Study On The Isolation, Purification And Taxonomy Of Myxobacteria

The soil samples collected from Yunnan, Hebei, Qinghai and other regions of China, and also from Vietnam, were used as the materials in this experiment. And dung pellets of rabbits or goats that had been autoclaved can be used to induce many kinds of fruiting bodies of the Myxobacteria in different colors, sizes, and shapes. We isolated and purified strains under traditional procedure. According to the special character of Myxobacteia, we designed several new purification methods, and improved some traditional methods, which made it easier for those strains that were difficult to purify in usual way. The methods accelerated the purification process. Purification and verification can be finished in one step-CAS test, thus the purification cycle is grea.tly shortened. And through combining of all the isolation and purification methods, we obtained a best scheme, overcome a long-term bottleneck for the exploitation and utilization of myxobacteria resources.Through studying on ecological diversity of myxobacteria in certain areas of Hebei, Yunnan and Qinghai province, more than 150 strains of 10 genera(Archangium , Myxococcus , Cystobacter, Corallococcus , Melittangium , Sorangium, Polyangium , Chondromyces ,Angiococcus , Stigmatella) of Myxococcales were isolated from 42 samples, including some strains that had never been described before . Myxobacteria statistic comparisons on different site, vegetation and nutrition source of these special habitats show wide distribution and variety ecological diversity of myxobacteria. This sets a strong base for the development and utilization of myxobacteria efficiently.These strains were primarily identified in generic or species level by their fruiting bodies, swarms, myxospores and vegetative cells. The 16S rDNA/RNA sequencing analysis of 4 morphological representative strains (BD86, YN78, BD54, SHX9) wascarried out. Complete sequences of them were obtained and phylogenesis analysis was carried out of suborder Cystobacterineae, their phylogenetic position was determined. We did also G+Cmol%, physiological and biochemical characteristics tests. The results show that strain BD86, YN78 should be clustered into the genus Myxococcus; BD86 is a related taxon of Myxococcus xanthus; YN78 is similar to Myxococcus stipitatus; BD54 and SHX9 are similar to Cystobacter ferrugineus. Obviously, it is far from the requirement to determine the taxonomy condition depending on morphological characters alone, for there are too many reasons that will lead to wrong classification. The 16S rDNA sequences result are almost identical to the physiological and biochemical result, this conformed the importance of molecular, physiological and biochemical function in the taxonomy of myxobacteria .We observed fruiting body formation of 6 strains with dissection microscope, input the pictures into computer and recorded the whole development process of them on rabbit dung substrate. And small chamber cultivate experiment and glycerol induced test were carried out to study the formation of myxospores under different conditions. This will benefit the biological evolution, phylogenetic analysis and metabolism study of myxobacteria.