Dietary Administered Bacillus sp. PP9 Enhances Growth, Nutrition and Immunity in Cirrhinus mrigala (Hamilton)

Abstract

Bacillus sp. PP9, a noble bacterial isolate of mrigal (Cirrhinus mrigala) gut was investigated for its efficacy as a dietary probiotic against mrigal (C. mrigala) through a dose dependent impact assessment. Mrigal fingerlings (avg.wt. 2.5 ± 0.20 g) were fed with three different doses (2 × 104, 2 × 105 and 2 × 106 CFU) of Bacillus sp. PP9 admixed with 100 g feed for a period of 60 days. It was found that the feed with Bacillus concentration of 2 × 104 CFU exhibited significantly higher growth, maximum RNA DNA ratio, lower food conversion ratio in comparison to other two feed types. Enhanced intestinal protease and α-amylase activity followed by maximum hepatic glutamic oxaloacetic transaminase and glutamate pyruvate transaminase levels were also monitored in this specific feed type. Important hematological parameters like hemoglobin percentage, total erythrocyte count, total leukocyte count, corpuscular hemoglobin also indicated a healthy trend in this dose. Furthermore, the same dietary treatment exhibited highest levels of total serum protein, albumin globulin ratio and serum bactericidal activity. The growth, nutrition and immunological parameters showed a declining trend with increase in the bacterial concentration as well as in the control group (without probiotic). In summary, dietary supplement of 2 × 104/100 g appears as a potential probiotic dose of Bacillus sp. PP9 for growth, nutritional efficacy as well as immunological modulation of C. mrigala and denotes a recommended concentration for its future field applications.