Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology最新文献

Polypropylene (PP) products are extensively utilized in both clinical and laboratory environments due to their advantageous physicochemical properties and cost-effectiveness. In this study, we investigated phenotypic alterations and oxidative stress responses of Pseudomonas aeruginosa (PA) under short-term PP exposure (24 h) through three experimental treatments: 0 mg/L PP (control), 10 mg/L PP (low concentration), and 1000 mg/L PP (high concentration). The results demonstrated that, compared to the control group, treatment with the low concentration and high concentration groups of PA led to enhanced resistance to four antibiotics: ciprofloxacin, imipenem, amikacin, and gentamicin. Biofilm formation increased by 45.68% and 140.93%, respectively, while pyocyanin production rose by 42.77% and 62.07%, respectively. At the same time, both swimming and twitching motilities were significantly enhanced. Furthermore, after treatment with the low- and high-concentration groups, the levels of H₂O₂ increased by 103.44% and 149.97%, respectively, malondialdehyde by 89.10% and 210.87%, and glutathione by 50.40% and 83.47%, respectively. Molecular dynamics simulations revealed that PP spontaneously formed a stable complex with the LasR receptor protein in PA through hydrogen bond interactions. The study concluded that under PP stress, PA exhibited enhanced resistance to certain antibiotics, altered phenotypic traits, and increased oxidative stress responses. These findings provide novel insights for public health strategies in preventing PA infections.

The microbial mineralization of struvite from high-salinity wastewater offers a promising approach for the simultaneous removal and recovery of phosphorus and nitrogen. Fish processing wastewater (FPW) is characterized by high organic pollutant loads, containing heavy metal copper ions, and variable salinity levels ranging from 2 to 21% NaCl. Such fluctuations in salinity can affect the efficiency of struvite biomineralization. The presence of heavy metal copper ions will also further restrict the function of the struvite-producing strains under high-salt conditions. This study focuses on screening microbial strains capable of producing struvite under high-salt stress and to investigate the impact of salt (NaCl) concentration on the treatment efficiency of synthetic FPW. Microorganisms were screened across a broad salinity range, and key parameters, including yield, pH, phosphate concentration, magnesium ion levels, and other indicators, were evaluated during the mineralization process. Furthermore, the ARTP mutagenesis technique was applied to identify mutant strains with enhanced copper ion tolerance and improved crystal production at 10% NaCl. A total of 54 microbial species were found to produce struvite while achieving elevated phosphorus (P) and magnesium (Mg) removal under 5% NaCl conditions. Among them, Halomonas olivaria MG-4 demonstrated broad salinity tolerance. Strain MG-4 exhibits a high recovery rate of P reaching 67% (p <  0.001) at 5% NaCl, and maintains 48–50% (p < 0.001) at 8–10% NaCl. Strain MG-4 exhibits a high recovery rate of P reaching 67% (p < 0.001) at 5% NaCl, and maintains 48–50% (p < 0.001) at 8–10% NaCl. The mutant strain MG-4(100 s-3) sustained high P and Mg removal and recovery efficiencies even at 8–10% NaCl in artificial wastewater systems. Compared with the wild-type MG-4, the mutant strain MG-4(100 s-3) exhibits enhanced tolerance to copper ions and significantly promotes struvite production at copper ion concentrations of 0.4–1.6 mM. These findings highlight valuable microbial resources for struvite biomineralization in FPW, offering potential for both efficient wastewater treatment and resource recovery.

Two aerobic bacterial isolates, designated as strains CA2-7^T and CA1UV-4^T, were isolated from soil samples collected at a construction site in Cheonan. Both strains were identified as Gram-stain-negative, rod-shaped and a phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains constitute a distinct lineage within the family Hymenobacter (order Cytophagales, class Cytophagia). The closest genetic relatives were found to be members of the genus Hymenobacter, specifically Hymenobacter ginkgonis HMF4947^T (with 16S rRNA gene sequence similarity of 97.28%) and Hymenobacter segetis S7-3-11^T (98.10%). Both strains grew optimally at pH 7.0, 25 °C, without NaCl. Fatty acid analysis revealed distinctive profiles, with C_15:0 anteiso and C_15:0 iso predominating in strain CA2-7^T, while C_15:0 iso and summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) were the primary fatty acids in strain CA1UV-4^T. Both strains exhibited MK-7 as the major respiratory quinone. Biochemical, chemotaxonomic, and phylogenetic data support CA2-7^T and CA1UV-4^T as new Hymenobacter species. Accordingly, we suggest the names Hymenobacter cheonanensis and Hymenobacter convexus for strains CA2-7^T (= KCTC 92968^T = NBRC 116577^T) and CA1UV-4^T (= KCTC 92970^T = NBRC 116576^T), respectively.

Pseudomonas gelidaquae IB20^T is a rod-shaped, motile bacterium distinguished by the presence of multiple polar flagella. The average nucleotide identity (ANIb) and average amino acid identity (AAI) values between P. gelidaquae IB20^T and its closest phylogenetic relatives were all below the 95–96% thresholds currently accepted for delineating a novel species. Pseudomonas antarctica CMS 35 ^T displayed the highest ANIb and AAI values, at 92.67% and 95.98%, respectively. A distinctive feature of the P. gelidaquae IB20^T genome is the presence of a Type III Secretion System (T3SS), which is absent in the genomes of all closely related strains, making it the first Pseudomonas species isolated from Antarctica to carry this virulence system. Notably, we identified a novel candidate effector protein encoded within the T3SS gene cluster of P. gelidaquae IB20^T, exhibiting similarity to VopS T3SS effector proteins, which are predominantly found in Vibrio species. A comprehensive search of publicly available databases confirmed that this candidate effector protein is not present in any other Pseudomonas genome. Additionally, chemotaxonomic analysis showed that the dominant cellular fatty acids include summed feature 3 (C16:1ω7c/C15:0 iso 2-OH), C16:0, and C18:1ω7c. Based on extensive phenotypic and genotypic evidence, we propose that strain IB20^T represents a novel species within the genus Pseudomonas, for which the name P. gelidaquae sp. nov. is proposed, with IB20 designated as the type strain.

