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Frontiers in Microbiology 2024Lettuce is an economically major leafy vegetable that is affected by numerous diseases. One of the most devastating diseases of lettuce is white mold caused by . Control...
Lettuce is an economically major leafy vegetable that is affected by numerous diseases. One of the most devastating diseases of lettuce is white mold caused by . Control methods for this fungus are limited due to the development of genetic resistance to commonly used fungicides, the large number of hosts and the long-term survival of sclerotia in soil. To elaborate a new and more sustainable approach to contain this pathogen, 1,210 strains previously isolated from agricultural soils in Canada were screened for their antagonistic activity against . Nine strains showed strong inhibition in dual-culture confrontational assays. Whole genome sequencing of these strains revealed their affiliation with four phylogenomic subgroups within the group, namely , , , and . The antagonistic strains harbor several genes and gene clusters involved in the production of secondary metabolites, including mycin-type and peptin-type lipopeptides, and antibiotics such as brabantamide, which may be involved in the inhibitory activity observed against . Three strains also demonstrated significant biocontrol abilities against the pathogen when either inoculated on lettuce leaves or in the growing substrate of lettuce plants grown in pots. They however did not impact populations in the rhizosphere, suggesting that they protect lettuce plants by altering the fitness and the virulence of the pathogen rather than by directly impeding its growth. These results mark a step forward in the development of biocontrol products against .
PubMed: 38516010
DOI: 10.3389/fmicb.2024.1304682 -
Angewandte Chemie (Weinheim An Der... Nov 2023Mupirocin is a clinically important antibiotic produced by a -AT Type I polyketide synthase (PKS) in . The major bioactive metabolite, pseudomonic acid A (PA-A), is...
Mupirocin is a clinically important antibiotic produced by a -AT Type I polyketide synthase (PKS) in . The major bioactive metabolite, pseudomonic acid A (PA-A), is assembled on a tetrasubstituted tetrahydropyran (THP) core incorporating a 6-hydroxy group proposed to be introduced by α-hydroxylation of the thioester of the acyl carrier protein (ACP) bound polyketide chain. Herein, we describe an in vitro approach combining purified enzyme components, chemical synthesis, isotopic labelling, mass spectrometry and NMR in conjunction with in vivo studies leading to the first characterisation of the α-hydroxylation bimodule of the mupirocin biosynthetic pathway. These studies reveal the precise timing of hydroxylation by MupA, substrate specificity and the ACP dependency of the enzyme components that comprise this α-hydroxylation bimodule. Furthermore, using purified enzyme, it is shown that the MmpA KS shows relaxed substrate specificity, suggesting precise spatiotemporal control of MupA recruitment in the context of the PKS. Finally, the detection of multiple intermodular MupA/ACP interactions suggests these bimodules may integrate MupA into their assembly.
PubMed: 38515435
DOI: 10.1002/ange.202312514 -
Colloids and Surfaces. B, Biointerfaces May 2024Biofilms are complex porous materials formed by microorganisms, polysaccharides, proteins, eDNA, inorganic matter, and water. They are ubiquitous in various...
Biofilms are complex porous materials formed by microorganisms, polysaccharides, proteins, eDNA, inorganic matter, and water. They are ubiquitous in various environmental niches and are known to grow at solid-liquid, solid-air and air-liquid interfaces, often causing problems in several industrial and sanitary fields. Their removal is a challenge in many applications and numerous studies have been conducted to identify promising chemical species as cleaning agents. While these substances target specific components of biofilm structure, the role of water content in biofilm, and how it can influence wettability and detergent absorption have been quite neglected in the literature. Estimating water content in biofilm is a challenging task due to its heterogeneity in morphology and chemical composition. In this study, we controlled water content in Pseudomonas fluorescens AR 11 biofilms grown on submerged glass slides by regulating environmental relative humidity after drying. Interfacial properties of biofilm were investigated by measuring wetting of water and soybean oil. The morphology of biofilm structure was evaluated using Confocal Laser Scanning Microscopy and Scanning Electron Microscopy. The results showed that biofilm water content has a significant and measurable effect on its wettability, leading to the hypothesis that a preliminary control of water content can play a crucial role in biofilm removal process.
Topics: Wettability; Pseudomonas fluorescens; Humidity; Biofilms; Water
PubMed: 38508084
DOI: 10.1016/j.colsurfb.2024.113831 -
Ecotoxicology and Environmental Safety Apr 2024Lead (Pb) is one of the most dreadful non-essential elements whose toxicity has been well reported worldwide due to its interference with the major plant functions and...
