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BMC Microbiology Jul 2023Microorganisms that activate plant immune responses are useful for application as biocontrol agents in agriculture to minimize crop losses. The present study was...
BACKGROUND
Microorganisms that activate plant immune responses are useful for application as biocontrol agents in agriculture to minimize crop losses. The present study was conducted to identify and characterize plant immunity-activating microorganisms in Brassicaceae plants.
RESULTS
A total of 25 bacterial strains were isolated from the interior of a Brassicaceae plant, Raphanus sativus var. hortensis. Ten different genera of bacteria were identified: Pseudomonas, Leclercia, Enterobacter, Xanthomonas, Rhizobium, Agrobacterium, Pantoea, Rhodococcus, Microbacterium, and Plantibacter. The isolated strains were analyzed using a method to detect plant immunity-activating microorganisms that involves incubation of the microorganism with tobacco BY-2 cells, followed by treatment with cryptogein, a proteinaceous elicitor of tobacco immune responses. In this method, cryptogein-induced production of reactive oxygen species (ROS) in BY-2 cells serves as a marker of immune activation. Among the 25 strains examined, 6 strains markedly enhanced cryptogein-induced ROS production in BY-2 cells. These 6 strains colonized the interior of Arabidopsis plants, and Pseudomonas sp. RS3R-1 and Rhodococcus sp. RS1R-6 selectively enhanced plant resistance to the bacterial pathogens Pseudomonas syringae pv. tomato DC3000 and Pectobacterium carotovorum subsp. carotovorum NBRC 14082, respectively. In addition, Pseudomonas sp. RS1P-1 effectively enhanced resistance to both pathogens. We also comprehensively investigated the localization (i.e., cellular or extracellular) of the plant immunity-activating components produced by the bacteria derived from R. sativus var. hortensis and the components produced by previously isolated bacteria derived from another Brassicaceae plant species, Brassica rapa var. perviridis. Most gram-negative strains enhanced cryptogein-induced ROS production in BY-2 cells via the presence of cells themselves rather than via extracellular components, whereas many gram-positive strains enhanced ROS production via extracellular components. Comparative genomic analyses supported the hypothesis that the structure of lipopolysaccharides in the outer cell envelope plays an important role in the ROS-enhancing activity of gram-negative Pseudomonas strains.
CONCLUSIONS
The assay method described here based on elicitor-induced ROS production in cultured plant cells enabled the discovery of novel plant immunity-activating bacteria from R. sativus var. hortensis. The results in this study also suggest that components involved in the ROS-enhancing activity of the bacteria may differ depending largely on genus and species.
Topics: Brassicaceae; Reactive Oxygen Species; Arabidopsis; Pseudomonas syringae; Plant Immunity; Plant Diseases
PubMed: 37407947
DOI: 10.1186/s12866-023-02920-y -
Chemosphere Dec 2023Cr(VI) widely exists in the environment and has highly toxic, carcinogenic and mutagenic effects on all organisms. Physical/chemical methods to remove chromium pollution...
Cr(VI) widely exists in the environment and has highly toxic, carcinogenic and mutagenic effects on all organisms. Physical/chemical methods to remove chromium pollution are economically expensive and have disadvantages like high reagent consumption, energy requirements and so on, while bioremediation is an eco-friendly, simple and cost-effective way. In this study, a novel Cr(VI)-reducing strain, Microbacterium sp. NEAU-W11, was reported, and its reduction mechanism was investigated. Microbacterium sp. NEAU-W11 could effectively degrade Cr(VI) under the conditions of pH 7-10, 15-35 °C, and the coexistence of metal pollutants such as Pb and Ni, etc. In addition, both Fe and Cu could improve the reducing ability of strain NEAU-W11, and glucose and lactose as electron donors also had promoting effect. Heat treatment of resting cells confirmed that chromium removal was not biological sorption but biological reduction. The active reductase of strain NEAU-W11 to chromium(VI) mainly existed in the cell cytoplasm, which is the first report in the genus Microbacterium. Micro-characterization of strain NEAU-W11 and the reduction products identified the reduction products as Cr(III)-ligand complexes bound to extracellular polymeric substances (EPS). Collectively, this study systematically investigated the degradation mechanism of Microbacterium sp. NEAU-W11 and the distribution of degradation product Cr(III), providing a new reduction mechanism for the genus Microbacterium, providing a new perspective for a comprehensive understanding of the degradation and transport of chromium by bacteria, and providing theoretical reference for the migration of metal ions in environmental governance.
PubMed: 37734508
DOI: 10.1016/j.chemosphere.2023.140232 -
Environmental Pollution (Barking, Essex... Oct 2023Monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and o, m, and p-xylenes (BTEX) are high-risk pollutants because of their mutagenic and carcinogenic...
Monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and o, m, and p-xylenes (BTEX) are high-risk pollutants because of their mutagenic and carcinogenic nature. These pollutants are found with elevated levels in groundwater and soil in Canada at several contaminated sites. The intrinsic microbes present in the subsurface have the potential to degrade pollutants by their metabolic pathways and convert them to non-toxic products. However, the low subsurface temperature (5-10 °C) limits their growth and degradation ability. This study examined the feasibility of subsurface heat augmentation using geothermal heating for BTEX bioremediation. Novel potent BTEX-degrading bacterial strains were isolated from soil at 3.0, 42.6, and 73.2 m depths collected from a geothermal borehole during installation and screened using an enrichment technique. The selected strains were identified with Sanger sequencing and phylogenetic tree analysis, revealing that all the strains except Bacillus subtilis are novel with respective to BTEX degradation. The isolates, Microbacterium esteraromaticum and Bacillus infantis showed the highest degradation with 67.98 and 65.2% for benzene, 72.8 and 71.02% for toluene, 77.52 and 76.44% for ethylbenzene, and 74.58 and 74.04% for xylenes respectively. Further, temperature influence at 15 ± 1 °C, 28 ± 1 °C and 40 ± 1 °C was observed, which showed increased growth by two-fold and on average 35-49% more biodegradation at higher temperatures. Results showed that temperature is a positive stimulant for bioremediation, hence geothermal heating could also be a stimulant for in-situ bioremediation.
Topics: Xylenes; Benzene; Phylogeny; Benzene Derivatives; Toluene; Biodegradation, Environmental; Environmental Pollutants
PubMed: 37558195
DOI: 10.1016/j.envpol.2023.122303 -
International Journal of Systematic and... May 2024A novel Gram-staining-positive actinobacterium with antimicrobial activity, designated CFH 90308, was isolated from the sediment of a salt lake in Yuncheng, Shanxi,...
A novel Gram-staining-positive actinobacterium with antimicrobial activity, designated CFH 90308, was isolated from the sediment of a salt lake in Yuncheng, Shanxi, south-western China. The isolate exhibited the highest 16S rRNA gene sequence similarities to G72, NBRC 15708 and S3-E (98.5, 98.4 and 98.2 %, respectively), and formed a separate clade with S3-E in phylogenetic trees. The strain grew at 15-40 ºC, pH 6.0-8.0 and could tolerate NaCl up to a concentration of 15 % (w/v). The whole genome of strain CFH 90308 consisted of 4.33 Mbp and the DNA G+C content was 69.6 mol%. The acyl type of the peptidoglycan was glycolyl and the whole-cell sugars were galactose and mannose. The cell-wall peptidoglycan mainly contained alanine, glycine and lysine. The menaquinones of strain CFH 90308 were MK-12, MK-13 and MK-11. Strain CFH 90308 contained anteiso-C, anteiso-C, iso-C and iso-C as the predominant fatty acids. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CFH 90308 and the other species of the genus were found to be low (ANIb <81.3 %, dDDH <25.6 %). The secondary metabolite produced by strain CFH 90308 showed antibacterial activities against , , and methicillin-resistant . Based on genotypic, phenotypic and chemotaxonomic results, the isolate is considered to represent a novel species of the genus , for which the name sp. nov is proposed. The type strain is CFH 90308 (=DSM 105964=KCTC 49052).
Topics: Base Composition; Phylogeny; RNA, Ribosomal, 16S; Fatty Acids; DNA, Bacterial; China; Vitamin K 2; Bacterial Typing Techniques; Sequence Analysis, DNA; Microbacterium; Geologic Sediments; Peptidoglycan; Lakes; Nucleic Acid Hybridization; Sodium Chloride; Genome, Bacterial
PubMed: 38695865
DOI: 10.1099/ijsem.0.006362 -
Applied and Environmental Microbiology Nov 2023Polyhydroxyalkanoate (PHA) is a highly biodegradable microbial polyester, even in marine environments. In this study, we incorporated an enrichment culture-like approach...
Polyhydroxyalkanoate (PHA) is a highly biodegradable microbial polyester, even in marine environments. In this study, we incorporated an enrichment culture-like approach in the process of isolating marine PHA-degrading bacteria. The resulting 91 isolates were suggested to fall into five genera (, , , , and ) based on 16S rRNA analysis, including two novel genera ( and ) as marine PHA-degrading bacteria. (DSM 20489) and (NBRC 102226), the type strains closest to the several isolates, have an extracellular poly(3-hydroxybutyrate) [P(3HB)] depolymerase homolog that does not fit a marine-type domain composition. However, exhibited no PHA degradation ability, unlike . This result demonstrates that the isolated spp. are different species from . P(3HB) depolymerase homologs in the genus should be scrutinized in the future, particularly about which ones work as the depolymerase.
