(562e) The Application of a Box-Behnken Design in the Study of Microcystin Production

Microcystin is a cyanotoxin produced by harmful algal blooms such as Microcystis aeruginosa PCC7806. Warmer temperatures favor algal bloom and algal growth. The biggest concern is if more incidents of algal bloom would also produce microcystin. The purpose of this study was to determine whether microcystin is favored by other environmental parameters such as: volume, concentration, aeration, pH and temperature or the combination of some or all of them. In this sense, a Box-Behnken design was used as a statistical tool. The optimization of this design uses fewer experiments which is a great asset for the duration of 30 days of the growth of this bacterial strain. Thus, more possibilities are tested during the same period of time as opposed to test every possible combination. Results revealed that microcystin is affected by temperature and the combination of temperature and pH. To have a higher concentration of the toxin, the water body needs to have been exposed to cooler temperatures (20ºC) and neutral pH (7). This does not mean that a water system has to be at cool temperatures or neutral pH, but it means that microcystin production is enhanced by stressful conditions such as abrupt changes in temperature and pH from high to low in a short period.