Diversity and Effect of Increasing Temperature on the Activity of Methanotrophs in Sediments of Fildes Peninsula Freshwater Lakes, King George Island, Antarctica

Abstract

Global warming has a strong impact on polar regions. Particularly, the Antarctic Peninsula and nearby islands have experienced a marked warming trend in the past 50 years. Therefore, higher methane (CH4) emissions from this area could be expected in the future. Since mitigation of these emissions can be carried out by microbial oxidation, understanding this biological process is crucial since to our knowledge, no related studies have been performed in this area before. In this work, the aerobic CH4 oxidation potential of five freshwater lake sediments of Fildes Peninsula (King George Island, South Shetland Islands) was determined with values from 0.07 to 10 μmol CH4 gdw–1 day–1 and revealed up to 100-fold increase in temperature gradients (5, 10, 15, and 20°C). The structure and diversity of the bacterial community in the sediments were analyzed by next-generation sequencing (Illumina MiSeq) of 16S rRNA and pmoA genes. A total of 4,836 ASVs were identified being Proteobacteria, Actinobacteriota, Acidobacteriota, and Bacteroidota the most abundant phyla. The analysis of the pmoA gene identified 200 ASVs of methanotrophs, being Methylobacter Clade 2 (Type I, family Methylococcaceae) the main responsible of the aerobic CH4 oxidation. Moreover, both approaches revealed the presence of methanotrophs of the classes Gammaproteobacteria (families Methylococcaceae and Crenotrichaceae), Alphaproteobacteria (family Methylocystaceae), Verrucomicrobia (family Methylacidiphilaceae), and the candidate phylum of anaerobic methanotrophs Methylomirabilota. In addition, bacterial phospholipid fatty acids (PLFA) biomarkers were studied as a proxy for aerobic methane-oxidizing bacteria and confirmed these results. Methanotrophic bacterial diversity was significantly correlated with pH. In conclusion, our findings suggest that aerobic methanotrophs could mitigate in situ CH4 emissions in a future scenario with higher temperatures in this climate-sensitive area. This study provides new insights into the diversity of methanotrophs, as well as the influence of temperature on the CH4 oxidation potential in sediments of freshwater lakes in polar regions of the southern hemisphere.

Study of Wetland Soils of the Salar de Atacama with Different Azonal Vegetative Formations Reveals Changes in the Microbiota Associated with Hygrophile Plant Type on the Soil Surface

“…A microbiota that does not show significant differences between strict and transitional hygrophiles is the microbiota of the mixed zone (strict and transitional). These soil samples are reported to be dominated by member of the phylum Methylomirabilota , the candidate phylum of anaerobic methanotrophs ( 57 ), involved in the process of methane oxidation with electron acceptors ( 58 ). Perhaps for a biotechnological application, isolation of bacteria such as “ Candidatus Methylomirabilis oxyfera” ( 59 ) would be of great interest.…”

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“…Furthermore, the core microbiota exhibited a notable abundance of genes associated with methanogenic bioprocesses (methanogenesis, methanotrophy, methylotrophy, hydrogenotrophic methanogenesis, and methanogenesis by CO 2 reduction to H 2 ) ( Fig 4 ). Candidatus Methanoperedens nitroreducens and Candidatus Methylomirabilis oxyfera, both classified under group A of the Methylomirabilota phylum, have been identified as key players in the nitrogen and methane cycles [ 30 ]. Moreover, an increased temperature found to enhance the CH 4 oxidation potential in sediments of Fildes Peninsula freshwater lakes, King George Island, Antarctica [ 31 ].…”

High-Throughput Sequencing as a Tool for Detecting Microbial Communities in Lake Ecosystem and Its Implications in Fish Farming in Lake Buluan, Mindanao, Philippines

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