In Vitro Fermentation Patterns of Rice Bran Components by Human Gut Microbiota

Abstract

Whole grain rice is a rich source of fiber, nutrients, and phytochemicals that may promote gastrointestinal health, but such beneficial components are typically removed with the bran during polishing. Soluble feruloylated arabinoxylan oligosaccharides (FAXO) and polyphenols (RBPP) isolated from rice bran are hypothesized to have positive impacts on human gut microbiota through a prebiotic function. Using an in vitro human fecal fermentation bioassay, FAXO and RBPP treatments were assessed for short-chain fatty acids (SCFA) production patterns and by evaluating their impacts on the phylogentic composition of human gut microbiota by 16S rRNA gene sequencing. Fresh fecal samples collected from healthy adults (n = 10, 5 males, 5 females) were diluted with anaerobic medium. Each sample received five treatments: CTRL (no substrates), FOS (fructooligosaccharides), FAXO, RBPP, and MIX (FAXO with RBPP). Samples were incubated at 37 °C and an aliquot was withdrawn at 0, 4, 8, 12, and 24 h Results showed that SCFA production was significantly increased with FAXO and was comparable to fermentation with FOS, a well-established prebiotic. RBPP did not increase SCFA productions, and no significant differences in total SCFA production were observed between FAXO and MIX, indicating that RBPP does not modify FAXO fermentation. Changes in microbiota population were found in FAXO treatment, especially in Bacteroides, Prevotella, and Dorea populations, indicating that FAXO might modulate microbiota profiles. RBPP and MIX increased Faecalibacterium, specifically F. prausnitzii. Combined FAXO and RBPP fermentation increased abundance of butyrogenic bacteria, Coprococcus and Roseburia, suggesting some interactive activity. Results from this study support the potential for FAXO and RBPP from rice bran to promote colon health through a prebiotic function.

Current Hypothesis for the Relationship between Dietary Rice Bran Intake, the Intestinal Microbiota and Colorectal Cancer Prevention

“…In another study, intake of rice bran for 14 days was shown to result in a decreased ratio of the intestinal abundance of Firmicutes and Bacteroidetes (decreased Firmicutes–Bacteroidetes ratio), as well as an increased production of some health-promoting SCFAs such as acetate, among American CRC survivors [ 77 ]. This is consistent with the recent finding that the intake of feruloylated arabinoxylan oligosaccharides, a carbohydrate contained in rice bran [ 78 ], would lead to an elevation in the intestinal production of SCFAs including butyrate and propionate [ 79 ]. These SCFAs were previously suggested to exhibit cancer-preventive properties [ 17 ].…”

Galactooligosaccharides and Resistant Starch Altered Microbiota and Short-Chain Fatty Acids in an in vitro Fermentation Study Using Gut Contents of Mud Crab (Scylla paramamosain)

“…Apart from the production of SCFAs from fermentation, prebiotics are expected to have the capacity to selectively promote the growth and/or activity of gut bacteria involved in health and well-being (Pham et al, 2017). Changes in the community composition due to the ingestion of dietary fibers occur as a result of differences in their physicochemical and metabolic properties (Umu et al, 2015).…”

“…Supplementation with prebiotics might be a promising method that could confer positive health benefits in aquatic animals, including cultured crustaceans (Daniels et al, 2013;Chen et al, 2017;Duan et al, 2017;Elshopakey et al, 2018;Safari and Paolucci, 2018). In vitro anaerobic fermentation studies provide a primary approach for initial evaluation of the positive benefits of compounds through their effects on metabolic activities of gut microbiota (Pham et al, 2017). Many research efforts aimed at assessing the impacts of potential prebiotics on the dynamics of human gut microbiota have applied in vitro fermentation approaches (Scott et al, 2014;Pham et al, 2017;Sato et al, 2017;Baxter et al, 2019).…”

“…In vitro anaerobic fermentation studies provide a primary approach for initial evaluation of the positive benefits of compounds through their effects on metabolic activities of gut microbiota (Pham et al, 2017). Many research efforts aimed at assessing the impacts of potential prebiotics on the dynamics of human gut microbiota have applied in vitro fermentation approaches (Scott et al, 2014;Pham et al, 2017;Sato et al, 2017;Baxter et al, 2019). These studies have demonstrated that prebiotics (i.e., L-sorbose, xylitol, and resistant starch) can selectively stimulate the growth of butyrate producers and increase the production of butyric acid in batch cultures.…”

Deep Processing of Rice and Comprehensive Utilization of Its By-products

“…In addition, the solid beverage produced from rice bran nutrients and rice bran nutrition fiber has a rich cocoa flavor and a favorite rich moisturizing taste. The eater supplements the daily protein, unsaturated fatty acids, vitamins, minerals, etc., and can also supplement the dietary fiber to obtain a smooth and laxative health care function [46]. The rice bran nutrient solid beverage and the rice bran nutrient fiber solid beverage have pure natural and low price.…”