Journal of Basic Microbiology最新文献

From seed to harvest, cultivated crops face numerous biotic stresses, including insects, nematodes, and diseases, which significantly hinder their growth and vigor, resulting in substantial crop losses. In contrast to use of toxic agrochemicals, seed biopriming with microbial inoculants has emerged as an effective and eco-friendly alternative against pathogens and pests. Seed biopriming involves coating seeds with beneficial microorganisms that enhance protection and immunity against a variety of harmful pests and pathogens. These microbial agents colonize the seeds and establish themselves in the rhizosphere, reducing the impact of biotic stresses while fostering a healthier environment for plant growth. They are known to exhibit several mechanisms against pathogens and pests, like production of cell wall degrading enzymes, antibiosis, competition, induced systemic resistance, chelation of iron etc. Additionally, these microorganisms regulate phytohormone levels, further optimizing the physiological and metabolic characteristics of plants. This approach not only promotes robust plant growth but also enhances tolerance to deleterious bacteria, fungi, nematodes and arthropods, ensuring healthier crops. These interactions can further be well studied and expressed by using different omics approaches like metagenomics (of seed microbiome), proteomics, transcriptomics, metabolomics and differential gene expression. This review highlights the role and benefits of seed biopriming as a sustainable strategy to manage biotic stresses effectively, and the importance of omics for better understanding of complex processes during such interactions, contributing to resilient agricultural production systems and environmental sustainability.

Sodium dodecyl sulfate, an anionic detergent, has extensive usage in several pharmaceuticals and household products. SDS contaminates the environment due to failure of conventional treatment methods to remove it completely from wastewater. Due to the eco-toxicity and health hazards of SDS, there is need of new and efficient methods of SDS removal. The present study is the first description on highly efficient SDS biodegradation and chemotaxis by Pseudomonas nitritireducens isolated from river sediments. SDS degradation kinetics using 50−1000 mg/L SDS concentration showed the highest degradation rate of 30.88 mg/L/h at 600 mg/L. The central composite design-face centered was used for optimization of SDS degradation resulting in 1.25-fold increase in degradation. 99.6% ± 0.018% SDS was degraded within 8 h of incubation in M9 minimal medium containing 200 mg/L SDS as the sole carbon source. The time of degradation reduced to 6 h when inoculum was induced for SDS degradation. To the best of our knowledge, the present study is the first description on SDS chemotaxis of P. nitritireducens showing the lowest period for degradation of environmentally relevant SDS concentration. Furthermore, the article provides the earliest report on use of response surface methodology for optimization of SDS degradation. The reported bacterium may provide competent alternative for SDS removal in wastewater treatment as well as new insights of SDS metabolism in bacteria on further exploration.

Shiga toxigenic Escherichia coli (STEC) is known to cause severe diarrhea and other gastrointestinal disorders in animals and humans. The galE gene encodes the galE protein, which acts as an essential catalyst required to convert UDP-galactose into UDP-glucose, and vital for exopolysaccharide synthesis. In this study, a knockout mutant of the STEC galE gene (ΔgalE) was constructed and the biological functions of galE were analyzed. Relative to the wild-type strain, O-antigen synthesis within the ΔgalE mutant changed and displayed distinct profiles via SDS-PAGE coupled with silver staining and Western blot analysis. Furthermore, this mutant showed a reduction in swimming motility, diminished biofilm formation, and reduced replication within macrophages. In the complement-killing assay, the membrane attack complex (MAC) was deposited in greater amounts on the ΔgalE-deficient strain relative to the wild-type strain, indicating a higher susceptibility of the ΔgalE strain toward complement-dependent lysis. However, the mutant manifested a more pronounced tolerance to extreme environments despite exhibiting comparable replication in a growth medium. These results indicate that galE plays a significant roles in O-antigen biosynthesis and contributes to STEC pathogenicity.

Rapidly emerging antimicrobial resistance (AMR) in Staphylococcus aureus is a global health issue that causes life-threatening infections in nosocomial and community-acquired settings. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) infections is higher in clinical practices, which causes a major hurdle in the treatment. The epidemiology of such systemic and invasive infections results in higher morbidity and mortality, especially in middle-income countries where hospitalization rates and improper drug use escalate the threat. Nanotechnology has gained more attention for preventing acute and chronic microbial infections. The present study aimed to synthesize silver nanoparticles (AgNPs) using the cell-free extract of B. subtilis and to examine their antimicrobial effect against MRSA. The synthesized AgNPs were characterized by spectroscopy (UV-VIS, FT-IR) and imaging spectroscopy (SEM, TEM), zeta potential, X-ray diffraction (XRD), and Energy Dispersive X-ray (EDX) analysis. The efficacy of AgNPs was examined with different Gram-negative and Gram-positive strains, including MRSA with 0.4 mg/mL MIC, and was significantly potent against other pathogens. The AgNPs also displayed bactericidal effects assessed by ROS production, macromolecule leakage, and biofilm formation inhibition, which was inhibited up to 82% at 1.6 mg/mL AgNPs concentration. Our findings suggest that green-synthesized AgNPs show a potent antimicrobial activity against a diverse range of bacterial pathogens by greatly reducing cell susceptibility via elevating ROS production, DNA, and protein leakage. AgNPs equally hamper biofilm inhibition, suggesting the emergence of drug-resistant infections in S. aureus. Further research is warranted to explore their potential in clinical applications.

