Biotechnology Bulletin ›› 2022, Vol. 38 ›› Issue (7): 236-246.doi: 10.13560/j.cnki.biotech.bull.1985.2021-1234

Previous Articles     Next Articles

Physiological and Biochemical Response Characteristics of Bacillus sp. ZJS3 Under As3+ Stress

YUAN Cun-xia1,2(), LI Yan-nan1,2, ZHANG Xiao-chong1,3, YANG Rui1,2, LIU Jian-li1,2,3, LI Jing-yu1,2,3()   

  1. 1. College of Biological Science & Engineering,North Minzu University,Yinchuan 750021
    2. Ningxia Key Laboratory of Microbial Resources Development and Applications in Special Environment,Yinchuan 750021
    3. Key Laboratory of Ecological Protection of Agro-pastoral Ecotones in the Yellow River Basin,National Ethnic Affairs Commission of the People`s Republic of China,Yinchuan 750021
  • Received:2021-09-26 Online:2022-07-26 Published:2022-08-09
  • Contact: LI Jing-yu E-mail:y264333@163.com;lijingyu1986@126.com

Abstract:

We aim to investigate the response mechanism of strain Bacillus sp. ZJS3 to As3+ stress under optimal growth conditions. The tolerance range was determined by the growth of the strain Bacillus sp. ZJS3 in solid medium. The activities of antioxidant enzymes,the content of malondialdehyde(MDA)and the contents of protein and polysaccharide in extracellular polymeric substances(EPS)were determined under the influence of different arsenic concentrations. The mechanism of tolerance of Bacillus sp. ZJS3 was studied by photographing biological scanning electron microscope(SEM),measuring the adsorption rate and redox activity,detecting tolerance genes. The tolerance range of Bacillus sp. ZJS3 to As3+ was 100-300 mg/L. According to the single factor experiments,the suitable culture conditions were pH 7.0,rotation speed 200 r/min,and temperature 30℃. Through silver nitrate staining and arsenic molybdenum blue method,it was detected that Bacillus sp. ZJS3 oxidized As3+ to As5+. Under different arsenic concentration stress,the contents of peroxidase(POD),catalase(CAT),superoxide dismutase(SOD)and MDA increased significantly,and the polysaccharide content in EPS increased continuously,while the protein increased first and then decreased. It was observed by SEM that the cell morphology gradually lengthened and granular substances appeared on the surface after arsenic pollution. Within 24 h,the maximum adsorption rate of arsenic by the strain was 25.00% and the adsorption capacity was 3.23 mg/g. In conclusion,Bacillus sp. ZJS3 can oxidize high toxic As3+ to low toxic As5+,and has adsorption effect on arsenic. Its antioxidant enzymes and extracellular polymers play an important role in the process of arsenic stress.

Key words: As3+, redox activity, exopolysaccharides, anti-oxidative enzyme activity, adsorption rate