Effect of Biofloc Technology On Gut Microbial Proliferation of Macrobrachium Rosenbergii

Abstract

A new approach of microbial community management like biofloc technology in the culture of aquatic organisms is very needed to increase the production along with less feed application and environmental friendly culture practice. The present study was conducted from August to December, 2017 at water quality laboratory, Fisheries and Marine Resource Technology discipline, Khulna University. The study was furnished to investigate the effect of biofloc technology and C/N ratios on the potential gut microflora of Macrobrachium rosenbergii. In this experiment different C/N ratios e.g. 10:1 (T₁), 15:1 (T₂) and 20:1 (T₃) along with a control group (C) without any additional carbon source were planned to apply in prawn culture. The results of this study demonstrated that although it was not significant (P>0.05) but we observed highest heterotrophic bacterial count in T₂ followed by T₁ and T₃ while lowest in control. However, Enterococcus spp. density was found in T₂ (9 ± 1.1) × 10⁴ MPN/g) and T₃ (6.7 ± 1.5) × 10⁴ MPN/g) compared to T₁ (8.8 ± 1.08) × 10³ MPN/g) and C (1.07 ± 0.4) × 10³ MPN/g) (P<0.05). Similarly, although it was not significant (P>0.05), but Lactobacillus spp. was found higher in the T₁ (9.9 ± 5.2) × 10⁵ CFU/g), T₂ (1.3 ± 0.5) × 10⁶ CFU/g) and T₃ (1.5 ± 0.7) × 10⁶ CFU/g) compared to C (6.3 ± 5.4) × 10⁵ CFU/g). In conclusion, different C/N ratios have different effects on potential bacterial composition in prawn gut. Therefore, further study should be conducted for total bacterial composition determination through 16S rRNA gene analysis.