Synergistic application of Pseudomonas strains and compost mitigates lead (Pb) stress in sunflower (Helianthus annuus L.) via improved nutrient uptake, antioxidant defense and physiology.
Lead (Pb) is one of the most dreadful non-essential elements whose toxicity has been well reported worldwide due to its interference with the major plant functions and its overall yield. Bioremediation techniques comprising the application of beneficial microorganisms have gained attention in recent times owing to their ecofriendly nature. Addition of organic matter to soil has been reported to stimulate microbial activities. Compost application improves soil structure and binds toxic contaminants due to its larger surface area and presence of functional groups. Furthermore, it stimulates soil microbial activities by acting as C-source. So, in current study, we investigated the individual and synergistic potential of two lead (Pb)-tolerant Pseudomonas strains alongwith compost (1% w/w) in sustaining sunflower growth under Pb contaminated soil conditions. Lead chloride (PbCl) salt was used for raising desired Pb concentration (500 mg kg). Results revealed that Pb stress drastically affected all the measured attributes of sunflower plant, however joint application of rhizobacteria and compost counteracted these adverse effects. Among them, co-application of str-1 and compost proved to be significantly better than str-2, as its inoculation significantly improved shoot and root lengths (64 and 76%), leaf area and leaves plant (95 and 166%), 100-achene weight (200%), no. of flowers plant (138%), chl 'a', 'b' and carotenoid (86, 159 and 33%) contents in sunflower as compared to control treatments. Furthermore, inoculation of Pseudomonas fluorescens along with compost increased the NPK in achene (139, 200 and 165%), flavonoid and phenolic contents (258 and 185%) along with transpiration and photosynthetic rates (54 and 72%) in leaves as compared to control treatment under Pb contamination. In addition, Pb entry to roots, shoots and achene were significantly suppressed under by 87, 90 and 91% respectively due to integrated application of compost and str-1 as evident by maximum Pb-immobilization efficiency (97%) obtained in this treatment. Similarly, bioconcentration factors for roots, shoots and achene were found to be 0.58, 0.18 and 0.0055 with associated translocation factor (0.30), which also revealed phytostabilization of Pb under combined application of PGPR and compost. Since, phytoremediation of heavy metals under current scenario of increasing global population is inevitable, results of the current study concluded that tolerant PGPR species along with organic amendments such as compost can inhibit Pb uptake by sunflower and confer Pb tolerance via improved nutrient uptake, physiology, antioxidative defense and gas exchange.
Topics: Antioxidants; Helianthus; Pseudomonas; Lead; Composting; Biodegradation, Environmental; Plant Roots; Soil; Nutrients; Soil Pollutants
PubMed: 38479312
DOI: 10.1016/j.ecoenv.2024.116194 -
MBio Apr 2024The natural microbiota isolates MYb11 and MYb115 protect the host against pathogens through distinct mechanisms. While produces an antimicrobial compound and...
The natural microbiota isolates MYb11 and MYb115 protect the host against pathogens through distinct mechanisms. While produces an antimicrobial compound and directly inhibits pathogen growth, MYb115 protects the host without affecting pathogen growth. It is unknown how these two protective microbes affect host biological processes. We used a proteomics approach to elucidate the response to MYb11 and MYb115. We found that both isolates increase vitellogenin protein production in young adults, which confirms previous findings on the effect of microbiota on reproductive timing. Moreover, the responses to MYb11 and MYb115 exhibit common signatures with the response to other vitamin B-producing bacteria, emphasizing the importance of vitamin B in -microbe metabolic interactions. We further analyzed signatures in the response specific to MYb11 or MYb115. We provide evidence for distinct modifications in lipid metabolism by both symbiotic microbes. We could identify the activation of host-pathogen defense responses as an MYb11-specific proteome signature and provide evidence that the intermediate filament protein IFB-2 is required for MYb115-mediated protection. These results indicate that MYb11 not only produces an antimicrobial compound but also activates host antimicrobial defenses, which together might increase resistance to infection. In contrast, MYb115 affects host processes such as lipid metabolism and cytoskeleton dynamics, which might increase host tolerance to infection. Overall, this study pinpoints proteins of interest that form the basis for additional exploration into the mechanisms underlying microbiota-mediated protection from pathogen infection and other microbiota-mediated traits.IMPORTANCESymbiotic bacteria can defend their host against pathogen infection. While some protective symbionts directly interact with pathogenic bacteria, other protective symbionts elicit a response in the host that improves its own pathogen defenses. To better understand how a host responds to protective symbionts, we examined which host proteins are affected by two protective bacteria in the model nematode . We found that the response to its protective symbionts is manifold, which was reflected in changes in proteins that are involved in metabolism, the immune system, and cell structure. This study provides a foundation for exploring the contribution of the host response to symbiont-mediated protection from pathogen infection.
