月桂酸单甘油酯对珍珠龙胆石斑鱼源海豚链球菌体外抑菌活性及其作用机制  

In vitro Antibacterial Activity and Mechanism of Glycerol Monolaurate Against Streptococcus iniae Isolated from Pearl Gentian Grouper

作　　者：李妍萍 孙恒 杨林狄 王浩宇 黄洁 黄郁葱[1] LI Yanping;SUN Heng;YANG Lindi;WANG Haoyu;HUANG Jie;HUANG Yucong(Fisheries College of Guangdong Ocean University/Guangdong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture/Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes,Zhanjiang 524088,China)

机构地区：[1]广东海洋大学水产学院/广东省水产动物病害防控与健康养殖重点实验室/水产经济动物病害控制广东省普通高等学校重点实验室,广东湛江524088

出　　处：《广东海洋大学学报》2024年第5期22-30,共9页Journal of Guangdong Ocean University

基　　金：国家重点研发计划(2022YFD2401204);广东省驻镇帮镇扶村农村科技特派员项目;广东海洋大学科研启动经费资助项目。

摘　　要：【目的】研究月桂酸单甘油酯(Glycerol monolaurate,GML)对海豚链球菌(Streptococcus iniae)的体外抑菌效果及其作用机制,为鱼类养殖中防控海豚链球菌感染提供新的依据。【方法】以珍珠龙胆石斑鱼(♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatus)源海豚链球菌为研究对象,运用微量二倍稀释法测定GML对海豚链球菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),并通过生长曲线、电导率、菌体形态变化、菌体蛋白表达、生物被膜形成和毒力相关基因转录的测定评估GML对海豚链球菌的潜在作用机制。【结果】GML对海豚链球菌的最小抑菌浓度和最小杀菌浓度别为16 mg/L和32 mg/L;抑制作用呈现浓度依赖性,浓度越高抑制效果越强,且在MIC浓度作用下对菌体生长及生物被膜形成抑制作用最强;不同浓度GML作用后的菌体均能观察到细胞排列松散、大小不均一、胞间间距增大,并出现显著凹陷、皱褶等不同程度的损伤。此外,在1/2 MIC与MIC浓度GML处理后,菌悬液电导率明显上升,表明在此浓度下药物导致菌体出现一定损伤;1/4 MIC浓度促进蛋白条带增多,而MIC浓度则呈现出抑制效应引起蛋白条带变淡甚至消失。【结论】月桂酸单甘油酯对珍珠龙胆石斑鱼源海豚链球菌具有良好的体外抑菌活性。其主要作用途径是通过破坏细胞结构完整性,导致内容物流失,抑制细菌的生长及生物被膜形成,影响细菌毒力基因及蛋白表达等方面发挥抗菌作用。【Objective】To investigate the in vitro antibacterial effect and mechanism of action of Glycerol monolaurate(GML)against Streptococcus iniae for providirg new evidence for the control of S.iniae infecion in fish farming.【Method】This study focused on S.iniae from pearl gentian grouper(♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatus),and the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of GML against S.iniae were determined using the microdilution method.The potential mechanism of action of GML against S.iniae was evaluated through detection of growth curves,conductivity,changes in bacterial morphology,bacterial protein expression,biofilm formation,and transcription of virulence-related genes.【Result】The MIC and MBC of GML against S.iniae were 16 mg/L and 32 mg/L,respectively.The inhibitory effect showed a concentration-dependent pattern,with higher concentrations resulting in stronger inhibition.Particularly,the inhibition of bacterial growth and biofilm formation were most pronounced at the MIC.After treatment with different concentrations of GML,bacterial cells exhibited loose arrangement,uneven sizes,increased intercellular spaces,and significant damage such as concavities and folds.Additionally,treatment with 1/2 MIC and MIC concentrations of GML led to a significant increase in the electrical conductivity of the bacterial suspension,indicating damage to the bacteria at these concentrations.The 1/4 MIC concentration promoted the increase in protein bands,while the MIC concentration exhibited an inhibitory effect causing the protein bands to become faint or disappear.【Conclusion】GML showed excellent in vitro antibacterial activity against S.iniae isolated from the pearl gentian grouper.It played an antibacterial role by destroying the integrity of cell structure,leading to the loss of contents,inhibiting the growth of bacteria and biofilm formation,and affecting the expression of bacterial virulence genes and proteins.

关 键 词：海豚链球菌 月桂酸单甘油酯 抗菌机制 绿色养殖 抗生素 

分 类 号：S941.42[农业科学—水产养殖]