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BioRxiv : the Preprint Server For... May 2024are exposed to a variety of pathogenic and non-pathogenic bacteria species in their natural environment. Correspondingly, has evolved an ability to discern between...
are exposed to a variety of pathogenic and non-pathogenic bacteria species in their natural environment. Correspondingly, has evolved an ability to discern between nutritive and infectious bacterial food sources. Here we show that can learn to avoid the pathogenic bacteria (PF15), and that this learned avoidance behavior is passed on to progeny for four generations, as we previously demonstrated for (PA14) and , using similar mechanisms, including the involvement of both the TGF-β ligand DAF-7 and retrotransposon-encoded virus-like particles. PF15 small RNAs are both necessary and sufficient to induce this transgenerational avoidance behavior. Unlike PA14 or , PF15 does not use P11, Pv1, or a small RNA with homology for this avoidance; instead, an unrelated PF15 small RNA, Pfs1, that targets the Ephrin receptor gene is necessary and sufficient for learned avoidance, suggesting the evolution of yet another bacterial sRNA/ gene target pair involved in transgenerational inheritance of pathogen avoidance. As VAB-2 Ephrin receptor ligand and MACO-1 knockdown also induce PF15 avoidance, we have begun to understand the genetic pathway involved in small RNA targeted pathogenic avoidance. Moreover, these data show that axon guidance pathway genes (VAB-1 and VAB-2) have previously unknown adult roles in regulating neuronal function. may have evolved multiple bacterial specificity-encoded small RNA-dependent mechanisms to avoid different pathogenic bacteria species, thereby providing progeny with a survival advantage in a dynamic environment.
PubMed: 38826453
DOI: 10.1101/2024.05.23.595334 -
Frontiers in Plant Science 2023The use of biocontrol agents with plant growth-promoting activity has emerged as an approach to support sustainable agriculture. During our field evaluation of potato...
The use of biocontrol agents with plant growth-promoting activity has emerged as an approach to support sustainable agriculture. During our field evaluation of potato plants treated with biocontrol rhizobacteria, four bacteria were associated with increased plant height. Using two important solanaceous crop plants, tomato and potato, we carried out a comparative analysis of the growth-promoting activity of the four bacterial strains: SLU99, S412, AV10, and EV23. Greenhouse and experiments showed that SLU99 promoted plant height, biomass accumulation, and yield of potato and tomato plants, while EV23 promoted growth in potato but not in tomato plants. SLU99 induced the expression of plant hormone-related genes in potato and tomato, especially those involved in maintaining homeostasis of auxin, cytokinin, gibberellic acid and ethylene. Our results reveal potential mechanisms underlying the growth promotion and biocontrol effects of these rhizobacteria and suggest which strains may be best deployed for sustainably improving crop yield.
PubMed: 37534284
DOI: 10.3389/fpls.2023.1141692 -
World Journal of Microbiology &... Jan 2024Pseudomonas fluorescens complex consists of environmental and some human opportunistic pathogenic bacteria. It includes mainly beneficial and few phytopathogenic species... (Review)
Review
Pseudomonas fluorescens complex consists of environmental and some human opportunistic pathogenic bacteria. It includes mainly beneficial and few phytopathogenic species that are common inhabitants of soil and plant rhizosphere. Many members of the group are in fact known as effective biocontrol agents of plant pathogens and as plant growth promoters and for these attitudes they are of great interest for biotechnological applications. The antagonistic activity of fluorescent Pseudomonas is mainly related to the production of several antibiotic compounds, lytic enzymes, lipopeptides and siderophores. Several volatile organic compounds are also synthesized by fluorescent Pseudomonas including different kinds of molecules that are involved in antagonistic interactions with other organisms and in the induction of systemic responses in plants. This review will mainly focus on the volatile compounds emitted by some members of P. fluorescens complex so far identified, with the aim to highlight the role played by these molecules in the interaction of the bacteria with phytopathogenic micro and macro-organisms and plants.
Topics: Humans; Pseudomonas; Pseudomonas fluorescens; Plants; Rhizosphere; Plant Development; Plant Diseases
PubMed: 38281212
DOI: 10.1007/s11274-023-03873-0 -
MicroLife 2024Pyoverdin is a water-soluble metal-chelator synthesized by members of the genus and used for the acquisition of insoluble ferric iron. Although freely diffusible in...
Pyoverdin is a water-soluble metal-chelator synthesized by members of the genus and used for the acquisition of insoluble ferric iron. Although freely diffusible in aqueous environments, preferential dissemination of pyoverdin among adjacent cells, fine-tuning of intracellular siderophore concentrations, and fitness advantages to pyoverdin-producing versus nonproducing cells, indicate control of location and release. Here, using time-lapse fluorescence microscopy to track single cells in growing microcolonies of SBW25, we show accumulation of pyoverdin at cell poles. Accumulation occurs on cessation of cell growth, is achieved by cross-feeding in pyoverdin-nonproducing mutants and is reversible. Moreover, accumulation coincides with localization of a fluorescent periplasmic reporter, suggesting that pyoverdin accumulation at cell poles is part of the general cellular response to starvation. Compatible with this conclusion is absence of non-accumulating phenotypes in a range of pyoverdin mutants. Analysis of the performance of pyoverdin-producing and nonproducing cells under conditions promoting polar accumulation shows an advantage to accumulation on resumption of growth after stress. Examination of pyoverdin polar accumulation in a multispecies community and in a range of laboratory and natural species of , including PAO1 and KT2440, confirms that the phenotype is characteristic of .
