Toxin production by cyanobacteria

• Main Author: Lam, Jonathan Han Jie
• Other Authors: Gin Yew-Hoong Karina
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Environmental engineering::Water supply
• Online Access: http://hdl.handle.net/10356/39547
• Institution: Nanyang Technological University

In recent years, with the effect of rising global temperatures and the pollution of water ways due to industrial and farming activities, cyanobacteria blooms have been on the rise globally. These blooms have been recorded not only to cause major disruptions to the delicate balance of the aquatic ecosystem but also to produce toxins that can adversely affect the health of mammalians, when the toxins are ingested in considerable amount. Within Singapore, strains of cyanobacteria have been discovered in many major freshwater bodies and in particular the two most common genera detected locally are the Microcystis and Anabaena. Overseas studies have recorded that these two genera of cyanobacteria are massive producers of the toxin microcystin. However, till date, the levels of microcystin recorded in the local waterbodies are minimal. As no studies have been executed to study on these local species, this project provides a pilot study, devoted to the behavioral growth of Strain E of the Microcystis spp under the 4 different light conditions i.e. Control(White) Red, Blue and Green. Within the confinements of this project, the strain was first purified through the sulphide gradient selection method and then isolated into 96 various tissue culture flasks each filled with 45mL of MLA liquid medium. The bottles were then equally divided among the 4 light conditions and the experiment was executed over a period of 12days so that the exponential growth phase of the strain can be observed. Parameters that were sampled during the this period include the cell no. concentration, the phycobilin concentration, the chlorophyll-a concentration, toxin concentration and the toxin gene copy no. concentration. This report discusses on the phycobilin, chlorophyll-a and toxin gene copy no. concentrations in relation to the cell no. concentration, in hope of discovering a behavioral trend that maybe exhibited by Strain E. The report has concluded that, subjected to control condition and under white light, Strain E exhibits the highest cell growth over time and generates the highest toxin gene copy no. biomass per cell. In addition, the report has also proposed that for Strain E, the reproduction of cells is inversely related to that of the production of chlorophyll-a biomass, such that a high increase in the former would result in a low increase in the latter.