Topics: Polyhydroxyalkanoates; RNA, Ribosomal, 16S; Bays; Seawater; Pseudoalteromonas
PubMed: 37855636
DOI: 10.1128/aem.01488-23 -
Ecotoxicology and Environmental Safety Apr 2024Plastic pollution is a common concern of global environmental pollution. Polystyrene (PS) and polyethylene (PE) account for almost one-third of global plastic...
Plastic pollution is a common concern of global environmental pollution. Polystyrene (PS) and polyethylene (PE) account for almost one-third of global plastic production. However, so far, there have been few reports on microbial strains capable of simultaneously degrading PS and PE. In this study, Microbacterium esteraromaticum SW3, a non-pathogenic microorganism that can use PS or PE as the only carbon source in the mineral salt medium (MM), was isolated from plastics-contaminated soil and identified. The optimal growth conditions for SW3 in MM were 2% (w/v) PS or 2% (w/v) PE, 35°C and pH 6.3. A large number of bacteria and obvious damaged areas were observed on the surface of PS and PE products after inoculated with SW3 for 21 d. The degradation rates of PS and PE by SW3 (21d) were 13.17% and 5.39%, respectively. Manganese peroxidase and lipase were involved in PS and PE degradation by SW3. Through Fourier infrared spectroscopy detection, different functional groups such as carbonyl, hydroxyl and amidogen groups were produced during the degradation of PS and PE by SW3. Moreover, PS and PE were degraded into alkanes, ketones, carboxylic acids, esters and so on detected by GC-MS. Collectively, we have isolated and identified SW3, which can use PS or PE as the only carbon source in MM as well as degrade PS and PE products. This study not only provides a competitive candidate strain with broad biodegradability for the biodegradation of PS and/or PE pollution, but also provides new insights for the study of plastic biodegradation pathways.
Topics: Polystyrenes; Polyethylene; Soil; Actinomycetales; Biodegradation, Environmental; Carbon; Plastics; Microbacterium
PubMed: 38492484
DOI: 10.1016/j.ecoenv.2024.116207 -
Microorganisms Jul 2023The members of isolated from different environments are known to form peptidoglycan. In this study, we compared the biofilm-forming abilities of sp. PAMC22086...
The members of isolated from different environments are known to form peptidoglycan. In this study, we compared the biofilm-forming abilities of sp. PAMC22086 (PAMC22086), which was isolated from the soil in the South Shetland Islands and sp. PAMC21962 (PAMC21962), which was isolated from algae in the South Shetland Islands. The analysis of average nucleotide identity and phylogeny of PAMC22086 revealed a 97% similarity to VIU2A, while PAMC21962 showed a 99.1% similarity to SGAir0570. For the comparative genomic analysis of PAMC22086 and PAMC21962, the genes related to biofilm formation were identified using EggNOG and KEGG pathway databases. The genes possessed by both PAMC22086 and PAMC21962 are , , , and , which regulate virulence, biofilm formation, and multicellular structure. Among the genes indirectly involved in biofilm formation, unlike PAMC21962, PAMC22086 possessed , , and , which are responsible for attachment and glycogen biosynthesis. Additionally, in PAMC22086, additional functional genes which is involved in mobility and polysaccharide production, and , GTPase, and which play roles in cell cycle and stress response, were identified. In addition, the biofilm-forming ability of the two isolates was examined in vivo using the standard crystal violet staining technique, and morphological differences in the biofilm were investigated. It is evident from the different distribution of biofilm-associated genes between the two strains that the bacteria can survive in different niches by employing distinct strategies. Both strains exhibit distinct morphologies. PAMC22086 forms a biofilm that attaches to the side, while PAMC21962 indicates growth starting from the center. The biofilm formation-related genes in are not well understood. However, it has been observed that species form biofilm regardless of the number of genes they possess. Through comparison between different species, it was revealed that specific core genes are involved in cell adhesion, which plays a crucial role in biofilm formation. This study provides a comprehensive profile of the Microbacterium genus's genomic features and a preliminary understanding of biofilm in this genus, laying the foundation for further research.
