Stimulating effects of reduced graphene oxide on the growth and nitrogen fixation activity of nitrogen-fixing bacterium Azotobacter chroococcum

Peng Ouyang; Chengzhuang Liang; Fangshi Liu; Qian Chen; Ziqiao Yan; Junyao Ran; Shiyu Mou; Yue Yuan; Xian Wu; Sheng-Tao Yang

doi:10.1016/j.chemosphere.2022.133702

Stimulating effects of reduced graphene oxide on the growth and nitrogen fixation activity of nitrogen-fixing bacterium Azotobacter chroococcum

Chemosphere. 2022 May:294:133702. doi: 10.1016/j.chemosphere.2022.133702. Epub 2022 Jan 20.

Authors

Affiliations

¹ Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu, 610041, China.
² Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu, 610041, China; Key Laboratory of General Chemistry of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu, 610041, China.
³ Key Laboratory of Pollution Control Chemistry and Environmental Functional Materials for Qinghai-Tibet Plateau of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu, 610041, China; Key Laboratory of General Chemistry of the National Ethnic Affairs Commission, School of Chemistry and Environment, Southwest Minzu University, Chengdu, 610041, China. Electronic address: yangst@swun.edu.cn.

PMID: 35066073
DOI: 10.1016/j.chemosphere.2022.133702

Abstract

Graphene has found important applications in various areas and hundred tons of graphene materials are annually produced. It is crucial to investigate both the negative and positive environmental effects of graphene materials to ensure the safe applications and develop environmental applications. In this study, we reported the stimulating effects of reduced graphene oxide (RGO) to nitrogen-fixing bacterium Azotobacter chroococcum. RGO stimulated the cell growth of A. chroococcum at 0.010-0.500 mg/mL according to the growth curves and the colony-forming unit (CFU) increases. RGO wrapped over the A. chroococcum cells without inducing ultrastructural changes. RGO decreased the leakage of cell membrane, but slight oxidative stress was observed in A. chroococcum. RGO promoted the nitrogen fixation activity of A. chroococcum at 0.5 mg/mL according to both isotope dilution method and acetylene reduction activity measurements. Consequently, the increases of soil nitrogen contents were evidenced, in particular about 30% increase of organic nitrogen occurred at 0.5 mg/mL of RGO. In addition, RGO might possibly benefit the plant growth through enhancing the indoleacetic acid production of A. chroococcum. These results highlighted the positive environmental effects of graphene materials to nitrogen-fixing bacteria in nitrogen cycle.

Keywords: Environmental effects; Graphene; Nitrogen fixing bacteria; Stimulation; Toxicity.

MeSH terms

Azotobacter* / metabolism
Graphite* / metabolism
Nitrogen / metabolism
Nitrogen / pharmacology
Nitrogen Fixation

Substances

graphene oxide
Graphite
Nitrogen

Supplementary concepts

Azotobacter chroococcum