Biotin is an essential cofactor across the three domains of life. Since humans lack the de novo synthesis of biotin, bacterial biotin synthesis pathway is an attractive target for the development of new antibacterial. The pathway is divided into two phases: the early and late segments. The late stage of biotin biosynthesis is a conserved pathway in which biotin is synthesized from a pimelate precursor using four conserved enzymes, whereas the early stage remained largely unknown until its discovery in Escherichia coli in 2010. Since then, the early stage of biotin biosynthesis has emerged as divergent and varies among different species. In this review, the early stage of biotin biosynthesis and its diversity across species is discussed. The review also highlights the structural biology of the enzymes involved in generating the pimelate moiety, the precursor molecule utilized in the late stage to synthesize biotin molecules.

Hexavalent Cr(VI) is well known hazardous pollutant which not only impairs the soil health but also drastically reduces the plant developmental processes. Here, we observed a plant growth promoting rhizobacterium (Bacillus sp. AKS_bp1) isolated from rice rhizosphere modulating dual roles in Cr(VI) detoxification and plant responses. Initially, Bacillus sp. (AKS_bp1) showing PGPR characteristic along with a high tolerance to varying Cr(VI) concentrations in laboratory condition. Moreover, the strain also reduce the Cr(VI) concentration (~80%) with a bio-sorption capacity reaching 95.21% under 72 h incubation followed by pseudo first order kinetics. Further, biosorption studies through infrared spectroscopy and scanning micrograph showing the presence of hydroxyl, polysaccharides, and amino-nitrogen based functional groups for Cr binding. Likewise, internal Cr(VI) bio-removal the activity of Cr reductase was recorded with changes through 20, 40, 60, and 80 ppm of Cr(VI) in solution. Enzyme activity was validated with varying pH (5-8), temperature (21°C-45°C) and metal (Ag2+), salt (sodium dodecyl sulphate) etc. In detoxification pathways, the strain recorded further upregulation of antioxidative enzymes highlighting a well-established defence against Cr induced toxicity. Remarkably, application the strain was able to remove 36.86% of Cr(VI) when incubated in tannery effluents through 72 h. Conclusively, the present work provides importance of Bacillus sp. (AKS_bp1) mediated bio-removal of contaminated industrial effluents, which predominantly rich in Cr(VI). This bacterial strain also significantly reduced lipid peroxidation and polyphenol oxidation. Moreover, it offers potential for additional chemical modifications and sustainable bioremediation of Cr and other toxic metals, thereby improving crop growth and productivity.

Antimony (Sb) contamination threatens food security by lowering crop yields, reducing nutritional quality, and harming agroecosystems, underscoring the need for sustainable and eco-friendly strategies to alleviate heavy metal stress. Here arbuscular mycorrhizal fungi (AMF) role to mitigate Sb-induced stress in maize, was examined. AMF-inoculated and non-inoculated plants were grown under control and Sb stress conditions for 10 weeks, and growth, nutrient uptake, metabolic profiles, antioxidant capacity, and antimicrobial activity were assessed. Sb exposure markedly suppressed maize performance, reducing fresh and dry biomass by 66% and 65%, respectively, while also impairing the growth-promoting effects commonly associated with AMF. However, AMF inoculation significantly alleviated Sb toxicity, enhancing fresh biomass by 43% and dry biomass by 40%. The recovery was linked to improved nutrient uptake and the accumulation of primary metabolites, which promoted physiological adjustments. Moreover, AMF-inoculated plants under Sb stress showed enriched bioactive metabolites, leading to stronger antimicrobial activity and a 65% increase in antioxidant capacity. Collectively, these findings demonstrate that AMF enhance maize resilience to Sb stress by promoting growth, nutritional quality, and bioactive properties. This study demonstrates that AMF offer a sustainable strategy to enhance crop resilience and biofortification in contaminated environments.

Phage adsorption, genome injection, and immediate activation of host genes are critical steps that determine whether phages can complete their infection cycle. Elucidating the early molecular dynamic network of phage-host interactions is essential for understanding the dynamic balance between phage invasion and bacterial defense. In this study, Pseudomonas aeruginosa PAO1 was used as a model to investigate the early transcriptional responses during infection by lytic phage vB_Pae_QDWS, which features an extremely short latent period. Transcriptomic analysis at 0, 3, 6, and 20 min postinfection revealed a transient expression of early phage genes (gp01-gp08, gp13). Concurrently, the host exhibited broad transcriptional reprogramming, particularly in genes related to receptors such as flagella, pili, and lipopolysaccharide (LPS) biosynthesis, as well as quorum-sensing (QS) regulators including lasI, lasR, and rhlI. Correlation analyses revealed strong associations between specific early phage genes and host QS-related genes. Notably, the early phage gene gp08 exhibited a strong negative correlation with the QS regulator lasR, implying a potential inhibitory interaction. This study highlights the critical role of early phage gene expression in the initial takeover of the host and demonstrates the host's rapid transcriptional response under phage pressure, offering new insights into phage-host interactions and phage-based control strategies.

Tyrosine recombinases (YRs) are widespread among prokaryotes and archaea, catalyzing site-specific DNA recombination reactions in a variety of cellular processes like chromosome dimer resolution, transfer of mobile genetic elements, and DNA insertion. Deinococcus radiodurans is a gram-positive bacteriumwhich is highly resistant to ionizing radiation. This bacterium harbors a tightly condensed nucleoid containing polyploid, and multipartite genome. Deinococcal FtsK protein was earlier reported to stimulate site-specific recombination catalyzed by Escherichia coli YRs- XerC and XerD in vitro. The trans expression of Escherichia coli XerC and XerD proteins in D. radiodurans resulted in diffused nucleoids and sensitivity to gamma radiation compared to control cells indicative of the role of YRs in nucleoid morphology. Protein-protein interaction studies revealed the interaction of putative deinococcal YRs- Dr0513 (IntTn916 type YR), DrA0155 and DrB0104 with DrFtsK. Overexpression of these putative YRs in E. coli resulted in filamentous cells with partitioned nucleoids. D. radiodurans Δdr0513 single mutant as well as Δdr0513ΔftsK double mutant cells exhibited altered nucleoid morphologies. The Δdr0513ΔftsK double mutant had slow growth rates both under normal and post gamma radiation recovery periods. Mislocalization of the HU protein on the nucleoid was also observed in the double mutant cells. Further, in vivo recombination experiments performed with a reporter plasmid containing E. coli dif sequence revealed that Dr0513 could perform site-specific recombination in the ∆xerC E. coli strain. These results functionally validate the role of uncharacterized Dr0513 protein as tyrosine recombinase in D. radiodurans, with a probable role in nucleoid compaction and genome maintenance in conjunction with DrFtsK.

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.