Expression of heterologous PEP-carboxylase in <I>Methylococcus capsulatus</I> MIR: the influence on growth characteristics and amino acid composition of methanotrophic biomass

Methylococcus capsulatus MIR is a strain of methanotrophic bacteria that is potentially suitable for producing feed protein and other value-added products from methane. Genomic analysis did not reveal in Mc. capsulatus MIR known pathways of C3-carboxylation, necessary for the replenishment of intermediates of the tricarboxylic acid cycle and the full functioning of metabolism. The pepc gene encoding PEP carboxylase in Methylomonas rapida 12 was introduced into Mc. capsulatus MIR cells on a plasmid under the control of a medium-strength promoter. Expression of heterologous PEP carboxylase led to an increase in the content of glutamate, glycine and lysine in the cells of the recombinant strain, but did not increase to the growth rate of the culture. Consequently, the introduction of heterologous PEP carboxylase, which carries out the C3-carboxylation reaction, helps to increase the nutritional value of the methanotroph biomass.