The acid tolerant l-arabinose isomerase from the food grade Lactobacillus sakei 23K is an attractive d-tagatose producer

• Published in: Bioresource technology 2010-12, Vol.101 (23), p.9171-9177
• Main Authors: Rhimi, Moez, Ilhammami, Rimeh, Bajic, Goran, Boudebbouze, Samira, Maguin, Emmanuelle, Haser, Richard, Aghajari, Nushin
• Format: Article
• Language: English
• Subjects: Acidotolerant; Acids - metabolism; Aldose-Ketose Isomerases - genetics; Aldose-Ketose Isomerases - metabolism; Biological and medical sciences; Cloning, Molecular; d-Tagatose; Enzyme Stability - drug effects; Escherichia coli; Food grade; Food Microbiology; Fundamental and applied biological sciences. Psychology; Galactose - metabolism; Genes, Bacterial - genetics; Hexoses - biosynthesis; Hydrogen-Ion Concentration - drug effects; Ions; Kinetics; l-Arabinose isomerase; Lactobacillus - drug effects; Lactobacillus - enzymology; Lactobacillus - genetics; Lactobacillus sakei; Life Sciences; Metals - pharmacology; Psychrotrophic; Recombinant Proteins - isolation & purification; Temperature
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2010.07.036

The araA gene encoding an l-arabinose isomerase ( l-AI) from the psychrotrophic and food grade Lactobacillus sakei 23K was cloned, sequenced and over-expressed in Escherichia coli. The recombinant enzyme has an apparent molecular weight of nearly 220 kDa, suggesting it is a tetramer of four 54 kDa monomers. The enzyme is distinguishable from previously reported l-AIs by its high activity and stability at temperatures from 4 to 40 °C, and pH from 3 to 8, and by its low metal requirement of only 0.8 mM Mn 2+ and 0.8 mM Mg 2+ for its maximal activity and thermostability. Enzyme kinetic studies showed that this enzyme displays a high catalytic efficiency allowing d-galactose bioconversion rates of 20% and 36% at 10 and 45 °C, respectively, which are useful for commercial production of d-tagatose.