Helena Solo-Gabriele, Environmental Engineering Labs

1. Survival Potential of Enterococci in Beach Sand Sumbul Khan, Helena Solo-Gabriele, Matthew Phillips, Yifan Zhang, Amir M. Abdelzaher, Laura Vogel, Amber Enns, Noha Abdel-Mottaleb MATERIALS & METHODS RESULTS ABSTRACT Inoculation of Sand Prior work has questioned the meaning of enterococci measurements, the most commonly used microbe to evaluate sewage impacts to marine waters. Reports indicate that enterococci are capable of growing on beach sand, which defies one of the standards of indicator bacteria of not growing in natural surroundings. This research evaluated the conditions which enhance the growth of enterococci in wet sand. To conduct this study, wet sand samples were collected from a non-point source pollution beach in Florida. The sand was inoculated with enterococci and the indicator’s growth was monitored under varying conditions including varying growth periods, temperature (41.5°C and 19°C) and the nature of the sand on which the indicator was grown, which included sterile and natural beach sand. Results suggest that enterococci might not be an appropriate indicator organism since its growth varies under different conditions and as a result it may not indicate sewage impacts. • Preparation of enterococci working stock • Number of enterococci in stock calculated (~39 CFU/g) • Intertidal wet sand samples collected for inoculation from Hobie Cat Beach, FL • Half of the sand autoclaved for sterile sand inoculation and remaining half set aside for natural sand inoculation • Isolates prepared from both sterile and natural sand consisting of 100 g sand and 50 mL thoroughly mixed enterococci stock Autoclaved sand at incubator temperature Autoclaved sand at room temperature incubator temp.room temp. Initial: 39 CFU/g ±1 39 CFU/g±1 2 hours: 43 CFU/g±1 45 CFU/g ±1 24 hours: 98 CFU/g±3 98 CFU/g±2 OBJECTIVES • Explain abundances of enterococci in beach sand • Asses enterococci survival in sand under varying conditions: • Growth period • Temperature (41.5 °C and 19 °C) • Nature of sand (sterile and natural) Natural sand at incubator temperature STUDY SITE Sand Analysis incubator temp.room temp. Initial: 39 CFU/g ±1 39 CFU/g±1 3 days: 0.5 CFU/g±0.01 10 CFU/g ±1 4 days: 0 CFU/g 5 CFU/g ±1 5 days 0 CFU/g 4 CFU/g ± 1 Natural sand at room temperature • Membrane filtration performed on the inoculated sand samples DISCUSSION & CONCLUSIONS RECOMMENDATIONS • Increase in time period lead to an increase in growth in sterile sand • Increase intime period lead to a decrease in concentration compared to initial count in natural sand • No growth in natural systems due to predation and competition • Growth in sterile systems due to protection and moisture • Decrease in survival at high temperature due to predation and competition in natural sand • Enterococci survives better in sand compared to water since sand provides moisture, nutrients, and UV protection in biofilms • Enterococci is not an appropriate indicator organism since its growth varies under different conditions and complicates interpretation of levels detected • The need for additional sampling in deeper water • Studies be conducted 10m offshore to test improved risk assessment • Hobiie Cat BeachMiami-Dade County, Florida, USA. ACKNOWLEDGEMENTS Helena Solo-Gabriele, Environmental Engineering Labs mEI Agar