Bacterial content in the intestine of frozen common carp <i>Cyprinus carpio</i>

Abstract

The quantitative and qualitative analyses of bacterial flora associated with the intestine of common carp Cyprinus carpio in fresh and frozen storage conditions for 16 months was determined. Aerobic plate counts (APC) ranged from 1.8 ± 2.7 × 10⁹ to 1.1 ± 2.9 x 10⁴ colony forming unit (CFU) g^-1, 2.0 ± 2.1 x 10¹⁰ to 6.1 ± 1.4 x 10⁴ CFU g^-1, and 1.3 ± 3.2 x 10¹⁰ to 4.3 ± 3.3 x 10⁴ CFU g^-1 each of 3 storage tank, respectively from the intestine of common carp in fresh and frozen storage. The APC decreased c. 3-log cycles after 1 month storage and then counts declined more slowly during frozen storage over 16 months. In total, 14 bacterial genera with 18 species were identified. Gram-negative rods bacteria (77%) dominated the population. Aeromonas hydrophila, Aeromonas sp., Bacillus sp., Enterobacter sp., Micrococcus sp., Photobacterium damselae, Serratia liquefaciens, Shewanella putrefaciens, Staphylococcus sp., Streptococcus sp. and Vibrio sp. survived after prolonged freezing. Two bacterial species viz. Shewanella putrefaciens and Aeromonas hydrophila were dominant with a prevalence of > 10% both in fresh and frozen fish. S. putrefaciens was the dominant bacteria (19% of the total isolates) throughout the period of study.

Keywords: Bacterial enumeration, species composition, intestine, frozen common carp