Analysis on Construction and Property of the Constitutively Desulfurization Engineered Strain

[Objective] The research aimed to study construction and property of the constitutively desulfurization engineered strain. [Method] Des- ulfurization gene dszABC in Pseudomonas delafieldii R-8 strain was cloned into expression vector pPR9TT with gap promoter to build a constitutive expression plasmid pRT-C. Then, pRT-C was reintroduced into R-8-0 strain to obtain constitutively engineered strain R-8-C. Moreover, its desulfu- rization property was studied. [ Result ] Strain R-8-C still had higher desulfurization activity in BSM medium with 0.10 mmol/L of Na2 SO4. Within 72 h, its desulfurization activity was 93% of the strain R-8 using DBT as the sole sulfur source, while control （strain R-8） nearly couldn＇t desulphate. When DBT was the sole sulfur source, in different growth periods, the desulfurization activity of strain R-8-C was all higher than that of the strain R-8. Within 24 h, its activity was 1.3 times of the strain R-8. [ Conclusion] These results were theoretically and technically helpful for understanding regulation mechanism of the desulfurization gene and constructing highly active desulphurization engineering strain.

Biological decomposition of Na_2S_2O_3 into sulfur by a newly isolated facultative thermophilic alkaline desulphuricant strain

A facultative thermophilic alkaline desulphuricant strain named GDJ-3 was isolated from neutral soils,enriched on sulfur synthetic medium,and detected in previous work.Conventional and chemotax-onomic analyses and 16s RNA gene sequencing showed that the strain was in good agreement with Alpha proteobacterium sp.(97%) and ochrobactrum sp.(98%).The regenerative processes of the solu-tion containing sulfur compounds(SCS) from the strain through an orthogonal test were investigated to get the optimum regenerative condition.The results showed that regenerative temperature,air flow,and stirring speed of the agitator were the main three variables influencing the regenerative processes of the SCS.The optimum regenerative efficiency of the SCS from the strain was obtained when tem-perature,air flow,and stirring speed of the agitator were 318.2 K,3.0 L/min,and zero r/min,respectively.Under this condition,when the cell concentration of the strain was adjusted to 107/mL,the concentra-tions of Na2S2O3 and Na2S in the SCS decreased from 112.68 g/L to 96.88 g/L and from 0.87 g/L to 0.11 g/L in 9.5 h.Meanwhile,XRD spectrum shows that sulfur was formed in the regeneration process.These results suggest that the strain has potential application to the regeneration of the industrial so-lution containing sulfur compounds.