Corellation between bacteriological infection and chemical changes in fish constituents in Bohira province

ABSTRACT

This study was applied on 100 fish samples [50 of each, Tilapia and Mugil] either diseased or apparently healthy. The aim of this work is to throw a light on the relation between the bacterial infection and some chemical changes in tissues of the examined fish as an index to quality and freshnes of raw materials. The results of bacteriological examination revealed that out of diseased tilapia[20] 39 bacterial isolates were recorded, but in apparently healthy tilapia[30]isolates were 41, while diseased Mugil [10] showed 13 bacterial isolates, and apparently healthy[40] was had 33 isolates. The rate of isolation was higher in the gills and viscera than the tissues as follow Gills [80/50%], viscera[70/60%] and tissues[45/26.7%] in diseased/healthy tilapia respectively. In case of Mugil the corresponding ratio were 60/30%, 50/37.5% and20/15. Different microorganisms were isolated, Aeromonas hydrophila, Pseudomonas fluorescens, Vibrio spp., E.coli, Streptococcus iniae, Staph. aureus and Clostridium perfringens at different percentages. Three items were stastically calculated as chemical changes in this work, indicative to spoilage of the fish samples in comparison to control one. Thiobarbituric acid as mg malonaldhyde/ kg[TBA] was not significant<[t.value 0.77], while the FFA[free fatty acids] and Peroxide value, milliquivalent O2/kg [PV] appeared with significant values [6.38 and 21.1], respectively. On the other hand in mugil samples the three items of chemical examination appeared with significant values<[8.31, 4.78 and 40.95 respectively]