Myxobacteria Separation, Identification And Activity

Myxobacteria is a kind of higher prokaryote with social behavior. They have complicated cooperative motility behavior and appearance formation, so they are important to the research of cell differentiation,development and evolution. In late years, myxobacteria are valued for their large number of biologically active secondary metabolites. In this research 171 myxobacteria strains were separated from 52 samples collected from soils, plants, water in 11 areas such as Jilin, Shandong, Shanxi, Sichuan,Shanghai, Zhejiang, etc. ,and 63 pure stains were got. By observating colonies, myxospores, vegetable cells of the strains and ability of fibrin dissolving, these pure strains were divided into four types. Myxobacteria usually grow poorly in liqiud media, and different strains need certain media. Strain P22-4 and strain X-1 were cultured in YS,E,Ht,IR1,ME and M26 liqiud media. It was found that strain P22-4 grew better in ME,M26 and YS media, strain X-1 were suitable in YS and Ht media. Fermenters of 63 strains were detected with the models of resistance to bacteria, fungi, anti-medication bacteria and agglutination. As the result, 18 strains can resist Staphylococcus aureus. 18 strains can resist agglutination. They are 29% of the whole strains. Bacillus subtilis is sensitive to strain S1-6 and S3-3, whereas Candida albicans is sensitive to strain A-2 and A-4. These two kinds of bioactive strains are 3% in the whole strains. No strains were found to resist E.coli, Enterococus faecalis 458 V8 and S.aureus 9918 V8. Strain A-1 with dissolving cellulose ability and strain A-4 which can resist Candida albicans were classified. According to the appearance of nutrient cells, fruiting bodies, myxospores of this two strains, and the colonies in media ST21CX, WCX, VY/2,etc., in addition to physiological characteristics such as congo red reaction, nitrate recover, fibrin dissolving, antibiotic sensitivity, and G+C mol%, 16S rRNA sequences analysis, strain A-1 was classified to Polyangium cellulosum and strain A-4 to Polyangium fumosum. Six strains with higher extracellular cellulase activity were separated and purified from 316 colonies. Strain A-1 had the highest cellulase activity, so the influence of different culture consists and conditions on three kinds of extracellular cellulase activity were compared. As the conclusion, the cellulase activity reached the highest level on the condition of 2h as reacting time, Ht-starch medium as seed medium, 3d as seed age, starch as carbon source, peptone as nitrogen source, 0.10% as concentration of Mg2+ and PO43-, 30℃, pH7.2, 100mL/250mL as bottle holding, 6d as culture period. Through the experiments of 4 factors and 3 levels, the best culture condition was chosen: starch as carbon source, yeast extract as nitrogen source, 30℃, pH7.2. On this condition, extracellular FPase is 2.501U/mL, microlite cellulase is 4.259U/mL, CMCase is 0.267U/mL.