Growth of Thermophilic Methanogen KN-15 on H_2-CO_2 under Batch and Continuous Conditions

概要

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The addition of H_2S(500 ppm) to the gaseous substrate (H_2 : CO_2=80 : 20) and an increase of mineral components could enhance the growth of a thermophilic methanogen, KN-15,which was isolated from a hot spring in Kyushu, Japan. After 28 h of cultivation, the cell concentration reached 19.5 g dry cell/l and the maximum methane productivity was 12.5 l/l/h in batch culture. Although productivities of cell and methane increased exponentially up to 1.1 g dry cell/l/h and 10 l/l/h, respectively, these became almost constant after the exponential growth phase by a limitation of the mass-transfer capacity of the fermentor. Cell productivity during the gas limiting phase was proportional to the volumertic mass-transfer coefficient (k_La) of hydrogen. On the contrary, in continuous culture, cell productivity was almost constant giving 1.1 g dry cell/l/h under a wide range of dilution rates, so that the cell concentration was inversely proportional to the dilution rate. The growth of KN-15 was dependent only on the mass-transfer capacity of the fermentor in both batch and continuous cultures.
社団法人日本生物工学会の論文
1991-10-25