Lysobacter

Abstract

The genus Lysobacter is among the youngest bacterial genera encompassing plant beneficial strains. In the last 40 years the number of bacterial species included in this genus increased, and the advent of sequencing technologies helped to show the characteristics of these bacteria. In this regard, it was proven that the absence of a flagellum is a feature not shared by all the Lysobacter species and, moreover, the cell motility of some species mainly relies on the formation of type IV pili. Culture dependent and independent methods revealed that Lysobacter members are cosmopolitan bacteria able to colonize different environments and to persist in extreme environments. Looking at the agroecosystem, strong evidence was provided on the association of these bacteria with plants, and their correlation with the phenomenon of soil suppressiveness was also shown. Although their ability to actively colonize plants and soils, the number of Lysobacter spp. strains studied for their plant beneficial potential is still limited. This might be related to the unavailability of growth media specific for the isolation of Lysobacter members. In this chapter, a semiselective growth medium was designed for the isolation of strains belonging to L. antibioticus, L. capsici, L. enzymogenes, and L. gummosus species, based on their capability to resist antibiotics. Moreover, these species are composed mostly of the plant beneficial Lysobacter spp. strains characterized so far. Their ability to control plant pathogenic bacteria, fungi, nematodes, oomycete, and protists mainly relied on various mechanisms of action such as the competition for space, the induction of plant defense mechanisms, the predation and the release of antibiotics, lytic enzymes, and volatile organic compounds. In the last ten years, more evidence has been provided about the presence of Lysobacter spp. in agricultural soils contaminated by heavy metals and petroleum derivatives. Although in their infancy, several studies proved that bacteria belonging to this genus may be applied for the bioremediation of contaminated agricultural soils. Overall, Lysobacter spp. may be considered a valuable reservoir of novel bacterial strains that may be developed to make the future of crop production more sustainable.