Multienzymatic capacity of cultivable intestinal bacteria from captive Litopenaeus vannamei (Boone, 1931) shrimp reared in green water

Abstract

Equilibrium between the gastrointestinal bacterial population and the environment is a critical factor for the health of captive aquatic animals. The bacterial enzymes are fundamental for proper nutrition and pathogen resistance in shrimp. Therefore, enzymatic profiles reveal essential characteristics for the selection of probiotic strains that can improve animal development. In this work, we analysed shrimp from a green water system where infectious myonecrosis virus (IMNV) was present. We isolated transient and intestine resident bacterial populations, characterising eight functional groups through different culture media. To identify each isolated bacteria, we used sequences from regions V6–V8 of the 16S rRNA. To determine viral load of shrimp samples, we used real-time PCR. The number of colony forming units (CFU) was similar between IMNV-infected and IMNV-uninfected shrimps. The growth of transient bacteria was higher than the growth of resident. In general, lipolytic bacteria presented higher frequency and genus diversity than the other functional groups. All groups showed higher frequency among transitory bacteria, except the amylolytic functional group, which was more frequent among the resident. We found two major orders of cultivable bacteria, Vibrionales and Bacillales. The genus Vibrio was predominant among the Vibrionales, while Staphylococcus and Bacillus were the most frequent among the Bacillales. Recorded Vibrionales and Bacillales included pathogenic and beneficial species of high importance for aquaculture. The results presented here will serve as a basis for improving the nutritional and health conditions of Litopenaeus vannamei in green water farming systems.