Microbiological assessment of irrigation water from the Boumerzoug River, Algeria, and associated contamination of fresh vegetables.

The use of microbiologically contaminated surface water for irrigation poses a significant threat to food safety and public health, particularly in regions where untreated or inadequately treated wastewater is discharged into rivers used for agricultural purposes. In northeastern Algeria, the Boumerzoug River represents an important source of irrigation water for vegetable production; however, information regarding its microbiological quality and the potential contamination of irrigated vegetables remains limited. This study aimed to assess the microbiological quality of irrigation water from the Boumerzoug River and to evaluate the microbial contamination of vegetables irrigated with this water. A total of 40 irrigation water samples and 160 vegetable samples, including tomato (Solanum lycopersicum), lettuce (Lactuca sativa), and pepper (Capsicum annuum), were collected from 20 agricultural fields during both the dry and wet seasons. Standard culture-based methods were used to enumerate total aerobic heterotrophic bacteria, total coliforms, fecal coliforms, fecal streptococci, and Escherichia coli. The irrigation water exhibited substantial microbiological contamination, with fecal coliform concentrations exceeding the WHO reference value of 103 CFU/100 mL for unrestricted irrigation. All vegetable samples were contaminated with total and fecal coliforms, while E. coli was detected at varying concentrations among the different vegetable types. Microbial contamination varied significantly according to season and vegetable type, with lettuce generally exhibiting higher contamination levels than tomato and pepper. These findings highlight the poor microbiological quality of the Boumerzoug River and suggest that contaminated irrigation water may contribute substantially to the microbial contamination of fresh vegetables.