Published in Scientific Papers. Series E. Land Reclamation, Earth Observation & Surveying, Environmental Engineering, Vol. IV
Written by Roxana Gabriela CRISTINA, Ioan I. ARDELEAN
The accidental multiplication of conditional pathogen bacteria such as E.coli in the territorial sea waters of Romaniahas an important impact on human health and requires a continuous evaluation of its risks. This study is focused on theeffect of some physical factors (temperature, salinity, nutrient concentration) on the viability of Escherichia coli cells.In our experiments, we analysed the response of E.coli grown in normal conditions (LB at 37°C ) when subjected to anutritional, saline and osmotic shock by introducing sub-samples of the culture in three (4°C, 15°C, 37°C) separatesterile sea water (sea water filtered through a Millipore filter- pores of 0.22 μm ) microcosms. The samples werecollected at different times (ranging from minutes to days) and analysed with respect to total cell densities (cellspermeable to Syber green), dead cells (cells permeable to propidium iodide) densities and colony forming units. Theresults showed that the stress conditions determined by osmotic shock, saline shock and nutrients deprivation cannotsuppress the resistance and multiplication capacity of E.coli after two days, even though the stress conditionsdiminished them. Although the temperature of the sea water is an important factor regarding the resistance of E.coli, arather large proportion of cells continue to remain alive at 4°C, and able to multiply when transferred to LB at 37°C.
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