Myxobacteria are fascinating Gram-negative bacteria whose life cycle includes the formation of multicellular fruiting bodies that contain about 100,000 cells differentiated as asexual spores for their long-term survival. They move by gliding on surfaces, an activity that helps them carry out their primitive kind of multicellular development. Myxobacteria have multiple traits that are clearly social in nature; they move and feed socially. These processes require specific intercellular signals, thereby exhibiting a sophisticated level of the interorganismal communication. Myxobacteria are predators. Predation is social not only with respect to searching for prey (motility) but also in the killing of prey. Swarming groups of cells secrete antibiotics and bacteriolytic compounds that kill and lyse their prey, and food is thereby released. Since the last three decades, myxobacteria are known as valuable producers of secondary metabolites exhibiting various biological activities. Myxobacterial metabolites exhibit many unique structural features as well as rare or novel modes of action, making them attractive lead structures for drug development. Both genome sequencing and metabolic profiling of myxobacterial strains suggest that the diversity of myxobacterial secondary metabolism is far greater than previously appreciated. The present review discusses the structure, cytology, physiology, and ecology of myxobacteria, as well as their secondary metabolite production and social interactions.

The broad biocontrol properties of myxobacteria (mainly members of the genera Corallococcus and Myxococcus) isolated from forest soils against main fungal pathogens of pine seedlings were estimated. Among the myxobacterial strains studied (in vivo tests), the strongest antagonism towards fungi was noticed for the strains of the species Myxococcus virescens Thaxter and Corallococcus exiguus Reichenbach. They inhibited the fungal growth within the range 38-63%. The strongest inhibitory reaction towards Cylindrocarpon destructans (Zinssm.) Scholten was observed. A predominating part of myxobacteria (22 from among 30) inhibited the growth of Rhizoctonia solani Kühn. Myxobacteria suppressed any pathogenic action of Rhizoctonia solani (strain 411) towards Scots pine seedlings (in vitro tests). They produced extracellular (but not intracellular) acidic and neutral proteinases. None of the myxobacterial strain under examination produced chitinases. The 57% of the myxobacterial strains studied produced siderophores. The numbers of myxobacterial strains, obtained from under forest trees were in the following order: Betula pendula Roth. > Pinus sylvestris L. > Alnus glutinosa Gaertn. = Quercus robur L. The results gained in present work have proved potential use of myxobacteria as biocontrol agents against Rhizoctonia solani, common fungal pathogen of pine seedlings.