Topics: Animals; Caenorhabditis elegans; Proteome; Pseudomonas; Caenorhabditis elegans Proteins; Anti-Infective Agents; Vitamins
PubMed: 38411078
DOI: 10.1128/mbio.03463-23 -
Frontiers in Plant Science 2024Rhizobacteria are capable of inducing defense responses via the expression of pathogenesis-related proteins (PR-proteins) such as chitinases, and many studies have...
Rhizobacteria are capable of inducing defense responses via the expression of pathogenesis-related proteins (PR-proteins) such as chitinases, and many studies have validated the functions of plant chitinases in defense responses. Soybean () is an economically important crop worldwide, but the functional validation of soybean chitinase in defense responses remains limited. In this study, genome-wide characterization of soybean chitinases was conducted, and the defense contribution of three chitinases (GmChi01, GmChi02, or GmChi16) was validated in transgenic lines against the soil-borne pathogen . Compared to the Col-0 and empty vector controls, the transgenic lines with GmChi02 or GmChi16 exhibited fewer chlorosis symptoms and wilting. While GmChi02 and GmChi16 enhanced defense to , GmChi02 was the only one significantly induced by . The observation indicated that plant chitinases may be induced by different rhizobacteria for defense responses. The survey of 37 soybean chitinase gene expressions in response to six rhizobacteria observed diverse inducibility, where only 10 genes were significantly upregulated by at least one rhizobacterium and 9 genes did not respond to any of the rhizobacteria. Motif analysis on soybean promoters further identified not only consensus but also rhizobacterium-specific transcription factor-binding sites for the inducible chitinase genes. Collectively, these results confirmed the involvement of GmChi02 and GmChi16 in defense enhancement and highlighted the diverse inducibility of 37 soybean chitinases encountering and six rhizobacteria.
PubMed: 38405589
DOI: 10.3389/fpls.2024.1341181 -
ACS Omega Feb 2024Microbial degradation of dyes is vital to understanding the fate of dyes in the environment. In this study, a fungal strain A-3 and a bacterial strain L-6, which were...
Microbial degradation of dyes is vital to understanding the fate of dyes in the environment. In this study, a fungal strain A-3 and a bacterial strain L-6, which were identified as and , respectively, had been proven to efficiently degrade crystal violet (CV) dye. The decolorization of CV dye by fungal and bacterial cocultivation was investigated. The results showed that the decolorization rate of cocultures was better than monoculture ( in L-6 (PF), and that of A-3 (AF)). Furthermore, enzymatic analysis further revealed that Lac, MnP, Lip, and NADH-DCIP reductases were involved in the biodegradation of CV dyes. UV-visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS) were used to examine the degradation products. GC-MS analysis showed the presence of 4-(dimethylamino) benzophenone, 3-dimethylaminophenol, benzyl alcohol, and benzaldehyde, indicating that CV was degraded into simpler compounds. The phytotoxicity tests revealed that CV degradation products were less toxic than the parent compounds, indicating that the cocultures detoxified CV dyes. As a result, the cocultures are likely to have a wide range of applications in the bioremediation of CV dyes.
PubMed: 38405495
DOI: 10.1021/acsomega.3c06978 -
Microorganisms Feb 2024This study aimed to explore the phenotype and relationship of drug resistance genes in livestock and poultry farm wastewater and drinking water reservoirs to provide...
