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International Journal of Biological... Dec 2021Serratia plymuthica strain IV-11-34 belongs to the plant growth promoting bacteria (PGPR). In the sequenced genome of S. plymuthica IV-11-34, we have identified the...
Serratia plymuthica strain IV-11-34 belongs to the plant growth promoting bacteria (PGPR). In the sequenced genome of S. plymuthica IV-11-34, we have identified the genes involved in biodegradation and metabolisms of xenobiotics. The potential of S. plymuthica IV-11-34 for the degradation of biodegradable aliphatic polyester polylactide (PLA) and resistant to biodegradation - poly(ethylene terephthalate) (PET) was assessed by biochemical oxygen consumption (BOD) and carbon dioxide methods. After seven days of growth, the bacteria strain showed more than 80% and 60% increase in respiratory activity in the presence of PLA and PET, respectively. We assume that during biodegradation, S. plymuthica IV-11-34 colonise the surface of PLA and PET, since the formation of a biofilm on the surface of polymers was shown by the LIVE/DEAD method. We have demonstrated for the relA gene, which is an alarmone synthetase, a 1.2-fold increase in expression in the presence of PLA, and a 4-fold decrease in expression in the presence of PET for the spoT gene, which is a hydrolase of alarmones. Research has shown that the bacterium has the ability to biodegrade PLA and PET, and the first stage of this process involves bacterial stringent response genes responsible for survival under extreme conditions.
Topics: Bacterial Proteins; Biodegradation, Environmental; Biofilms; Polyesters; Polyethylene Terephthalates; Serratia
PubMed: 34678385
DOI: 10.1016/j.ijbiomac.2021.10.063 -
Food Research International (Ottawa,... Dec 2022Isomaltulose (IM) is a non-cariogenic sugar and substitute for sucrose that has been widely used in candies and soft drinks. This sugar is obtained from sucrose through...
Isomaltulose (IM) is a non-cariogenic sugar and substitute for sucrose that has been widely used in candies and soft drinks. This sugar is obtained from sucrose through enzymatic conversion, catalyzed by microbial glucosyltransferases. In this study, alternative gums, namely: gum Arabic (GA), algaroba gum (AG), and cashew gum (CG) were combined with alginate (ALG) for the immobilization of Serratia plymuthica, with the aim of improving its capability for conversion of sucrose into IM. Prior to the immobilization, the gums were characterized using FTIR spectroscopy, TGA, and XRD analysis. Then, they were combined with ALG and used to immobilize a cell mass of S. plymuthica by ionic gelation. The morphology of the produced beads was visualized using SEM, and the sucrose into IM conversion using the beads was performed in batch and continuous processes. CG showed the highest thermal stability and crystallinity. The use of CG (2.0 %, w/v) combined with ALG (2.0 %, w/v) showed the highest value for isomaltulose (236.46 g/L) produced in the first batch, and high stability in the continuous conversion process; resulting in an IM production of 199.24 g/L at 72 h of reaction. In addition, this combination produced less porous beads, able to maintain the entrapped cells longer. In conclusion, the production of IM by Serratia plymuthica cells immobilized in a matrix composed of ALG and CG is recommended, due to its high conversion capacity and high stability.
Topics: Alginates; Isomaltose; Anacardium; Sucrose
PubMed: 36461264
DOI: 10.1016/j.foodres.2022.112050 -
BMC Biology Mar 2021Iron is essential for bacterial survival. Bacterial siderophores are small molecules with unmatched capacity to scavenge iron from proteins and the extracellular milieu,...
BACKGROUND
Iron is essential for bacterial survival. Bacterial siderophores are small molecules with unmatched capacity to scavenge iron from proteins and the extracellular milieu, where it mostly occurs as insoluble Fe. Siderophores chelate Fe for uptake into the cell, where it is reduced to soluble Fe. Siderophores are key molecules in low soluble iron conditions. The ability of bacteria to synthesize proprietary siderophores may have increased bacterial evolutionary fitness; one way that bacteria diversify siderophore structure is by incorporating different polyamine backbones while maintaining the catechol moieties.
