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.

Influence of Processing on Bacteriological Quality of Frozen Shrimp.

Line and finished product samples (668) from two shrimp processing plants located at the Karachi fish harbor were collected and examined bacteriologically. Frozen shrimp samples (100) collected from Plant A had the following bacterial profile: average (geometric) total aerobic plate count 9.4 × 106 CFU/g; MPN coliforms 94/g; and MPN fecal coliforms 41/g. The bacterial profile of 114 frozen shrimp samples from Plant B were 8.3 × 106 CFU/g, 180/g and 133/g for total plate count, MPN coliform and MPN fecal coliforms, respectively. Samples (126) of raw and laboratory-processed (simulating commercial processing) shrimp were also examined. Processing conditions of Plant A were better and resulted in a better quality end-product as compared to that of Plant B. Three of 338 samples from Plant B yielded Salmonella . The composition of microbial flora was nearly the same for both species of shrimps from both plants. Pseudomonads were the predominant microflora followed by Micrococcus sp. When shrimp were handled expeditiously under good sanitary conditions in the laboratory, the bacterial counts were significantly lower than on shrimp from the plants. Laboratory-processed shrimp had an average (geometric) total aerobic plate count of 8.1 × 105 CFU/g and average (geometric) coliform and fecal coliform MPNs were <3/g.