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Folia Microbiologica Aug 2023Volatile compounds emitted by bacteria can play a significant role in interacting with microorganisms, plants, and other organisms. In this work, we studied the effect...
Volatile compounds emitted by bacteria can play a significant role in interacting with microorganisms, plants, and other organisms. In this work, we studied the effect of total gaseous mixtures of organic as well as inorganic volatile compounds (VCs) and individual pure volatile organic compounds (VOCs: ketones 2-nonanone, 2-heptanone, 2-undecanone, a sulfur-containing compound dimethyl disulfide) synthesized by the rhizosphere Pseudomonas chlororaphis 449 and Serratia plymuthica IC1270 strains, the soil-borne strain P. fluorescens B-4117, and the spoiled meat isolate S. proteamaculans 94 strain on Arabidopsis thaliana plants (on growth and germination of seeds). We demonstrated that total mixtures of volatile compounds emitted by these strains grown on Luria-Bertani agar, Tryptone Soya Agar, and Potato Dextrose Agar media inhibited the A. thaliana growth. When studied bacteria grew on Murashige and Skoog (MS) agar medium, volatile mixtures produced by bacteria could stimulate the growth of plants. Volatile compounds of bacteria slowed down the germination of plant seeds; in the presence of volatile mixtures of P. fluorescens B-4117, the seeds did not germinate. Of the individual VOCs, 2-heptanone had the most potent inhibitory effect on seed germination. We also showed that the tested VOCs did not cause oxidative stress in Escherichia coli cells using specific lux-biosensors. VOCs reduced the expression of the lux operon from the promoters of the katG, oxyS, and soxS genes (whose products involved in the protection of cells from oxidative stress) caused by the action of hydrogen peroxide and paraquat, respectively.
Topics: Pseudomonas; Agar; Escherichia coli; Serratia; Volatile Organic Compounds
PubMed: 36790684
DOI: 10.1007/s12223-023-01038-y -
Environmental Pollution (Barking, Essex... Apr 2023Arctic contamination by diesel fuel (DF) is of great concern because of the uncertain feedback of permafrost carbon (C) and soil microbiota to DF in the context of...
Arctic contamination by diesel fuel (DF) is of great concern because of the uncertain feedback of permafrost carbon (C) and soil microbiota to DF in the context of climate change in high latitudes. We conducted a laboratory incubation experiment with a gradient of DF addition ratios to examine the responses of the soil microbiota of the typical permafrost soils in the tundra ecosystems of the Norilsk region (Siberia). The study revealed initial heterogeneity in the microbial activity of the studied soils (Histic Gleyic Cryosols (CR-hi,gl), Turbic Cryosols (CR-tu), Turbic Spodic Folic Cryosols (CR-tu,sd,fo), Gleyic Fluvisols (FL-gl)). We applied the two-pool model for evaluation of the effect of DF on the proportions of C pools and revealed significant differences between soil types in the fast and slow C pools in response to DF addition. The results showed that DF addition treatments had varying effects on the fast and slow C pools, microbial activity, and microbial community structure in the studied soils. For minor exceptions, DF dramatically accelerated C loss from the slow C pool in all soil types. We assume that differences in C pool and microbiota responses to DF addition were caused by soil texture and changes in microbial community structure. We isolated Serratia proteamaculans, S. liquefaciens, S. plymuthica, Rhodococcus erythropolis, Pseudomonas antarctica, P. libanensis, P. brassicacearum, and P. chlororaphis from the DF-polluted soils. These species are recommended for bioremediation to mitigate the DF contamination of permafrost soils, especially regarding climate change and the sustainable well-being of Arctic ecosystems.
Topics: Permafrost; Soil; Gasoline; Ecosystem; Soil Microbiology; Arctic Regions; Carbon
PubMed: 36780979
DOI: 10.1016/j.envpol.2023.121269 -
Frontiers in Microbiology 2022Currently, plant growth-promoting rhizobacteria (PGPR) microbial inoculants are heavily used in agricultural production among which sp. and sp. are two excellent...
