Optimization of fermentation conditions for production of l‐arabinose isomerase of Lactobacillus plantarum WU14

As a substitute sweetener for sucrose, d‐tagatose is widely used in products, such as health drinks, yogurt, fruit juices, baked goods, confectionery, and pharmaceutical preparations. In the fermentation process of l‐AI produced by Lactobacillus plantarum, d‐tagatose is produced through biotransformation and this study was based on the fermentation process of Lactobacillus plantarum WU14 producing l‐AI to further research the biotransformation and separation process of d‐tagatose. The kinetics of cell growth, substrate consumption, and l‐arabinose isomerase formation were established by nonlinear fitting, and the fitting degrees were 0.996, 0.994, and 0.991, respectively, which could better reflect the change rule of d‐tagatose biotransformation in the fermentation process of L. plantarum WU14. The separation process of d‐tagatose was identified by decolorization, protein removal, desalination, and freeze drying, initially. Finally, the volume ratio of whole cell catalysts, d‐galactose, and borate was 5:1:2 at 60°C, pH 7.17 through borate complexation; then, after 24 hr of conversion, the yield of d‐tagatose was 58 g/L.