Preliminary study on the modulation of diet-induced malnutrition in BALB/c mice using a probiotic consortium: a physiological, biochemical, histopathological, and gut microbiota evaluation.

Protein-energy malnutrition (PEM) remains a major global health challenge that adversely affects growth, metabolism, immune function, and organ integrity. This study evaluated the efficacy of a food-derived Bacillus-based probiotic consortium in alleviating PEM and investigated its effects on gut microbial composition in BALB/c mice. Forty-eight male mice were allocated to Control (C), Disease Control (DC), Treatment (TG), Preventive (PG), and Healthy + Probiotic (HPG) groups. Malnutrition was induced using a 4% low-protein diet (LPD) for six weeks. The TG received probiotic supplementation during the recovery phase (weeks 6-9), whereas PG and HPG received probiotics throughout the study. The consortium consisted of Bacillus spizizenii, Bacillus tequilensis, and Bacillus rugosus (1 × 10⁹ CFU/mL each).LPD feeding significantly reduced body weight, total protein, albumin, cholesterol, and alkaline phosphatase activity while increasing C-reactive protein, serum glutamic oxaloacetic transaminase (SGOT), and serum glutamic pyruvic transaminase (SGPT), indicating metabolic impairment, systemic inflammation, and hepatic stress. Probiotic supplementation during nutritional rehabilitation significantly improved body weight gain, restored protein and albumin levels, normalized alkaline phosphatase activity, and reduced inflammatory and hepatic injury markers compared with dietary rehabilitation alone. Histopathological analyses demonstrated improved intestinal architecture, hepatocyte morphology, splenic organization, and renal integrity in the treatment group, whereas preventive supplementation under continued protein restriction resulted in only limited protection.Gut microbiota profiling using 16 S rRNA amplicon sequencing revealed that all groups were dominated by the phyla Bacteroidetes and Firmicutes. The treatment group exhibited increased relative abundance of beneficial taxa, including Barnesiella and Lactobacillus, together with reduced Proteobacteria abundance compared with the preventive group. Microbial community composition in the treatment group more closely resembled that of healthy animals, suggesting partial restoration of gut microbial homeostasis during nutritional rehabilitation.Collectively, these findings indicate that probiotic supplementation is most effective when combined with adequate nutritional support and may serve as a valuable adjunct strategy for improving physiological recovery, tissue regeneration, and gut microbial balance during protein-energy malnutrition.