Production of D-tagatose, a low caloric sweetener during milk fermentation using L-arabinose isomerase.
Lactobacillusdelbrueckii subsp. bulgaricus and Streptococcus thermophilus are used for the biotransformation of milk in yoghurt. During milk fermentation, these lactic acid bacteria (LAB) hydrolyze lactose producing a glucose moiety that is further metabolized and a galactose moiety that they are enable to metabolize. We investigated the ability of L. bulgaricus and S. thermophilus strains expressing a heterologous L-arabinose isomerase to convert residual D-galactose to D-tagatose. The Bacillus stearothermophilus US100l-arabinose isomerase (US100l-AI) was expressed in both LAB, using a new shuttle vector where the araA US100 gene is under the control of the strong and constitutive promoter of the L. bulgaricus ATCC 11842 hlbA gene. The production of L-AI by these LAB allowed the bioconversion of D-galactose to D-tagatose during fermentation in laboratory media and milk. We also established that the addition of L-AI to milk also allowed the conversion of D-galactose into D-tagatose during the fermentation process.
Laboratoire d'Enzymes et de Métabolites des Procaryotes, Centre de Biotechnologie de Sfax, Sfax, Tunisia.
Moez
M
Rhimi
Hichem
H
Chouayekh
Isabelle
I
Gouillouard
Emmanuelle
E
Maguin
Samir
S
Bejar
D019747:Aldose-Ketose Isomerases / Q000378:metabolism*; D000818:Animals; D031204:Caloric Restriction; D002417:Cattle; D006601:Hexoses / Q000096:biosynthesis*; D007778:Lactobacillus / Q000201:enzymology*; D008892:Milk / Q000382:microbiology*; D048249:Streptococcus thermophilus / Q000201:enzymology*; D013549:Sweetening Agents / Q000378:metabolism*
D006601:Hexoses; D013549:Sweetening Agents; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase; C030192:tagatose