Abstract
Enterococci have been used as indicators to assess illness risks in recreational waters. Traditional monitoring focuses on enterococci counts and cannot discriminate sources of contamination. To solve this issue, Quanti-Tray-Based Amplicon Sequencing (QT-AMP) has been developed for enterococci characterization, utilizing amplicon sequencing from Quanti Trays after quantifying the most probable numbers (MPN). The impact of Hurricane Ian on southwest Florida included heavy rainfall and widespread flooding, raising concerns about water contamination, particularly during recovery efforts. This study aimed to assess the microbiological quality of estuary water post-Hurricane Ian using QT-AMP targeting enterococci. Seven surface water samples collected after the hurricane landing from the Charlotte Harbor estuary were tested, revealing 12 Enterococcus species post-hurricane, including four rare (Enterococcus cecorum, E. lactis, E. pseudoavium, E. rivorum) and eight cosmopolitan species (E. faecalis, E. faecium, E. casseliflavus, E. hirae, E. mundtii, E. gallinarum, E. avium, E. durans). The major dissimilarity between pre- and post-hurricane water samples was caused by the difference between E. hirae and E. gallinarum. E. hirae was less abundant in pre-hurricane samples but abundant in the post-hurricane samples. E. gallinarum showed the opposite relationship. The relative abundance of E. hirae notably correlated (r = 0.97) with MPN counts, suggesting its usefulness as an indicator of hurricane aftermath, potentially attributed to multiple animal and plant sources from the watershed. Overall, we demonstrated that the QT-AMP approach could contribute to environmental monitoring and public health through the enhancement of enterococci quantification and identification in water management and health risk assessments, especially when environmental disturbances occur.
