L-arabinose isomerase from Lactobacillus fermentum C6: Enzymatic characteristics and its recombinant Bacillus subtilis whole cells achieving a significantly increased production of D-tagatose

• Published in: International journal of biological macromolecules Vol. 278; no. Pt 1; p. 134753
• Main Authors: Ma, Donglin, Qiu, Lu, Wang, Xiaofang, Li, Lilang, Peng, Shuaiying, Liao, Yan, Li, Kuntai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2024
• Subjects: L-arabinose isomerase; Lactobacillus fermentum; Whole-cell biotransformation of D-tagatose; L-arabinose isomerase; Whole-cell biotransformation of D-tagatose; Lactobacillus fermentum
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.134753

L-arabinose isomerase (L-AI) is a functional enzyme for the isomerizing of D-galactose to produce D-tagatose. In this study, L-AI-C6-encoding gene from the probiotic Lactobacillus fermentum C6 was cloned and expressed in Bacillus subtilis WB600 for investigating enzymatic characteristics and bioconverting D-tagatose by means of whole-cell catalysis. Results showed that the engineered B. subtilis WB600-pMA5-LAI achieved a maximum specific activity of L-AI-C6 (232.65 ± 15.54 U/mg protein) under cultivation in LB medium at 28 °C for 40 h. The recombinant L-AI-C6 was purified, and enzymatic characteristics test showed its optimum reaction temperature and pH at 60 °C and 8.0, respectively. In addition, L-AI-C6 exhibited good stability within the pH range of 5.5–9.0. By using B. subtilis WB600-pMA5-LAI cells as whole-cell catalyst, the highest D-tagatose yield reached 42.91 ± 0.28 % with D-galactose as substrate, which was 2.41 times that of L. fermentum C6 (17.79 ± 0.11 %). This suggested that the cloning and heterologous expression of L-AI-C6 was an effective strategy for improving D-tagatose conversion by whole-cell catalysis. In brief, the present study demonstrated that the reaction temperature, pH, and stability of L-AI-C6 from L. fermentum C6 meet the demands of industrial application, and the constructed B. subtilis WB600-pMA5-LAI shows promising potential for the whole-cell biotransformation of D-tagatose. [Display omitted] •L-AI-C6 originates from the GRAS Lactobacillus fermentum C6.•L-AI-C6 exhibits excellent enzymatic properties for industrial application.•The engineered B. subtilis shows promising whole-cell catalytic activity on D-tagatose production.