Subramaniam Sathivel, Keenan, Michael J.
Subramaniam Sathivel, Arranee Chotiko, Chen Liu, Emmanuel Kyereh, Bennett Dzandu and Mike Keenan
Probiotics are known for beneficial health effects, such as the improvement of gut microbial composition, protection against pathogenic bacteria and modulation of immune systems. Probiotics have been incorporated into various food products, including dairy products, such as yogurt, cheese and ice cream, and nondairy products, such as cereals and juices.
Attempting the introduction of probiotics via foods, however, may result in the probiotics not surviving during processing and passage through the gastrointestinal tract. Losses of probiotic cells could result from not only unfavorable conditions of food processing, such as heating, freezing, dehydration and acidification, but also digestive system environments that contain gastric fluids, bile salts and bile enzymes. Providing probiotics with a physical barrier can be an approach to resist harmful environments and improve probiotic viability and delivery through the stomach to the large intestine.
LSU AgCenter researchers have developed immobilization and encapsulation techniques that provide protection of probiotic bacteria cells and can be incorporated into delivery systems for probiotics to provide protection for bacteria cells. Dietary fibers may be used to immobilize bacterial cells throughout the fiber matrix. They provide surfaces for bacteria to attach onto, and they function as a protective agent against physiochemical changes because of adverse pH levels, temperature and bile.
The researchers have conducted studies on the extraction and use of rice bran fibers. The lab team has demonstrated that rice bran fiber acts as a protectant for probiotics during freezing and freeze drying, spray drying and storage. Probiotics immobilized in rice bran fibers were tested, and they had higher survival rates in gastrointestinal juice conditions compared to nonimmobilized probiotics without rice bran fiber.
The researchers have tested the immobilized probiotics on rice bran fiber in a rat model. They fed rats with the immobilized probiotics for a 31-day period. Feeding continued with a diet containing 10% rice bran fiber and no probiotics for an additional 11 days after the ingestion period. This preliminary study showed that probiotics immobilized in rice bran fiber colonized in the gut. This is significant because there is good evidence that probiotics are beneficial for good health if taken daily. However, it would be more convenient, and thus preferable, if probiotics could colonize the gut, change the microbiota for better health, and not need to be taken repeatedly to maintain their effectiveness.
The researchers conducted another small pilot study with three rats per group to test whether immobilized probiotics would improve gut immunity. The immobilized probiotics reduced gut inflammation in rats. The researchers also found that some pathogen species present in the older rat gut had been reduced and that some beneficial bacteria increased in rats fed with the immobilized probiotics. This small study, although indicative, is not sufficient to be definitive. Therefore, the researchers are planning to conduct a larger, more robust preclinical study.
AgCenter researchers conducted another preliminary study with colonic mucosal alterations induced by Citrobacter rodentium (mice pathogen) infection in mice. The pathogen promotes intestinal inflammation, or colitis, in mice. Mice were infected with Citrobacter rodentium and then treated with probiotics for three days. After the probiotics treatment, the C. rodentium damage had been reduced. The researchers also investigated the in vitro and in vivo (mouse model) efficacy of probiotic bacteria incorporated in tomato juice for reducing colitis. They found that probiotics may modulate the gastrointestinal microbiota and immune response to help relieve complications of colitis or diarrhea.
In summary, the AgCenter research demonstrated that rice bran fibers could have potential as a delivery system for probiotics, and the delivery of the probiotics increased the population and diversity of beneficial bacteria in gut microbiota. The study indicated that the successful delivery of probiotics to the gut could improve gut health via immune system regulation and modulation of the microbiota.
Subramaniam Sathivel is a professor in the Department of Biological and Agricultural Engineering; Arranee Chotiko, Chen Liu, Emmanuel Kyereh and Bennett Dzandu are former graduate students working with Sathivel; and Mike Keenan is a professor in the School of Nutrition and Food Sciences.
(This article appears in the fall 2019 issue of Louisiana Agriculture.)
LSU AgCenter researchers have incorporated probiotics into rice bran. Sample No. 1 includes the strain Pediococcus acidilactici RS2-10, and No. 3 includes the strain Lactococcus lactic subsp. lactis ATCC 11454. Photo by Olivia McClure