Isolation of different cyanobacteria types from Singapore reservoirs

• Main Author: Sim, Alvin, Jia Qing.
• Other Authors: Gin Yew-Hoong Karina
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Environmental engineering::Water supply
• Online Access: http://hdl.handle.net/10356/15674
• Institution: Nanyang Technological University

Eutrophication of reservoirs is of increasing public concern due to the formation of harmful algal blooms with toxin-producing capabilities that affect human and aquatic life. Cyanobacteria (blue-green algae) are one type of algae which are capable of producing toxins that can damage the liver, nervous system, cells and the skin or mucous membranes. In this study, the eutrophic Kranji Reservoir was screened for different cyanobacterial species to understand what exists in the local tropical environment. A systematic procedure for the isolation works was developed. Four isolation techniques – liquid enrichment, direct isolation, agar culture and disaggregation and 2-step centrifugation were utilized to isolate cultures of cyanobacteria, with particular focus in isolating the Microcystis and Anabaena genera. Forty-three isolates were obtained from design experiments, with thirty-five isolates confirmed as cyanobacteria, the majority belonging to two of the most abundant cyanobacterial genera in Kranji reservoir – Microcystis (12) and Anabaena (14). Four Microcystis isolates were found to be toxic. Cyanobacterial identification was done by using both microscopic and molecular methods. The use of 11 PCR assays enabled identification of isolates down to genera level and their toxin-producing ability, with species and strain levels yet to be determined. The first toxic species of Microcystis (possibly Microcystis aeruginosa) in Singapore were successfully cultured under laboratory conditions in this study.