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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 -
Environmental Science and Pollution... May 2024Fertilization can change the composition of antibiotic resistance genes(ARGs) and their host bacteria in agricultural fields, while complex microbial activities help...
Fertilization can change the composition of antibiotic resistance genes(ARGs) and their host bacteria in agricultural fields, while complex microbial activities help ARGs into crops and transmit them to humans through agricultural products.Therefore, this study constructed a farmland food chain with soil-lettuce-snail as a typical structure, added genetically engineered Pseudomonas fluorescens containing multidrug-resistant plasmid RP4 to track its spread in the farmland food chain, and used different fertilization methods to explore its influence on the spread and diffusion of ARGs and intl1 in the farmland food chain. It was found that exogenous Pseudomonas can enter plants from soil and pass into snails' intestines, and there is horizontal gene transfer phenomenon of RP4 plasmid in bacteria. At different interfaces of the constructed food chain, the addition of exogenous drug-resistant bacteria had different effects on the total abundance of ARGs and intl1. Fertilization, especially manure, not only promoted the spread of Pseudomonas aeruginosa and the transfer of RP4 plasmid levels, but also significantly increased the total abundance of ARGs and intl1 at all interfaces of the constructed food chain. The main ARGs host bacteria in the constructed food chain include Proteobacteria, Bacteroides, and Firmicutes, while Flavobacterium of Bacteroides is the unique potential host bacteria of RP4 plasmid. In conclusion, this study provides a reference for the risk assessment of ARGs transmitted to the human body through the food chain, and has important practical significance to reduce the antibiotic resistance contamination of agricultural products and ensure the safety of vegetable basket.
Topics: Plasmids; Soil Microbiology; Drug Resistance, Microbial; Animals; Food Chain; Snails; Soil; Gene Transfer, Horizontal; Anti-Bacterial Agents
PubMed: 38700770
DOI: 10.1007/s11356-024-33509-1 -
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 -
Archives of Microbiology May 2024The objective of this study was to investigate the effectiveness of a phage cocktail against Pseudomonas fluorescens group and its effect on the microbial, physical and...
The objective of this study was to investigate the effectiveness of a phage cocktail against Pseudomonas fluorescens group and its effect on the microbial, physical and chemical properties of raw milk during different storage conditions. A phage cocktail consisting of Pseudomonas fluorescens, Pseudomonas tolaasii, and Pseudomonas libanensis phages was prepared. As a result, reductions in fluorescent Pseudomonas counts of up to 3.44 log units for the storage at 4 °C and 2.38 log units for the storage at 25 °C were achieved. Following the phage application, it is found that there was no significant difference in the total mesophilic aerobic bacteria and Enterobacteriaceae counts. However, it was observed that the number of lactic acid bacteria was higher in phage-treated groups. The results also showed that pH values in the phage added groups were lower than the others and the highest titratable acidity was obtained only in the bacteria-inoculated group. As a future perspective, this study suggests that, while keeping the number of target microorganisms under control in the milk with the use of phages during storage, the microbiota and accordingly the quality parameters of the milk can be affected. This work contributes to the development of effective strategies for maintaining the quality and extending the shelf life of milk and dairy products.
Topics: Milk; Pseudomonas fluorescens; Animals; Pseudomonas Phages; Food Microbiology; Hydrogen-Ion Concentration; Bacteriophages
PubMed: 38806864
DOI: 10.1007/s00203-024-04008-1 -
Environmental Management Aug 2023Biotic stress management through bio-priming is a common practice among the farmers of the Indo-Gangetic Plains. However, this indigenous technology is less explored for...
Biotic stress management through bio-priming is a common practice among the farmers of the Indo-Gangetic Plains. However, this indigenous technology is less explored for the sustainable management of soil resources. Therefore, field-based experiments (2016-17 and 2017-18) were conducted in Varanasi to evaluate the combined effect of seedling bio-priming and fertilization on biochemical properties, microbiological properties, and fertility of red cabbage soil at harvest. Based on the farmers' fertilization practice, the recommended dose of fertilizers (RDF) of N:PO:KO were applied @ 120:60:60 kg ha. Three compatible bio-agents, viz., Trichoderma harzianum, Pseudomonas fluorescens, and Bacillus subtilis were applied alone and in combination with 75% RDF. The effect of treatment combinations was also analyzed for carbon (C) mineralization by conducting an incubation experiment for 90 days. Bio-priming treatments recorded a higher richness of soil microflora and soil fertility than control and sole application of chemical fertilizers. Application of 75% RDF + T. harzianum + P. fluorescens resulted in highest urease and cellulase activities and soil organic C. Inclusion of dual-species bacterial consortium (P. fluorescens and B. subtilis) in integrated system resulted in highest dehydrogenase activity and available P. These priming agents also exhibited significantly higher CO fluxes and C mineralization in our incubation study. A microbial consortium of T. harzianum and B. subtilis increased the microbial biomass C and available K. Although application of triple-species consortium improved C mineralization in laboratory conditions, the positive effects lowered down in field conditions. As a bottom-up approach, customization of bio-priming technology among farmers will help in attaining the UN-Sustainable Development Goals.
