D-Tagatose production in the presence of borate by resting Lactococcus lactis cells harboring Bifidobacterium longum L-arabinose isomerase.
Bifidobacterium longum NRRL B-41409 L-arabinose isomerase (L-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum L-AI were used for production of D-tagatose from D-galactose in the presence of borate buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of D-galactose to D-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L⁻¹ substrate and at 37.5 °C after 5 days. The D-tagatose production rate of 185 g L⁻¹ day ⁻¹ was obtained at 300 g L⁻¹ galactose, at 1.15 M borate, and at 41 °C during 10 days when the production medium was changed every 24 h. There was no significant loss in productivity during ten sequential 24 h batches. The initial D-tagatose production rate was 290 g L⁻¹ day⁻¹ under these conditions.
Department of Biotechnology and Chemical Technology, Aalto University, Finland. noora.j.salonen@aalto.fi
Noora
N
Salonen
Kalle
K
Salonen
Matti
M
Leisola
Antti
A
Nyyssölä
D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism*; D001644:Bifidobacterium / Q000201:enzymology* / Q000235:genetics; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology; D001881:Borates; D002021:Buffers; D004800:Enzymes, Immobilized / Q000235:genetics / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005798:Genes, Bacterial; D006601:Hexoses / Q000096:biosynthesis*; D007700:Kinetics; D013294:Lactococcus lactis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016192:Resting Phase, Cell Cycle
D001881:Borates; D002021:Buffers; D004800:Enzymes, Immobilized; D006601:Hexoses; D011994:Recombinant Proteins; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase; C030192:tagatose; D005690:Galactose