Mutagenesis And Cultivation Of High Performance Thiobacillus Ferrooxidans

The desulfurization microorganism Thiobacillus ferrooxidans（T.f）is cultivated in the bio-smoke desulfurization technology.In order to solve the problems of low temperature resistance and low desulfurization efficiency of T.f,it is improved by low temperature plasma mutagenesis.The main research contents and conclusions are as follows:（1）In this paper,four strains of T.f were isolated from an acidic water sample in a coal mine.The M1 with the shortest growth cycle was selected as the follow-up study object.The optimum pH of the strain was 2 and the optimum temperature was 30°C,and the optimal inoculum was 10%by measuring the Fe²⁺oxidation rate of the strain.And the Fe²⁺oxidation rate reflects the biological activity and growth of the bacteria to a certain extent.（2）The low temperature plasma mutagenesis M1 results show:The bacterial lethality increases as the mutagenic time increases and the mutagenic power increases.The mutation rate does not have a significant linear relationship with changes in power and time.The optimal mutagenesis time for M1 is60s and the mutagenic power is 50W.M1 was mutagenized under optimal conditions,and high-performance positive mutant Y-2 was screened by measuring the average oxidation rate of Fe²⁺.The average oxidation rate of Fe²⁺in the Y-2 strain during the bacterial growth cycle was 74%.After 6 generations of subculture,the average oxidation rate of Fe²⁺decreased by only 10%,and the genetic performance was more stable than other groups.（3）The Y-2 strain was cultured at 35°C,38°C,and 42°C.The results showed that the mutagen and the control bacteria could maintain their activity at 38°C.The change of pH value in the third-stage culture increased first and then decreased.The oxidation rate of Fe²⁺and the activity of T.f bacteria accord with the"S"growth curve of microorganisms under limited environmental capacity.Mutagenesis of the strain by low temperature plasma can increase the tolerance of the bacteria to high temperature.However,it is impossible to reverse the law that the activity of the strain decreases with increasing temperature.The mutagenized Y-2 strain maintains good biological activity at 38°C.（4）In the desulfurization test of the simulated biological flue gas desulfurization device,the desulfurization rate of T.f bacteria decreased with the increase of gas flow.The optimum gas flow rate for Y-2 positive mutant desulfurization is 0.3m³/h.Increasing the initial Fe³⁺concentration increases the desulfurization efficiency but also inhibits the oxidation of Fe²⁺by bacteria.Adding a certain amount of Fe²⁺before the reaction can accelerate the oxidation rate of the bacteria and promote the coordinated catalytic oxidation of Fe³⁺and bacteria.