THE STUDY OF FLUOROMETRIC RESPONSES OF NATURAL PHOTOSYNTHETIC MICROORGANISM CONSORTIUM TOWARD HEAVY METALS

• Main Author: Nurul Afiqah binti Khishamuddin
• Format: text::Thesis
• Language: English
• Published: 2023

Heavy metals discharged through industrial and agricultural activities caused contamination especially to the water sources and affecting the flora and fauna. In this study, photosynthetic microorganism consortium that were collected from natural water bodies consists of Chlorella sp., Haematococcus sp., cyanobacteria and diatoms. This consortium cells were chosen for the development of bio-indicator for the detection of heavy metals. The purpose of using natural photosynthetic microorganism was due to their availability in the freshwater, marines and terrestrial environment and their sensitivity to any environmental disturbance. On the other hand, photosynthetic microorganism have the ability to emit fluorescence light naturally indicated as a transmitted signal for stress condition. It has become a great interest for this study in the detection of Cd, Cu, Ni and Co at different concentration by the photosynthetic microorganism consortium. The consortium cells from day-7 which in its exponential phase was selected to be used in this study. Before the response studies, the optimized cell number was successfully been determined with OD700 = 0.30A. The measurement was based on the differential of the fluorescence signal of the microorganism before and after the exposure to metal, with excitation and emission set at 460 nm and 680 nm for chlorophyll. The study was proceeded by exposing the consortium to Cd, Cu, Ni and Co at concentrations (0.01 mg L-1, 0.05 mg L-1, 0.10 mg L-1, 0.50 mg L-1, 1.00 mg L-1 and 5.00 mg L-1). The intensity of the fluorescence emission was measured before the exposure and then measured again after at t = 30, 60, 120, 240, 360, 480 minutes of exposure. The fluorometric responses and sensitivity of consortium were discussed between three locations (Tasik Biru Kundang, Taman Tasik Titiwangsa and Taman Metropolitan Kepong). The fluorometric response revealed that consortium cells achieved fluorescence response between 30 to 60 minutes of exposure. The change in fluorescence intensities shown that the consortium cells were very adaptable and responsive in various conditions. On the other hand, the response showed that the consortium cells able to detect the presence of Cd, Cu, Ni and Co within the range of 0.05 – 5.00 mgL-1qualitatively. The lowest limit of detection (LLD) was 0.05 mgL-1. This study also provided information regarding the response trends by the consortium cells from three locations.