Acidithiobacillus caldus transcription factor EpsR-SM-1 binding to c-di-GMP enhances biofilm formation and copper tolerance

• 1、School of biotechnology, Jiangnan University, Wuxi City, Jiangsu Province,214000

Abstract：Bioleaching of low grade copper ore is an important method for smelting copper resources. Leaching microorganisms promote ore leaching mainly through "indirect action", in which "contact" mechanism is that microorganisms form biofilm on the ore surface and secrete extracellular polymers to accelerate the ore leaching process. Improving biofilm formation ability is an important method to improve the efficiency of this effect. At the same time, biofilm can also improve the tolerance of microorganisms to metal ion stress in the late leaching stage. So that microbes can do their job better. Cyclic di-GMP is the main secondary messenger that regulates the biofilm formation of bacteria, and regulates the biofilm formation process by binding to receptors. In this paper, a transcriptional regulator containing cyclic di-GMP receptor binding domain that regulates extracellular polymer secretion was found in Acidithiobacillus caldus. In vitro mutation and in situ overexpression verified that it can enhance biofilm formation and copper tolerance. The growth of strains overexpressing this transcription regulator was significantly improved under copper stress.

Keywords： Bioleaching, Biofilm, Extracellular polymer, Cyclic di-GMP, Acidithiobacillus caldus