Isolation and Characterization of Flavobacteriaceae from Farmed and Wild Nile Tilapia in Tanzania.

Abstract

The present study was conducted to explore the occurrence of Flavobacteriaceae in wild Nile Tilapia Oreochromis niloticus (n=108) collected from Lake Victoria and farmed Nile Tilapia (n=187) collected from 12 ponds in the Morogoro region of Tanzania. The size of the ponds surveyed ranged from 130 to 150m2 . Pond parameters and fish morphometric data were recorded during sampling. In total, 67 Flavobacterium-like isolates (n=44 from farmed fish; n=23 from wild fish) were identified on the basis of colony morphology and biochemical tests. Sequences from the 16S ribosomal RNA (rRNA) gene revealed that all 67 isolates belonged to the genera Flavobacterium and Chryseobacterium. Based on 16S rRNA nucleotide identity, 26 isolates showed high similarity with C. indologenes (99-100% identity), 16 showed similarity to C. joostei (98-99.9%), and 17 were similar to diverse species of Chryseobacterium (97-99%). Three isolates were similar to F. aquatile and three were similar to F. indicum, with 99-100% nucleotide identity in both cases, and two isolates were similar to F. oryzae (99-100% identity). The findings obtained in this study provide a baseline for future studies and contribute to an understanding of the threats presented by the aquatic Flavobacteriaceae reservoir toward the development of healthy fish farming in Tanzania. Such knowledge is vital for the development of a sustainable aquaculture industry in Tanzania that will contribute to increased food security.