RESULTS
We report that Serratia plymuthica V4 produces a variety of siderophores, which we term the siderome, and which are assembled by the concerted action of enzymes encoded in two independent gene clusters. Besides assembling serratiochelin A and B with diaminopropane, S. plymuthica utilizes putrescine and the same set of enzymes to assemble photobactin, a siderophore found in the bacterium Photorhabdus luminescens. The enzymes encoded by one of the gene clusters can independently assemble enterobactin. A third, independent operon is responsible for biosynthesis of the hydroxamate siderophore aerobactin, initially described in Enterobacter aerogenes. Mutant strains not synthesizing polyamine-siderophores significantly increased enterobactin production levels, though lack of enterobactin did not impact the production of serratiochelins. Knocking out SchF0, an enzyme involved in the assembly of enterobactin alone, significantly reduced bacterial fitness.
CONCLUSIONS
This study shows the natural occurrence of serratiochelins, photobactin, enterobactin, and aerobactin in a single bacterial species and illuminates the interplay between siderophore biosynthetic pathways and polyamine production, indicating routes of molecular diversification. Given its natural yields of diaminopropane (97.75 μmol/g DW) and putrescine (30.83 μmol/g DW), S. plymuthica can be exploited for the industrial production of these compounds.
Topics: Multigene Family; Polyamines; Serratia; Siderophores
PubMed: 33722216
DOI: 10.1186/s12915-021-00971-z -
Microorganisms Apr 2022Bacterial endophytes were isolated from nodules of pea and fava bean. The strains were identified and characterized for plant beneficial activities (phosphate...
Bacterial endophytes were isolated from nodules of pea and fava bean. The strains were identified and characterized for plant beneficial activities (phosphate solubilization, synthesis of indole acetic acid and siderophores) and salt tolerance. Based on these data, four strains of and three strains of were selected. To shed light on the mechanisms underlying salt tolerance, the proteome of the two most performant strains (Ra4 and Sp2) grown in the presence or not of salt was characterized. The number of proteins expressed by the endophytes was higher in the presence of salt. The modulated proteome consisted of 302 (100 up-regulated, 202 down-regulated) and 323 (206 up-regulated, 117 down-regulated) proteins in Ra4 and Sp2, respectively. Overall, proteins involved in abiotic stress responses were up-regulated, while those involved in metabolism and flagellum structure were down-regulated. The main up-regulated proteins in Sp2 were thiol: disulfide interchange protein DsbA, required for the sulfur binding formation in periplasmic proteins, while in Ra4 corresponded to the soluble fraction of ABC transporters, having a role in compatible solute uptake. Our results demonstrated a conserved response to salt stress in the two taxonomically related species.
PubMed: 35630335
DOI: 10.3390/microorganisms10050890 -
Applied Microbiology and Biotechnology Apr 2018The antibiotic pyrrolnitrin (PRN) is a tryptophan-derived secondary metabolite that plays an important role in the biocontrol of plant diseases due to its broad-spectrum...
The antibiotic pyrrolnitrin (PRN) is a tryptophan-derived secondary metabolite that plays an important role in the biocontrol of plant diseases due to its broad-spectrum of antimicrobial activities. The PRN biosynthetic gene cluster remains to be characterised in Serratia plymuthica, though it is highly conserved in PRN-producing bacteria. To better understand PRN biosynthesis and its regulation in Serratia, the prnABCD operon from S. plymuthica G3 was cloned, sequenced and expressed in Escherichia coli DH5α. Furthermore, an engineered strain prnind which is a conditional mutant of G3 prnABCD under the control of the Ptac promoter was constructed. This mutant was able to overproduce PRN with isopropylthiogalactoside (IPTG) induction by overexpressing prnABCD, whilst behaving as a conditional mutant of G3 prnABCD in the absence of IPTG. These results confirmed that prnABCD is responsible for PRN biosynthesis in strain G3. Further experiments involving lux-/dsRed-based promoter fusions, combined with site-directed mutagenesis of the putative σ extended -10 region in the prnA promoter, and liquid chromatography-mass spectrometry (LC-MS) analysis extended our previous knowledge about G3, revealing that quorum sensing (QS) regulates PRN biosynthesis through cross talk with RpoS, which may directly activated prnABCD transcription. These findings suggest that PRN in S. plymuthica G3 is produced in a tightly controlled manner, and has diverse functions, such as modulation of cell motility, in addition to antimicrobial activities. Meanwhile, the construction of inducible mutants could be a powerful tool to improve PRN production, beyond its potential use for the investigation of the biological function of PRN.
Topics: Gene Expression Regulation, Bacterial; Mutation; Operon; Pyrrolnitrin; Quorum Sensing; Serratia
PubMed: 29511844
DOI: 10.1007/s00253-018-8857-0 -
Frontiers in Microbiology 2021High fertilizer rates are often applied to horticulture crop production systems to produce high quality crops with minimal time in production. Much of the nutrients...
