ASSESSMENT OF BACTERIAL CONTAMINATION OF IRRIGATED VEGETABLES CULTIVATED ALONG THE KUBANNI IRRIGATION SITE IN ZARIA, NIGERIA

Abstract

Bacterial contamination of vegetables becomes a significant health challenge. This study identified and categorized bacterial contaminants in vegetables cultivated along the Kubanni irrigation area in order to inform consumers about their safety and quality. Aerobic Colony count, gram stain and biochemical test was conducted on five vegetables which include cabbage, lettuce, spinach, onion and tomatoes. Samples were obtained from 25 farmlands within the study area. A total of 175 samples of vegetables, soil and irrigation water were analyzed. Result shows that all the vegetables were contaminated with bacteria above the WHO limits of 10². Spinach, cabbage, lettuce, onion and tomatoes recorded 5.1 x 10⁶, 5.7 x 10⁶, 5.2 x 10⁶, 4.8 x 10⁶, and 4.6 x 10⁶ respectively. Cabbage had the highest ACC while tomatoes had the lowest. ACC for the Kubanni river is 4.7 x 10⁶ against the WHO limit of <500. soil recorded highest ACC (6.1 x 10⁶) than irrigation water (4.7 x 10⁶). Correlation analysis shows that bacteria in all the vegetables and that of soils are positively related except lettuce and tomatoes. It also shows a positive relationship between bacteria in irrigation water and all vegetables except onion and tomatoes. Bacillus is the most prevalence gram positive bacteria with 57 (45%) while Citrobacter and salmonella are the most prevalent gram negative bacteria in vegetables with 38 (30.4%) and 28%. Vegetables should be properly cleaned before consumption.