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Performance evaluation of microbial inocula as biological reference material for biodegradability and ecotoxicity
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Abstract(s)
Several biological methods employ activated sludge (AS) as inoculum to assess toxicity or biodegradability of pollutants, since pollutants that ultimately enter the environment are often discharged through wastewater treatment plants. The use of AS to evaluate the environmental impact of chemicals and wastewaters suffers from several drawbacks related with the heterogeneity, absence of standardization and health risk associated with this mixed sewage population. To search for reliable testing inocula alternatives, the potential of several well-defined microbial inocula as reference material, for ready and inherent biodegradability and toxicity screening tests (BOD5 test, Zahn-Wellens test and respiration inhibition test, respectively), was evaluated and the results were compared with AS’ results. In overall, the most relevant results in terms of environmental application were obtained with bacterial mixtures, namely with three standardized microbial consortia: two commercial inocula (BI-CHEM and BIOLEN M112) and a designed inoculum (DI, a standardized soil inoculum). A community-level physiological profile (CLPP) analysis was also performed for each inoculum tested, being its metabolic fingerprint compared with AS’ CLPPs. From biodegradability results obtained, DI stands out a good choice as reference material for biodegradability tests, while from toxicity results the BI-CHEM appears as the suitable alternative to AS, since its sensitivity is similar to that of AS. Moreover, in terms of the overall metabolic potential, DI and BI-CHEM were the most representative inocula of AS’ CLPPs among the consortia tested. In addition, beyond other inocula also studied, DI and BI-CHEM were validated as seed for BOD5 test, by testing several real samples in a comparative study with a treatment plant inoculum. The use of well-predefined microbial consortia, with simple maintenance and manipulation, can be helpful for the normalisation of biological assays leading to an improvement of the quality of chemical and effluent testing and monitoring.
Description
Dissertação apresentada no Departamento de Biologia Vegetal da Faculdade de Ciências da Universidade de Lisboa para Doutoramento em Microbiologia
Keywords
Biological reference materials Model communities Activated sludge Biodegradability tests Toxicity tests Materiais biológicos de referencia Comunidades modelo Perfis metabólicos
Citation
Paixão, Susana M. Performance evaluation of microbial inocula as biological reference material for biodegradability and ecotoxicity. Lisboa : Faculdade de Ciências da Universidade de Lisboa, 2005