Change Of Microbial Communities And Algal Facies In Large Water Pond For Sea Cucumber Apostichopus Japonicus Farming At All Seasons And Probiotics Screening

Into the 21 st century, with the improvement of people’s living standard and the trepang demand is increasing, trepang breeding industry rapid development. Large water aquaculture and sea cucumber and jellyfish polyculture began to appear.In this paper adopt traditional bacteria separation technology and high-throughput sequencing to studied the change of large water aquaculture of trepang ab OTU water quality index、microbial communities and algal facies at all seasons and the influence of water quality index、microbial communities in sea cucumber and jellyfish polyculture pond, At the same time screening a potential probiotic. Through these studies can clear understanding of the change rule of water quality index、microbial communities and micro algae and eucaryon. Provide theoretical basis for large water aquaculture system of trepang.1 、 Large water pond for sea cucumber Apostichopus japonicus farming water quality,microbial population structures and variation of eukaryotes.From December 2014 to December 2015 large water pond for sea cucumber Apostichopus japonicus farming water quality indicators of Sea cucumber, studied results showed that the structure of the bacteria and eukaryotes four seasons temperature range between 0.23²7.77℃, the salinity in 30 or so, p H=7.5, the content of chlorophyll a in 0.4².5 mg/L, COD content in 0.58⁰.96 mg/L, NO₂-N content in 8.43¹5.95μg/L, NH₄-n content in 17.16³7.19 μg/L, NO³-N content in 6.89¹54.94μg /L, inorganic nitrogen content in 41.58¹91.28μg/L, PO⁴-P content in 5.93⁵.93μg/L. Total plate count in the water content is between 8× 10³³× 10³ cfu/m L, the number of vibrio of 6.4× 10²³.4× 10²cfu/m L, total plate count 3.6× 104⁸.0× 10³cfu/g of sediment and the vibrio number of 5.1 × 10³¹.5× 10³ cfu/g of sediment.In spring and winter water and sediment in vibrio ratio is relatively high. The results showed that through highthroughput sequencing all the samples at the gate level relative abundance of the top ten largest species mainly Proteobacteria,Firmicutes,Actinobatceria,Crenarchaeota, Bacteroidetes, Cyanobacteria, Verrucomicrobia, Acidobacteria, Nitrospirae, Chloroflexi, etc.al Firmicutes in the proportion of all kinds of varieties is large.Water and sediment samples in the summer kind of content is very few, content is higher in the water and sediment in winter. Bacteroidetes in water and sediment as spring, summer, autumn and winter seasons change ratio decreases.Through a traditional method to investigate the micro algae in the water analysis showed that the micro algae in the water main is given priority to with Diatomea, spring and autumn micro algae content is higher, in different seasons algae dominance has great difference, in the spring Skeletonema costatum,Bacillaria paxillifera,Chaetoceros tortissimus as the dominant population, Nitzschia, Pinnularia, summer Skeletonema costatum, Bacillaria paxillifera) the dominant position, the autumn Pinnularia,Bacillaria paxillifera and Navicula dominant, winter Pinnularia and Bacillaria paxillifera the dominant position.By 18 s r DNA sequencing analysis results show that the eukaryotes top 10 Basidiomycota, Diatomea, main Cercozoa, Alveolata,Chlorophyta, Ciliophora, Mollusca,Annelida,etc.al.Through analyzing the diversity of samples show the diversity of spring, summer and autumn of sediment eukaryotes is greater than the water in eukaryotic biodiversity, winter to the diversity of eukaryotes in water is greater than the sediment eukaryotic biodiversity.2、The influence of sea cucumeber and jellyfis polyculture to the index of water quality, the structure microflora and eukaryotesIt’s revealed that polyculture had a significant influence to the water quality by measuring the quality on polyculture ponds and non polyculture in August and October. The content of COD polyculture pond is significantly higher than the non polyculture, but it’s less predominant in the polyculture of water, ammonia nitrogen, nitrate nitrogen, inorganic nitrogen.By using high-throughput sequencing showed polyculture pond water and sediment in the flora diversity is significantly higher than the polyculture pond, diversity in eukaryotes polyculture pond water is higher than the polyculture pond.It’s showed that the sea cucumeber pond polyculture jelly fish had significant impact on group structure,and to water quality index, bacteria and eukaryotes3、The screening of probiotics in sea cucumeber aquaculture pondsBased on the bacterial extracellular amylase, protease activities, safety onto sea cucumber, and the antagonism to Pseudoalteromonas nigrifaciens and Vibrio splendidus associated with the disease‘skin ulcer syndrome’, one potential probiotic bacterium YQ-2 was obtained. The results showed that this strain has good inhibition to P. nigrifaciens and V. splendidus, in which the diameter of inhibition zone were 22 mm and 24 mm, respectively; While the diameter of amylase and protease hydrolysis were 22 mm and 36mm; In addition, the challenge test revealed that the strain YQ-2 was found to be safe for sea cucumber which were challenged by bathing the bacterial strain at concentration of 10⁸cfu/m L, or fed with bacterial cells at 10⁸cfu/g once daily for one month. The present study also found that the body weight increased obviously relative to the control group, and the relative growth rate was 39.31% as they were fed with the bacterial cells at10⁸cfu/g. Similarity analysis of 16 s r DNA sequences indicated that the strain YQ-2 had 99% similarity to Bacillus subtilis strain KLP2015. Thus, the strain YQ-2 was tentatively identified as Bacillus subtilis.