Development and in vivo evaluation of a probiotic-enriched functional beverage with Bacillus licheniformis for gut microbiota modulation in a high-fat diet model in C57BL/6 mice

Abstract

Obesity, type 2 diabetes, and other metabolic diseases are increasing across the globe. The necessity for public health to discover new interventions that can aid in fighting these conditions is crucial. Obesity, overweight, and diabetes are common conditions in Mexico. Over 70% of adults are overweight. Over a third are obese. Over 14 million people have diabetes. Understanding the link between these metabolic disorders with gut microbiota dysbiosis could therefore be critical to developing novel strategies for the prevention and treatment of these conditions.

This PhD thesis intends to develop a functional drink using Bacillus licheniformis to modulate the gut microbiota and subsequently metabolism in general. In this thesis, a review of B. licheniformis was performed, enhancing its probiotic properties and mechanism of action concerning metabolic disorders such as obesity and diabetes. B. licheniformis was chosen due to its probiotic properties regarding microbiome modulation and its helpful effects on metabolic disorders. A native strain was isolated, sequenced, and optimized for use as a single-strain probiotic.

Microencapsulation of the probiotic by spray drying using a maltodextrin-alginate-inulin matrix was statistically optimized and yielded microcapsules that have low moisture content (3.02%) and high yield (51.06%) and encapsulation efficiency (80.53%), solubility (90.52%), and stability at 4 °C, 25 °C, and 37 °C for at least six months, maintaining probiotic viability under simulated gastrointestinal conditions. Structural analyses (SEM, DLS, Zeta potential, FTIR, XRD, and DSC) showed interactions between the bacterium and the matrix, promoting an improvement in the amorphization, thermal stability, and release profile.

The encapsulated probiotic has been added to a non-dairy functional beverage and shown to be viable through storage for over 6 months. Finally, it was evaluated in a high-fat diet Model using C57BL/6 mice. This functional beverage supplementation revealed a decrease in weight gain, prevention of hepatic steatosis, and systemic inflammation. At the same time, it improved glucose tolerance, biochemical profiles, gut microbiota diversity, and gene expressions compared to unsupplemented controls.

By combining microbiology, materials science, and metabolic physiology, we present Bacillus licheniformis as a viable alternative platform for functional food products to aid in the control of obesity, diabetes, and other possible metabolic diseases through gut microbiota modulation.