Aerobic Bacterial Flora of Common Carp (Cyprinus carpio L.) Cultured in Earthen Ponds in Saudi Arabia

ABSTRACT

Quantitative and qualitative estimation of bacterial flora present in pond water, sediments, gills, and intestine of healthy common carp Cyprinus carpio cultured in Saudi Arabia were performed and identified to species level where possible. Mean total viable bacterial counts in pond water ranged from 1.2?±?2.9?×?10⁴ to 2.5?±?3.5?×?10⁵ cfu/mL; in sediments, 9.3?±?2.1?×?10⁷ to 2.7?±?3.5?×?10⁹ cfu/g; in gills filaments, 4.3?±?2.9?×?10⁶ to 1.6?±?3.9?×?10⁷ cfu/g; and in intestine, 8.7?±?4.1?×?10⁹ to 5.4?±?3.2?×?10¹⁰ cfu/g. Gram-negative rod-shaped bacteria dominated (76%) the populations. In total, 12 bacterial genera and 15 species were identified. Pond water and sediment bacteria had the reflection on bacterial composition of gills and intestine of carp. Intestinal bacteria showed more diversification in contrast to gill bacteria. Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Corynebacterium urealyticum, Vibrio vulnificus, Vibrio sp., and Staphylococcus sp. were the common bacteria in all the populations. In pond water and carp intestine, A. hydrophila, S. putrefaciens, V. cholerae, and C. urealyticum were the most dominant bacteria (prevalence ≥ 10%) where pond sediments and the carp gills experienced with more one dominant bacterium V. vulnificus. Only the A. hydrophila covered one fourth (25%) of the total bacterial populations.