Effects of Arsenite Resistance on the Growth and Functional Gene Expression ofLeptospirillum ferriphilumandAcidithiobacillus thiooxidansin Pure Culture and Coculture

Abstract

The response of iron-oxidizingLeptospirillum ferriphilumYSK and sulfur-oxidizingAcidithiobacillus thiooxidansA01 to arsenite under pure culture and coculture was investigated based on biochemical characterization (concentration of iron ion and pH value) and related gene expression.L. ferriphilumYSK andAt. thiooxidansA01 in pure culture could adapt up to 400 mM and 800 mM As(III) after domestication, respectively, although arsenite showed a negative effect on both strains. The coculture showed a stronger sulfur and ferrous ion oxidation activity when exposed to arsenite. In coculture, the pH value showed no significant difference when under 500 mM arsenite stress, and the cell number ofAt. thiooxidanswas higher than that in pure culture benefiting from the interaction withL. ferriphilum. The expression profile showed that the arsenic efflux system in the coculture was more active than that in pure culture, indicating that there is a synergetic interaction betweenAt. thiooxidansA01 andL. ferriphilumYSK. In addition, a model was proposed to illustrate the interaction between arsenite and thearsoperon inL. ferriphilumYSK andAt. thiooxidansA01. This study will facilitate the effective application of coculture in the bioleaching process by taking advantage of strain-strain communication and coordination.