Journal of Basic Microbiology最新文献

Rauvolfia serpentina L. is a plant with medicinal and antimicrobial properties. The coexistence of endophytes inside plants plays a crucial role in their medicinal properties, imparting plant growth potential (PGP) and antimicrobial potential. To explore this, 58 bacterial endophytes were isolated from tissues of Sarpgandha. While screening for in vitro PGP activity, 19 isolates were indole-3-acetic acid producers (≥ 20 μg/mL), whereas 37, 15, and 12 isolates showed siderophore production and, phosphate and zinc-solubilization ability, respectively. Notably, 29, 18 and 9 endophytes showed nitrate reduction, DNase and urease production abilities, respectively. These endophytes also produce hydrolytic enzymes viz. as amylase, cellulase, protease, and lipase. Thirty endophytes showed antifungal activity among which 17, 16, and 18 isolates exhibited antagonism against Sclerotium rolfsii, Fusarium oxysporum and Rhizoctonia solani, respectively. Molecular characterization identified 14 endophytes belonging to phyla Firmicutes and Pseudomonadota representing three genera Bacillus, Pseudomonas and Aeromonas. Lipopeptide genes, namely surfactin and iturin were identified in the endophyte Bacillus velezensis and bacillomycin-D in Bacillus tropicus. In planta PGP evaluation of potential endophytes in chickpea demonstrated significant increase in germination percentage, shoot and root length, and fresh and dry biomass parameters in endophyte-bioprimed plants, particularly Bacillus xiamenensis NIBSM_SgR3. Similarly, during bioefficacy study, endophyte biopriming protects plants significantly from S. rolfsii infection up to 76.11% compared to infected control at 14 dpi, with maximum protection being conferred by Bacillus velezensis NIBSM_SgL59. Thus, promising endophytes especially Bacillus xiamenensis and Bacillus velezensis with multifaceted PGP and antimicrobial potential can be explored to develop bio-stimulants and biocontrol agents.

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 bacterium which 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 (Int_Tn916 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.

This study identifies Clonostachys reniana sp. nov., a newly recognized mycoparasitic fungus with potential as a biocontrol agent in sustainable agriculture and forestry. Dual cultivation experiments demonstrated a significant antagonistic activity of C. reniana against tree canker pathogens Botryosphaeria dothidea and Cytospora chrysosperma, achieving over 80% colonization of pathogenic colonies within 15 days, ultimately leading to the demise of the pathogenic colonies. Morphological assessment reveals differential features in conidiophore and conidia size and colony formation, setting C. reniana apart from closely related species, despite its phylogenetic proximity to C. pseudochroleuca as inferred from multilocus sequence analysis (ITS, LSU, RPB2, TEF1, TUB2). Phylogenomic tree and some gene families related to mycoparasitism also presented that this strain exhibits unique traits to the other species in Clonostachys, including the well-known biocontrol agents Trichoderma atroviride and C. rosea strains. Therefore, the distinct taxonomic status, antagonistic efficacy, and genetic attributes, making the native species a promising new mycoparasitic fungus for a potential candidate in integrated disease management in agricultural and forest ecosystems.

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.

A destructive fungal disease called Fusarium oxysporum f. sp. cubense can reduce agricultural productivity in banana fields by up to 100%. The current work investigates cordycepin, a naturally occurring substance obtained from Cordyceps species, as a sustainable antifungal agent to address this issue. Using molecular docking and simulation tools, we examined cordycepin's interactions with three essential Foc proteins: Secreted in Xylem 13 (SIX13), Foc secreted protein 9 (Fosp9), and a Cupin-type-1 domain-containing protein (FocTR4). Cordycepin demonstrated substantial binding affinities and produced stable complexes with all three targets: −9.3 kcal/mol (SIX13), −5.7 kcal/mol (Fosp9), and −8.3 kcal/mol (FocTR4), surpassing commercial fungicides such as prothioconazole and tebuconazole. Protein-protein interaction study further suggested that these targets are fundamental to broader functional networks, suggesting that cordycepin may interfere with essential physiological functions. Its antifungal action was validated by in vitro tests, where cordycepin demonstrated concentration-dependent inhibition of Foc mycelial growth, reaching almost total suppression at 1000 ppm. These results demonstrate cordycepin's promise as a cutting-edge, powerful antifungal therapy for treating Foc TR4 infections.

Cereal cyst nematode (Heterodera avenae) significantly hampers barley production by causing stunted growth and yield losses. This study explored the biocontrol potential of multitrait root endophytic bacteria isolated from H. avenae-infested barley roots to suppress nematode infestation. Ten endophytic bacterial strains were isolated and screened for their inhibitory effects on cyst hatching. Among them, Bacillus subtilis BREB 03 exhibited the highest hatching inhibition (48.31%), outperforming the bio-control check Azotobacter chroococcum HT-54. The promising root endophytic bacterium BREB 03, identified as a Gram-positive rod-shaped bacterium, exhibited optimal growth at 25°C and halotolerance up to 10% NaCl, along with diverse metabolic capabilities including positive catalase, oxidase, citrate utilization, and fermentation of multiple sugars. Whole-genome sequencing and phylogenomic analysis confirmed the identity of BREB 03 as B. subtilis. Further in vitro assays revealed BREB 03 capabilities for siderophore production, ammonia excretion, indole acetic acid (IAA) synthesis, and phosphorus solubilization, contributing to both nematode suppression and plant growth promotion. Seed treatment with BREB 03 significantly enhanced barley growth parameters, indicating its dual role as a biocontrol agent and biofertilizer. This study highlights B. subtilis BREB 03 as a promising alternative for sustainable management of cereal cyst nematode in barley, with potential to reduce reliance on chemical nematicides.

Rhizosphere engineering offers a promising strategy to improve crop productivity and soil health by optimizing plant-microbe interactions through targeted modulation of rhizosphere functioning. A key step in this approach is effective recruitment and functional activation of inoculated plant growth-promoting rhizobacteria (PGPR), mainly driven by root exudate-mediated signaling. This study investigates the response of five phylogenetically diversified PGPR strains, Azotobacter chroococcum (Ac1), Azospirillum lipoferum (Az204), Pseudomonas chlororaphis (ZSB15), Bacillus altitudinis (FD48), and Pristia endophytica (NE14) to root exudates derived from three different rice cultivars (BPT5204, Co51, and Co55) at active tillering and panicle initiation stages. Functional traits including growth, chemotaxis, biofilm formation, and cell wall-degrading enzyme activity of rhizobacteria were assessed. The results revealed strain- and cultivar-specific modulation of these traits, with NE14 and FD48 showing significant upregulation of assessed traits in response to exudates from BPT5204 and Co51. Gas chromatography-mass spectrometry profiling of root exudates confirmed compositional differences between cultivars and developmental stages, highlighting key metabolites such as hexadecanoic acid, propionic acid, octadecenoic acid methyl ester, and trans-3-hydroxycinnamic acid as potential regulators of PGPR chemotaxis, colonization, and biofilm formation. Principal component and correlation analyses identified cell wall-degrading enzymes and chemotaxis as contributors to strain variability, underscoring their role in establishing rhizosphere competence. These findings strengthen the importance of functional trait-based screening for identifying PGPR strains with high adaptability to the rhizosphere environment. By demonstrating that root exudate-mediated modulation of PGPR traits can enhance bacterial colonization and functionality, this study offers a conceptual foundation and experimental framework for PGPR-mediated rhizosphere engineering.