Journal of Basic Microbiology最新文献

Arbuscular mycorrhizal (AM) symbiosis is increasingly recognized as a tripartite interaction involving the fungal symbiont, the host plant, and a diverse assemblage of associated bacteria. Through this study, propagule-specific bacteriome of Funneliformis mosseae was explored, particularly its taxonomic composition and plant growth-promoting (PGP) potential. Using a polyphasic approach integrating Illumina high-throughput sequencing with culture-dependent techniques, bacterial communities associated with monosporal hyphae and spores were characterized. Sequencing analyses revealed distinct taxonomic profiles between two propagule types: spores were dominated by Pseudomonas, whereas hyphae harbored higher relative abundances of Sphingobium and Rhodococcus. Culture-dependent screening on NBRIP medium yielded 53 phosphate-solubilizing bacterial isolates—21 from spores and 32 from hyphae. While hyphae-associated propagules contained a greater number of phosphate-solubilizing isolates, those from spores exhibited significantly higher solubilization capacities, ranging from 16.87 to 273 µg mL⁻¹, with 47.6% exceeding 100 µg mL⁻¹. In contrast, hyphae-derived isolates ranged from 35.03 to 142.20 µg mL⁻¹, with 28.1% surpassing the 100-µg mL⁻¹ threshold. Functional screening further revealed that 38% of spore and 31% of hyphae-associated isolates exhibited diverse PGP traits. The five most potent strains were identified through 16S rDNA sequencing as Pseudomonas aeruginosa, Lactiplantibacillus plantarum, Bacillus haynesii, Bacillus licheniformis, and Enterococcus innesii. This study represents the first attempt to characterize a propagule-specific core bacteriome in Funneliformis mosseae, revealing clear taxonomic and functional divergence between spore and hyphae-associated bacterial communities. These findings highlight the specialized ecological roles of distinct propagule microbiomes and offer novel avenues for targeted manipulation of AM symbiosis to enhance plant nutrient acquisition and growth.

This study aims to determine the shelf life of four batches of sodium alginate pellets containing the Arthrobotrys flagrans chlamydospores different storage conditions. Results showed that the germination rates of the chlamydospores in batches A and B increased in varying degrees at the indoor storage for 1 month but until 17 months of storage gradually declined to 0.52% and 0.48%, respectively. The germination rates in batches C and D gradually dropped to a minimum value at room temperature for 3–6 months but increased to the maximum value by 12 months and then again decreased to 1.26% and 2.22%, respectively, by 16 months. These pellets stored indoors were transferred to 4°C and −20°C storage. After storage for 2–5 months, the spore germination rates increased in different degrees. After the batch A and B pellets were stored at 4°C for 6, 12, and 30 months each, the chlamydospore germination rates increased to 10.76%, 11.87%, and 15.71%, respectively, for batch A and 29.63%, 8.34%, and 19.89%, respectively, for batch B. After the batch C and D pellet formulations were stored at −20°C for 1 year, the spore germination rates became twice as high as the initial values but close to their initial values at storage for 27 months. The data obtained in this study indicated that the shelf life of the pellets can be maintained for more than 2 years whether stored at 4°C or −20°C, between which the storage at −20°C was better.

Antimicrobial resistance (AMR) is a serious global health issue. This review aims to explore alternative therapeutic strategies for combating AMR. The goal is to evaluate emerging treatments that target resistant pathogens through novel mechanisms, bypassing the limitations of traditional antibiotics. Recent researches highlight several promising alternatives, including antibodies, antimicrobial peptides, bacteriocins, bacteriophages, and probiotics (in the clinical trials) and synthetic antimicrobial peptides, anti-virulence strategies, genetically modified phages, antibacterial oligonucleotides, CRISPR-Cas9, and predatory bacteria (in the research stage). These therapies demonstrate potential to overcome AMR by targeting specific bacterial mechanisms, reducing toxicity, and evading resistance. Alternative therapies for AMR present significant promise, offering new avenues for treatment. Despite challenges in optimization and delivery, these therapies could revolutionize the way bacterial infections are treated. Continued research is crucial to address hurdles and ensure these therapies can be safely and effectively implemented in clinical settings, shaping the future of infection management.

Rac-metalaxyl is a widely used fungicide for managing plant diseases; however, its environmental persistence and potential toxicity to aquatic microorganisms raise significant ecological concerns. Despite its widespread application, there is limited understanding of how cyanobacteria, which play vital ecological roles in aquatic systems, respond to such chemical stressors. This study addresses this gap by investigating the physiological and metabolic responses of the cyanobacterium Anabaena laxa to rac-metalaxyl exposure. Cultures were treated with 100 mg/L and 200 mg/L concentrations of the fungicide. Results showed increased intracellular accumulation of rac-metalaxyl at 200 mg/L, leading to significant reductions in cell growth, photosynthetic pigments, and the activities of key enzymes such as phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase/oxygenase. Further elevated lipid peroxidation levels indicated oxidative damage. Consequently, rac-metalaxyl triggered substantial metabolic shifts, total soluble sugars increased by 7.66% at 100 mg/L and 67.48% at 200 mg/L; malic acid rose to 76.23% at 200 mg/L; amino acids increased by 27.14% at 100 mg/L and 48.8% at 200 mg/L; total fatty acids rose by 10.11% at 100 mg/L and 35.06% at 200 mg/L. These findings suggest that Anabaena laxa exhibits coordinated oxidative and metabolic responses to mitigate rac-metalaxyl toxicity, highlighting its potential resilience and role in the bioremediation of contaminated aquatic environments.