This study aimed to explore the phenotype and relationship of drug resistance genes in livestock and poultry farm wastewater and drinking water reservoirs to provide evidence for the transmission mechanisms of drug resistance genes, in order to reveal the spread of drug resistance genes in wastewater from intensive farms in Central China to urban reservoirs that serve as drinking water sources and provide preliminary data for the treatment of wastewater from animal farms to reduce the threat to human beings. DNA extraction and metagenomic sequencing were performed on eight groups of samples collected from four water reservoirs and four related wastewaters from animal farms in Central China. Metagenomic sequencing showed that the top 20 AROs with the highest abundance were _gene, _gene, , , , _gene_, _gene, , _gene, _gene, , , , , _gene, , _gene, , , and . The resistance genes mentioned above belong to the following categories of drug resistance mechanisms: antibiotic target replacement, antibiotic target protection, antibiotic inactivation, and antibiotic efflux. The resistomes that match the top 20 genes are and ; ; ; and . ; ; and ; and ; , , , , , , , , , and ; and ; , , , , , and ; and ; and ; , , and ; , , , , , , and . Unreported drug resistance genes and drug-resistant bacteria in Central China were identified in 2023. In the transmission path of drug resistance genes, the transmission path from aquaculture wastewater to human drinking water sources cannot be ignored. For the sake of human health and ecological balance, the treatment of aquaculture wastewater needs to be further strengthened, and the effective blocking of drug resistance gene transmission needs to be considered.
PubMed: 38399800
DOI: 10.3390/microorganisms12020396 -
International Journal of Molecular... Feb 2024(MI) colonizing metalworking fluids (MWFs) has been associated with chronic hypersensitivity pneumonitis (HP) in machinists. However, it is etiologically unclear why...
Differential Immunogenicity and Lung Disease-Inducing Potential of Genotypes and Impact of Co-Exposure with Pseudomonas: Optimizing a Mouse Model of Chronic Hypersensitivity Pneumonitis.
(MI) colonizing metalworking fluids (MWFs) has been associated with chronic hypersensitivity pneumonitis (HP) in machinists. However, it is etiologically unclear why only certain mycobacteria-contaminated fluids induce this interstitial lung disease. We hypothesized that this may be due to differential immunogenicity and the HP-inducing potential of MI strains/genotypes as well as the confounding effect of co-inhaled endotoxin-producers. To test this hypothesis, we optimized a chronic HP mouse model in terms of MI antigen dose, timepoint of sacrifice, and form of antigen (cell lysates vs. live cells) and compared six different field-isolated MI strains. Overall, MJY10 was identified as the most immunogenic and MJY4 (or MJY13) as the least immunogenic genotype based on lung pathoimmunological changes as well as Th1 cellular response (IFN-γ release). Infection with MI live cells induced a more severe phenotype than MI cell lysate. Co-exposure with caused a greater degree of lung innate immune response and granuloma formation but a diminished adaptive (Th1) immune response (IFN-γ) in the lung and spleen. In summary, this study led to the first demonstration of differential immunogenicity and the disease-inducing potential of field strains of MI and an interfering effect of the co-contaminating Pseudomonas. The improved chronic MI-HP mouse model and the identified polar pair of MI strains will facilitate future diagnostic and therapeutic research on this poorly understood environmental lung disease.
Topics: Mice; Animals; Pseudomonas; Alveolitis, Extrinsic Allergic; Lung; Genotype; Mycobacteriaceae
PubMed: 38396736
DOI: 10.3390/ijms25042058 -
Antibiotics (Basel, Switzerland) Jan 2024Industrial biocides aim to keep water systems microbiologically controlled and to minimize biofouling. However, the resulting dead cells are usually not removed from the...
Industrial biocides aim to keep water systems microbiologically controlled and to minimize biofouling. However, the resulting dead cells are usually not removed from the water streams and can influence the growth of the remaining live cells in planktonic and sessile states. This study aims to understand the effect of dead cells killed by industrial biocides-benzalkonium chloride (BAC) and 2,2-dibromo-3-nitrilopropionamide (DBNPA)-on biofilm formation. Additionally, the effect of different dead/live cell ratios (50.00% and 99.99%) was studied. The inoculum was recirculated in a Parallel Plate Flow Cell (PPFC). The overall results indicate that dead cells greatly affect biofilm properties. Inoculum with DBNPA-dead cells led to more active (higher ATP content and metabolic activity) and thicker biofilm layers in comparison to BAC-dead cells, which seems to be linked to the mechanism of action by which the cells were killed. Furthermore, higher dead cell ratios (99.99%) in the inoculum led to more active (higher culturability, metabolic activity and ATP content) and cohesive/compact and uniformly distributed biofilms in comparison with the 50.00% dead cell ratio. The design of future disinfection strategies must consider the contribution of dead cells to the biofilm build-up, as they might negatively affect water system operations.
PubMed: 38391526
DOI: 10.3390/antibiotics13020140