The influence of enzyme EII of the cellobiose-phosphotransferase system on the virulence of Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus)

Abstract Streptococcus agalactiae is the main pathogen of tilapia, causing huge economic losses to the tilapia aquaculture industry in China. To elucidate the role of the EII complexes of the cellobiose-phosphotransferase system (cel-PTS) in the regulation of S. agalactiae virulence, the △cel-EII mutants of a high virulence strain (THN0901) and a low virulence strain (TFJ0901) were constructed using homologous recombination. The results showed that after the deletion of cel-EII complexes, the biological characteristics of THN0901 and TFJ0901 were consistent, including their cellobiose metabolism. Their biofilm formation abilities were significantly reduced (P