Culture-Dependent and Culture-Independent Analyses of the Effects of Signal Compounds on Microbial Community Dynamics in Lake Sediment

Currently, a vast majority of bacteria in the natural environment cannot be cultured or isolated under laboratory conditions mainly due to interdependence and interaction of cells. Quorum sensing (QS) is a cell-to-cell communication through which microbial cells regulate their biological activities. In this study, the interfacial sediments from Lake Taihu were induced by three types of signal compounds, including N-butanoyl-L-homoserine lactone (C4-HSL), autoinducer-2 (AI-2), and cyclic adenosine monophosphate (cAMP) under the laboratory conditions, and the variations in microbial diversity and composition after induction were investigated by culture-independent and culture-dependent methods, respectively. High-throughput sequencing analysis revealed that the dominant genera Vogesella and Cloacibacterium in the original sediment were supplanted by Aeromonas and Comamonas genera in response to AI-2 addition. However, the major microbial community in sediments induced by cAMP and C4-HSL was basically the same as that of the original sediment. The screen results indicated cAMP-like of Massilia strains and C4-HSL activity of Bacillus strains. Furthermore, cAMP and AI-2 stimulated Microbacterium strains, whereas C4-HSL and AI-2 promoted Arthrobacter. These findings together confirm the role of QS in mediating microbial community diversity and composition.