This study established a food-grade Bacillus subtilis expression system for a maltopentaose-forming amylase derived from Bacillus megaterium STB10 (BmMFA). The enzymatic properties and product synthesis pattern of the expressed enzyme were studied. Results showed that BmMFAse exhibited excellent catalytic activity, and the enzymatic activity in the fermentation supernatant of B. subtilis was 196.57 U/mL. The optimal reaction temperature and pH of BmMFA were 50 ℃ and pH 7.0, respectively, and BmMFAse could adapt to a wide pH range. The action pattern of BmMFA was found to tend to be endo-type. BmMFAse showed superior product specificity, and the maltopentaose content in maltodextrin hydrolyzed by BmMFAse for 24 h was over 42%. The substrate conversion rate and the relative content of maltopentaose as the major product were higher using amylopectin as the substrate for BmMFA than amylose. This study provides a theoretical basis for the efficient production of maltopentaose.

Resistant starch (RS) has attracted much researchers’ attention because of its health-beneficial effects. Gut microbiota obviously shapes human health, but the effects of RS supplementation on the changes of human gut microbiota remain unclear. This observational meta-analysis aimed to reveal the effects of RS intake on α-diversity and composition of gut microbiota through meta-analysis. Two independent authors systematically searched articles from inception until February 2023 on four electronic databases. Twenty-four highly relevant trials were included conforming to Preferred Reporting Items for Systematic reviews and Meta-Analysis protocol, and a total of 816 individuals were included. Significant heterogeneity analyses revealed that RS intake notably decreased Shannon index (weighted mean difference (WMD): –0.11; 95% confidence interval (CI): –0.21, –0.01), and stimulated the composition of health promoting bacteria genera, including Bifidobacterium (relative abundance: WMD: 1.75; 95% CI: 0.39, 3.11; bacterial populations: WMD: 0.36; 95% CI: 0.04, 0.69), Faecalibacterium (relative abundance: WMD: 0.70; 95% CI: 0.20, 1.20; fold change: effect size: 0.91; 95% CI: 0.60, 1.23), and Prevotella (relative abundance: WMD: 0.35; 95% CI: 0.01, 0.69). Taken together, the present study revealed that changes in the gut microbiota diversity and genera were correlated with RS supplementation, which may contribute to benefits in human health.