Modulation of Quorum-Regulatory sRNA on Various Physiological Functions and Virulence of Vibrio alginolyticus

Vibrio alginolyticus is one of the important fish pathogen in China, bringing about serious economic loss to aquaculture. sRNA (Small non-coding RNA, sRNA) modulate the target genes on the post-transcriptional level with the aid of the chaperon protein, Hfq and play essential roles in the regulation of various physiological functions, like virulence. In this paper, a quorum regulatory sRNA, Qrr1, was screened and cloned. Besides, An in-frame deletion was made in qrr1 by allelic exchange, using the suicide plasmid. Meanwhile, the plasmid, pMMB206 was utilized to carry the contact qrr1 gene into the mutant strain Delta qrr1 to generate the complemented strain, qrr1(+). The roles of this gene in different physiological functions of Vibrio alginolyticus were characterized. The results demonstrated that Qrr1 obviously promoted the growth of Vibrio alginolyticus during exponential and stationary stage. Moreover, the ability of mobility was almost absent, the biofilm formation and extracellular protease production were all impaired in the Delta qrr1 mutant strain, contrast to the wild-type strain, which means Qrr1 participates in the virulence regulation as an important regulator in Vibrio alginolyticus.