PRODUCTION OF OFF-FLAVORS BY BENTHIC CYANOBACTERIA

Abstract

Off-flavors, such a 2-MIB and geosmin, are found to affect drinking water quality globally. This thesis focuses on benthic cyanobacteria and their production of off-flavors in Singapore’s freshwater systems. 2-MIB and geosmin concentrations were observed to increase during the monsoon periods, while low water temperature and dry periods promoted geosmin production. Several off-flavors-producing benthic cyanobacteria species were successfully isolated and identified using a targeted qPCR detection method. In addition, the effect of environmental variables on the production of off-flavors were investigated using independent microcosm studies. Phosphorus and temperature were found to have positive impact on the growth and 2-MIB production of a benthic isolate, Hapalosiphon sp MRB220. An in-situ column experiment was conducted to compare off-flavor production rate difference between actinobacteria, benthic and planktonic cyanobacteria. Results showed that planktonic cyanobacteria displayed higher 2-MIB and geosmin production rates compared to other potential producers.