PubMed: 38370141
DOI: 10.1093/femsml/uqae001 -
Microorganisms Sep 2023An experimental study by the Paul-Ehrlich Institute (PEI) demonstrated that temperatures between 35 and 37 °C are too high for the growth of some bacterial strains...
An experimental study by the Paul-Ehrlich Institute (PEI) demonstrated that temperatures between 35 and 37 °C are too high for the growth of some bacterial strains (e.g., ), leading to false negative results. Thus, the question of whether it is necessary to adapt incubation temperatures for the microbiological control of blood products, especially platelet concentrates (PCs), to enhance safety and regulatory compliance has arisen. In order to further elucidate this issue, the growth capability of different bacterial strains of interest in PCs and the detection efficacy of cultivation of these at different incubation temperatures must be taken into account. Therefore, we inoculated PCs with 46 different strains (3-6 PCs from different donors per strain) from different origins (PC isolates, reference strains) and stored PCs at 20-22 °C under constant agitation. On day three of storage, the inoculated PCs were sampled; aerobic and anaerobic culture bottles (BacT/Alert AST/NST) were each inoculated with 5 mL of sample, and culture bottles were incubated at 25 and 35 °C using the automated BacT/Alert Dual-temperature system. Bacterial proliferation was enumerated using a colony-forming assay. All strains of ( = 5), spp. ( = 11), spp. ( = 5), and spp. ( = 4) and most strains (4 of 5) tested showed the capability to grow in most inoculated PCs, revealing a faster time to detection (TTD) at an incubation temperature of 35 °C. The tested ( = 3) strains showed a noticeably reduced capability to grow in PCs. Nonetheless, those with a notable growth capability revealed a faster TTD at an incubation temperature of 35 °C. Only one of the four strains tested (strain ATCC 13525) was able to grow in PCs, showing a faster TTD at an incubation temperature of 25 °C but also detection at 35 °C. The commonly detected bacteria involved in the bacterial contamination of PCs showed a superior TTD at 35 °C incubation. Only one strain showed superior growth at 25 °C; however, the microbiological control at 35 °C did not fail to identify this contamination. In conclusion, the use of PC screening using a dual-temperature setting for microbiological control is presently not justified according to the observed kinetics.
PubMed: 37764194
DOI: 10.3390/microorganisms11092350 -
Microbiology (Reading, England) Oct 2023The observed mutational spectrum of adaptive outcomes can be constrained by many factors. For example, mutational biases can narrow the observed spectrum by increasing...
The observed mutational spectrum of adaptive outcomes can be constrained by many factors. For example, mutational biases can narrow the observed spectrum by increasing the rate of mutation at isolated sites in the genome. In contrast, complex environments can shift the observed spectrum by defining fitness consequences of mutational routes. We investigate the impact of different nutrient environments on the evolution of motility in Pf0-2x (an engineered non-motile derivative of Pf0-1) in the presence and absence of a strong mutational hotspot. Previous work has shown that this mutational hotspot can be built and broken via six silent mutations, which provide rapid access to a mutation that rescues swimming motility and confers the strongest swimming phenotype in specific environments. Here, we evolved a hotspot and non-hotspot variant strain of Pf0-2x for motility under nutrient-rich (LB) and nutrient-limiting (M9) environmental conditions. We observed the hotspot strain consistently evolved faster across all environmental conditions and its mutational spectrum was robust to environmental differences. However, the non-hotspot strain had a distinct mutational spectrum that changed depending on the nutrient environment. Interestingly, while alternative adaptive mutations in nutrient-rich environments were equal to, or less effective than, the hotspot mutation, the majority of these mutations in nutrient-limited conditions produced superior swimmers. Our competition experiments mirrored these findings, underscoring the role of environment in defining both the mutational spectrum and the associated phenotype strength. This indicates that while mutational hotspots working in concert with natural selection can speed up access to robust adaptive mutations (which can provide a competitive advantage in evolving populations), they can limit exploration of the mutational landscape, restricting access to potentially stronger phenotypes in specific environments.
Topics: Mutation; Phenotype
PubMed: 37815519
DOI: 10.1099/mic.0.001395 -
Journal of Agricultural and Food... Aug 2023Carbon metabolism is critical for microbial physiology and remarkably affects the outcome of secondary metabolite production. The production of...
