Journal of Basic Microbiology最新文献

Escherichia coli is considered a major extended-spectrum β-lactamases producer, of which CTX-M is the most common member. However, the different variants of this primary resistance-determinant make it challenging to detect by conventional PCR-based techniques. Therefore, in this study, we investigated the transcriptional response of 2 secondary resistance genes, repB and mtgA, under sub-inhibitory concentrations of oxy-imino cephalosporins in resistant isolates of E. coli harboring bla_CTX-M. The STRING database and Cytoscape software were used to identify the secondary resistance genes by gene network analysis. The cephalosporin-resistant isolate of E. coli co-harboring repB and mtgA, along with bla_CTX-M, was employed for the current study. The bla_CTX-M-carrying plasmid was successfully eliminated from the native-type isolate using 6% and 8% SDS treatment for 7 days. The plasmid was also transformed into a recipient strain, E. coli DH5α, by the heat-shock method. All three models were grown under sub-inhibitory stress of cephalosporins, and the transcriptional response of repB and mtgA was determined by quantitative real-time PCR. The study revealed that the transcriptional responses of both repB and mtgA were antibiotic-specific, which potentially can serve as a secondary resistance reporter for cephalosporin resistance in E. coli.

Mushrooms have long been valued for their nutritional, pharmaceutical, and culinary benefits. Recent studies showcased mushrooms as bio-factories for protein production, and as a source of value-added products by employing genetic manipulation and molecular transformation techniques. Advancements in molecular tools and transformation methods have enhanced the efficiency of genetic improvements in mushrooms by both conventional and modern genetic engineering techniques, paving the way for their use in various industrial applications. Genetic transformation in mushrooms involves transferring genes within and across species to understand gene functions and improve mushroom qualities. The techniques involved in transformation includes Agrobacterium-mediated transformation, hybridization, mutation breeding, particle bombardment, protoplast fusion, and CRISPR/Cas9. This review outlines the life cycle of mushrooms, major difficulties in mushroom transformation, various transformation techniques, their history, efficiency, and success rate. It also highlights the potential of genetic engineering to revolutionize mushroom cultivation and their applications.

Quorum sensing (QS), a cell-density-dependent intercellular communication system, regulates bacterial gene expression and is widespread in microbial populations. However, the role of QS in the vitamin C fermentation consortium, comprising Ketogulonicigenium vulgare and Bacillus pumilus, remains unclear. This study analyzed QS-related gene expression in K. vulgare 25B-1 and B. pumilus during mono- and co-fermentation. We identified a novel quorum-quenching lactonase, YtnP, in B. pumilus, which degraded signaling molecules of 25B-1. YtnP inhibited QS-associated gene expression in 25B-1 and enhanced 2-keto-L-gulonic acid (2-KLG) production at high cell densities. Additionally, YtnP suppressed cell lysis and alleviated oxidative stress in 25B-1. These findings provided insights into interspecies communication in vitamin C fermentation and other more complex microbial consortia interactions.

Microalgae are emerging as a valuable resource of bioenergy, value-added products, and contribute significantly to carbon sequestration. However, the diversity of endogenous algae in countries like India and their bioprospecting potential is not yet fully explored. During this study, microalgae from the freshwater of Aligarh, India, were isolated, identified using 18S rRNA, ITS and 16S rRNA gene sequences, and screened using GC-MS analysis for their potential use as biofuel. Two isolated strains were identified as members of the genus Chlorella based on ribosomal gene sequences, cell, and colony morphologies. When detected using GC-MS analysis, the strain was found to produce significant quantities of phytol, pentadecanone, and other compounds typically found in algal oil. The influence of silver nanoparticles (~32 nm) and TiO₂ nanoparticles (~23 nm) on the cell integrity of algae was checked using direct microscopy and CSLM analysis after staining with propidium iodide and Syto9. It was found that with 50, 100, and 200 µg/mL of Ag-NPs, the population of intact cells decreased by 20%, 51%, and 79%, as seen under a light microscope, while TiO₂-NPs were less toxic to the cells, decreasing population only by 0%, 12%, and 35%, respectively. When checked using Scanning Laser Microscope after growing with 100 and 200 µg/mL of Ag-NPs and TiO₂-NPs, the population of dead cells increased to 59% and 93%, and 16% and 46%, respectively. These results show that the isolated strains can serve as a source of bioenergy, and nanomaterials can promote cell lysis for downstream processes.

Casuarina equisetifolia, a key species in subtropical coastal shelterbelts, faces serious challenges in sustainable plantation management due to continuous planting obstacles. This study explores how AHL-mediated quorum sensing (QS) influences these obstacles by regulating microbial dynamics in the rhizosphere of continuously planted C. equisetifolia. Results show that with increasing generations of continuous planting, the abundance of QS bacteria—especially pathogenic strains—significantly increased, with notable shifts in community composition. The number of QS isolates rose from 32 (FCP) to 68 (SCP) and 81 (TCP), with Enterobacteriaceae being the most abundant. Among 10 identified QS species, Pantoea ananatis showed the highest AHL activity, while Burkholderia lata had the lowest. Short-chain AHL (C4-HSL and C6-HSL) were most common, with P. ananatis producing the highest diversity and concentration. Pathogenicity tests indicated that seven QS bacteria damaged roots and inhibited water uptake, leading to wilting. In contrast, three Burkholderia species were non-pathogenic. Meanwhile, the abundance of quorum quenching (QQ) bacteria decreased significantly across planting generations (94, 70, to 63), and key QQ strains like Bacillus spp. showed no pathogenicity. These findings suggest that continuous planting enriches pathogenic AHL-mediated QS bacteria while reducing beneficial QQ populations, altering microbial community structure and exacerbating replant issues. This study offers important theoretical insights into the mechanisms behind continuous planting obstacles in C. equisetifolia.