Quantitative determination of 2-mercaptoethane sulphonate as biomarker for methanogens in soil by high performance liquid chromatography using UV detector

Abstract

All methanogens, irrespective of their preferred carbon sources, form coenzyme M (Co-M: 2-mercaptoethane sulphonate) as an intermediate to produce methane (CH4). But the quantification of Co-M in soil is not done before. In this experiment, the method for quantifying Co-M was standardized by HPLC using UV detector and the values of Co-M were compared with CH4 emission flux and methanogen activity of soil. The objectives of this experiment were to standardize the Co-M quantification technique and to evaluate its feasibility as a biomarker for methanogens in soil. The Co-M was extracted from soil by rupturing the cell membrane of methanogens using lysis buffer. Trichloroacetic acid solution (0.5 M) and acetonitrile mixture (70: 30, v/v) was used as a mobile phase for measuring Co-M by HPLC at 270 nm. The precision of the method was more than 97% and 90.3 +/- 8.1% of the added Co-M standard was recovered from soil by this method. The Co-M concentration in soil was varied at the different rice cultivation stages and the highest concentration of Co-M was recorded at the maximum CH4 emission period (60 days after seedling transplanting). Application of organic substrates significantly (P <= 0.05) increased methanogen activity and Co-M concentration in rice paddy soil. The conversion factor, 155.03 +/- 14.20 mu g CH4 produced mmol(-1) Co-M d(-1), could be used to calculate methanogen activity from Co-M concentration of soil. Based on these results, it could be proposed that the Co-M concentration could be used as a biomarker for methanogen activity and the above-mentioned method can be used for an easy but precise quantification of Co-M in soil. (C) 2012 Elsevier Ltd. All rights reserved.