Carbon metabolism is critical for microbial physiology and remarkably affects the outcome of secondary metabolite production. The production of 2,4-diacetylphloroglucinol (2,4-DAPG), a bacterial secondary metabolite with a broad spectrum of antibiotic activity, is a major mechanism used by the soil bacterium 2P24 to inhibit the growth of plant pathogens and control disease occurrence. Strain 2P24 has evolved a complex signaling cascade to regulate the production of 2,4-DAPG. However, the role of the central carbon metabolism in modulating 2,4-DAPG production has not been fully determined. In this study, we report that the gene, which encodes citrate synthase, affects the expression of the 2,4-DAPG biosynthesis gene and is essential for the biocontrol capacity of strain 2P24. Our data showed that the mutation of remarkably decreased the biosynthesis of 2,4-DAPG. Consistent with this result, the addition of citrate in strain 2P24 resulted in increased 2,4-DAPG production and decreased levels of RsmA and RsmE. In comparison with the wild-type strain, the mutant was severely impaired in terms of biocontrol activity against the bacterial wilt disease of tomato plants caused by . Moreover, the mutant exhibited increased antioxidant activity, and the expression of oxidative, stress-associated genes, including , , and , was significantly upregulated in the mutant compared to the wild-type strain. Overall, our data indicate that the citrate synthase GltA plays an important role in the production of 2,4-DAPG and oxidative stress and is required for biocontrol capacity.
Topics: Pseudomonas fluorescens; Citrate (si)-Synthase; Bacterial Proteins; Phloroglucinol
PubMed: 37523467
DOI: 10.1021/acs.jafc.3c03051 -
Microbiology Resource Announcements Jun 2024We provide the complete genome sequence for a novel bacteriophage named UNO-G1W1. This phage was isolated from a single ice cover sampling. The genome was sequenced on...
We provide the complete genome sequence for a novel bacteriophage named UNO-G1W1. This phage was isolated from a single ice cover sampling. The genome was sequenced on the Nanopore MinION, generated with the direct terminal repeat-phage-pipeline and polished with Illumina short reads. Sequence identity classifies the phage as an .
PubMed: 38847506
DOI: 10.1128/mra.00384-24 -
Microbiology Spectrum Sep 2023The monothiol glutaredoxin GrxD plays an essential role in the biosynthesis of the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) and the biocontrol capacity of the...
The monothiol glutaredoxin GrxD plays an essential role in the biosynthesis of the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) and the biocontrol capacity of the soil bacterium 2P24. However, the detailed mechanism underlying GrxD-mediated activation of the production of 2,4-DAPG remains unclear. Here, we found that GrxD directly interacted with IbaG, a BolA protein family member. The mutation of significantly decreased 2,4-DAPG production. Furthermore, expressing restored the production of 2,4-DAPG in the double mutant to wild-type levels in the presence of dithiothreitol, suggesting that IbaG was required for GrxD-mediated regulation of 2,4-DAPG production. Transcriptome sequencing analyses revealed that IbaG plays a global role in gene regulation by affecting the expression of numerous genes throughout the genome. We also demonstrated that IbaG is an important regulator of several cellular processes, including swarming motility, biofilm formation, siderophore production, and acid resistance. Altogether, our data suggest that IbaG has an essential role in 2,4-DAPG production, motility, and biofilm formation. We also propose a regulatory mechanism linking GrxD to 2,4-DAPG production via IbaG. IMPORTANCE The production of 2,4-diacetylphloroglucinol (2,4-DAPG) is positively influenced by the monothiol glutaredoxin GrxD in 2P24. However, the regulatory mechanism underlying GrxD-mediated regulation of 2,4-DAPG biosynthesis is mostly uncharacterized. Here, we show the function of the BolA-like protein IbaG in 2,4-DAPG biosynthesis. We also demonstrate that GrxD directly interacts with IbaG and influences the redox state of IbaG. Altogether, this work provides new insights into the role of the highly conserved IbaG protein in regulating 2,4-DAPG synthesis, biofilm formation, and other biocontrol traits of .
PubMed: 37724877
DOI: 10.1128/spectrum.00985-23 -
MicrobiologyOpen Apr 2024Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream...
Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream products of its metabolism remain undefined in various gut bacteria. To bridge this knowledge gap, we employed genomic screening to pinpoint relevant metabolic targets. We also devised a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method to measure the levels of arginine, its upstream precursors, and downstream products in cell-free conditioned media from enteric pathobionts, including Escherichia coli, Klebsiella aerogenes, K. pneumoniae, Pseudomonas fluorescens, Acinetobacter baumannii, Streptococcus agalactiae, Staphylococcus epidermidis, S. aureus, and Enterococcus faecalis. Our findings revealed that all selected bacterial strains consumed glutamine, glutamate, and arginine, and produced citrulline, ornithine, and GABA in our chemically defined medium. Additionally, E. coli, K. pneumoniae, K. aerogenes, and P. fluorescens were found to convert arginine to agmatine and produce putrescine. Interestingly, arginine supplementation promoted biofilm formation in K. pneumoniae, while ornithine supplementation enhanced biofilm formation in S. epidermidis. These findings offer a comprehensive insight into arginine-ornithine metabolism in enteric pathobionts.
Topics: Ornithine; Putrescine; Arginine; Escherichia coli; Chromatography, Liquid; Staphylococcus aureus; Tandem Mass Spectrometry; Bacteria; Klebsiella pneumoniae
PubMed: 38560776
DOI: 10.1002/mbo3.1408