Time-dependent effects of dietary qualitative and quantitative protein malnutrition on some members of the cecal microbiota in male Wistar rats

Objective : Protein deficiencies are common conditions around the world. They may affect organisms directly or indirectly by changing their normal microbiota. This study aimed to determine time-dependent effects of the quality and quantity of dietary proteins on intestinal microbiota. Materials and methods : Sixty young male Wistar rats were used in four experiments with durations of 1, 2, 3 or 4 weeks, respectively. In each experiment 15 animals were divided into 3 equal groups and given either a complete rat chow (controls) or semi-synthetic diets containing almost no protein (N-free) or 20% gelatin ad libitum . Total aerobes, Enterobacteriaceae, coliform, and lactobacilli colonies were counted in cecal contents. Results : Generally, total aerobic bacteria and lactobacilli were most affected by protein malnutrition in all experiments. Both types of protein malnutrition decreased the numbers of total aerobic bacteria in all experiments except for the gelatin-fed animals in experiment I. Mean lactobacilli counts also decreased in both malnutrition groups but the decrease in lactobacilli count was more severe in N-free groups than in gelatin-fed groups. Conclusion: These results suggest that the effects of dietary proteins on cecal bacteria are dependent on the type of bacteria and partly time-dependent. Key words: Dietary protein, malnutrition, cecum, microbiota, time, rat