Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei University of Technology, Nanli Road, Wuhan 430068, PR China; Glyn O. Phillips Hydrocolloid Research Centre, School of Food and Biological Engineering, Hubei University of Technology, Nanli Road, Wuhan 430068, PR China.
Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei University of Technology, Nanli Road, Wuhan 430068, PR China.
Food Res Int. 2023 Dec;174(Pt 1):113552. doi: 10.1016/j.foodres.2023.113552. Epub 2023 Oct 4.
Slow fermentable dietary fibers can be utilized by human gut microbiota in the distal region of the colon and thus exert a sufficient short-chain fatty acids (SCFAs) supplement in the distal region of the human colon. Alginate (Alg) based microgels are widely fabricated and used to control their digestion by digestive enzymes releasing active substances site-specifically. Herein, sodium alginate microgels with gradient calcium-ion (Ca) cross-linking densities were developed, restricting their degradation by gut microbiota. Alg microgels were prepared using high-speed shearing after Alg was cross-linked with 10, 40, and 60 mmol/L Ca, respectively (named 10-Alg, 40-Alg, and 60-Alg). The fluorescence and atomic force microscopic results showed that the 40-Alg particle has the densest structure among the three cross-linked Alg. In vitro human fecal fermentation results revealed that the Ca cross-linking exerted more restricting effects than delaying effects on the fermentation of Alg, and the 40-Alg exhibited the slowest fermentation rate and the least fermentation extent, by characterizing the residual total carbohydrate content, residual monosaccharide content, pH, and total short-chain fatty acids. The 16S rRNA gene sequencing results indicated that cross-linking structures shaped a high specifical Bacteroides-type microbial community and that OTU205 (Bacteroides_xylanisolvens) highly correlated to the cross-linking density (R = 0.65, p = 0.047). In sum, Ca cross-linking generated a dense and compact structure of sodium alginate that facilitated a more restricted fermentation property and specificity-targeting microbial community structure in comparison to the original sodium alginate.
缓慢发酵膳食纤维可被人体肠道远端微生物群利用，从而在人结肠远端补充足够的短链脂肪酸（SCFAs）。基于藻酸盐（Alg）的微凝胶被广泛制造和使用，以通过消化酶释放活性物质来控制其在特定部位的消化。在此，开发了具有梯度钙离子（Ca）交联密度的海藻酸钠微凝胶，以限制其被肠道微生物群降解。使用高速剪切制备藻酸盐微凝胶，分别用 10、40 和 60mmol/L Ca 交联藻酸盐（分别命名为 10-Alg、40-Alg 和 60-Alg）。荧光和原子力显微镜结果表明，三种交联藻酸盐中，40-Alg 颗粒的结构最致密。体外人体粪便发酵结果表明，Ca 交联对藻酸盐发酵的抑制作用大于延迟作用，40-Alg 发酵速度最慢，发酵程度最低，通过表征残留总碳水化合物含量、残留单糖含量、pH 值和总短链脂肪酸。16S rRNA 基因测序结果表明，交联结构形成了一个高特异性拟杆菌型微生物群落，OTU205（拟杆菌属 xylanisolvens）与交联密度高度相关（R=0.65，p=0.047）。总之，与原始的海藻酸钠相比，Ca 交联生成了海藻酸钠的致密和紧凑结构，这有利于更严格的发酵特性和特异性靶向微生物群落结构。