Topics: Humans; Soil; Agriculture; Fertilizers; Farmers; India; Soil Microbiology; Brassica
PubMed: 35391632
DOI: 10.1007/s00267-022-01638-3 -
Microbial Ecology Apr 2024Microorganisms produce siderophores, which are low-molecular-weight iron chelators when iron availability is limited. The present analyzed the role of LNPF1 as...
Purification and Characterization of Desferrioxamine B of Pseudomonas fluorescens and Its Application to Improve Oil Content, Nutrient Uptake, and Plant Growth in Peanuts.
Microorganisms produce siderophores, which are low-molecular-weight iron chelators when iron availability is limited. The present analyzed the role of LNPF1 as multifarious PGPR for improving growth parameters and nutrient content in peanut and soil nutrients. Such multifarious PGPR strains can be used as effective bioinoculants for peanut farming. In this work, rhizosphere bacteria from Zea mays and Arachis hypogaea plants in the Salem area of Tamil Nadu, India, were isolated and tested for biochemical attributes and characteristics that stimulate plant growth, such as the production of hydrogen cyanide, ammonia (6 µg/mL), indole acetic acid (76.35 µg/mL), and solubilizing phosphate (520 µg/mL). The 16S rRNA gene sequences identified the isolate LNPF1 as Pseudomonas fluorescens with a similarity percentage of 99% with Pseudomonas sp. Isolate LNPF1 was evaluated for the production of siderophore. Siderophore-rich supernatant using a Sep Pack C18 column and Amberlite-400 Resin Column (λmax 264) produced 298 mg/L and 50 mg/L of siderophore, respectively. The characterization of purified siderophore by TLC, HPLC, FTIR, and 2D-NMR analysis identified the compound as desferrioxamine, a hydroxamate siderophore. A pot culture experiment determined the potential of LNPF1 to improve iron and oil content and photosynthetic pigments in Arachis hypogaea L. and improve soil nutrient content. Inoculation of A. hypogea seeds with LNPF1 improved plant growth parameters such as leaf length (60%), shoot length (22%), root length (54.68%), fresh weight (47.28%), dry weight (37%), and number of nuts (66.66) compared to the control (untreated seeds). This inoculation also improved leaf iron content (43.42), short iron content (38.38%), seed iron (46.72%), seed oil (31.68%), carotenoid (64.40%), and total chlorophyll content (98.%) compared to control (untreated seeds). Bacterized seeds showed a substantial increase in nodulation (61.65%) and weight of individual nodules (95.97) vis-à-vis control. The results of the present study indicated that P. fluorescens might be utilized as a potential bioinoculant to improve growth, iron content, oil content, number of nuts and nodules of Arachishypogaea L., and enrich soil nutrients.
Topics: Arachis; Deferoxamine; Pseudomonas fluorescens; India; RNA, Ribosomal, 16S; Nutrients; Siderophores; Iron; Soil
PubMed: 38630182
DOI: 10.1007/s00248-024-02377-0 -
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 -
Scientific Reports Jan 2024There has recently been an explosion of studies implicating the human microbiome in playing a critical role in many disease and wellness states. The etiology of abnormal... (Observational Study)
Observational Study
There has recently been an explosion of studies implicating the human microbiome in playing a critical role in many disease and wellness states. The etiology of abnormal semen analysis (SA) parameters is not identified in 30% of cases; investigations involving the semen microbiome may bridge this gap. Here, we explore the relationship between the semen microbiome and alterations of sperm parameters. We recruited men presenting for fertility evaluation or vasectomy consultation with proven biological paternity. SA and next generation sequencing was performed. Differential abundance testing using Analysis of composition of Microbiota with Bias Correction (ANCOM-BC) was performed along with canonical correlational analysis for microbial community profiling. Men with abnormal (N = 27) sperm motility showed a higher abundance of Lactobacillus iners compared to those with normal (N = 46) sperm motility (mean proportion 9.4% versus 2.6%, p = 0.046). This relationship persisted on canonical correlational analysis (r = 0.392, p = 0.011). Men with abnormal sperm concentration (N = 20) showed a higher abundance of Pseudomonas stutzeri (2.1% versus 1.0%, p = 0.024) and Pseudomonas fluorescens (0.9% versus 0.7%, p = 0.010), but a lower abundance of Pseudomonas putida (0.5% versus 0.8%, p = 0.020), compared to those with normal sperm concentration (N = 53). Major limitations are related to study design (cross-sectional, observational). Our results suggest that a small group of microorganisms may play a critical role in observed perturbations of SA parameters. Some of these microbes, most notably Lactobacillus iners, have been described extensively within other, fertility-related, contexts, whereas for others, this is the first report where they have potentially been implicated. Advances in our understanding of the semen microbiome may contribute to potentially new therapeutic avenues for correcting impairments in sperm parameters and improving male fertility.
