Mutation of Arthrospira platensis by gamma irradiation to promote phenol tolerance and CO2 fixation for coal-chemical flue gas reduction

Abstract In order to promote phenol tolerance and the carbon fixation rate of cells during CO2 sequestration in coal chemical flue gas, γ-ray irradiation from cobalt-60 (60Co) was used to mutate Arthrospira platensis to generate efficient strains. A phenol-tolerant strain Mutant 11k was obtained with 11,000 Gy of gamma irradiation. The phenol degradation efficiency of the mutant was 34.7 % higher than that of wild strain, attributing to the increased activity of phenol hydroxylase that catalyzed phenol to generate catechol. The catechol 1,2-dioxygenase activity in mutant cells was enhanced by 39.5 % while catechol 2,3-dioxygenase was weakened by 23.8 %, revealing that the β-ketoadipate pathway plays a more important role than 2-hydroxymuconic semialdehyde pathway in phenol degradation. The activity of superoxide dismutase and catalase increased by 6.1 % and 39.8 %, respectively, reducing peroxide damage and maintaining rapid cell growth. The contents of chlorophyll-a and maximum quantum yield of photosystem II in mutant cells were higher than those in wild strain. The biomass yield and carbon fixation rate of mutant were 20.8 % and 22.4 % higher, respectively, than those of the wild strain.