Currently, plant growth-promoting rhizobacteria (PGPR) microbial inoculants are heavily used in agricultural production among which sp. and sp. are two excellent inoculum strains, which are widely used in plant growth promotion and disease control. However, few studies have been conducted on the combined use of the two bacteria. The aim of this study was to investigate the effects of co-inoculation of these two bacteria on soybean [ (L.) ] growth and physiological indexes and further study the effect of microbial inoculants on native soil bacterial communities and plant endophyte microbiota, especially microorganisms in rhizosphere and root. A pot experiment was conducted and four treatments were designed: group without any strain inoculant (CK); group inoculated with H1 inoculant (J); group inoculated with Y1 inoculant (Y) and group inoculated with equal volume of H1 inoculant and Y1 inoculant (H). Compared with CK, the three inoculant groups J, Y, and H exhibited improved soybean growth and physiological indexes, and group H was the most significant ( < 0.05). In terms of rhizosphere bacterial community structure, the relative abundance of native (9.31%) was higher in the H group than in the J (6.07%), Y (3.40%), and CK (5.69%) groups, which has potential value of disease suppression. Besides, compared with bacterial communities of the other three groups in soybean roots, group H increased the abundance of beneficial bacterial community for the contents of , , and significantly increased ( < 0.05). In conclusion, we found that the composite inoculum of H1 and Y1 could effectively promote soybean growth, increase yield and improve the beneficial bacterial community in root and rhizosphere and have certain value for soil improvement.
PubMed: 36699592
DOI: 10.3389/fmicb.2022.1079348 -
Frontiers in Plant Science 2022(Pc) representatives are found as part of the rhizosphere-associated microbiome, and different rhizospheric Pc strains frequently perform beneficial activities for the...
(Pc) representatives are found as part of the rhizosphere-associated microbiome, and different rhizospheric Pc strains frequently perform beneficial activities for the plant. In this study we described the interactions between the rhizospheric Pc strains PCL1601, PCL1606 and PCL1607 with a focus on their effects on root performance. Differences among the three rhizospheric Pc strains selected were first observed in phylogenetic studies and confirmed by genome analysis, which showed variation in the presence of genes related to antifungal compounds or siderophore production, among others. Observation of the interactions among these strains under lab conditions revealed that PCL1606 has a better adaptation to environments rich in nutrients, and forms biofilms. Interaction experiments on plant roots confirmed the role of the different phenotypes in their lifestyle. The PCL1606 strain was the best adapted to the habitat of avocado roots, and PCL1607 was the least, and disappeared from the plant root scenario after a few days of interaction. These results confirm that 2 out 3 rhizospheric Pc strains were fully compatible (PCL1601 and PCL1606), efficiently colonizing avocado roots and showing biocontrol activity against the fungal pathogen . The third strain (PCL1607) has colonizing abilities when it is alone on the root but displayed difficulties under the competition scenario, and did not cause deleterious effects on the other Pc competitors when they were present. These results suggest that strains PCL1601 and PCL1606 are very well adapted to the avocado root environment and could constitute a basis for constructing a more complex beneficial microbial synthetic community associated with avocado plant roots.
PubMed: 36589057
DOI: 10.3389/fpls.2022.1063182 -
Microbial Biotechnology Mar 2023Mediated extracellular electron transfer (EET) might be a great vehicle to connect microbial bioprocesses with electrochemical control in stirred-tank bioreactors....
Mediated extracellular electron transfer (EET) might be a great vehicle to connect microbial bioprocesses with electrochemical control in stirred-tank bioreactors. However, mediated electron transfer to date is not only much less efficient but also much less studied than microbial direct electron transfer to an anode. For example, despite the widespread capacity of pseudomonads to produce phenazine natural products, only Pseudomonas aeruginosa has been studied for its use of phenazines in bioelectrochemical applications. To provide a deeper understanding of the ecological potential for the bioelectrochemical exploitation of phenazines, we here investigated the potential electroactivity of over 100 putative diverse native phenazine producers and the performance within bioelectrochemical systems. Five species from the genera Pseudomonas, Streptomyces, Nocardiopsis, Brevibacterium and Burkholderia were identified as new electroactive bacteria. Electron discharge to the anode and electric current production correlated with the phenazine synthesis of Pseudomonas chlororaphis subsp. aurantiaca. Phenazine-1-carboxylic acid was the dominant molecule with a concentration of 86.1 μg/ml mediating an anodic current of 15.1 μA/cm . On the other hand, Nocardiopsis chromatogenes used a wider range of phenazines at low concentrations and likely yet-unknown redox compounds to mediate EET, achieving an anodic current of 9.5 μA/cm . Elucidating the energetic and metabolic usage of phenazines in these and other species might contribute to improving electron discharge and respiration. In the long run, this may enhance oxygen-limited bioproduction of value-added compounds based on mediated EET mechanisms.
