Salt-tolerant Myxococcus Sociological Behavior And Adaptation Strategies On The Marine Environment

The myxobacteria are considered to be the typical soil microorganisms, and none of them can tolerate the salt concentration of seawater. Recently, phylogenetic analyses of 16S rDNA fragments amplified from marine sediment DNA indicated the presence of bacterial phylotypes which are closely related to myxobacteria. Since 1998, more and more reports on myxobacteria from marine environments around the Pacific Ocean have appeared by microbiologists. The existence of "true" marine myxobacteria has been approved. The discovery of marine myxobacteria impels us to study how the myxobacteria adapt to the ocean. Depending on their adaptation to salinity, the marine myxobacteria include two types: marine halophiles and marine halotolerants. The two types of marine myxobacteria can both survive and propagate in the ocean conditions. But they are different among morphology, phylogeny, physiology and living patterns.The myxobacteria have a life cycle that is dominated by social behavior. During vegetative growth, cells prey on other bacteria in large groups by gliding motility. When faced with starvation, cells form a macroscopic fruiting body containing thousands of resting myxospores. The social behaviors of the myxobacteria mainly depend on their dual motility systems; the latter includes social motility (S-motility) and adventurous motility (A-motility). The two motility systems are not only different morphologically and genetically, but also functionally. The A-motility system functioned well on relatively firm and dry surfaces, whereas the S-motility system worked better in wet and soft conditions.The existence of social behavior (mainly the maintenance of dual motility systems) enables myxobacterial cells to move under different circumstances than would be possible with one motility system alone. We want to know whether the existence of social behavior also enables myxobacteria to survive in the ocean conditions, and how the marine myxobacteria adapt to the ocean.In this paper, we isolated and purified many marine myxobacteria from various marine samples. First, we observed the growth and the morphogenesis of the isolates. And then, we studied their social behaviors in the conditions without and with seawater. We reported the rules for the changes of the social behavior of marine myxobacteria by the presence of seawater for the first time. We tried to study the...