprehensive understanding of the plant-beneficial microbial consortia and the mechanisms underlying disease suppression may help to develop synthetic microbial communities for biocontrol of PPN, thereby reducing nematicides and fertilizers inputs.
PubMed: 32184773
DOI: 10.3389/fmicb.2020.00313 -
Foods (Basel, Switzerland) Mar 2023Milk is naturally a rich source of many essential nutrients; therefore, it is quite a suitable medium for bacterial growth and serves as a reservoir for bacterial... (Review)
Review
Milk is naturally a rich source of many essential nutrients; therefore, it is quite a suitable medium for bacterial growth and serves as a reservoir for bacterial contamination. The genus is a food-related bacterial group commonly present as a contaminant in milk and dairy products as primary and secondary microflora. bacteria frequently demonstrate the nutritional versatility to degrade different compounds even in extreme environments. As a result of their metabolic diversity, species have long been of interest to scientists for application in various industry and biotechnology sectors. In the dairy industry, strains from the genus are part of the microflora of raw milk known as an indicator of hygiene quality. Although they cause spoilage, they are also regarded as important strains responsible for producing fermented milk products, especially cheeses. Several spp. have reported their significance in the development of cheese color and flavor. Furthermore, based on the data obtained from previous studies about its thermostability, and thermoacidophilic and thermoresistant properties, the genus promisingly provides advantages for use as a potential producer of β-galactosidases to fulfill commercial requirements as its enzymes allow dairy products to be treated under mild conditions. In light of these beneficial aspects derived from spp. including pigmentation, flavor formation, and enzyme production, this bacterial genus is potentially important for the dairy industry.
PubMed: 36981196
DOI: 10.3390/foods12061270 -
Heliyon May 2022Drought stress is among the most destructive stresses for agricultural productivity. It interferes with normal metabolic activities of the plants resulting, a negative... (Review)
Review
Drought stress is among the most destructive stresses for agricultural productivity. It interferes with normal metabolic activities of the plants resulting, a negative impact on physiology and morphology of the plants. The management of drought stress requires various adaptive and alleviation strategies in which stress adaptive microbiomes are exquisite bioresources for plant growth and alleviation of drought stress. Diverse drought adaptive microbes belonging to genera and have been reported worldwide. These bioresources exhibit a wide range of mechanisms such as helping plant in nutrient acquisition, producing growth regulators, lowering the levels of stress ethylene, increasing the concentration of osmolytes, and preventing oxidative damage under water deficit environmental conditions. Horticulture is one of the potential agricultural sectors to speed up the economy, poverty and generation of employment for livelihood. The applications of drought adaptive plant growth promoting (PGP) microbes as biofertilizers and biopesticides for horticulture is a potential strategy to improve the productivity and protection of horticultural crops from abiotic and biotic stresses for agricultural sustainability.
PubMed: 35647359
DOI: 10.1016/j.heliyon.2022.e09493 -
Ecotoxicology and Environmental Safety Sep 2023Cadmium (Cd) removal from soil to reduce Cd accumulation in plants is essential for agroecology, food safety, and human health. Cd enters plants from soil and affects...
Cadmium (Cd) removal from soil to reduce Cd accumulation in plants is essential for agroecology, food safety, and human health. Cd enters plants from soil and affects plant growth and development. Hydrogels can easily combine with Cd, thereby altering its bioavailability in soil. However, few studies have evaluated the effects of hydrogel on the complex phytotoxicity caused by Cd uptake in plants and the microbial community structure. Herein, a new poly (acrylic acid)-grafted starch and potassium humate composite (S/K/AA) hydrogel was added to soil to evaluate its impact on tobacco growth and the soil microenvironment. The results indicate that the addition of S/K/AA hydrogel can significantly improve the biomass, chlorophyll (Chl) content, and photosynthetic capacity of tobacco plants during Cd stress conditions, and decrease Cd concentration, probably by affecting Cd absorption through the expression of Cd absorption transporters (e.g., NRAMP5, NRAMP3, and IRT1). Moreover, the application of S/K/AA hydrogel not only reduced the accumulation of reactive oxygen species (ROS), but also reduced the antioxidant activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), suggesting that S/K/AA hydrogel alleviates Cd toxicity via a non-antioxidant pathway. Notably, we further analyzed the effectiveness of the hydrogel on microbial communities in Cd-contaminated soil and found that it increased the Cd-tolerant microbial community (Arthrobacter, Massilia, Streptomyces), enhancing the remediation ability of Cd-contaminated soil and helping tobacco plants to alleviate Cd toxicity. Overall, our study provides primary insights into how S/K/AA hydrogel affects Cd bioavailability and alleviates Cd toxicity in plants.
