The Effect of Temperature on Carp (cyprinus Carpio, L., 1758) Microbiota, Reared in Intensive Conditions, by Using the BioPlus® 2B Probiotic

A 60-days experimental trial was conducted to examine the influence of probiotic BioPlus® 2B, in different concentration, on the gut microbial load and the organic load of technological water used for carp growth, in low water temperature (13.5-16.8 0C) conditions. Four variants were tested, as follows: V1-pellets with 30% crude protein, without probiotics; V2-pellets with 30% crude protein, with probiotics of 2.24×109 CFU/kg food; V3-pellets with 30% crude protein, with probiotics of 3.84×109 CFU/kg food; and V4-pellets with 30% crude protein, with probiotics of 7.04×109 CFU/kg food. BioPlus® 2B probiotics (a mixture of Bacillus licheniformis (DSM 5749) and Bacillus subtilis (DSM 5750) were used. In order to determine the total number of germs (NTG), microbiological analyses were made. As a result, it can be stated that during the first experimental stage, gut microbial load had registered a significant increase (p <0.05) compared to the initial values (from the 1×10-5 CFU/g dilution to the1×10-7 CFU/g dilution) in case of all fish samples corresponding to the variants where different concentrations of probiotic were administered. The results obtained from the microbial water load evaluation, that corresponds to each experimental variant, shows that the control variant (V1) has a lower average microbial water load (4.1 × 10-3 CFU/ml), compared with other experimental variants V3 (8.6 × 10-3 CFU/ml) and V4 (7.6 × 10-3 CFU/ml), where feed with different concentrations of probiotic was administered. In conclusion, the total number of germs (NTG) in experimental variants with different concentrations of probiotic, initially showed an upward trend compared to the control variant, with a higher load in case of V4 variant, where the highest concentration of probiotic was administrated. The reduced microbial load that appeared at the end of the experimental period is justified by the inhibitory action of temperature, seen as an interference factor.