High fertilizer rates are often applied to horticulture crop production systems to produce high quality crops with minimal time in production. Much of the nutrients applied in fertilizers are not taken up by the plant and are leached out of the containers during regular irrigation. The application of plant growth promoting rhizobacteria (PGPR) can increase the availability and uptake of essential nutrients by plants, thereby reducing nutrient leaching and environmental contamination. Identification of PGPR can contribute to the formulation of biostimulant products for use in commercial greenhouse production. Here, we have identified MBSA-MJ1 as a PGPR that can promote the growth of containerized horticulture crops grown with low fertilizer inputs. MBSA-MJ1 was applied weekly as a media drench to × (petunia), (impatiens), and × (pansy). Plant growth, quality, and tissue nutrient concentration were evaluated 8weeks after transplant. Application of MBSA-MJ1 increased the shoot biomass of all three species and increased the flower number of impatiens. Bacteria application also increased the concentration of certain essential nutrients in the shoots of different plant species. and genomic characterization identified multiple putative mechanisms that are likely contributing to the strain's ability to increase the availability and uptake of these nutrients by plants. This work provides insight into the interconnectedness of beneficial PGPR mechanisms and how these bacteria can be utilized as potential biostimulants for sustainable crop production with reduced chemical fertilizer inputs.
PubMed: 34925296
DOI: 10.3389/fmicb.2021.788198 -
Frontiers in Microbiology 2021Apple ring rot caused by is an economically significant plant disease that spreads across the apple production areas in China. The pathogen infects apple fruits during...
Apple ring rot caused by is an economically significant plant disease that spreads across the apple production areas in China. The pathogen infects apple fruits during the growing season and results in postharvest fruits rot during storage, which brings about a huge loss to plant growers. The study demonstrated that an endophytic bacterium isolated from Chinese leek () significantly suppressed the mycelial growth, severely damaging the typical morphology of , and exerted a high inhibition of 84.64% against apple ring rot on postharvest apple fruit. Furthermore, significantly reduced the titratable acidity (TA) content, enhanced the soluble sugar (SS) content, vitamin C content, and SS/TA ratio, and maintained the firmness of the fruits. Furthermore, comparing the transcriptomes of the control and the treated mycelia revealed that significantly altered the expressions of genes related to membrane (GO:0016020), catalytic activity (GO:0003824), oxidation-reduction process (GO:0055114), and metabolism pathways, including tyrosine metabolism (ko00280), glycolysis/gluconeogenesis (ko00010), and glycerolipid metabolism (ko00561). The present study provided a possible way to control apple ring rot on postharvest fruit and a solid foundation for further exploring the underlying molecular mechanism.
PubMed: 35310399
DOI: 10.3389/fmicb.2021.802887 -
Frontiers in Microbiology 2021Rhizobacteria live in diverse and dynamic communities having a high impact on plant growth and development. Due to the complexity of the microbial communities and the...
Rhizobacteria live in diverse and dynamic communities having a high impact on plant growth and development. Due to the complexity of the microbial communities and the difficult accessibility of the rhizosphere, investigations of interactive processes within this bacterial network are challenging. In order to better understand causal relationships between individual members of the microbial community of plants, we started to investigate the inter- and intraspecific interaction potential of three rhizobacteria, the isolates 4Rx13 and AS9 and B2g, using high resolution mass spectrometry based metabolic profiling of structured, low-diversity model communities. We found that by metabolic profiling we are able to detect metabolite changes during cultivation of all three isolates. The metabolic profile of 4Rx13 differs interspecifically to B2g and surprisingly intraspecifically to AS9. Thereby, the release of different secondary metabolites represents one contributing factor of inter- and intraspecific variations in metabolite profiles. Interspecific co-cultivation of 4Rx13 and B2g showed consistently distinct metabolic profiles compared to mono-cultivated species. Thereby, putative known and new variants of the plipastatin family are increased in the co-cultivation of 4Rx13 and B2g. Interestingly, intraspecific co-cultivation of 4Rx13 and AS9 revealed a distinct interaction zone and showed distinct metabolic profiles compared to mono-cultures. Thereby, several putative short proline-containing peptides are increased in co-cultivation of 4Rx13 with AS9 compared to mono-cultivated strains. Our results demonstrate that the release of metabolites by rhizobacteria alters due to growth and induced by social interactions between single members of the microbial community. These results form a basis to elucidate the functional role of such interaction-triggered compounds in establishment and maintenance of microbial communities and can be applied under natural and more realistic conditions, since rhizobacteria also interact with the plant itself and many other members of plant and soil microbiota.