Topics: Humans; Cadmium; Biological Availability; Nicotiana; Hydrogels; Arthrobacter
PubMed: 37597289
DOI: 10.1016/j.ecoenv.2023.115361 -
Archives of Microbiology Apr 2023Human activities, industrialization and civilization have deteriorated the environment which eventually has led to alarming effects on plants and animals by heightened... (Review)
Review
Human activities, industrialization and civilization have deteriorated the environment which eventually has led to alarming effects on plants and animals by heightened amounts of chemical pollutants and heavy metals in the environment, which create abiotic stress. Environmental conditions like drought, salinity, diminished macro-and micro-nutrients also contribute in abiotic stress, resulting in decrement of survival and growth of plants. Presence of pathogenic and competitive microorganisms, as well as pests lead to biotic stress and a plant alone can not defend itself. Thankfully, nature has rendered plant's rhizosphere with plant growth promoting rhizobacteria which maintain an allelopathic relationship with host plant to defend the plant and let it flourish in abiotic as well as biotic stress situations. This review discusses the mechanisms behind increase in plant growth via various direct and indirect traits expressed by associated microorganisms in the rhizosphere, along with their current scenario and promising future for sustainable agriculture. It also gives details of ten such bacterial species, viz. Acetobacter, Agrobacterium, Alcaligenes, Arthrobacter, Azospirillum, Azotobacter, Bacillus, Burkholderia, Enterobacter and Frankia, whose association with the host plants is famed for enhancing plant's growth and survival.
Topics: Humans; Rhizosphere; Plant Development; Bacteria; Bacillus; Plants; Alphaproteobacteria; Plant Roots; Soil Microbiology
PubMed: 37012531
DOI: 10.1007/s00203-023-03502-2 -
Archives of Microbiology Aug 2022Gram-stain-positive, aerobic, non-spore-forming strains CCNWLXL 1-35, CCNWLXL 12-2 and CCNWLXL 21-a, were isolated from wheat rhizosphere from Yangling, Shaanxi...
Gram-stain-positive, aerobic, non-spore-forming strains CCNWLXL 1-35, CCNWLXL 12-2 and CCNWLXL 21-a, were isolated from wheat rhizosphere from Yangling, Shaanxi Province, China. Comparison of the 16S rRNA gene sequences showed that they belonged to the genus Arthrobacter and were closely related to Arthrobacter globiformis NBRC 12137 (97.95% similarity). Genomic relatedness analyses based on the average nucleotide identity and the genome-to-genome distance showed these strains constituted a single species. The major fatty acids was anteiso-C. The polar lipids consist of diphosphatidylglycerol, phsophatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and glycolipid. The predominant menaquinone was MK-9. The peptidoglycan type was A4α. Thus, these strains were classified as representing a novel species in the genus Arthrobacter, for which the name Arthrobacter rhizosphaerae sp. nov. is proposed. The type strain is CCNWLXL 1-35 (=JCM 34638, =CCTCC AB 2021087) and additional strains are CCNWLXL 12-2 (=JCM 35018, =CCTCC AB 2021546), CCNWLXL 21-a (=JCM 35019, =CCTCC AB 2021545).
