Clarias gariepinus specimens often survive disease outbreak on farm, ma king way to hypothesize resilient strains. We investigated prevalence , pathogenic nature and strains of Aeromonas in the gut of survivor C. gariepinus at post Aeromonas hydrophila challenge period t o understand the possible implications of such survival.
Randoml y selected six gut samples of unchallenged(C) and the A. hydrophila challenged but survived (Ch ) C. gariepinus (8.00±0.02g ) were assessed for differences (p<0.05) in t otal counts o f bacteria(TBC), Coliform, E. coli , Salmonella, Shigella, Vibrio, Staphylococcus, Pseudomonas, and Aeromonas species. Aeromonas isolates were assessed for reaction (+ve) to none of haemolysis , gelatinase , and DNAse pathogenicity tests (0.00%pathogenic- NP) or all (100.00%pathogenic-P ). Np and P in C and Ch were analysed for phylogenetic cluster of 16S Ribosomal RNA gene nucle otide sequences.
The TBC ranged 2.02±0.63x106 (C) - 2.32±0.65x106 (Ch ). Significantly, bacteria count (104cfu/g) ranged 0.58±0.93 (Pseudomonas sp.)-1.55±0.87 (Coliform)-C, 0.58±0.53 (Pseudomonas sp.) - 1.83±0.58 (Aeromonas sp.)-Ch. Coliform, E. coli , Vibrio and Aeromonas were higher in Ch than C while Salmonella, Shigella, and Sta phylococcus species were higher in C than Ch. 100.00%C-sourced Aeromonads were NP ( denoted NPCS) ; 27.78%Ch-sourced Aeromonads were NP ( denoted NPChS), while 72.22%Ch-sourced Aeromonads reacted (+ve) to 33.33-100% P tests ( denoted PChS). Phylogenetically , 66.66%NPChS linked A. salmonicida vouchers, 33.33%NPChS linked A. sobria . 33.33%PChS linked A. hydrophila , but diverged from 66.66%NPCS. 66.66%PChS linked A. veronii ; while 33.33%NPCS outlied to link Lactobacill us helveticus voucher.
Gut of the Aeromonas hydrophila challenged but survived C. gariepinus has increased Aeromonas flora including pathogenic and non-pathogenic Aer omonas strains. The p athogenic A. hydrophila strain (PChS) was of relative small proportion (33.33%) in the gut of the challenged specimens indicating the survived C. gariepinus has tendencies to resist flourishing of the pathogenic strain.
Keywords: Non-pathogenic bacteria genotypes; Fish gut flora; Bacteria resilient African Catfish; Clarias gariepinus