Acinetobacter venetianus, a potential pathogen of red leg disease in freshwater-cultured whiteleg shrimp Penaeus vannamei

The genus Acinetobacter has recently emerged as bacterial pathogens associated with mass mortalities in aquaculture. Yet scarce information is available on Acinetobacter venetianus as a potential pathogen of whiteleg shrimp Penaeus vannamei. In the present study, an A. venetianus pathogen (SHF1) was confirmed as a causative agent of red leg disease in freshwater-cultured whiteleg shrimp. It showed a mean lethal dose (LD50) value of 3.8 × 105 CFU mL−1 and developed multiple resistances to phenicols, quinolones and tetracycline drugs used in aquaculture. In addition, the pathogenic A. venetianus could be effectively controlled by Bdellovibrio powder at 0.8 mg L−1, which exhibited significant antibacterial effect and displayed good protection against A. venetianus challenge in P. vannamei for six days. As far as we know, this is the first study to identify A. venetianus as a potential bacterial pathogen of red leg disease in freshwater-farmed whiteleg shrimp.