Topics: Arthrobacter; Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Nucleic Acid Hybridization; Phylogeny; RNA, Ribosomal, 16S; Rhizosphere; Sequence Analysis, DNA; Soil Microbiology; Triticum
PubMed: 35932431
DOI: 10.1007/s00203-022-03150-y -
Recent Patents on Biotechnology 2023Different compounds with bioactive constituents can be applied as biostimulants to increase plant growth and development under both normal and stressful conditions.... (Review)
Review
Different compounds with bioactive constituents can be applied as biostimulants to increase plant growth and development under both normal and stressful conditions. Biostimulant utilization can be considered a sustainable and beneficial nutritional crop management, and may decrease the negative impacts of excessive chemical fertilization. Google scholar, Science Direct, CAB Direct, Springer Link, Scopus, Web of Science, Taylor and Francis, and Wiley Online Library have been checked. The search was done to all manuscript sections according to the terms "Glomus intraradices", "Trichoderma atroviride", "Trichoderma reesei", "Heteroconium chaetospira", "Arthrobacter spp.", "Acintobacter spp.", "Enterobacer spp.", "Pseudomonas spp.", "Ochrobactrum spp.", "Bacilus spp.", "Rhodococcus spp.", "Biostimulants", and "Plant growth promotion". On the basis of the initial check, Titles and Abstracts were reviewed based on online literature, and then articles were read carefully. Within the framework of sustainable crop management, this review article aimed to provide an overview of the application of the most common fungi and bacteria as plant biostimulants on various crops.
Topics: Patents as Topic; Agriculture; Fungi; Bacteria; Crops, Agricultural
PubMed: 35570523
DOI: 10.2174/1872208316666220513093021 -
International Journal of Systematic and... Jun 2022A novel, Gram-stain-positive, aerobic, non-endospore-forming, non-motile and rod-shaped bacterium designated PO-11 was isolated from sediment of karst cave collected in...
A novel, Gram-stain-positive, aerobic, non-endospore-forming, non-motile and rod-shaped bacterium designated PO-11 was isolated from sediment of karst cave collected in Libo county, Guizhou Province, PR China. The isolate grew optimally on R2A agar at 25 °C, pH 8.0 and with 0.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that PO-11 belonged to the genus and was most closely related to TGA (98.3 % sequence similarity), LC6 (97.7 %) and CCM1646 (97.1 %). Genome sequencing revealed a genome size of 4 073 119 bp and the genomic DNA G+C content was 66.16 mol%. Its DNA-DNA relatedness values with TGA, LC6 and CCM1646 were 23.0, 22.9 and 23.2 %, respectively. The main fatty acids were anteiso-C, anteiso-C and iso-C. The major respiratory quinone was MK-9(H). The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, glycolipid, phosphatidylethanolamine, phosphatidylinositol and unidentified lipids. Thus, based on phylogenetic and phenotypic and chemotaxonomic data, strain PO-11 represents a novel species of the genus , for which the name sp. nov. is proposed. The type strain is strain PO-11 (=CCTCC AB 2021070=LMG 32459).
Topics: Arthrobacter; Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Peptidoglycan; Phospholipids; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA
PubMed: 35763420
DOI: 10.1099/ijsem.0.005445 -
The Science of the Total Environment Aug 2022Eutrophication has attracted extensive attention owing to its harmful effects to the organisms and aquatic environment. Studies on the functional microorganisms with the... (Review)
Review
Eutrophication has attracted extensive attention owing to its harmful effects to the organisms and aquatic environment. Studies on the functional microorganisms with the ability of simultaneously nitrogen (N) and phosphorus (P) removal is of great significance for alleviating eutrophication. Thus far, several strains from various genera have been reported to accomplish simultaneous N and P removal, which is primarily observed in Bacillus, Pseudomonas, Paracoccus, and Arthrobacter. The mechanism of N and P removal by denitrifying P accumulating organisms (DPAOs) is different from the traditional biological N and P removal. The denitrifying P removal (DPR) technology based on the metabolic function of DPAOs can overcome the problem of carbon source competition and sludge age contradiction in traditional biological N and P removal processes and can be applied to the treatment of urban sewage with low C/N ratio. This paper reviews the mechanism of N and P removal by DPAOs from the aspect of the metabolic pathways and enzymatic processes. The research progress on DPR processes is also summarized and elucidated. Further research should focus on the efficient removal of N and P by improving the performance of functional microorganisms and development of new coupling processes. This review can serve as a basis for screening DPAOs with high N and P removal efficiency and developing new DPR processes in the future.
Topics: Bioreactors; Denitrification; Nitrogen; Phosphorus; Sewage; Waste Disposal, Fluid
PubMed: 35469879
DOI: 10.1016/j.scitotenv.2022.155409