Staphylococcus aureus is an opportunistic human pathogen that is often involved in severe infections such as pneumonia and sepsis in which bacterial virulence factors play a key role. Infections caused by S. aureus are often difficult to eradicate, particularly when they are associated with biofilm. The physiological roles of the Crp/Fnr family regulator ArcR are elusive in S. aureus. In this study, it was found that the deletion of arcR increased the hemolytic ability and biofilm formation in S. aureus. Differential gene expression analysis by RNA-seq and real-time quantitative reverse transcription PCR showed that genes associated with hemolytic ability (hla and hlb) and biofilm formation (icaA, icaB, icaC and icaD) were significantly upregulated compared with those in the wild-type strain. The results revealed that ArcR regulated the expression of the hla and ica operon by binding to their promoter regions, respectively. This study provided new insights into the functional importance of ArcR in regulating the virulence and biofilm of S. aureus.

The objective of the present study was the detection of virulence-associated genes of E. coli isolated from chicken with colibacillosis. Seventeen (17) APEC isolates were examined by two panels of PCRs for the presence of 11 genes described for avian pathogenic (hlyF, iroN, iss, ompT, iutA and fimC) and diarrheagenic (eae, stx, est, elt, ipaH and aggR) E. coli. Results revealed that none of the APEC isolates harbored the genes eae, stx, est, elt, ipaH and aggR. In another hand, 88.2% of the isolates were positive for 3 or more of the virulence genes hlyF, iroN, iss, ompT, iutA and fimC. Also, 35.3% of the isolates harbored all the six genes. Genes fimC (88.2%), iss (82.3%) and ompT (76.5%) were the most prevalent while genes hylF, iutA and iroN which were present with the same frequency (52.9%) were mostly associated with highly pathogenic strains.

Mechanisms for cellular detoxification of drug compounds are of significant interest in human health. Cyclosporine A (CsA) and tacrolimus (FK506) are widely known antifungal and immunosuppressive microbial natural products. However, both compounds can result in significant side effects when used as immunosuppressants. The insect pathogenic fungus Beauveria bassiana shows resistance to CsA and FK506. However, the mechanisms underlying the resistance have remained unknown. Here, we identify a P4-ATPase gene, BbCRPA, from the fungus, which confers resistance via a unique vesicle mediated transport pathway that targets the compounds into detoxifying vacuoles. Interestingly, the expression of BbCRPA in plants promotes resistance to the phytopathogenic fungus Verticillium dahliae via detoxification of the mycotoxin cinnamyl acetate using a similar pathway. Our data reveal a new function for a subclass of P4-ATPases in cell detoxification. The P4-ATPases conferred cross-species resistance can be exploited for plant disease control and human health protection.