Topics: Humans; Male; Cross-Sectional Studies; Fertility; Infertility, Male; Lactobacillus; Semen; Semen Analysis; Sperm Count; Sperm Motility; Spermatozoa
PubMed: 38212576
DOI: 10.1038/s41598-024-51686-4 -
Food Microbiology Feb 2024Ultrasonic treatment is widely used for surface cleaning of vegetables in the processing of agricultural products. In the present study, the molecular and proteomic...
Ultrasonic treatment is widely used for surface cleaning of vegetables in the processing of agricultural products. In the present study, the molecular and proteomic response of Pseudomonas fluorescens biofilm cultured on lettuce was investigated after ultrasound treatment at different intensity levels. The results show that the biofilm was efficiently removed after ultrasound treatment with intensity higher than 21.06 W/cm. However, at an intensity of less than 18.42 W/cm, P. fluorescens was stimulated by ultrasound leading to promoted bacterial growth, extracellular protease activity, extracellular polysaccharide secretion (EPS), and synthesis of acyl-homoserine lactones (AHLs) as quorum-sensing signaling molecules. The expression of biofilm-related genes, stress response, and dual quorum sensing system was upregulated during post-treatment ultrasound. Proteomic analysis showed that ultrasound activated proteins in the flagellar system, which led to changes in bacterial tendency; meanwhile, a large number of proteins in the dual-component system began to be regulated. ABC transporters accelerated the membrane transport of substances inside and outside the cell membrane and equalized the permeability conditions of the cell membrane. In addition, the expression of proteins related to DNA repair was upregulated, suggesting that bacteria repair damaged DNA after ultrasound exposure.
Topics: Lactuca; Pseudomonas fluorescens; Proteomics; Biofilms; Quorum Sensing
PubMed: 37919011
DOI: 10.1016/j.fm.2023.104387 -
International Journal of Systematic and... Oct 2023Bacterial strain G20-18 was previously isolated from the rhizosphere of an Arctic grass on Ellesmere Island, Canada and was characterized and described as . However, new...
Bacterial strain G20-18 was previously isolated from the rhizosphere of an Arctic grass on Ellesmere Island, Canada and was characterized and described as . However, new polyphasic analyses coupled with phenotypic, phylogenetic and genomic analyses reported here demonstrate that the affiliation to the species was incorrect. The strain is Gram-stain-negative, rod-shaped, aerobic and displays growth at 5-25 °C (optimum, 20-25 °C), at pH 5-9 (optimum, pH 6-7) and with 0-4 % NaCl (optimum, 2 % NaCl). The major fatty acids are C (35.6 %), C cyclo 7 (26.3 %) and summed feature C/C ω7 (13.6 %). The respiratory quinones were determined to be Q9 (93.5 %) and Q8 (6.5 %) and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Strain G20-18 was shown to synthesize cytokinin and auxin plant hormones and to produce 1-aminocyclopropane-1-carboxylate deaminase. The DNA G+C content was determined to be 59.1 mol%. Phylogenetic analysis based on the 16S rRNA gene and multilocus sequence analysis (concatenated 16S rRNA, , and sequences) showed that G20-18 was affiliated with the subgroup within the genus . Comparisons of the G20-18 genome sequence and related type strain sequences showed an average nucleotide identity value of ≤93.6 % and a digital DNA-DNA hybridization value of less than 54.4 % relatedness. The phenotypic, phylogenetic and genomic data support the hypothesis that strain G20-18 represents a novel species of the genus . As strain G20-18 produces or modifies hormones, the name sp. nov. is proposed. The type strain is G20-18 (=LMG 33086=NCIMB 15469).
Topics: Fatty Acids; Phospholipids; Plant Growth Regulators; Sequence Analysis, DNA; Poaceae; Phylogeny; RNA, Ribosomal, 16S; Sodium Chloride; Genes, Bacterial; DNA, Bacterial; Base Composition; Bacterial Typing Techniques; Pseudomonas
PubMed: 37889848
DOI: 10.1099/ijsem.0.006119