Composition And Variation Of Intestinal Microbiota In Marine Shrimp Analyzed By Molecular Microbial Ecological Methods

The intestinal microflora of shrimp consists of numerous bacterial species that play an important role in the nutrition, physiology, immunity and disease resistance of the host. Recently, many probiotics have been introduced into shrimp culture as bio-friendly agents to control and compete with pathogenic bacteria as well as to promote the growth of the cultured organisms and increase the production yield. Aquatic probiotics, considered as the substitute of antibiotics, represent the orientation of the preventing and curing of aquacultural animal diseases. However, to understand the relationship between the intestinal microbiota and health, and the metabolic potential of the microbes, and to evaluate the effect of different diets, treatments or medical conditions on the microbiota, fundamental knowledge of the intestinal microbial populations is needed. It will be helpful to the development, popularization and application of aquatic probiotics.In the study reported here, PCR-DGGE and 16S rDNA clone library analysis approaches were applied to characterize the diversity of the microbial community in the gut samples of healthy adult Chinese shrimp and kuruma shrimp. The primary goal of the present study was to use molecular methods to characterize the intestinal microbial community in shrimp and evaluate the effect of probiotics, antibiotics and acidulant on the gut microbiota of kuruma shrimp. The present study will be helpful to further understand the significance of probiotics in auqaculture. The results are as follows:1. The use of PCR-DGGE and clone library analyses has been shown as appropriate methods for describing the intestinal microbiota of Chinese shrimp (Fenneropenaeus chinensis). And the two different molecular biological methods gave similar results. According to two methods, the gut microbiota of was composed of Firmicutes, Proteobacteria and Bacteroidetes. The results of our study indicated that the predominant bacterial population in the intestine of Chinese shrimp was Proteobacteria and Vibrio sp. was the most abundant bacteria.2. The normal gut microbiota of kuruma shrimp consisted of the genera Rhodobacter, Aranicola, Flavobacterium, Sphingomonas, Cellulophaga, Neptunomonas, Octadecabacter, Ralstonia, Desulfurella, Desulfovibrio, Roseobacter, Vibrio and uncultured bacterium, which belonged toα-proteobacteria,β-proteobacteria,γ-proteobacteria,δ-proteobacteria, Bacteroidetes and uncultured bacterium groups.3. The addition of Bacillus spp. to the feed of kuruma shrimp led to increased intersubjectvariation and total diversity. The gut microbiota was composed of the genera Aranicola, Sphingomonas, Xanthomonas, Flavobacterium, Vibrio, Selenomonas, Rhodobacter, Psychroflexus, Roseobacter, Bacillus, Propionibacterium, Cellulophaga, Neptunomonas and uncultured bacterium, which belonged toα-proteobacteria,γ-proteobacteria, Flavobacteria, Clostridia, Actinobacteria and Bacilli groups.After feeding without Bacillus spp., the gut flora consisted of the genera Vibrio, Rhodobacter, Arthrobacter, Olleya, Lacinutrix, Oceanistipes, Prevotella, Pantoea, Pirellula and uncultured bacterium, which belonged toα-proteobacteria,γ-proteobacteria, Flavobacteria, Bacteroidetes, Actinobacteria and Planctomycetacia groups.Or after starvation, the gut flora was coposed of Lacinutrix, Oceanistipes, Aquimarina, Olleya, Thalassobius, Roseobacter, Arthrobacter, Vibrio and uncultured bacterium, which belonged toα-proteobacteria,γ-proteobacteria, Flavobacteria and Actinobacteria groups.4. The addition of citric acid to the feed of kuruma shrimp led to increased gut microbial diversity. The gut microbiota was composed of the genera Aranicola, Flavobacterium, Rhodobacter, Acinetobacter, Desulfobulbus, Neptunomonas, Bacillus, Roseobacter, Spirochaeta, Vibrio and uncultured bacterium, which belonged toα-proteobacteria,γ-proteobacteria,δ-proteobacteria, Flavobacteria, Bacilli and Spirochaetes groups.5. The addition of florfenicol to the feed of kuruma shrimp led to decreased gut microbial diversity. The gut microbiota was composed of the genera Aranicola, Granulosicoccus, Kocuria, Vibrio, Arthrobacter, Rhodanobacter, and uncultured bacterium, which belonged toα-proteobacteria,γ-proteobacteria and Actinobacteria groups.Overall, the present study characterized the diversity of the microbial community in the gut samples of healthy adult Chinese shrimp and kuruma shrimp and evaluated evaluate the effect of probiotics, antibiotics and acidulant on the gut microbiota of kuruma shrimp. The results will be helpful to the development, popularization and application of aquatic probiotics.