Corrinoid-dependent enzymes either catalyze methyltransfer reactions, or they generate substrate radicals using adenosylcobalamin for subsequent rearrangement reactions. The corrinoid-dependent methyltransferases are present in all domains of life and assumed to be exclusive for methyl-groups. In Methanosarcina, however, trace ethane production from ethanol has been shown in vivo, which led to the hypothesis that corrinoid-dependent methanol-specific methyltransferases are promiscuous towards also accepting ethyl-groups. Here, we show that the conversion of ethanol to trace amounts of ethane in Methanosarcina acetivorans involves homologous reactions of the known methanol-to-methane metabolism. The methanol methyltransferase (MtaB) activates ethanol and loads the ethyl-group onto the corrinoid-containing methyl-accepting protein (MtaC). Besides MtaCB, substrate promiscuity in corrinoid:coenzyme M methyltransferase (MtaA) and methyl-coenzyme M reductase (Mcr) are required to grant the microbe the capacity for ethane production. We show that the MtaCB subunits of M. acetivorans can activate ethanol, however, the ethane yields compared to methane are ca. 3 orders of magnitude lower. The ethyl-transfer capability was confirmed for each of the three MtaCB isozyme by quantifying the amount of ethane produced by mtaCB double deletion strains during growth in ethanol-supplemented media and in resting-cell suspensions. Ethane formation requires the cells to be grown on methanol to trigger the expression of the mtaCB genes, and detectable ethane formation starts only after all methanol has been consumed. Demonstrating that corrinoid-dependent methanol-specific methyltransferases process ethyl groups extends the pool of reactions to be considered in metabolic networks and suggests possible routes for biogenic ethane in nature.

Bacillus cereus is a significant foodborne pathogen whose infection can trigger gastrointestinal symptoms or systemic diseases in hosts, with severe cases potentially leading to sepsis or even death. In recent years, the misuse of antibiotics has led to varying degrees of drug resistance in foodborne pathogens, making the development of novel antimicrobial agents an urgent necessity. Natural active substances have become a focal point of current research due to their broad-spectrum and highly efficient antibacterial capabilities against foodborne pathogens. Prodigiosin (PG), initially garnering widespread attention in the pharmaceutical field for its multifunctional bioactivities, also demonstrates significant potential in the food industry. However, there is currently no reported research on the antibacterial effects of PG against B. cereus, its anti-infection mechanisms, and its impact on the host's intestinal microbiota. Based on this, our study focuses on PG as the research subject and B. cereus as the test strain, systematically investigating its therapeutic effect in B. cereus-infected mice. Additionally, we employed 16S rRNA-based microbiota analysis and metabolomics approaches to explore the effects of PG on the composition of the gut microbiota and metabolomic profiles. Collectively, PG exerts its therapeutic effects in B. cereus-infected mice by alleviating tissue damage, reducing inflammation, and modulating the abundance and diversity of the intestinal microbiota. These results highlight a novel strategy for alleviating B. cereus infections.

Although the buildup of plastic in the marine environment is a long-standing problem, it has only lately been realized how relevant this pollution may be to the ocean. Microplastic fragments are an emerging concern in this field. Due to their small size, they are easily consumed by marine animals and, combined with the poisons and bacteria that colonize the plastic, can accumulate in the food chain. Unlike non-plastic biofilms, plastic biofilms are diverse and driven by a complex web of elements, including seasonal and spatial parameters and substratum characteristics like size, texture, and polymer type. The major topic of the paper is the discussion of preliminary findings and knowledge gaps about microbial biofilm communities connected to microplastics. Additionally, the review addresses microplastic sources, associated toxicity, and the role of both bacterial and fungal communities in their degradation.

The gut-brain axis serves as a foundational communication channel between the intestinal microbiome and the brain, facilitating microbial impact on neural functions. Probiotics, defined as health-promoting live microorganisms, are being increasingly investigated for their regulatory effects on neuroplasticity and mental acuity. Recent evidence suggests that probiotics modulate hippocampal neurogenesis, a crucial process underlying learning, memory, and cognitive flexibility. Through the suppression of pro-inflammatory mechanisms, enhancement of neurotrophic factor biosynthesis, alleviation of oxidative burden, and stabilization of HPA axis function, probiotics contribute to sustaining hippocampal neural resilience and promoting synaptic adaptability. Evidence from both preclinical experiments and clinical evaluations suggests that strains like Lactobacillus rhamnosus, Bifidobacterium longum, and Lactobacillus plantarum may play a beneficial role in promoting adaptive cognitive functioning. These benefits are thought to be mediated via increased expression of brain-derived neurotrophic factor, modulation of microglial activation, and alteration of neurotransmitter metabolism including serotonin, dopamine, and GABA. This review synthesizes current findings on the molecular and cellular pathways through which probiotics support hippocampal neurogenesis and cognitive flexibility, and discusses their potential as a non-invasive, adjuvant strategy for cognitive enhancement in neurological disorders and age-related cognitive decline.