تاثير بكتريا (Bacillus subtilis )على المجتمع المايكروبي ودلائل تحسين النمو والمؤشرات الدموية والمناعية لأسماك الكارب (Cyprinus carpio )

Effect of Bacillus subtilis on microbial community , growth performance, and some haemato - immunological parameters of common carp (Cyprinus carpio)

Summary:

        The current study was carry out for aperiod of six weeks from 24 February to Aprile/ 2019 and conducted to investigate the influence of dietary supplementation of Bacillus subtilis on intestinal microbial community, growth performance, haematological parameters, serum biochemistry parameters and the levels of cytokines including transforming growth factor beta (TGF β) and Interleukin1beta (IL1 β) of common carp. A total of 70 fish (77.2 ± 0.86 g) were collected from AL-hafiz farm a local commercial at Karbala city and randomly distributed into (14 ) groups in plastic tanks, each group contain five fish. Seven tanks were allocated for the probiot group and the other seven tanks were allocated for the control group. Fish were fed at 1.5-2% of body weight twice daily. The probiotic was isolated from local soils and using polymerase chain reaction ( PCR) technique for the amplification of Ribosomal ribonucleic acid (16S rRNA). Fish were fed a diet containing B. subtilis at dose of ~107 CFU g−1 control diet for 6 weeks. Total viable count (TVC) bacterial populations and subtlilus were enumerated using tryptone soy agar (TSA) and de Man, Rogosa and Sharpe agar (MRS),respectively. The results of microbiology revealed that the resident total viable count (TVC) and lactic acid bacteria (LAB) microbial community significantly decreased in the probiotic fed fish group compared to the control group, while the microbial community of TVC in the digesta samples was significantly increased in the probiotic fed fish compared to the control group. The bacterial diagnosis for microbial community of B common carp revealed that the communities grouped into two distinct phyla, Proteobacteria and Firmicutes. The results of growth performance profiles were not influenced by probiotic diet. Compared to the control group, the carp fed probiotic supplemented diet displayed a significant elevation in mean corpuscular haemoglobin concentration (MCHC), (P < 0.05). The other haematology parameters were not significantly affected. The blood serum profiles i.e. blood urea, cholesterol and random blood sugar, were not affected by the experimental diet. However, serum creatinine was significantly higher in the probiotic group compared to the control group. The experimental carp displayed elevation level of IL1β compared to the control group (P=0.004). On the other hand, the level of TGFβ was lower in the probiotic treated fish but no significant differences were observed (P=0.05). The results of the present study, demonstrate potential role for B. subtilis to modulate intestinal microbiota and the health status of common carp.