Seasonal Variation in Bacterial Load and Genetic Diversity in Groundwater from Aïn Tawjdate, Morocco

Groundwater represents an essential resource for domestic and agricultural use, and its physicochemical and microbiological quality directly affects public health. This study assessed the bacteriological quality of untreated well water in the province of Fez-Meknes, specifically in the Aïn Tawjdate area, and evaluated seasonal variations in bacterial contamination. During the spring and summer of 2023, groundwater samples were collected from several wells. A total of 139 bacterial strains were isolated and identified using API biochemical galleries. The most frequently detected species were Aeromonas hydrophila gr.1 (6.47%), Aeromonas hydrophila gr.2 (9.35%), Enterobacter cloacae (7.19%), Pseudomonas aeruginosa (10.07%), and Flavimonas oryzihabitans (6.47%), among others. Genetic variability among ten E. cloacae isolates was further explored using ERIC-PCR profiling; the strains differed by more than three fragments and showed less than 80% similarity; therefore, they were considered as distinct ERIC types. Statistical analyses (Chi-square, Fisher’s exact, Tukey HSD, one-way ANOVA, and two-sided Dunnett tests) revealed no significant differences in bacterial load between wells within the same season, with p-values > 0.05 according to ANOVA. However, a significant increase in contamination levels was observed in summer compared with spring. These findings highlight the potential health risks associated with the consumption of untreated groundwater and underline the need for regular microbiological monitoring and improved water treatment practices in rural communities.