Isolation,Identification,Sulfur Oxidation And Optimization Of Fermentation Of An Efficient Desulfurization Strain

Acidithiobacillus thiooxidans has the ability to oxidize low-grade sulfur to sulfuric acid.It is widely used in bioleaching,amelioration of salinization soil,biodesulfurization,heavy metal removal from urban sewage sludge,and so on.SO,isolate and select an efficient acid-producing Acidithiobacillus thiooxidans has important research significance and application value.In this study,DS1 was isolated and screened from the high-sulfur coal mine soil.The sulfur oxide curve and influence of different factors on its sulfur oxidation were studied,and by optimizing the fermentation conditions to increase the biomass of the strain.We want to provide excellent bacteria resources and technical support for environmental governance.The results are got as following:?1?A strain with sulfur oxidation was isolated from the soil of coal storage area of Wuda Coal Mine,Wuhai City,Inner Mongolia.The strain was identified as acidithiobacillus thiooxidans DS1?A.thiooxidans DS1?by gram staining,colony morphology,microscopic observation and 16S rRNA gene sequence analysis.The similarity of DS1 to A.thiooxidans DSM 14887 and A.albertensis DSM 14366 both reached 99%.?2?Acidithiobacillus thiooxidans DS1 has an efficient desulfurization capability,when the sulfur in the medium is 0.1%,the oxidation rate can reach91.39%,when the sulfur in the medium is 1%or 2%,the oxidation rate can over70%,when the sulfur in the medium is 3%,the oxidation rate nearly 60%.DS1 has an efficient acid-producing capability,when the sulfur in the medium is 2%,the p H of the medium can eventually be reduced to 0.15,when the sulfur in the medium is 3%,the pH of the medium can eventually be reduced to 0.06.Co²⁺had an obvious inhibitory effect to DS1,but Fe³⁺,Cu²⁺,Ni²⁺,Zn²⁺,K⁺,Mg²⁺,Ca²⁺,and Mn²⁺all promoted the oxidation of sulfur by the DS1.?3?Using response surface methodology,the fermentation conditions of DS1were optimized.Single-factor tests were used to select the main factors from temperature,strain volume,pH,liquid volume and sulfur on the growth of DS1.The main factors were temperature and strain volume,then used them to central composite design.It was found that the optimum temperature was 31?and the optimal strain volume was 15.5%.So,the optimal fermentation conditions for DS1 were:31°C,strain volume was 15.51%,p H was 5,sulfur was 2%,and volume of 20mL in a50mL erlenmeyer flask.The system predicts that under this conditions,the biomass of DS1 is 0.362 and the verification test result is 0.349,which is close to the predicted value.