Screening for pentachlorophenol-degrading bacterial candidates for bioaugmentation in anaerobic bioprocesses and development of pentachlorophenol-induced toxicity bioassay.

• Main Author: Lio, Ivan Zong Long.
• Other Authors: Sze Chun Chau
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/52511
• Institution: Nanyang Technological University

Refractory organic compounds, e.g. pentachlorophenol (PCP), have been reported to inhibit bioprocesses during anaerobic wastewater treatment. PCP-induced toxicity compromises treatment performance in these anaerobic biosystem possibly by affecting the stability of indigenous microbial communities. In this study, anaerobic PCP-degrading bacterial candidates were screened from environmental isolates for use in bioaugmentation in such wastewater treatment. The strains were selected on the basis of their tolerance to PCP on agar and their cell viability in liquid culture containing PCP. The isolates were also screened for Desulfitobacterium spp., a genus established for its effectiveness in PCP biodegradation, by colony polymerase chain reaction. The potential PCP-degrading candidates identified through these screens would then need to be assessed for their capacity to degrade PCP. To this end, a bioassay to measure PCP-induced toxicity was developed. Suitable bioindicators were first selected – E. faecalis and L. acidophilus – and then model strains of PCP degrader (Pseudomonas aeruginosa) and non-degrader (Escherichia coli) were tested to pilot the bioassay. Residual PCP toxicity could be quantified by the growth of the bioindicators in the supernatants collected from PCP-supplemented model strain cultures. Results obtained could be used to assess PCP degradative capacity of a test strain or a consortium.