PubMed: 34135882
DOI: 10.3389/fmicb.2021.685224 -
Frontiers in Microbiology 2021Water stress decreases the health and quality of horticulture crops by inhibiting photosynthesis, transpiration, and nutrient uptake. Application of plant growth...
Water stress decreases the health and quality of horticulture crops by inhibiting photosynthesis, transpiration, and nutrient uptake. Application of plant growth promoting rhizobacteria (PGPR) can increase the growth, stress tolerance, and overall quality of field and greenhouse grown crops subjected to water stress. Here, we evaluated MBSA-MJ1 for its ability to increase plant growth and quality of × (petunia), (impatiens), and × (pansy) plants recovering from severe water stress. Plants were treated weekly with inoculum of MBSA-MJ1, and plant growth and quality were evaluated 2 weeks after recovery from water stress. Application of MBSA-MJ1 increased the visual quality and shoot biomass of petunia and impatiens and increased the flower number of petunia after recovery from water stress. In addition, characterizations showed that MBSA-MJ1 is a motile bacterium with moderate levels of antibiotic resistance that can withstand osmotic stress. Further, comprehensive genomic analyses identified genes putatively involved in bacterial osmotic and oxidative stress responses and the synthesis of osmoprotectants and vitamins that could potentially be involved in increasing plant water stress tolerance. This work provides a better understanding of potential mechanisms involved in beneficial plant-microbe interactions under abiotic stress using a novel strain as a model.
PubMed: 34046022
DOI: 10.3389/fmicb.2021.653556 -
Journal of Applied Microbiology Jan 2011To examine the biocontrol activity of broad-range antagonists Serratia plymuthica IC1270, Pseudomonas fluorescens Q8r1-96 and P. fluorescens B-4117 against tumourigenic...
AIM
To examine the biocontrol activity of broad-range antagonists Serratia plymuthica IC1270, Pseudomonas fluorescens Q8r1-96 and P. fluorescens B-4117 against tumourigenic strains of Agrobacterium tumefaciens and A. vitis.
METHODS AND RESULTS
Under greenhouse conditions, the antagonists, applied via root soak prior to injecting Agrobacterium strains into the wounded stems, significantly suppressed tumour development on tomato seedlings. A derivative of P. fluorescens Q8r1-96 tagged with a gfp reporter, as well as P. fluorescens B-4117 and S. plymuthica IC1270 marked with rifampicin resistance, stably persisted in tomato tissues for at least 1 month. Mutants of P. fluorescens Q8r1-96 and S. plymuthica IC1270 deficient in 2,4-diacetylphloroglucinol or pyrrolnitrin production, respectively, also proficiently suppressed the tumour development, indicating that these antibiotics are not responsible for the observed biocontrol effect on crown gall disease. The volatile organic compounds (VOCs) produced by the tested P. fluorescens and S. plymuthica strains inhibited the growth of A. tumefaciens and A. vitis strains in vitro. Solid-phase microextraction-gas chromatography-mass spectrometry analysis revealed dimethyl disulfide (DMDS) as the major headspace volatile produced by S. plymuthica IC1270; it strongly suppressed Agrobacterium growth in vitro and was emitted by tomato plants treated with S. plymuthica IC1270. 1-Undecene was the main volatile emitted by the examined P. fluorescens strains, with other volatiles, including DMDS, being detected in only relatively low quantities.
CONCLUSIONS
S. plymuthica IC1270, P. fluorescens B-4117 and P. fluorescens Q8r1-96 can be used as novel biocontrol agents of pathogenic Agrobacterium. VOCs, and specifically DMDS, might be involved in the suppression of oncogenicity in tomato plants. However, the role of specific volatiles in the biocontrol activity remains to be elucidated.
SIGNIFICANCE AND IMPACT OF THE STUDY
The advantage of applying these antagonists lies in their multiple activities against a number of plant pathogens, including Agrobacterium.
Topics: Agrobacterium tumefaciens; Gas Chromatography-Mass Spectrometry; Solanum lycopersicum; Phloroglucinol; Plant Tumors; Pseudomonas fluorescens; Serratia; Volatile Organic Compounds
PubMed: 21091861
DOI: 10.1111/j.1365-2672.2010.04891.x