PhD Defense Seminar cum Oral Examination
“Toxic cyanobacteria in the tropics: Effects of environmental factors on the growth and toxin production of Microcystis species isolated from Singapore reservoirs.”
Maxine Allayne Darlene Mowe
Dept. of Biological Sciences, NUS
Mon 26 Oct 2015: 4.00pm
DBS Seminar Room 2 (S2 Level 4, #04-15)
Supervisor: Darren Yeo Chong Jinn
All are welcome
Cyanobacterial blooms are a global problem for water resources due to toxin production. The majority of studies have focused on blooms in temperate areas with less focus on the tropics. A global meta-analysis of cyanobacteria blooms in tropical lakes conducted to better understand prevailing trends revealed Microcystis and microcystin to be the most commonly encountered cyanobacterial genus and toxin.
To investigate this trend in Singapore, potentially toxic species from Singapore’s reservoirs were isolated and cultured, including species of Microcystis, Cylindrospermopsis, Planktothrix and Planktothricoides, which were found to produce microcystins (RR and LR) and cylindrospermopsins. Focussing on Microcystis, laboratory and field experiments were then conducted to investigate the effects of light, temperature, and nutrients on their growth and toxin production.
Low light and high nutrient levels were found to increase Microcystis growth, while low light and lower phosphorus levels increased toxin cell quotas. This study is the first to record the effects of environmental variables on toxin cell quotas of Microcystis ichthyoblabe, M. flos-aquae and M. viridis isolated in the tropics. This information will benefit water management in Singapore by improving the understanding the growth conditions conducive Microcystis growth and how these influence toxin production.
Photo by Priya Jean Alexander.