PubMed: 37512929
DOI: 10.3390/microorganisms11071757 -
Frontiers in Microbiology 2024Legumes are renowned for their distinctive biological characteristic of forming symbiotic associations with soil bacteria, mostly belonging to the familiy, leading to... (Review)
Review
Legumes are renowned for their distinctive biological characteristic of forming symbiotic associations with soil bacteria, mostly belonging to the familiy, leading to the establishment of symbiotic root nodules. Within these nodules, rhizobia play a pivotal role in converting atmospheric nitrogen into a plant-assimilable form. However, it has been discerned that root nodules of legumes are not exclusively inhabited by rhizobia; non-rhizobial endophytic bacteria also reside within them, yet their functions remain incompletely elucidated. This comprehensive review synthesizes available data, revealing that and are the most prevalent genera of nodule endophytic bacteria, succeeded by , , , , and . To date, the bibliographic data available show that followed by and are the main hosts for nodule endophytic bacteria. Clustering analysis consistently supports the prevalence of and as the most abundant nodule endophytic bacteria, alongside , , and . Although non-rhizobial populations within nodules do not induce nodule formation, their presence is associated with various plant growth-promoting properties (PGPs). These properties are known to mediate important mechanisms such as phytostimulation, biofertilization, biocontrol, and stress tolerance, emphasizing the multifaceted roles of nodule endophytes. Importantly, interactions between non-rhizobia and rhizobia within nodules may exert influence on their leguminous host plants. This is particularly shown by co-inoculation of legumes with both types of bacteria, in which synergistic effects on plant growth, yield, and nodulation are often measured. Moreover these effects are pronounced under both stress and non-stress conditions, surpassing the impact of single inoculations with rhizobia alone.
PubMed: 38812696
DOI: 10.3389/fmicb.2024.1386742 -
The Science of the Total Environment Nov 2023Atrazine, a widely used herbicide, has adverse effects on the growth and metabolism of amphibians. Due to the cyclical application use of the pesticide atrazine in...
Atrazine, a widely used herbicide, has adverse effects on the growth and metabolism of amphibians. Due to the cyclical application use of the pesticide atrazine in agricultural production, atrazine concentrations in water occur in the form of pulses. However, knowledge of the effects of atrazine pulse exposure on the gut microbiota and metabolism of amphibians is limited. In this study, Pelophylax nigromaculatus tadpoles (Gs 26) were exposed to continuous and pulse atrazine (100 μg/L) for 60 days. The results showed that continuous exposure and pulse exposure had different effects on the diversity of gut microbiota. At the phyla level, pulse exposure significantly increased the relative abundance of Actinobacteria, and decreased the relative abundance of Firmicutes compared to continuous exposure. At the genus level, continuous and pulse exposure to atrazine significantly altered the relative abundance of Acetobacterium, Microbacterium, Bacteroides, Eulopiscium and Leuconostoc. Compared to continuous exposure, pulse exposure significantly increased the relative abundance of Microbacterium, and significantly decreased the relative abundance of Acetobacterium and Eplopiscium. In terms of metabolism, pulse exposure significantly increased the relative abundance of creatine, guanine, and inosine and significantly decreased the relative abundance of 3-hydroxysebacic acid, ganoderic acid F, hypoxanthine, and withaperuvin H compared to continuous exposure. Continuous and pulse exposure to atrazine significantly altered the relative abundance of metabolites of the pymidine metabolism, purine metabolism, beta-alanine metabolism and other pathways in the gut of P. nigromaculatus tadpoles. In addition, changes in most metabolites had a significant correlation with changes in gut microorganisms. In conclusion, our study confirmed that pulse exposure to atrazine has a greater effect on the composition of the gut microflora and the metabolism of P. nigromaculatus tadpoles than continuous exposure.
PubMed: 37495155
DOI: 10.1016/j.scitotenv.2023.165757 -
International Journal of Biological... Oct 2023Levan is a high-valued β-(2,6)-linked fructan with promising physicochemical and physiological properties and has diverse potential applications in the food,...
Levan is a high-valued β-(2,6)-linked fructan with promising physicochemical and physiological properties and has diverse potential applications in the food, nutraceutical, pharmaceutical and cosmetic industry, but its commercial availability is still restricted to the relatively high costs of production. In this study, a strain identified as Microbacterium sp. XL1 was isolated from soil and highly produced exopolysaccharide (EPS). HPLC, FTIR and NMR spectroscopy revealed XL1-EPS is a levan-type fructan connected by β-(2, 6) linkages. SEM, DLS and TGA-DSC analysis showed that XL1-EPS processed high morphological versatility, narrow size distribution in its solutions and excellent thermal stability. The levan yield reached 83.67 ± 4.06 g/L with corresponding productivity of 3.49 ± 0.17 g/L/h and a conversion yield of 39.8 ± 1.9 % using sucrose (210 g/L) as substrates under the optimal cultivation conditions concluded by the response surface methodology (RSM). More strikingly, the XL1 strain also has multi-type fructanases to generate levanbiose, kestose, DFA IV and other L-FOSs. These results suggest Microbacterium sp. XL1 is a promising strain to produce levan and can provide various levan/inulin-degrading enzymes to create a great diversity of FOSs.
PubMed: 37579898
DOI: 10.1016/j.ijbiomac.2023.126330