Screening for Pentachlorophenol-degrading microbial candidates for bioaugmentation of anaerobic waste water treatment and analysis of microbial community in anaerobic bioreactors exposed to Pentachlorophenol and its metabolic intermediates

• Main Author: Tan, Serene Xiao Lin
• Other Authors: Sze Chun Chau
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/59587
• Institution: Nanyang Technological University

Pentachlorophenol (PCP) is a recalcitrant compound that can sometimes be found in waste water. Improper disposal of PCP has led to its accumulation in the environment. Bioaccumulation of PCP not only poses a threat to human but its high toxicity and low biodegradability causes inhibition to bioremediation processes, making it difficult to eliminate from contaminated sites. Anaerobic Sequencing Batch Reactors were previously set up and in this work, preliminary analysis of their microbial community was carried out to examine the changes when they were exposed to PCP and several metabolic intermediates in the PCP biodegradation pathway. Metabolic indicators such as Chemical Oxygen Demand (COD), Volatile Fatty Acid accumulation (VFA) and concentration of toxic compounds were closely monitored to assess the metabolic and bioremediation activities in each reactor. Denaturing gradient gel electrophoresis (DGGE) was carried out to investigate the changes in microbial community in response to acclimatization of sludge with PCP and its metabolic intermediates. Findings from the microbial community analysis reveal that specific changes were related to the changes in metabolic activities of the reactor. Works in progress include purifying DNA extracted from DGGE bands, followed by DNA sequencing for species identification. On the other hand, analysis of PCP removal by selected bacterial strains was carried out to identify PCP-degrading microbial candidates that can potentially be used for bioaugmentation of anaerobic waste water treatment. Several strains have shown active PCP degradation, and they were subjected to growth condition test to have a better understanding of the condition required to culture these strains. Results show that sulfite exerts repressive effect on the growth of these candidates. In addition, improved and preferential growth was observed in PCP environment as compared to non-PCP environment. Studies can be done to investigate sulfite metabolism and future works can be carried out to characterize and identify these strains.