Bacillaene and Sporulation Protect Bacillus subtilis from Predation by Myxococcus xanthus

Abstract

ABSTRACTMyxococcus xanthusandBacillus subtilisare common soil-dwelling bacteria that produce a wide range of secondary metabolites and sporulate under nutrient-limiting conditions. Both organisms affect the composition and dynamics of microbial communities in the soil. However,M. xanthusis known to be a predator, whileB. subtilisis not. A screen of various prey led to the finding thatM. xanthusis capable of consuming laboratory strains ofB. subtilis, while the ancestral strain, NCIB3610, was resistant to predation. Based in part on recent characterization of several strains ofB. subtilis, we were able to determine that thepksgene cluster, which is required for production of bacillaene, is the major factor allowingB. subtilisNCIB3610 cells to resist predation byM. xanthus. Furthermore, purified bacillaene was added exogenously to domesticated strains, resulting in resistance to predation. Lastly, we found thatM. xanthusis incapable of consumingB. subtilisspores even from laboratory strains, indicating the evolutionary fitness of sporulation as a survival strategy. Together, the results suggest that bacillaene inhibitsM. xanthuspredation, allowing sufficient time for development ofB. subtilisspores.