Isolation and Identification of Pathogenic Bacteria Associated with Frozen Mackerel Fish (Scomber Scombrus) in a Humid Tropical Environment Isolation and Identification of Pathogenic Bacteria Associated with Frozen

Isolation and identification of pathogenic bacteria associated with frozen mackerel fish (Scomber scombrus) in a humid tropical environment
Eze, E. I.
1
, Echezona, B. C.
1
* and Uzodinma, E. C.
2
1
Department of Crop Science, University of Nigeria, Nsukka, Nigeria.
2
Department of Science Laboratory Technology, University of Nigeria, Nsukka, Nigeria.
Accepted 8 January, 2010
Aquaculture products can harbour pathogenic bacteria which are part of the natural micro-flora of the environment. An in-vitro assay was carried out to ascertain and identify major bacterial contaminants of frozen fish, which hitherto had constituted an important dietary intake of the people of Nsukka, Nigeria.
Fish samples collected were identified and bacterial load of the samples determined using agar plate method. Differentiations and characterizations of various isolates were based on biochemical reactions and gram-staining technique. Frozen mackerel fish (Scomber scombrus) was used for the study. Invitro assay result revealed that the samples were predominantly contaminated by three bacteria species viz: Staphylococcus aureus, Escherichia coli and Lactobacillus plantarum. Incidences of the various isolates in the culture were found to be 60, 20 and 15%, respectively. The mean bacteria load of the isolates was 1.135 x 10
6
CFU g
-1
. This value was found to be markedly higher than the recommended public health and safety standard value of between 5.0 x 10
5
CFU g
-1
, approved by Nigerian National
Agency for Drug Administration and Control (NAFDAC).
Key words: Isolation, identification, pathogenic bacteria, Scomber scombrus.
INTRODUCTION
Fish constitute the cheapest source of animal protein in
Africa (Clucas and Ward, 1996). It is one of the main food components of humans for many centuries and still constitutes an important part of the diet of many countries. The advantage of fish as a food resulted from its easy digestibility and high nutritional value. Since 70% of the earth’s surface

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