Production of single-cell protein by methane-oxidizing bacteria using different nitrogen sources
Methane-oxidizing bacteria(MOB)use methane as a carbon and energy source to regulate the expression of methane monooxygenase(MMO)through metal Cu2+under different nitrogen sources.The effect of different MMO expressions on the production of single-cell protein(SCP)yield by MOB was investigated.MOBs were cultured with nitrate nitrogen,ammonium nitrogen,and nitrogen gas as nitrogen sources under the expression of soluble MMO(sMMO)and particulate MMO(pMMO).The cell yield,SCP production,MMO characteristic activity,and nitrogenase activity were the main indexes,and the effects of nitrogen source species on MOB growth and SCP production under different MMO expressions were observed.The experimental results show that the SCP production of MOBs cultured with nitrate nitrogen as nitrogen source under pMMO expression is 9.2%higher than that under sMMO expression,while the SCP production of MOBs cultured with ammonium nitrogen as nitrogen source is higher under sMMO expression,and the SCP production of MOBs cultured with nitrogen gas as the nitrogen source is the lowest.