Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates

Marwa Abd El-Kader; Tarek Mahmoud Mousa-Balabel

doi:10.5455/ajvs.265631

2025, Vol: 86

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Original Article

AJVS. 0; 0(0):

doi: 10.5455/ajvs.265631

Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates

Marwa Abd El-kader, Tarek Mahmoud Mousa-balabel.

Abstract
In the last years, there were some bacterial outbreaks occurred during the summer season of farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates resulting in high fish mortalities and severe economic losses in these farms. So, this study aimed to detect the causes of the summer fish mortalities in these governorates to facilitate the diagnosis methods of study pathogens. Thirty fish farms were surveyed (20 in Kafr El-Sheikh and 10 in Dakahlia). 150 examined diseased fish (five from each farm) were succumbed for bacteriological isolation and biochemical and molecular identification. LD50 experiments were done to detect the infectivity and pathogenicity of some strains of bacterial isolates. The obtained results cleared that O. niloticus summer mortalities were caused by mixed infections with different bacterial species. The isolated bacterial species were 9 types of bacteria; 7 gram negative bacteria; 78 (30.5%) Aeromonas hydrophila, 52 (20.3%) Pseudomonas aeruoginosa, 40 (15.6%) Vibrio anguillarum, 20 (7.8%) Ewardsiella tarda, 12 (4.7%) Ewardsiella ictulari, 10 (3.9%) Pseudomonas flourescence, 7 (2.7%) Flavobacterium columnare and 2 gram positive bacteria; 30 (11.7%) Streptococcus agalactia and 7 (2.8) Enterococcus feacalis which were the most prevalent bacteria affecting fish farms and implicated in the O. niloticus seasonal summer mortalities and LD50 experiments confirmed the pathogenicity of some isolated bacteria. From the obtained results, it could be concluded that, the main cause of summer fish mortalities in studied farms was 81.82% gram negative bacteria and 18.18% was gram positive bacteria.

Key words: Infectivity, LD50, Oreochromis niloticus, summer mortalities.

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Pubmed Style

El-kader MA, Mousa-balabel TM. Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates. AJVS. 0; 0(0): -. doi:10.5455/ajvs.265631

Web Style

El-kader MA, Mousa-balabel TM. Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates. https://www.alexjvs.com/?mno=265631 [Access: May 03, 2025]. doi:10.5455/ajvs.265631

AMA (American Medical Association) Style

El-kader MA, Mousa-balabel TM. Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates. AJVS. 0; 0(0): -. doi:10.5455/ajvs.265631

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El-kader, M. A. & Mousa-balabel, . T. M. (0) Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates. AJVS, 0 (0), -. doi:10.5455/ajvs.265631

Turabian Style

El-kader, Marwa Abd, and Tarek Mahmoud Mousa-balabel. 0. Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates. Alexandria Journal of Veterinary Sciences, 0 (0), -. doi:10.5455/ajvs.265631

Chicago Style

El-kader, Marwa Abd, and Tarek Mahmoud Mousa-balabel. "Isolation and Molecular Characterization of Some Bacteria Implicated in the Seasonal Summer Mortalities of Farm-raised Oreochromis niloticus at Kafr El-Sheikh and Dakahlia Governorates." Alexandria Journal of Veterinary Sciences 0 (0), -. doi:10.5455/ajvs.265631

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