"Methylotrophic biomass as 2H-labeled substrate for biosynthesis of inosine"
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factors and additional source of nitrogen the yeast extract. Since the small availability of commercial available 2H-labeled biomass prepared from yeast, it was necessary to find the more suitable microbial source, from which the 2H-labeled growth substrates could be obtained. For this purpose we employed the available RuMP facultative methylotroph Brevibacterium methylicum  with the content of the total protein and
polycarbohydrates in biomass 53 and 10% respectively . The content of amino acids in biomass of B. methylicum and the deuterium enrichment are shown in Table. Table: The content of amino acids in biomass of B. methylicum and the deuterium enrichment. Amino Acids The content in biomass, % Deuterium enrichment , %
Glycine 9,69 90,0 Alanine 13,98 97,5 Valine 3,74 50,0 Leucine/Isoleucine 7,33/3,64 49,0 Phenylalanine 3,94 95,0 Tyrosine 1,82 92,8 Serine 4,90 90,0 Threonine 5,51 not determined Methionine 2,25 not determined Aspartic Acid 9,59 66,6 Glytamic Acid 10,38 70,0 Lysine 3,98 58,9 Arginine 5,27 not determined
Histidine 3,72 not determined The hydrolysis of 2H-labeled biomass was performed in mild conditions via its autoclaving (30 min, 08 atm) in 0.5 N solution of 2HCl (in 2H2O). The data on the amino acid composition of hydrolysate and levels of the enrichment are shown in Fig. 2. The contents of tyrosine and histidine in hydrolysate were 1.82 and 3.72% and can ensure the polyauxotrophy of the inosine producing strain. Another important parameter is a high level of amino
acid enrichment. Bacterial growth and production of inosine Two following media were used for the bacterial growth: 1). FM medium, prepared from ordinary protonated water and yeast extract. 2). dHM medium, prepared from 87.5% (v/v) 2H2O and 2.5% (m/m) of 2H-labeled methylotrophic hydrolisate, obtained accordingly from medium dМ9. Fig.1 Curves, reflecting the growth dynamics (a), convercionСкачать сочинение