Methane Removal of Isolated Methylocystis Strains in the Culture Medium Designed by Evaluating Strain Capacity under Adverse Conditions

Abstract

Introduction: Methanotrophs are microorganisms that play an important role in reducing up to 15% of environmental CH4 concentration. These bacteria can oxidize methane to methanol. Methane is an atmosphere-polluting greenhouse gas with increasing atmospheric concentrations and is considered a serious threat to the environment and the sustenance of life on the planet. Possible unfavorable future weather and the extensive use of different types of pesticides necessitate the use of methanotrophic bacteria that are resistant to these conditions. The present study focused on the isolation and specific study of Methylocystis methanotrophic bacteria. Materials and Methods: The bacterial strains were isolated from different environments such as wetlands, rivers, and paddy fields. The isolated strains were concentrated with Methane gas enriched cultures and purified by serial dilution-extinction, alternating liquid, and solid subcultures. Then, molecular identification was performed and a suitable culture medium was designed for Methylocystis strains in the name of Methylocystis Culture (MOC). Strains were cultured in MOC to evaluate their viability in different conditions by changing important parameters such as the temperature, pH, salinity, and drought. In addition, they were affected by pesticides. The methane gas reduction in the upper space of the culture medium of each strain, in accordance with the control samples, is considered as the methane oxidation of that strain. Results: Methane gas oxidation rate was determined in vitro for the cultures of several strains. The growth curve of the strains was plotted. According to the results, Methylocystis methanotrophs had high survivability in different conditions and were resistant to common pesticides, and consumed more than 75% of methane gas over a period of 14 days. Discussion and Conclusion: Methylocystis methanotrophic bacteria can greatly reduce the release of methane into the atmosphere and alter the fate of the atmosphere.

Keywords

• ability
• compatibility
• methane oxidation
• methanotroph
• optimization
• pesticide
• rice field
• river
• wetland