Lactobacillus reuteri biofilms formed on porous zein/cellulose scaffolds: Synbiotics to regulate intestinal microbiota.

Supplementing probiotics or indigestible carbohydrates is a usual strategy to prevent or revert unhealthy states of the gut by reshaping gut microbiota. One criterion that probiotics are efficacious is the capacity to survive in the gastrointestinal tract. Biofilm is the common growth mode of microorganisms with high tolerances toward harsh environments. Suitable scaffolds are crucial for successful biofilm culture and large-scale production of biofilm-phenotype probiotics. However, the role of scaffolds containing indigestible carbohydrates in biofilm formation has not been studied. In this study, porous zein/cellulose composite scaffolds provided nitrogen sources and carbon sources simultaneously at the solid/liquid interfaces, being beneficial to the biofilm formation of Lactobacillus reuteri. The biofilms showed 2.1-17.4 times higher tolerances in different gastrointestinal conditions. In human fecal fermentation, the biofilms combined with the zein/cellulose composite scaffolds act as the "synbiotics" positively modulating the gut microbiota and the short-chain fatty acids (SCFAs), where biofilms provide probiotics and scaffolds provide prebiotics. The "synbiotics" show a more positive regulation ability than planktonic L. reuteri, presenting potential applications in gut health interventions. These results provide an understanding of the synergistic effects of biofilm-phenotype probiotics and indigestible carbohydrates contained in the "synbiotics" in gut microbiota modulation.

Electrospun Nanofibrous Membranes Accelerate Biofilm Formation and Probiotic Enrichment: Enhanced Tolerances to pH and Antibiotics.

Biofilms are the oldest, most successful, and most widely distributed form of microorganism life on earth, existing even in extreme environments. Presently, probiotics in biofilm phenotype are thought as the most advanced fourth-generation probiotics. However, high-efficiency and large-scale biofilm enrichment in an artificial way is difficult. Here, fibrous membranes as probiotic biofilm-enriching materials are studied. Electrospun cellulose acetate nanofibrous membranes with nano-sized fibers show outstanding superiority over fibrous membranes with micron-sized fibers in Lactobacillus paracasei biofilm enrichment. The special 3D structure of electrospun nanofibrous membranes makes other facilitating biofilm formation factors insignificant. With a suitable scaffold/culture medium ratio, nearly 100% of L. paracasei cells exist as biofilm phenotype on the membrane from the very beginning, not planktonic state. L. paracasei biofilms possess a potential for long-term survival and high tolerances toward strong acidic and alkali conditions and antibiotics. RNA sequencing results explain why L. paracasei biofilms possess high tolerances toward harsh environments as compared to planktonic L. paracasei. Electrospun nanofibrous membranes can serve as powerful biofilm-enriching scaffolds for probiotics and other valuable microbes.