Diversity and network structure of epiphytic bacterial communities on different submerged macrophytes

Abstract

沉水植物叶表附着大量细菌,与沉水植物构成了复杂的共生体系.叶片附着细菌是水生态的重要组成部分,能影响沉水植物自身生长和水体物质循环过程.目前,对于沉水植物多样性对植物叶片附着细菌群落的影响知之甚少.本研究比较了不同沉水植物物种多样性对浮游细菌和叶片附着细菌群落的影响,同时探究不同植物——苦草(Vallisneria natans)、穗状狐尾藻(Myriophyllum spicatum)、微齿眼子菜(Potamogeton maackianus)和黑藻(Hydrilla verticillata)叶片附着细菌的群落结构和多样性特征.结果表明,浮游细菌和叶片附着细菌的群落α多样性和β多样性具有显著差异.与单一植物物种体系相比,高植物物种多样性体系中植物叶片附着细菌群落α多样性较高.在高植物物种多样性体系中,黑藻叶片附着细菌群落的α多样性显著较高而β多样性显著较低,苦草叶片附着细菌群落的α多样性较低.沉水植物叶片附着细菌群落优势菌群属于变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes).高植物物种多样性体系中苦草的物种共现网络最具模块性.嗜甲基菌(g_Methylophilus)、红杆菌(f_Rhodobacter)、黄杆菌(g_Flavobacterium)是物种共现网络的关键物种.本文研究植物物种多样性对淡水湖泊细菌群落结构的影响,并强调宿主植物对附着细菌群落的重要选择作用,加深对细菌群落在水生植物叶片定殖机制的理解.;Epiphytic bacteria, adhering to the leaf surface of aquatic submerged macrophytes, develop a complex symbiotic relationship with submerged macrophytes. Epiphytic bacteria are an important component of the aquatic ecosystem, which can affect not only the growth of submerged macrophytes but also the nutrient cycling in aquatic ecosystems. Currently, the effect of submerged macrophyte diversity on the epiphytic bacteria communities is far from well understood. This study compared the effects of submerged macrophyte on bacterioplankton and epiphytic bacterial communities, meanwhile explored the community structure and diversity of epiphytic bacterial communities on different macrophytes-Vallisneria natans,Myriophyllum spicatum, Potamogeton maackianus andHydrilla verticillata. The results showed that the α diversity and structure of planktonic bacterial communities were significantly different from those of the epiphytic bacterial communities. With the increase of submerged macrophyte diversity, the α diversity of epiphytic bacterial communities increased slightly. In the systems with high submerged macrophyte diversity, significantly higher α diversity and lower β diversity were found for the epiphytic bacterial community on H. verticillata. Bacteroidetes and Proteobacteria were dominant phyla on the submerged macrophyte leaves. Co-occurrence network analysis revealed that the modularity value of V. natans epiphytic bacterial network was relatively high. Methylophilus, Rhodobacter andFlavobacterium were core species in the co-occurrence networks. This study demonstrated the effect of submerged macrophytes on bacterial community structure in freshwater lakes, emphasizing the importance of host-specific selection for epiphytic bacterial communities, and deepening our understanding of the mechanism of bacterial colonization on submerged macrophytes.