Effect of Potential Probiotic Lactococcus lactis Subsp. lactis on Growth Performance, Intestinal Microbiota, Digestive Enzyme Activities, and Disease Resistance of Litopenaeus vannamei

The aims of this study were to evaluate the effects of Lactococcus lactis subsp . lactis on the growth, intestinal microbiota, digestive enzyme activity, and disease resistance of Litopenaeus vannamei . Diets containing four different concentrations of L. lactis (0 [basal diet], 10 6 , 10 7 , and 10 8 CFU g −1 ) were fed to white shrimps L. vannamei (average weight 5.89 ± 0.36 g) for 8 weeks. At the end of the feeding trial, shrimps were immersed in Caspian Seawater (10.8 ppt) contaminated with 10 6 CFU ml −1 pathogenic V. anguillarum for 2 h. Results revealed that growth rate, survival, and body protein level were increased with dietary supplementation of L. lactis . The activities of digestive enzymes (cellulose, lipase, amylase, and protease) were significantly higher in the groups fed with diets containing 10 7 or 10 8 CFU g −1 L. lactis than those in the control. The Lactobacillus and Bacillus counts were higher ( P