High Cell Density Cultivation of Methylosinus Trichosporium IMV 3011

Methanotrophs are aerobic microorganisms that can only utilize C1- such as methane and methanol as primary growth substrates. Methane is the most widely used substrate employed in cultivating methanotrophs. However, a major problem encountered in high cell density cultivation of this organism, is the solubility of methane in liquid medium. This study investigates the cultivation of M. trichosporium IMV 3011 on methanol and methane. It has been found that methanol although inhibits the growth of M. trichosporium IMV 3011 above certain concentrations, is a good alternative due to its infinite solubility in water. With the addition of 0.05% (v/v) methanol, the highest density of cultivated cells was 1.03g dry wtL(-1), which were 3 times of the without methanol addition. However, a longer lag time of 60.4 h prolonged the fermentation time. Paraffin as the methane vector can also shorten the lag phase and help methanotrophs to reach high cell density. With the addition of 2.5% (v/v) paraffin, the highest density of cultivated cells was 0.72 g dry wtL(-1), which were 2 times of the without methanol addition. The lag time was shortened to 11.1h. With the co-addition of 0.05% methanol and 2.5% paraffin, the highest density of cultivated cells was 1.224g dry wtL(-1). the lag time was shortened to 18.6 h and the growth rate was increased to 0.0415h(-1).