Peculiarities of the SprIR Quorum Sensing System of Serratia proteamaculans 94 and Its Involvement in Regulation of Cellular Processes

The quorum sensing (QS) system SprIR of the psychrotrophic strain Serratia proteamaculans 94 was investigated. A mutant was constructed with the inactivated s prR gene encoding the regulatory receptor protein SprR. Inactivation of this gene was shown to affect the composition of fatty acids synthesized by S. proteamaculans 94 and did not affect the synthesis of N -acyl-L-homoserine-lactones (AHL); the activities of extracellular proteases, chitinases, and hemolysins; the swimming motility of cells; and the suppression of mycelium growth of fungal plant pathogens by volatile compounds emitted by this strain. Inactivation of the sprI gene (but not the s prR gene) reduced the biofilm formation, which increased when exogenous AHL was added to the culture. The comparative proteomic analysis of cell of the parent strain and mutant strains with inactivated sprI and sprR genes showed that the expression of 30 proteins in S. proteamaculans 94 is affected by the SprIR quorum sensing system.