Antimicrobial resistance (AMR) is a global issue; however, in lower resource settings, uncontrolled measures and uncontrolled use of antibiotics in human, animal, and agricultural practices have increased their prevalence in developing countries. Various mechanisms have been implicated to explain the AMR, like the circulation of the plasmid carrying antibiotic resistance genes (ARG), mutation in target genes (intrinsic and plasmid), overexpression of efflux pumps, underexpression of porins, etc. Various therapeutic strategies used to combat AMR exist, such as nonantibiotic approaches (vaccinations or immunotherapy, nano-derived treatments, and bacteriophage therapy), Anti-plasmid and plasmid curing approaches, combinatorial approaches (combination of antibiotics as well as a combination of two different approaches), and plant-based therapeutics. In this focused review, we have discussed the potential use of bacteriophage-based therapy to combat AMR and biofilm formation through multifaceted ways, including lysis of the drug-resistant bacteria, targeting the pili of AMR plasmids conjugation systems, and use of phage-derived lytic proteins. Phages can also be used to decontaminate surfaces in healthcare settings, prevent bacterial contamination in food (meat and dairy), and control bacterial populations in environmental settings, such as water and soil. Therefore, the bacteriophages-based approach served as a dual sword and could not only prevent the spread of infectious diseases but also manage the AMR.

Wastewater from a furfural plant in Argentina contains 791 mg L⁻¹ of furfural, posing toxicity risks if untreated. This study aimed to isolate actinobacteria from these furfural-contaminated sites, select tolerant strains, and assess their removal efficiency individually and in consortium. Six microorganisms with macroscopic characteristics corresponding to the phylum Actinomycetota were isolated. These microorganisms and Streptomyces sp. A5, A12 and M7, isolated from pesticide and heavy metal contaminated environments, showed tolerance to furfural 800 mg L⁻¹. The isolate L9 (identified as Nocardiopsis sp. L9) and Streptomyces sp. A12 and M7 were selected because they were the most efficient with respect to their growth capacity and furfural removal in MM supplemented with furfural 400 mg L⁻¹. The consortium formulated with the three actinobacteria (L9-A12-M7) exhibited significantly higher growth (123%) and furfural removal efficiency (58%) compared to individual cultures, when exposed to a pollutant concentration similar to that of the actual effluent (800 mg L⁻¹). Ecotoxicity tests using Raphanus sativus seeds showed that the toxic effects caused by furfural were reversed by the treatment, confirming the effectiveness of the bioremediation process. These results suggest that the actinobacterial consortium is a promising bioremediation tool for the treatment of industrial effluents contaminated with furfural.

Acinetobacter baylyi ADP1 has garnered attention as a promising synthetic biology chassis due to its compact genome, rapid growth, innate competence for horizontal gene transfer, and ease of genetic manipulation. To assess its potential for natural product biosynthesis, we engineered ADP1 for the production of l-leucine. First, feedback inhibition was relieved by overexpressing the endogenous leuA and ilvBN genes, alongside the replacement of transcriptional attenuation regions within the leuBCD operon. These interventions derepressed the native biosynthetic pathway, resulting in a substantial increase in l-leucine titers from 0.10 to 0.82 g/L. Next, we augmented the eda gene in the Entner–Doudoroff pathway, while disrupting poxB, which diverts carbon toward acetate, further promoting l-leucine biosynthesis. To resolve carbon competition between the tricarboxylic acid (TCA) cycle and l-leucine synthesis, an inducible sRNA-based system was developed to dynamically repress TCA cycle-associated genes. This balanced the cell growth with l-leucine anabolism, ultimately achieving a titer of 1.16 g/L with a yield of 0.08 g/g glucose. Interestingly, the l-leucine feedback regulation diverges markedly from classical prokaryotic chassis like Escherichia coli and Corynebacterium glutamicum, in which feedback-resistant variants of leuA and ilvBN are typically required to overcome repression. In contrast, in ADP1, overexpression of the native, wild-type genes was sufficient to drive efficient product synthesis. Moreover, the unique glucose catabolism network in ADP1 limits its pyruvate availability, supplementing pyruvate and minimizing carbon loss proved critical for optimizing l-leucine production. Collectively, our findings offer mechanistic insights into chassis-specific metabolic regulation and optimizing precursor supply in nonmodel organisms.

The putative two-component system (TCS) CgtRS5, encoded by the ncgl2572–ncgl2573 gene cluster, plays a critical role in environmental adaptation in Corynebacterium glutamicum. Comparative transcriptomic analysis between the wild-type strain and a ΔcgtRS5 mutant revealed three upregulated and 107 downregulated genes in the mutant. Among these, genes involved in iron metabolism (ncgl1959), aromatic compound degradation (ncgl2320), and drug resistance (cssR) were significantly downregulated. Phenotypic assays demonstrated that the ΔcgtRS5 mutant exhibited impaired growth in media supplemented with the divalent form of iron (Fe²⁺) or the alkylating agent iodoacetamide (IAM), but showed no significant differences under benzoate, resorcinol, or antibiotic stress. These results suggest that CgtRS5 specifically regulates the stress response to iron and IAM in C. glutamicum, providing new insights into TCS-mediated regulatory mechanisms in this organism.