Bacterial community profiling in artificial lagoons and groundwater of Qatar using a MALDI-TOF MS approach

In Qatar, potable water depends largely on desalination, while groundwater and treated wastewater are used for irrigation, with the latter having limited reuse opportunities that have led to the establishment of artificial storage lagoons across the country. Those artificial lagoons can act as microbial reservoirs, raising interest in their potential interaction and possible infiltration into the groundwater aquifers in Qatar. Hence, this study investigated bacterial community dynamics and their possible infiltration in nine lagoons and 13 nearby wells using culture-based methods and MALDI-TOF MS. A total of 150 strains were identified, representing 33 species, dominated by Pseudomonas (37%), Acinetobacter (15%), Aeromonas (12%), and Enterobacter (10%), with the remaining 26% from other genera. Both lagoons and wells contained coliform bacteria at levels exceeding regulatory thresholds for irrigation water. Alpha diversity indices showed significantly higher richness and diversity in lagoons compared with wells (Shannon, p = 0.038; Simpson, p = 0.045; and Chao1, p = 0.012), indicating the lagoon open system supports microbial diversity. PCA and GLM analyses highlighted associations between treated wastewater-related bacterial communities in lagoons and adjacent wells, with P. aeruginosa found to be abundant across both environments. Protein profile clustering of E. coli and P. aeruginosa further supported similarities between lagoon and groundwater strains. These findings demonstrate that MALDI-TOF MS can provide rapid and reliable insight into bacterial communities in arid region water systems and highlight the value of expanding microbial monitoring beyond traditional coliform indicators.