Bacterial Diversity Analysis Of Holothurian Digestive Tract And Aquaculture Environment And Identification Of A Novel Strain

Sea cucumber aquaculturing is the new economic industry in bohai area. Pond culture is the main mode of farming, but it’s easily affected by the change of evirenment, the change of strains in the sediment and the digestive tract of sea cucumber is easy to cause the disease,we aim to study their change in different season to provide reference for the disease preventing.Using the method of pure culture and16S rRNA gene sequences comparison, sampling four times a year. Through analysis, there are151strains in total, we find that they belong to31genus;72strains are found from the intestine of sea cucumber,32of them are Vibrios;79strains from pond sediment,28of them are Vibrios; Vibrio is the most dominant genus. And, their variation shows a seasonal and a certain regularity.DNA of soil samples was extracted by using PowerSoilDNA Isolation kit,at the same time, enriching sediments for5,7,9days, then separate and purify the strains from them using the cultured method and extract the DNA of the enriching samples. Using the method of high throughput sequencing, we obtained the16S genes of all the strain in the sample. We constructed the database according to the_bioinformatics. We obtained more than70000sequences,more than58000of which are high quality sequences.The sequence length distribution between480bp to520bp. The similarity of97%as the standard, we divided the sequences into10575operational taxonomic units (OTU); drawed the dilution curve,sample abundance distribution curves, analyzed Alpha diversity.With them,we evaluated the abundance of the sample and compared differences of them. Based on the analysis of community structure, we study the single sample distribution of species, species distribution,diversity of products containing phylogenetic relationships between species abundance, cluster analysis and Beta diversity analysis of the samples.A novel Gram-negative, facultatively anaerobic, amphitrichous, Short rod and off-white bacterial strain, designated C4T was isolated from the sea cucumber intestine in Shandong Weihai China. Optimal growth of the strain was observed at28-30℃, pH6.5-7.2and at an NaCl concentration of3%(w/v). The G+C content of the DNA from the bacterium was49.3mol%.Phylogenetic analysis based on16S rRNA gene sequence indicated that C4is a member of Alteromonadales, had a similarity with the members of Psychromonadaceae (92%). The major cellular fatty acids were summed feature3(16:1ω7c/16:1ω6c), sum in feature3(16:1co7c/16:1ω6c),16:0. Q8was the major isoprenoid quinone. The predominant polar lipids in strain C4T were hosphatidylethanolamine(PE),phospholipidl and phosphatidylglycerol. Based on morphology, and physiological and biochemical characteristics, strain C4should be classified as a new genus and species, for which Pelagimicrobium weihaiensis is proposed, the type strain is C4(GenBank Accession NumberKJ652011)...