池塘冷能气雾降温设备对高温期刺参养殖池塘环境理化指标及沉积物细菌群落结构的影响

Effects of the cooling equipment based on cooled atomization air on environmental physicochemical indexes and sedimental microbial community structure of sea cucumber culture ponds in summer

中文关键词: 刺参  养殖池塘  池塘冷能气雾机  高通量测序  菌群分析

英文关键词: Apostichopus japonicus  Culture pond  Cooling equipment based on cooled atomization air  High-throughput sequencing  Bacterial composition analysis

中文摘要:

      近年来，极端高温灾害已成为限制仿刺参(Apostichopus japonicus)产业可持续发展的重要瓶颈之一。本团队前期研发出一款可实现池塘养殖刺参安全度夏的池塘冷能气雾降温设备，取得了较好的应用效果。为解析使用该设备对池塘环境的调控作用，本研究选取安装并使用该设备的5个池塘(实验组，根据相对区域的不同，标记为E1和E2组)和无任何降温措施的3个池塘(对照组，标记为C组)为研究对象，测定夏季高温期实验池塘水质及底质指标，并利用高通量测序技术对相应池塘沉积物中菌群结构差异进行解析，进一步分析细菌群落结构与相关环境影响因子的相关性。研究结果显示，2个实验组池塘的底层平均水温显著低于对照组，水体溶解氧含量显著高于对照组，水体氨氮和沉积物氨氮、亚硝酸氮以及化学需氧量均显著低于对照组池塘(P<0.05)。对2个实验组和1个对照组共8个测试池塘的沉积物菌群结构进行测定后分别获得707~880个分类操作单元(optical transform unit, OTU)，α多样性计算结果显示，实验组沉积物菌群群落丰度和微生物群落多样性均高于对照组。对8个样品的PCoA分析结果显示，各组内养殖池塘沉积物样本的菌群组成及群落结构相似性较高，组间差异明显。在目水平的物种分布统计结果显示，2个实验组的物种组成相似性较高，实验组中根瘤菌目(Rhizobiales)、乳杆菌目(Lactobacillales)和微球菌目(Micrococcales)的相对丰度显著高于对照组(P<0.05)。LefSe分析筛选到在不同组间存在显著差异的13个细菌群类(P<0.05)。对菌群结构与环境因子的相关性分析显示，参与氮循环过程的微生物种类丰度显著高于对照组(P<0.05)，进一步筛选到与实验池塘水体氨氮含量显著相关的3个OTUs，分别为OTU7、OTU29和OTU108，依次归属为变形菌门(Proteobacteria)下的苍白杆菌属(Ochrobactrum)和埃希氏菌属(Escherichia-Shigella)以及厚壁菌门(Firmicutes)下的芽孢杆菌属(Bacillus)。在所预测到的25个原核生物COG代谢途径中，实验组和对照组在18个代谢途径上存在显著性差异(P<0.05)。以上研究结果表明，使用该设备可显著改善池塘水质及底质环境，并影响沉积物菌群结构，相关研究结果可为该设备的推广应用提供数据支撑。

英文摘要:

      In recent years, continuous high temperature and marine heat waves in summer have become major limitations for the sustainable development of sea cucumber aquaculture. In 2019, our team invented a cooling equipment based on cooled atomization air, which can reduce the water temperature of the culture pond in summer. Previous tests showed that the survival rates of the sea cucumbers in the equipped ponds were higher than the unequipped ponds during the high temperature. In this study, five equipped ponds were selected as experimental groups (groups E1 and E2 were labeled according to their geographic location) and three unequipped ponds were selected as control groups (labeled group C), then the water quality, sedimental quality, and the sedimental microbial community structure of the eight ponds were analyzed in order to reveal the mechanism of the higher survival rate using the cooling equipment. The results showed that the temperature of the bottom water of the two experimental groups was significantly lower than that of the control group (P<0.05). The dissolved oxygen (DO) level in the bottom water of the experimental groups was significantly higher than that of the control group (P<0.05). Both the ammonia nitrogen concentration in the bottom water and the concentrations of nitrite nitrogen, and chemical oxygen demand (COD) and ammonia nitrogen in pond sediments of the two experimental groups were significantly lower than that of the control group (P<0.05). The sedimental microbial community structure of all the ponds was also investigated, and the OTUs (optical transform units) were numbered from 707 to 808. Alpha diversity analysis showed that the abundance and diversity of the experimental group were higher than those of the control group. PCoA (principal coordinates analysis) showed that the bacterial composition and community structure among the two experimental groups were more similar, while there were significant differences between the experimental and the control groups. The species distribution analysis on the order level showed that the similarity between the two experimental groups is higher than that between the experimental and control groups. The relative abundance of Rhizobiales, Lactobacillales, and Micrococcineae in the experimental groups were significantly higher than that in the control groups. Thirteen OTUs with significant differences among three groups were selected using LEfSe (LDA effect size) analysis. The correlation analysis between microbial community structure and environmental factors showed that the abundance of microbial species involved in the nitrogen cycle was significantly higher in the experimental groups than that of the control groups. Then OTU7, OTU29 and OTU108 were screened and significant correlation was found with ammonia nitrogen concentration in all of the tested ponds, and they are classified as Ochrobactrum, Escherichia-Shigella and Bacillus, respectively. In the 25 predicted COG (clusters of orthologous groups of proteins) metabolic pathways in prokaryotes, 18 metabolic pathways exhibited significant differences (P <0.05) between the experimental groups and the control groups. All the results indicated that the use of the equipment could significantly improve the pond water quality and sediment environment, and positively affect the sedimental microbial community structure of the bottom water. The results of this study would provide scientific support for the popularization and application of the equipment.