The rise of carbapenem resistance in Escherichia coli is mainly due to the rapid spread of carbapenemase-encoding genes through horizontal gene transfer, particularly via bacterial conjugation. Recent research has highlighted the role of a small RNA molecule known as RydB in bacterial conjugation, specifically through its interaction with the protein SdiA. This study investigated the effects of sub-inhibitory concentrations of imipenem and N-acyl homoserine lactones (AHLs) on the expression of rydB in E. coli strains that overexpress sdiA. Additionally, we examined how AHLs influence the bacterial conjugation of plasmids that contain carbapenem resistance genes. We selected a carbapenem-resistant isolate of E. coli harbouring the bla_NDM gene and its corresponding plasmid-cured derivative, based on the overexpression of the sdiA gene in response to AHLs. Conjugation experiments were conducted, both without AHL treatment and with AHL treatments, to assess the transferability of the bla_NDM plasmid. The transcriptional response of rydB gene was evaluated in the plasmid-cured derivative, the native type, the transconjugant, and E. coli J53. Our findings indicated that AHLs and imipenem inhibit the expression of the rydB gene. Interestingly, while RydB does not seem to impact bacterial conjugation when suppressed by these agents, the combination of AHLs enhances the conjugation of plasmid that carry the bla_NDM gene. This study enhances our understanding of the regulatory roles that quorum sensing signal molecules, including C4 AHL and C12AHL, as well as imipenem, play in bacterial conjugation and sRNA expression.

Actinobacteria have shown significant potential in promoting the growth of various plant species, especially those that inhabit in association with plants. However, previous research has mainly focused on higher plant species. Bryophytes are a large group of non-vascular, non-flowering land plants without true vascular bundles, roots, stems, and leaves. Despite the extensive diversity of bryophytes in Thailand, research on the diversity of actinobacteria associated with bryophytes remains scarce. This study aimed to isolate actinobacteria from three bryophyte species in northern Thailand: Koponobryum papillosum Printarakul & Chantanaorr, Pseudotrismegistia undulata, and Sphagnum cuspidatulum C. Müll. A total of 52 isolates were identified, including 6 endophytic and 46 epiphytic isolates. These isolates were assigned to four genera: Brevibacterium (1 isolate), Microbacterium (1 isolate), Rhodococcus (6 isolates), and Streptomyces (44 isolates). All isolates were assessed for their plant-growth promoting abilities both in vitro and in planta. Most actinobacteria exhibited the in vitro ability to produce indole-3-acetic acid (IAA), siderophores, and solubilize tricalcium phosphate. Three isolates—Streptomyces brevispora RHP2, S. halstedii WS1, and Rhodococcus triatomae RHK22—were selected to evaluate their potential to enhance the growth of S. cuspidatulum C. Müll in soil. R. triatomae RHK22 was highly effective in promoting the regeneration of new shoots and significantly enhancing thallus height, fresh weight, dry weight, total chlorophyll content, and total carotenoid content (p < 0.05) of S. cuspidatulum C. Müll when applied as cell suspension and cell free supernatant.

The emergence of multidrug-resistant pathogens has significantly reduced the efficacy of current antimicrobial treatments against bacterial and fungal infections. To combat this challenge, the exploration of novel antimicrobial sources or the development of synthetic antibiotics is imperative. Microbes have emerged as promising natural reservoirs for antimicrobial compounds, with slime molds garnering attention due to their unique bioactive metabolites in recent years. Some of these metabolites demonstrate potent antibiotic properties. This study investigates the inhibitory effects of slime mold extracts on pathogenic bacteria, attributing this activity primarily to symbiotic bacteria associated with the slime molds rather than to the slime mold cells themselves. Furthermore, we demonstrate that this antibacterial effect can be horizontally transferred through bacterial ingestion, enabling recipient slime molds to exhibit antibacterial properties upon extraction. Importantly, slime molds selectively acquire bacteria from their environment to enhance their antibacterial characteristics, a process that appears non-random and persists through sexual cycles. These findings underscore slime molds as valuable reservoirs of antimicrobial agents. Nevertheless, it remains critical to ascertain whether these antimicrobial agents originate solely from symbiotic bacteria or result from complex interactions between these bacteria and their slime mold hosts. Understanding the mechanisms behind this antimicrobial activity not only expands our knowledge of host-microbe interactions but also provides new avenues for bioprospecting novel antibiotics. Investigating how slime molds selectively acquire and retain beneficial bacteria may offer insights into microbial symbiosis that could be leveraged for antimicrobial discovery, potentially addressing the urgent need for alternative treatments against resistant pathogens.