Growth and Methane Oxidation Activity of Methanotrophic Bacteria in Different Media

Abstract

Methanotrophs are bacteria that can utilize methane or C1 compounds as their sole carbon and energy source. Previous study resulted that BGM 1, BGM 3, BGM 9, and SKM 14 isolates could oxidized CH4. Objective of this research was to formulate medium composition for production of methanotrophic bacteria. The substances that we used as carbon sources were methanol, mollase. And a nitrate was as a nitrogen source. Specific growth rate of bacteria in methanol and nitrate was different for each isolate. The best carbon and nitrogen sources of medium for bacterial growth was methanol 2% and nitrate 1 g/L. Methane oxidation rate of BGM 1, BGM 3, BGM 9, and SKM 14 isolates was 0.01, 0.04, 0.03, and 0.03 mol/ml culture/day respectively. The highest activity of methane oxidation was perfomed by BGM 3 isolate, and the highest ammonium accumulation was perfomed by BGM 9 isolate. The bacterial cells produced by medium of combination methanol 2% and nitrate 1 g/L were tested in soil of a rice field in laboratorium scale. The result showed that methane concentration was decreased in twelveth days of incubation. The methane reduction activity of the isolates during incubation of 8 to 12 days was 88.5%, 85.1%, 47.8%, and 66.4% for BGM 1, BGM 3, BGM 9, and SKM 14 isolates respectively.

Metan (CH4) merupakan salah satu gas rumah kaca yang berpotensi menyebabkan pemanasan global. Gas metan (CH4) di atmosfer menunjukkan peningkatan konsentrasi sebesar 715 hingga 1732 ppb pada awal tahun 1990, dan telah meningkat lagi sebesar 1774 ppb pada tahun 2005. Penggenangan seperti pada tanah sawah dan lahan basah lainnya merupakan salah satu sumber munculnya emisi CH4. Salah satu upaya untuk menekan emisi CH4 yaitu dengan pemanfaatan mikrob metanotrof. Mikrob ini akan memanfaatkan metan sebagai sumber karbon dan energinya. Bakteri metanotrof dapat tumbuh optimum pada media NMS (nitrate mineral salt), dapat juga tumbuh pada media NMS dengan modifikasi penambahan kalium nitrat. Metanotrof dapat memanfaatkan berbagai senyawa karbon yang berbeda, seperti metanol, metil amin, halometan sebagai sumber karbon dan energi. Penelitian ini bertujuan untuk memformulasi media produksi bakkteri metanotrof yang memiliki aktivitas oksidasi CH4 dan fiksasi N2 yang tinggi