BACTERIAL FLORA OF SHRIMPS SOLD IN MARKETS IN CALABAR, CROSS RIVER STATE, NIGERIA.

ABSTRACT Shrimp sold in markets in Calabar, Cross River State, Nigeria, may harbor significant bacterial contamination, posing health risks to consumers. Evaluating the total heterotrophic bacteria (THB) levels in these shrimps and understanding their relationship with shrimp biometrics (length and weight) is crucial for improving food safety. This study aimed to determine the microbial flora in two shrimp species (Macrobrachium vollrenhovenii and Macrobrachium macrobrachion), assess the correlation between shrimp biometrics and THB counts, and identify bacterial isolates using biological and biochemical tests. Shrimp samples were collected from markets over six sampling periods during dry and wet seasons. Length, weight, and THB colony counts were measured, with THB expressed as colony-forming units per gram (cfu/g). Biological and biochemical characteristics, including Gram reaction, motility, and various biochemical tests (oxidase, glucose fermentation), were used to identify isolates. Statistical analyses, including t-tests and correlation analysis, were conducted to compare bacterial counts across species and seasons. The mean THB counts for M. vollrenhovenii ranged from 1.14 × 105 cfu/g to 5.01 × 105 cfu/g, with an overall average of 3.16 × 105 cfu/g. For M. macrobrachion, THB counts ranged from 1.43 × 105 cfu/g to 6.5 × 105 cfu/g, with a mean value of 3.47 × 105 cfu/g. The t-test showed no significant difference between the THB levels of the two species (p > 0.05). Seasonal analysis indicated a significant increase in THB counts for M. vollrenhovenii during the wet season (1.4 × 105 cfu/g in the dry season vs. 4.85 × 105 cfu/g in the wet season; p < 0.05). However, M. macrobrachion did not show a significant difference between seasons (3.22 × 105 cfu/g in the dry season vs. 3.73 × 105 cfu/g in the wet season; p > 0.83). Correlation analysis revealed a positive relationship between shrimp biometrics and THB counts for M. vollrenhovenii, with a correlation coefficient of 0.72 for length and 0.85 for weight, while M. macrobrachion exhibited lower correlations of 0.12 for length and 0.80 for weight. The study demonstrates that shrimp in Calabar markets contain significant bacterial loads, particularly during the wet season, with M. vollrenhovenii showing higher seasonal variability. Improved hygiene practices, especially during the wet season, and consistent microbial monitoring are recommended to reduce contamination risks and ensure food safety.