Phenotypic, biochemical, and ultrastructural characterization of rumen bacteria from Pogasi beef cattle supplemented with yeast Saccharomyces cerevisiae
Description
Abstract Aims: This study aimed to characterize the phenotypic, biochemical, and ultrastructural features of culturable rumen bacteria from Pogasi beef cattle supplemented with Saccharomyces cerevisiae. Methods and Results: Rumen samples were collected from control and yeast-supplemented cattle across two experimental periods. Culture-based analyses were performed to evaluate colony morphology, biochemical characteristics, total viable bacterial counts using the total plate count (TPC) method, and cellular morphology using light microscopy and scanning electron microscopy (SEM). Differences in colony morphology were observed between treatments, including variations in colony color, diameter, margin, elevation, and consistency. Biochemical profiling revealed heterogeneity among bacterial isolates in motility, nitrate reduction, carbohydrate fermentation patterns, and selected enzymatic activities, indicating functional diversity within the culturable rumen bacterial community. Total viable bacterial counts ranged from 1.1 × 109 to 2.4 × 109 CFU/mL, with higher counts generally detected in yeast-supplemented samples compared with the control. Light microscopy confirmed the predominance of rod-shaped bacterial cells across all treatments. SEM analysis further demonstrated differences in bacterial aggregation, cellular arrangement, and cell-surface integrity between the control and yeast-supplemented groups. These ultrastructural features suggest physiological adaptations of culturable rumen bacteria associated with yeast supplementation. Conclusions: Overall, the findings demonstrate that Saccharomyces cerevisiae supplementation is associated with measurable phenotypic, biochemical, and ultrastructural variations in culturable rumen bacteria. This study highlights the relevance of culture-dependent and microscopic approaches for assessing microbial responses to dietary interventions in ruminant systems. Keywords: yeast, Pogasi, beef cattle, phenotypic, characterization