Quantitative and qualitative aspects of bacterial flora of Karachi coastal water shrimp (Penaeus merguiensis and Metapenaeus monoceros).

Bacterial counts were made over a period of two years of two important commercial shrimp varieties of Karachi coastal waters. Bacteria were also isolated and identified. Total number of bacteria were found to be remarkably equal at 37 degrees, 30 degrees and 25 degrees C. Aerobic plate count of Penaeus merguiensis at 37 degrees C ranged from 1.2 X 10(5) to 6.0 X 10(7) CFU/g (Median 1.8 X 10(6) CFU/g), and were predominantly Vibrio, Micrococcus, Pseudomonas, Staphylococcus, Bacillus, and Flavobacterium. The corresponding count at 30 degrees C ranged from 3.2 X 10(5) to 4.7 X 10(7) CFU/g (Median 2.6 X 10(6) CFU/g). The bacterial flora in order of predominance were Vibrio, Micrococcus, Pseudomonas, Moraxella, Flavobacterium, Bacillus, Alteromonas, and Acinetobacter. The 25 degrees C counts ranged from 5.3 X 10(5) to 8.5 X 10(7) CFU/g (Median 3.1 X 10(6) CFU/g), the flora was composed of Vibrio, Moraxella, Micrococcus, Pseudomonas, Flavobacterium, Bacillus, Alteromonas, and Acinetobacter in order of predominance. The aerobic plate count of Metapenaeus monoceros at 30 degrees C ranged from 8.4 x 10(5) to 3.8 x 10(7) CFU/g (Median 2.9 x 10(6) CFU/g). The bacterial flora in order of predominance were Vibrio, Micrococcus, Moraxella, Pseudomonas, Alteromonas, Flavobacterium and Staphylococcus. No significant qualitative or quantitative difference was obtained between the two shrimp species. The presence of Staphylococcus at 37 degrees C was attributed to favourable incubation temperature as well as to excessive unsanitary handling while the absence of Moraxella and Alteromonas putrefaciens at this temperature was considered due to the psychotrophic nature of these organisms.