Effect of Silk Fibroin Biomaterial Coating on Cell Viability and Intestinal Adhesion of

Probiotics are live microorganisms that provide health benefits in the human body through an adequate intake [1, 2]. Various effects have been reported, such as reduction in diarrhea, inhibition of pathogenic bacteria, lowered blood cholesterol, and improvements in liver cirrhosis and obesity [3-6]. Thanks to these effects, probiotics have been widely applied to food products, drugs and feed additives, with their use increasing each year globally [7, 8]. The most well-known genera of probiotics include Lactobacillus, Bifidobacterium, Streptococcus, Leuconostoc, Pediococcus, Enterococcus, and Lactococcus [3, 4]. In general, the commercialization of a probiotic product involves the cultivation of microorganisms and the processes of concentration and drying or freeze-drying for Probiotics can be processed into a powder, tablet, or capsule form for easy intake. They are exposed to frequent stresses not only during complex processing steps, but also in the human body after intake. For this reason, various coating agents that promote probiotic bacterial stability in the intestinal environment have been developed. Silk fibroin (SF) is a material used in a variety of fields from drug delivery systems to enzyme immobilization and has potential as a coating agent for probiotics. In this study, we investigated this potential by coating probiotic strains with 0.1% or 1% water-soluble calcium (WSC), 1% SF, and 10% trehalose. Under simulated gastrointestinal conditions, cell viability, cell surface hydrophobicity, and cell adhesion to intestinal epithelial cells were then measured. The survival ratio after freeze-drying was highest upon addition of 0.1% WSC. The probiotic bacteria coated with SF showed improved survival by more than 10.0% under simulated gastric conditions and 4.8% under simulated intestinal conditions. Moreover, the cell adhesion to intestinal epithelial cells was elevated by 1.0-36.0%. Our results indicate that SF has positive effects on enhancing the survival and adhesion capacity of bacterial strains under environmental stresses, thus demonstrating its potential as a suitable coating agent to stabilize probiotics throughout processing, packaging, storage and consumption.

Automated summary

Probiotics are live microorganisms that provide health benefits in the human body through an adequate intake and have been widely applied to food products, drugs, and feed additives. Coating probiotic strains with silk fibroin (SF) has shown positive effects in enhancing their survival and adhesion capacity under environmental stresses, demonstrating its potential as a suitable coating agent for stabilizing probiotics.