Salinity on growth and chromium reduction abilities of Magnetospirillum gryphiswaldense MSR-1

Use of bacteria in removal of heavy metals, including hexavalent chromium Cr(VI), has been proven to be as effective yet more eco-friendly compared to other existing technologies. However, polluted wastewater usually contains high amounts of salts in addition to the heavy metals and may interfere with the bioremediation process. Thus, the ideal bacterial strain for these scenarios must be resistant to the heavy metal and high salt concentration but still capable of removing the target pollutant. The current paper studies the effect of salinity on the growth and chromium reduction capabilities of the magnetotactic bacteria Magnetospirillum gryphiswaldense (MSR-1). MSR-1 was exposed to 20 mM, 50 mM, and 100 mM NaCl concentrations and monitored for 27 hours by measuring its optical density and chromium concentrations at different time periods. The results showed that the presence of NaCl does not greatly affect the growth of MSR-1 even at increased concentrations. On the other hand, the introduction of salt in the culture hampered the chromium reduction capacity of the strain with the addition 100 mM NaCl resulting in a decrease of 43% on the amount of chromium reduced.