Search

In this study, we investigated the effects of enzyme-producing probiotic bacteria isolated from the gastrointestinal tract of rainbow trout on the growth performance, feed conversion ratio, and digestive enzyme activity, of fry (Oncorhynchus mykiss). Three isolates (G8/2013, T7/2013 and U5/2013) of candidate bacteria elicited the highest protease, lipase, and amylase activities, respectively. Isolates were identified as Aeromonas sp., Bacillus sp. and Citrobacter braakii by morphological, physiological, biochemical characterizations as well as 16S rRNA gene sequence analysis. The fry basal diet was supplemented with probiotics at varying concentrations; G8 group, Aeromonas sp. 1.72 × 108 CFU/g; U5 group, Bacillus sp. 3.01 × 108 CFU/g; T7 group, C. braakii 2.96 × 108 CFU/g and a mixed group (same bacterial concentrations), and control group (no bacteria). The rainbow trout fry were fed ad libitum in triplicate treatments with supplemented and non-supplemented probiotic diets for 70-days. The total bacterial count in the intestine was significantly higher in the mixed group (30th and 50th days) and U5 group (50th and 70th days) compared with the control group. However, there was no significant difference in weight gain, specific growth rate (SGR), feed conversion ratio (FCR), nutrient digestibility, or digestive enzyme activity among the groups. [ABSTRACT FROM AUTHOR]

Denaturing Gradient Gel Electrophoresis (DGGE) is a molecular fingerprinting method that separates similar size (bp), but different sequence of PCR products using acrylamide gel that contain denaturing gradient of urea and formamide. GC clamp is added at the 5′ end of one of the primer to prevent the PCR amplicon from completely denature. Different bacteria have different DNA sequences that will denature at different denaturant concentrations. Different DGGE conditions are suitable for different bacterial communities. This research aimed to optimize the conditions for determining bacterial community of fish intestinal tract. The percent of polyacrylamide gel (8.0% and 10.0%), denaturant concentrations (45 - 55%, 30 - 60%, and 30 - 70%), running times (5 h and 12 h) and voltages used (120 V and 200 V) were varied. The results indicated that, 8.0% polyacrylamide gel, 30 - 60% denaturant, 12 h running time and 120 V was the optimum condition for separation of different species of fish intestinal tract micro flora. [ABSTRACT FROM AUTHOR]

Examines the effects of diet on gastrointestinal microbial community of fish. Number of viable aerobic and facultative aerobic bacteria associated with the digestive tract; Isolation of the bacterial species; Influence of dietary manipulation on the species composition of carnobacteria.