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Microorganisms 2015, 3(3), 484-499;

Novel Methanotrophs of the Family Methylococcaceae from Different Geographical Regions and Habitats

Department of Biology, University of Bergen, Thormøhlensgate 53B, Postboks 7803, 5006 Bergen, Norway
Uni Research Environment, Thormøhlensgate 49B, 5006 Bergen, Norway
Department of Microbiology, Plant and Microbe Biotechnology, Yerevan State University, A. Manoogian 1, 0025 Yarevan, Armenia
School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
Commonwealth Scientific and Industrial Research Organization (CSIRO), Marine and Atmospheric Research and Wealth from Oceans National Research Flagship, Hobart, TAS 7004, Australia
Author to whom correspondence should be addressed.
Academic Editors: Ricardo Amils and Elena González Toril
Received: 10 July 2015 / Revised: 4 August 2015 / Accepted: 7 August 2015 / Published: 21 August 2015
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Terrestrial methane seeps and rice paddy fields are important ecosystems in the methane cycle. Methanotrophic bacteria in these ecosystems play a key role in reducing methane emission into the atmosphere. Here, we describe three novel methanotrophs, designated BRS-K6, GFS-K6 and AK-K6, which were recovered from three different habitats in contrasting geographic regions and ecosystems: waterlogged rice-field soil and methane seep pond sediments from Bangladesh; and warm spring sediments from Armenia. All isolates had a temperature range for growth of 8–35 °C (optimal 25–28 °C) and a pH range of 5.0–7.5 (optimal 6.4–7.0). 16S rRNA gene sequences showed that they were new gammaproteobacterial methanotrophs, which form a separate clade in the family Methylococcaceae. They fell into a cluster with thermotolerant and mesophilic growth tendency, comprising the genera Methylocaldum-Methylococcus-Methyloparacoccus-Methylogaea. So far, growth below 15 °C of methanotrophs from this cluster has not been reported. The strains possessed type I intracytoplasmic membranes. The genes pmoA, mxaF, cbbL, nifH were detected, but no mmoX gene was found. Each strain probably represents a novel species either belonging to the same novel genus or each may even represent separate genera. These isolates extend our knowledge of methanotrophic Gammaproteobacteria and their physiology and adaptation to different ecosystems. View Full-Text
Keywords: Gammaproteobacteria; Methylococcaceae; methanotrophs; Methylocaldum; mesophilic; terrestrial Gammaproteobacteria; Methylococcaceae; methanotrophs; Methylocaldum; mesophilic; terrestrial

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Islam, T.; Larsen, Ø.; Torsvik, V.; Øvreås, L.; Panosyan, H.; Murrell, J.C.; Birkeland, N.-K.; Bodrossy, L. Novel Methanotrophs of the Family Methylococcaceae from Different Geographical Regions and Habitats. Microorganisms 2015, 3, 484-499.

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