Topics: Phenazines; Pseudomonas; Oxidation-Reduction
PubMed: 36571174
DOI: 10.1111/1751-7915.14199 -
Journal of Functional Biomaterials Nov 2022This paper reports the results of the large-scale field testing of composite materials with antibacterial properties in a tropical climate. The composite materials,...
This paper reports the results of the large-scale field testing of composite materials with antibacterial properties in a tropical climate. The composite materials, based on a cotton fabric with a coating of metal oxide nanoparticles (TiO2 and/or ZnO), were produced using high-power ultrasonic treatment. The antibacterial properties of the materials were studied in laboratory tests on solid and liquid nutrient media using bacteria of different taxonomic groups (Escherichia coli, Chromobacterium violaceum, Pseudomonas chlororaphis). On solid media, the coatings were able to achieve a >50% decrease in the number of bacteria. The field tests were carried out in a tropical climate, at the Climate test station “Hoa Lac” (Hanoi city, Vietnam). The composite materials demonstrated long-term antibacterial activity in the tropical climate: the number of microorganisms remained within the range of 1−3% in comparison with the control sample for the duration of the experiment (3 months). Ten of the microorganisms that most frequently occurred on the surface of the coated textiles were identified. The bacteria were harmless, while the fungi were pathogenic and contributed to fabric deterioration. Tensile strength deterioration was also studied, with the fabrics coated with metal oxides demonstrating a better preservation of their mechanical characteristics over time, (there was a 42% tensile strength decrease for the reference non-coated sample and a 21% decrease for the sample with a ZnO + CTAB coating).
PubMed: 36412874
DOI: 10.3390/jfb13040233 -
Frontiers in Microbiology 2022Rhizosphere microbes play a vital role in plant health and defense against soil-borne diseases. Previous studies showed that maize-soybean relay strip intercropping...
Rhizosphere microbes play a vital role in plant health and defense against soil-borne diseases. Previous studies showed that maize-soybean relay strip intercropping altered the diversity and composition of pathogenic species and biocontrol fungal communities in the soybean rhizosphere, and significantly suppressed soybean root rot. However, whether the rhizosphere bacterial community participates in the regulation of this intercropping on soybean root rot is not clear. In this study, the rhizosphere soil of soybean healthy plants was collected in the continuous cropping of maize-soybean relay strip intercropping and soybean monoculture in the fields, and the integrated methods of microbial profiling, dual culture assays , and pot experiments were employed to systematically investigate the diversity, composition, and function of rhizosphere bacteria related to soybean root rot in two cropping patterns. We found that intercropping reshaped the rhizosphere bacterial community and increased microbial community diversity, and meanwhile, it also recruited much richer and more diverse species of sp., sp., sp., and sp. in soybean rhizosphere when compared with monoculture. From the intercropping, nine species of rhizosphere bacteria displayed good antagonism against the pathogen B3S1 of soybean root rot, and among them, IRHB3 (), IRHB6 (), and IRHB9 () were the dominant bacteria and extraordinarily rich. In contrast, MRHB108 () and MRHB205 () were the only antagonistic bacteria from monoculture, which were relatively poor in abundance. Interestingly, introducing IRHB3 into the cultured substrates not only significantly promoted the growth and development of soybean roots but also improved the survival rate of seedlings that suffered from infection. Thus, this study proves that maize-soybean relay strip intercropping could help the host resist soil-borne root rot by reshaping the rhizosphere bacterial community and driving more beneficial microorganisms to accumulate in the soybean rhizosphere.
PubMed: 36386647
DOI: 10.3389/fmicb.2022.1009689 -
Microbial Ecology Aug 2023Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent...
First Study Case of Microbial Biocontrol Agents Isolated from Aquaponics Through the Mining of High-Throughput Sequencing Data to Control Pythium aphanidermatum on Lettuce.
Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent study using high-throughput sequencing (HTS) technologies highlighted that microbial communities from an aquaponic system could control one of the most problematic pathogens in soilless lettuce culture, namely, Pythium aphanidermatum. Therefore, this study aims at isolating the microorganisms responsible for this biocontrol action. Based on the most promising genera identified by HTS, an innovative strategy for isolating and testing original biocontrol agents from aquaponic water was designed to control P. aphanidermatum. Eighty-two bacterial strains and 18 fungal strains were isolated, identified by Sanger sequencing, and screened in vivo to control damping-off of lettuce seeds caused by P. aphanidermatum. Out of these 100 isolates, the eight most efficacious ones were selected and further tested individually to control root rot disease caused by the same pathogen at a later stage of lettuce growth. Strains SHb30 (Sphingobium xenophagum), G2 (Aspergillus flavus), and Chito13 (Mycolicibacterium fortuitum) decreased seed damping-off at a better rate than a propamocarb fungicide and a Pseudomonas chlororaphis registered biocontrol agent did. In root rot bioassays, lettuce mortality was prevented by applying strains G2 and Chito13, which were at least as efficacious as the fungicide or biopesticide controls. Lettuce disease symptoms and mortality were eradicated by strain SHb30 in the first bioassay, but not in the second one. These results show that aquaponic systems are promising sources of original biocontrol agents, and that HTS-guided strategies could represent interesting approaches to identify new biocontrol agents.
Topics: Animals; Fungicides, Industrial; Pythium; Lactuca; Pest Control, Biological; Plant Diseases; Water; High-Throughput Nucleotide Sequencing
PubMed: 36334118
DOI: 10.1007/s00248-022-02126-1 -
Microorganisms Oct 2022Grapevine trunk diseases (GTDs) are caused by multiple unrelated fungal pathogens, and their management remains difficult worldwide. Biocontrol is an attractive and...
Grapevine trunk diseases (GTDs) are caused by multiple unrelated fungal pathogens, and their management remains difficult worldwide. Biocontrol is an attractive and sustainable strategy given the current need for a cleaner viticulture. In this study, twenty commercial vineyards were sampled across California to isolate endophytic and rhizospheric bacteria from different grapevine cultivars with the presence and absence of GTD symptoms. A collection of 1344 bacterial isolates were challenged in vitro against and , from which a subset of 172 isolates exerted inhibition levels of mycelial growth over 40%. Bacterial isolates were identified as ( 154), spp. ( 12), ( 2) and others that were later excluded ( 4). Representative isolates of , and were challenged against six other fungal pathogens responsible for GTDs. Mycelial inhibition levels were consistent across bacterial species, being slightly higher against slow-growing fungi than against Botryosphaeriaceae. Moreover, agar-diffusible metabolites of strongly inhibited the growth of and , at 1, 15, and 30% /. The agar-diffusible metabolites of and , however, caused lower inhibition levels against both pathogens, but their volatile organic compounds showed antifungal activity against both pathogens. These results suggest that , and constitute potential biocontrol agents (BCAs) against GTDs and their application in field conditions should be further evaluated.
PubMed: 36296311
DOI: 10.3390/microorganisms10102035 -
Frontiers in Microbiology 2022Vaginal and cervical canal bacteria are associated with women's health and pregnancy outcomes. Here, we compared their composition and characteristics in 37...
Vaginal and cervical canal bacteria are associated with women's health and pregnancy outcomes. Here, we compared their composition and characteristics in 37 reproductive-aged Chinese women including 24 pregnant women with cervical incompetence (vaginal and cervical canal bacteria formed Groups A and B, respectively) and 13 healthy pregnant women (vaginal and cervical canal bacteria formed Groups C and D, respectively) using high-throughput sequencing of the V4 region of 16S rRNA gene. The results of alpha and beta diversity analysis, respectively, indicated no statistical differences between Groups A and B ( = 0.32, 0.06), nor Groups B and D ( = 0.69, 0.74); however, differences were found between Groups C and D ( = 0.02, 0.01) and between Groups A and C ( = 0.04, 0.02). PLS-DA analysis showed that the individuals from each group were irregularly distributed according to their clade. , and were the dominant genera in all groups. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSts) analysis identified 31 Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs associated with the bacterial communities from the four groups, including membrane transport, folding, sorting and degradation, xenobiotics biodegradation and metabolism, and nucleotide metabolism. We further determined relationships between pregnancy outcomes (Apgar scores) and certain bacterial species. A significant positive correlation was found between Apgar scores and and in the vagina and cervical canal of pregnant women with cervical incompetence while , and in the cervical canal displayed negative correlations with Apgar scores. Moreover, , , and in the vagina were negatively correlated with Apgar scores. These bacteria may serve as potential biomarkers, however, additional research is warranted to verify their role in clinical outcomes.
PubMed: 36246259
DOI: 10.3389/fmicb.2022.986326