Fig. 3.

Biofilm formation by soil bacteria and action of lactonase enzymes. Soil bacteria control cell density by molecular signals called autoinducers. N-acyl homoserine lactone (AHL) is the main cell–cell communication molecule studied, and acts directly in the control of cell density and regulates the expression of genes involved in the biofilm formation (formed by exopolysaccharides—EPS) and virulence. Some bacterial genera, especially involved in biological control, produce enzymes called lactonases that act by breaking the lactone ring and preventing signaling via AHL. The lactonase enzymes action is related to the attenuation of the pathogenic bacteria virulence and the reduction of bacterial biofilms formation, both by pathogenic bacteria and plant growth promoters