Quorum Sensing Signals Alter in vitro Soil Virus Abundance and Bacterial Community Composition

Abstract

Cell-density dependent quorum sensing (QS) is fundamental for many coordinated behaviors among bacteria. Most recently several studies have revealed a role for bacterial QS communication in bacteriophage (phage) reproductive decisions. However, QS based phage-host interactions remain largely unknown, with the mechanistic details revealed for only a few phage-host pairs and a dearth of information available at the microbial community level. Here we report on the specific action of eight different individual QS signals (acyl-homoserine lactones; AHLs varying in acyl-chain length from four to 14 carbon atoms) on prophage induction in soil microbial communities. We show QS autoinducers, triggered prophage induction in soil bacteria and the response was significant enough to alter bacterial community composition in vitro. AHL treatment significantly decreased the bacterial diversity (Shannon Index) but did not significantly impact species richness. Exposure to short chain-length AHLs resulted in a decrease in the abundance of different taxa than exposure to higher molecular weight AHLs. Each AHL targeted a different subset of bacterial taxa. Our observations indicate that individual AHLs may trigger prophage induction in different bacterial taxa leading to changes in microbial community structure. The findings also have implications for the role of phage-host interactions in ecologically significant processes such as biogeochemical cycles, and phage mediated transfer of host genes, e.g., photosynthesis and heavy metal/antibiotic resistance.

The Impact of Quorum Sensing on the Modulation of Phage-Host Interactions

“…The abundance of lysogens can be inversely correlated to primary productivity, since low nutrient conditions may reduce host densities and compromise further viral progeny (4). In agreement with this supposition, spontaneous induction of prophages has been observed under high-cell-density conditions (53,54), whereas treatment of soil and groundwater samples with AHLs significantly increased viral abundance (55,56). These findings strongly emphasize that population density may be a critical determinant of phage-host interactions; phages may exploit diverse QS communication systems to link host cell density and phage decisions, providing novel insights into the regulatory mechanisms implicated in the developmental fate of phages.…”

Bacteriophage-Mediated Control of Phytopathogenic Xanthomonads: A Promising Green Solution for the Future

“…On the contrary, native bacteria can protect themselves against colonization by sacrificing a part of the population and inducing their prophages’ lytic cycle [ 101 ]. Lysogenic bacteria can use their prophage weapon effectively, as observed in an in vitro experiment recently, where a lysogenic-lytic switch of bacteriophages to QS autoinducers strongly influenced the viral and bacterial abundance and diversity in soil communities [ 112 ].…”

Use of Acyl-Homoserine Lactones Leads to Improved Growth of Ginseng Seedlings and Shifts in Soil Microbiome Structure

“…A number of studies have shown that plant responses to certain AHL molecules are specific depending on the length of the acyl moiety [20][21][22]. Not only do AHL molecules affect plant responses, but a study by Liang et al [23] showed that a variety of AHLs can affect the bacterial community. In this study, we hypothesize that treatment of AHL could be potentially used to alleviate the problems that occur during monocropping by shifting the soil microbiome in addition to their plant growth promoting activity.…”