Methanogenic Activity And Methanogen Diversity In Marine Gas Field Sediments

Methanogens play an important role in marine sediments, which are related tomethane production and methane hydrate deposits. Methanogenic activity of marinegas field sediments was investigated using substrates that methanogens usually usedas carbon sources. This experiment studied the methanogenic activity of marine gasfield sediments under the common culture conditions and symbiotic mixed cultureconditions. The results of conventional cultivation show that H2/CO2, methanol andmethylamines could support the growth and methane production of gas fieldsediments. The methanogenic activity of25℃is higher than37℃under thecommon culture conditions.The bacteria of symbiotic mixed culture degrade thesubstrates such as:2-propanol,2-butanol, ethanol, propionate, butyrate into simplesubstrates that methanogens can use. The concentration of hydrogen that thefermentation bacteria produce is low, so the methanogenic activity under symbioticmixed culture is low. The results of symbiotic mixed cultivation show that ethanol,propionate and butyrate could support the growth and methane production of gas fieldsediments, and2-propanol and2-butanol could hardly support.16S rRNA genesequence analysis indicated that the predominant methanogens under the commonculture conditions were related to known cultured methanogens in familyMethanosarcinaceae of the order Methanosarcinales and family Methanomicrobiaceaeof the order Methanomicrobiales, with genera Methanococcoides, Methanogeniumand Methanosarcina as major methanogens.16S rRNA gene sequence analysisindicated that the predominant methanogens under the symbiotic mixed cultureconditions were related to known cultured methanogens in familyMethanomicrobiaceae of the order Methanomicrobiales, with genera Methanogeniumas major methanogens.