海洋假交替单胞菌端生和侧生鞭毛对生物膜形成的影响

Effects of polar and lateral flagella on biofilm formation in marine Pseudoalteromonas

海洋假交替单胞菌广泛分布于各种海洋环境中,能分泌多种生物活性物质和胞外酶类,多具有较强的生物膜形成能力。这些生物膜具有诱导矿化和吸引腐蚀生物幼体附着的功能,在海洋生态系统的能量和元素循环中扮演特殊角色。细菌的鞭毛系统介导细菌的运动行为,在营养的获取以及生物膜和浮游状态转化过程中发挥作用。有研究表明,鞭毛也是生物膜基质的有机组分,但目前海洋假交替单胞菌鞭毛系统在生物膜形成中的作用尚不清楚。本文以南海表层来源的假交替单胞菌(Pseudoalteromonas sp.SCSIO 11900)和深海沉积物来源的近源假交替单胞菌(Pseudoalteromonas.sp.SM9913)为研究对象,分别选取了编码鞭毛不同组分的基因进行敲除,研究鞭毛缺失对细胞游动性和生物膜形成能力的影响。结果表明,无论来自表层还是深海的假交替单胞菌都使用端生鞭毛维持细胞游动性,而且其缺失促进生物膜的形成。此外,深海来源的SM9913还具有侧生鞭毛。尽管这种鞭毛有助于提高细胞游动性,却不影响细菌的生物膜形成能力。这些端生鞭毛系统在近缘海洋假交替单胞菌中广泛分布,可能为该属菌株在不同海洋环境中获取营养、定殖及适应环境的过程中发挥重要作用。

Pseudoalteromonas are widely distributed in diverse marine environments.They can produce an array of bioactive compounds and enzymes,and have strong ability to form biofilms in general.The biofilms formed by Pseudoalteromonas are able to induce biomineralization and inhibit the settlement of fouling organisms.Flagella are essential for bacterial motility,mediating nutrient acquisition,and the transformation from planktonic living style to biofilm state.Flagella is also considered as a critical component of biofilm matrix.However,the function of flagella during biofilm formation of marine Pseudoalteromonas remains unclear.In this study,we focused on Pseudoalteromonas sp.SCSIO 11900 and SM9913,which were isolated from the surface water and the sediment of deep oceans,respectively.The influence of flagella on biofilm formation and motility was explored by analyzing mutants lacking the genes encoding components of different flagellar portions in both strains.The results showed that the polar flagella are essential for swimming motility,and inhibit biofilm formation in SM9913 and SCSIO 11900.In addition,the lateral flagella in SM9913 also plays a role in swimming motility,but has no effects on biofilm formation.We further showed that these polar flagella systems are present in different Pseudoalteromonas strains,implying that they may be important for these bacteria for nutrient acquisition,for colonization and environmental adaptation in diverse marine habitats.