TL;DR
A genome-wide screen using the Escherichia coli Keio knockout collection is performed to identify genes associated with FA sensitivity and tolerance and identifies candidate genes and cellular systems potentially involved in phenolic stress adaptation.
Flacherie is a major bacterial disease compromising silkworm health and cocoon productivity; however, the diversity and genomic features of larva-associated pathogens remain poorly characterized. In the present study, we isolated and characterized a Gram-negative bacterium, designated as Pseudomonas boreofloridensis strain RAC1, from the hemolymph of silkworm larvae with flacherie symptoms. The isolate exhibited clear swimming motility, indicating an active flagellar system. Biochemical profiling using the VITEK-2 platform revealed broad metabolic capabilities, including utilization of multiple organic acids and amino-acids, related enzymatic activities, highlighting its adaptability under nutrient-variable host conditions. Chemotaxonomic analysis using fatty acid methyl ester (FAME) profiling further supported its identity within the genus Pseudomonas. Whole-genome sequencing showed a 4.49 Mb GC-rich genome encoding diverse functional pathways related to central metabolism, aromatic compound degradation, and carbohydrate-active enzymes, suggesting strong ecological flexibility. Importantly, genomic screening identified virulence-associated gene and multiple antimicrobial resistance determinants, dominated by efflux pumps and outer membrane permeability factors. In addition, strain RAC1 contained several mobile genetic elements and three prophage regions, reflecting a highly plastic genome. Pangenome analysis across related Pseudomonas strains indicated an open pangenome, driven largely by accessory and cloud genes. Overall, P. boreofloridensis RAC1 represents a multidrug-resistant and genomically dynamic strain encoding virulence-associated genes and resistance genes. These genomic features suggest adaptive potential in host-associated environments and require further experimental investigation to evaluate its role in silkworm larval disease.
The integrated experimental and in silico approach highlights soil-derived actinomycetes as versatile and sustainable bioresources with significant pharmaceutical and biotechnological potential, emphasizing their role in combating antimicrobial resistance and enabling the rational development of novel therapeutic and industrial products.
The present study is the first to report the antifungal activity of bacillopeptins against Sclerotinia sclerotiorum, a fungus responsible for white mold.
1,6-Hexanediol (1,6-HDO) is an important chemical platform widely used in polymer and pharmaceutical industries, while its toxicity remains a major bottleneck limiting efficient microbial production. This study demonstrates that 1,6-HDO exhibited strong inhibitory effects on Escherichia coli, reducing the maximum OD600 to approximately 50% of the control level under 10 g/L stress. Transcriptomic analysis was performed under 1,6-HDO stress, identifying 779 differentially expressed genes enriched in pathways related to energy metabolism, sulfur metabolism and amino acid metabolism. To systematically identify functional targets associated with tolerance, genome-wide screening using the ASKA overexpression library identified 93 tolerance-related genes that improved E. coli growth under 1,6-HDO stress by 0.06- to 3.17-fold. Notably, multiple targets were functionally associated with energy and amino acid metabolism, consistent with the transcriptomic analysis. Furthermore, co-expression of rumA and yhbO showed the greatest improvement in growth, reaching a biomass of 9.43 under 1,6-HDO stress, which was 2.61-fold higher than that of the control strain. Collectively, this study systematically elucidates the global stress response and identifies key determinants contributing to tolerance, providing valuable targets for developing robust microbial cell factories for efficient 1,6-HDO bioproduction.
