High production of D-tagatose by the addition of boric acid.
An L-arabinose isomerase mutant enzyme from Geobacillus thermodenitrificans was used to catalyze the isomerization of D-galactose to D-tagatose with boric acid. Maximum production of D-tagatose occurred at pH 8.5-9.0, 60 degrees C, and 0.4 molar ratio of boric acid to D-galactose, and the production increased with increasing enzyme concentration. Under the optimum conditions, the enzyme (10.8 units/mL) converted 300 g/L D-galactose to 230 g/L D-tagatose for 20 h with a yield of 77% (w/w); the production and conversion yield with boric acid were 1.5-fold and 24% higher than without boric acid, respectively. In 24 h, the enzyme produced 370 g/L D-tagatose from 500 g/L D-galactose with boric acid, corresponding to a conversion yield of 74% (w/w) and a production rate of 15.4 g/L.h. The production and yield of D-tagatose obtained in this study are unprecedented.
Lim
Byung-Chul
BC
Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-747, South Korea.
Kim
Hye-Jung
HJ
Oh
Deok-Kun
DK
D001407:Bacillus / Q000378:metabolism; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D001888:Boric Acids / Q000737:chemistry*; D002855:Chromatography, Thin Layer; D004795:Enzyme Stability; D005690:Galactose / Q000737:chemistry; D006601:Hexoses / Q000096:biosynthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods*; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011994:Recombinant Proteins; D013696:Temperature; D013997:Time Factors
D001888:Boric Acids; D006601:Hexoses; D011994:Recombinant Proteins; C032688:boric acid; C030192:tagatose; D005690:Galactose