细菌运动性对生物被膜的动态演替及其对厚壳贻贝附着的影响

Effects of bacterial motility on dynamic succession of biofilms and settlement of the mussel Mytilus coruscus

中文关键词: 海洋假交替单胞菌  运动性  生物被膜  动态演替  厚壳贻贝附着

英文关键词: Pseudoalteromonas marina  Bacterial motility  Biofilms  Dynamic succession  Mytilus coruscus settlement

中文摘要:

      为研究海洋细菌的运动性在生物被膜形成和贝类附着过程中的作用，本研究以厚壳贻贝(Mytilus coruscus)为研究对象，开展了海洋假交替单胞菌(Pseudoalteromonas marina)野生型菌株和ΔcheW菌株不同时间段的运动性能分析，调查了运动性能不同的细菌形成生物被膜的膜厚、细菌密度以及胞外产物的动态变化，探究了其生物被膜的动态演替对厚壳贻贝附着的影响。研究发现，野生型菌株和ΔcheW菌株在6、12、24、48、72和96 h等不同时间的运动性能差异显著(P<0.05)。同时，对2株菌株形成菌圈的半径进行测量发现，随着时间的变化，菌圈的半径不断增加，均在96 h达到最大。整体上，野生型菌株在不同时间段形成的菌圈大于ΔcheW菌株。在运动性的作用下，2株菌株随着时间的变化形成生物被膜的细菌密度及膜厚在48 h达到最大值，在72 h后开始扩散。在运动性的影响下，野生型菌株在不同时间段形成的生物被膜对厚壳贻贝附着诱导效果显著高于ΔcheW菌株。在运动性介导下，2株菌株形成生物被膜对厚壳贻贝稚贝附着率随着时间变化呈现先增长后减少的趋势，在48 h达到最高，在72 h后开始降低，这一结果与不同时间段下形成生物被膜的胞外产物变化一致，且胞外产物分泌与细菌运动性密切相关。因此，运动性影响生物被膜的形成，且在生物被膜动态演替过程中介导了生物被膜的膜厚、细菌密度以及胞外产物的分泌，从而影响了厚壳贻贝的附着。本研究为后续开展细菌运动性、生物被膜形成和厚壳贻贝互作机制研究奠定了基础，为海洋经济物种的生产养殖提供了技术支撑。

英文摘要:

      To study the regulatory role of marine bacterial motility on biofilm formation and settlement of marine bivalves, this study used the economically important marine mussel Mytilus coruscus as the research target, and investigated the wild-type strain and ΔcheW strain of Pseudoalteromonas marina. These bacteria have different motility; thus, the motility analysis of these strains was carried out at various time points, and the differences in the biofilm thickness and composition and bacterial density were also analyzed at different time points. Finally, their effects on dynamic biofilm succession and settlement of M. coruscus were evaluated. This study found that the motility of the wild-type strain and the ΔcheW strain at 6 h, 12 h, 24 h, 48 h, 72 h, and 96 h was significantly different (P<0.05). It was found that both bacterial circle radii increased with time and reached their maximum at 96 h. Overall, the wild-type strain formed a larger bacterial circle than the ΔcheW strain. The two strains' bacterial density and biofilm thickness increased with time and reached their maximum at 48 h, begging to spread after 72 h. At all time points, the mussel settlement rates on the wild-type strain biofilm were higher than on the ΔcheW biofilm. Initially, the mussel settlement rates increased, but after 72 h a decreasing tendency was observed, reaching the highest value at 48 h. These settlement results were consistent with the changes in the biofilm composition under different time points. Therefore, this study concluded that bacterial motility affects biofilm formation, mainly biofilms thickness, bacterial density, and extracellular compounds during the dynamic succession of biofilms, thereby regulating the settlement of the mussel M. coruscus. This study provides novel insights into the interaction between bacterial motility, biofilm formation, and the settlement of M. coruscus, which may help optimize the production and breeding of economically important marine animals.