Growth Analysis of Methylotuvimicrobium buryatense 5GB1C and Its Utilization for Treating Low Methane Concentrations in a Packed-Bed Column Reactor

Abstract

In 2024, the global average temperature reached 1.55 °C above the pre-industrial level for the first time. However, we could still keep the long-term global average temperature below 2 °C if all possible measures are taken to mitigate greenhouse gases. It is widely accepted that methane (CH4) mitigation can slow global warming in the near term. Among all approaches toward this goal, the utilization of aerobic methanotrophs, which are natural catalysts for the conversion of CH4, emerges as a promising solution. Previously, we identified a candidate for CH4 mitigation, Methylotuvimicrobium buryatense 5GB1C, which exhibits a greater growth rate and CH4 consumption rate than other known methanotrophs at 500 ppm CH4. In this study, we address aspects of the practical applications of this methanotroph for CH4 mitigation. We first examined temperature and medium conditions to optimize M. buryatense 5GB1C growth at 500 ppm CH4. The results show that M. buryatense 5GB1C has a broad optimal temperature range for growth at 500 ppm, from 15 °C to 30 °C, and that its growth rate is consistently improved by 20–30% in 10-fold-diluted medium. Next, to demonstrate the feasibility of CH4 removal at low concentrations by this methanotroph, we applied it in a laboratory-scale packed-bed column reactor for the treatment of 500 ppm CH4 and tested different packing materials. The column reactor experiments revealed a maximum elimination capacity of 2.1 g CH4 m−3 h−1 with 2 mm cellulose beads as the packing material. These results demonstrate that with further technological innovation, this methanotroph has the potential for real-world methane mitigation.