Live and ultrasound-inactivated Lacticaseibacillus casei modulate the intestinal microbiota and improve biochemical and cardiovascular parameters in male rats fed a high-fat diet

This study aimed to evaluate the effects of ingestion of live (9 log CFU/mL) and ultrasound-inactivated (paraprobiotic, 20 KHz, 40 min) Lacticaseibacillus casei for 28 days on healthy parameters (biochemical and cardiovascular) and intestinal microbiota of rats fed a high-fat diet. Thirty-two male Wistar rats were divided into four groups: CTL (standard diet), HFD (high-fat diet), HFD-Lc (high-fat diet and live L. casei), and HFD-ILC (high-fat diet and inactivated L. casei). The ingestion of live and ultrasound-inactivated L. casei prevented the increase (p < 0.05) in cholesterol levels (total and LDL) and controlled the insulin resistance in rats fed with a high-fat diet. Furthermore, it promoted a modulation of the functionality and composition of the intestinal microbiota by increasing beneficial bacteria (Lachnospiraceae and Ruminoccocaceae) and decreasing harmful bacteria (Clostridiaceae, Enterobacteriaceae, and Helicobacteriacea), changing the microbiota toward a profile more similar to the CTL group. Only live cells could increase the HDL-cholesterol, while only inactivated cells caused attenuation of the blood pressure. Results indicate that inactivation of L. casei by ultrasound produces a paraprobiotic with similar or improved health properties compared to live cells.