School of Biological Engineering, Dalian Polytechnic University, Dalian, 116034, China.
School of Food Science and Engineering, Dalian Ocean University, Dalian, 116023, China.
Fish Shellfish Immunol. 2020 Jul;102:133-139. doi: 10.1016/j.fsi.2020.04.023. Epub 2020 Apr 17.
Winter is a high incidence period of skin ulceration syndrome in the sea cucumber Apostichopus japonicus. Disease control during the overwintering of sea cucumber can help increase yield and reduce losses. The purpose of this study was to study the effect of the low temperature-resistant probiotic Bacillus baekryungensis MS1 on the growth and immune parameters of sea cucumbers and preliminarily investigate the molecular mechanism of the effects. A low temperature-resistant bacterium, B. baekryungensis MS1, was isolated from a sea cucumber pond in winter and used for culture experiments. After 10 days of prefeeding, the experiment was divided into the control group (fed with commercial diet) and the MS1 group (fed with diet containing B. baekryungensis MS1 at 10 cfu g) for a total of 60 days. The specific growth rate was measured at the end of the culture period to evaluate the growth performance of the sea cucumber. Samples were taken on days 30 and 60 to determine the immune parameters (including superoxide dismutase activity, catalase activity, alkaline phosphatase activity, acid phosphatase activity, nitric oxide synthetase activity, phagocytosis and respiratory burst), aquaculture water microbiota and gut microbiota of the sea cucumber. Finally, transcriptome sequencing and qRT-PCR verification of the two groups of sea cucumbers were performed to study the mechanism of B. baekryungensis MS1 to improve the immunity of the sea cucumber. The results showed that after 60 days of feeding, B. baekryungensis MS1 significantly improved the growth performance and immune enzyme activity and formed a healthier structure of the gut microbiota in the sea cucumber. The challenge test showed that B. baekryungensis MS1 significantly reduced the mortality of sea cucumbers infected with Vibrio splendidus. Transcriptome and gene expression analysis indicated that B. baekryungensis MS1 activated the ubiquitin-mediated proteolysis pathway and inhibited the mTOR signaling pathway to regulate the immunity of the sea cucumber. In summary, the low temperature-resistant bacterium B. baekryungensis MS1 could be applied for the aquiculture of sea cucumber in winter to improve health status and resist pathogenic bacteria such as V. splendidus.
冬季是海参体表溃疡综合征的高发期。海参越冬期间的病害防治有助于提高产量、减少损失。本研究旨在研究低温耐受益生菌枯草芽孢杆菌 MS1 对海参生长和免疫参数的影响，并初步探讨其作用的分子机制。从冬季海参池塘中分离到一株低温耐受菌枯草芽孢杆菌 MS1，并进行培养实验。经过 10 天的预投喂，实验分为对照组（投喂商业饲料）和 MS1 组（投喂含枯草芽孢杆菌 MS1 的饲料，浓度为 10 cfu/g），共 60 天。在培养期末测量特定生长率以评估海参的生长性能。分别在第 30 天和第 60 天取样，以确定免疫参数（包括超氧化物歧化酶活性、过氧化氢酶活性、碱性磷酸酶活性、酸性磷酸酶活性、一氧化氮合酶活性、吞噬作用和呼吸爆发）、养殖水微生物群和海参肠道微生物群。最后，对两组海参进行转录组测序和 qRT-PCR 验证，以研究枯草芽孢杆菌 MS1 提高海参免疫力的机制。结果表明，经过 60 天的投喂，枯草芽孢杆菌 MS1 显著提高了海参的生长性能和免疫酶活性，形成了更健康的海参肠道微生物群结构。攻毒试验表明，枯草芽孢杆菌 MS1 显著降低了感染灿烂弧菌的海参的死亡率。转录组和基因表达分析表明，枯草芽孢杆菌 MS1 激活了泛素介导的蛋白酶体途径，抑制了 mTOR 信号通路，从而调节了海参的免疫力。综上所述，低温耐受菌枯草芽孢杆菌 MS1 可应用于冬季海参养殖，以提高健康状况，抵抗灿烂弧菌等病原菌。
