5 Remediation and Management of Produced Water for Beneficial Uses

Monday, 13 March 2023
10:00 AM - 12:00 PM
Room 109

CHARACTERIZATION OF METHANOTROPHIC ACTIVITIES BY MICROBIAL COMMUNITY IN ZODLETONE SPRING FOR POTENTIAL MITIGATION OF METHANE EMISSION IN ABANDONED GAS AND OIL WELLS

Paper number: 5-2
Program: Theme Sessions
Time: 10:20 AM – 10:40 AM

Authors

Abstract

Methane is a key greenhouse gas contributing toward roughly 20% of global warming and projected to be 28-fold more potent than CO2. Methane flux from anthropogenic sources is of great concern in terms of global warming. Abandoned oil and gas wells (AOG) are often high in salinity, providing additional challenge for microbial methane oxidation or methanotrophy. In the US, more than three million AOGs were estimated to be emitting 0.28 million metric tons of methane into the atmosphere in 2018. We aim to identify and characterize microbial community that can oxidize methane under saline condition typically found in oil wells.

Here we provide evidence of methane oxidation in sediment samples collected from Zodletone spring, a sulfur-rich spring in Oklahoma, USA. Microcosms were setup with sediment samples and mineral salts medium in serum bottles with 1% (v/v) methane in the headspace. Bottles were sealed with rubber septa and aluminum crimp and incubated at 30°C. Methane concentration was measured by gas chromatograph. Bottles were repeatedly fed methane for 3 months to develop enrichment culture. The enrichment culture degrades methane in the presence of NaCl concentration ranging from 0 M to 2.5 M with highest rate at 1 M. Amplicon sequencing of 16S rRNA-gene from DNA extracted from both original sediment and the enrichment at 2.5 M salinity revealed the phylum Balneolota (64%) and Proteobacteria (28%) to be the most abundant in the enrichment, while in the original sediment their abundance was relatively low (18% and 13% respectively). The most abundant methanotroph was Methylohalobrius, a known halophilic methanotroph. We detected the presence of particulate methane monooxygenase (pMMO) gene in both sediment and enrichment. However, the gene for soluble MMO (sMMO) was absent. Our experiments showed enhanced pMMO activity when the enrichment was provided with 2-10 μM CuSO4 as co-factor, with optimal concentration of 6 μM of Cu+. Our current efforts to isolate a pure culture of methanotroph from the enrichment are not successful. We will continue to culture the organisms on various media and growth conditions. Given the lack of mitigation strategy for this significant source of methane and severe knowledge gap on halophilic methanotrophs, isolation and characterization of methanotrophs in saline condition is crucial.

Geological Society of America Abstracts with Programs. Vol. 55, No. 1

doi: 10.1130/abs/2023SC-385045

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.