Mass spectrometric evaluation of the incorporation of 2H and 13C into amino acids of bacteria

A highly sensitive EIMS method was used to study the incorporation of stable isotopes 2H and 13C into amino acids secreted by the L-phenylalanine-producing strain of Brevibacterium methylium and the L-leucine-producing strain of Methylobacillus flagellatum, as well as into the amino acid residues of the total biomass proteins upon growing the bacteria on media containing [2H]methanol, [13C]methanol, and 2H2O as sources of Th stable isotopes. The incorporation of 2H and 13C into the secreted amino acids and the amino acid residues of the total biomass proteins depends on the content of labelled substrates in the growth media and are different for different amino acids (from 10% for L-leucine/isoleucine to 97.5% for L-alanine)