Differences Between Sorangium Cellulosum So2161and The Mutant SoL4-29

Sorangium cellulosum can produce epothilone which is a kind of new drugagainst cancer, Sorangium cellulosum cells show typical social behaviors, such as celldensity-dependent growth patterns and growing close together, this character impactthe cells growth and metabolism in some ways, and make it difficult to do geneticmanipulation.Sorangium cellulosum So2161were mutated with ultraviolet radiation, afteroptimizing the UV mutation of So2161cells at30cm distance for3min, we obtained adispersed strain named L4, then acclimated this strain and cells appeared recessionafter the29thgeneration, several generations of this acclimated strains were chosen toanalyzed both visually and the optical density at600nm (OD600) and have been foundto appear more and more dispersed from generation to generation, we chose the29thgeneration named SoL4-29to study in this paper.The exopolysaccharides coated the surface of myxobacteria and influencedcell-cell adhesion. In this paper, exopolysaccharides content of Sorangium cellulosumSo2161and the mutant SoL4-29in both exponential and stationary phase weredetected in congo red and trypan blue binding assays. wild-type cells in exponentialand stationary phases bounded more congo red than mutant SoL4-29, even thewild-type strain was almost twice the exopolysaccharides content of SoL4-29in theirstationary phase. For trypan blue, the result showed the same tendency. These datasuggested that the wild-type cells produced more EPS. In order to verify this deduction,we further detected the exopolysaccharides content by using the phenol-sulfuric acidmethod with glucose as the standard. We got the exopolysaccharides from brokenpellets of So2161and the SoL4-29incubated for0,1,2,3,4,5days respectively, theamount of polysaccharide of the wild-type increased over time, but the SoL4-29mutant did not obviously improve during its growing period, and the amount ofpolysaccharide in their stationary phase was almost only half of the wild-type cells.These data further suggested that the wild-type cells produced moreexopolysaccharides. This result further verified that the cells cohesion was related tothe exopolysaccharides content, higher the content of the exopolysaccharides, easierthe cells to gather.Protein tyrosine phosphatases can regulate the production of exopolysaccharides, we detected the phosphatase activity of So2161and SoL4-29in their exponential phase(3d) and stationary phase (5d), the results showed that the phosphatase activity ofSoL4-29mutant was more than that of Sorangium cellulosum So2161. Sce8244is apredicted protein tyrosine phosphatase gene, we used qRT-PCR to analyze the sce8244gene expression level of the So2161and the mutant SoL4-29in their exponential andstationary phase respectively, result showed that the relative cDNA quantities of thesce8244gene in SoL4-29were higher than the wild-type in both their exponential andstationary phase. At the same time, we found that the expression level of sce8244geneslightly increased during the growing period, which meant the transcription of sce8244could affect the protein tyrosine phosphatase activity. These results indicate that theprotein tyrosine phosphatase may negatively regulate the production ofexopolysaccharides in Sorangium cellulosum.