Title page for ETD etd-12072006-152703

Document Type Master's Dissertation
Author Van Heerden, Juanita
URN etd-12072006-152703
Document Title The determination of microbial species diversity and evenness in activated sludge systems using different biolog systems
Degree MSc Agric (Microbiology)
Department Microbiology and Plant Pathology
Advisor Name Title
Prof T E Cloete Committee Chair
Dr M M Ehlers Committee Co-Chair
  • sewage purification activated sludge process.
  • microbial biotechnology
  • biotechnology
Date 1999-12-01
Availability unrestricted
Diversity of micro-organism communities in activated sludge have been analyzed by culture -dependent methods, which exclude the majority of endogenous microbes due to the selective nature of the media. Molecular and biochemical techniques have been evaluated, but they are time - consuming, complex and the results are difficult to interpret. Methods such as community level carbon source utilization patterns (i.e. Biolog) are easy to use and detect different patterns, which could be related to diversity and function, in this and other studies.

Our aim was not to try and detect each and every metabolic reaction of all the individuals in the community, but the collective pattern for a specific community. Since, 1) a high species diversity should lead to a higher relative number of substrates utilized, because there are more possibilities and 2) upon dilution, some organisms will be lost (causing a decrease in species diversity) from the community, depending on their abundance and the relative contribution (perhaps only one metabolic reaction in the system), reducing the number of possibilities. The extent of the reduction of the possibilities upon dilution, should theoretically reflect something about the community structure. The key, therefore, lies in the interpretation of the results.

The Biolog system unlike traditional culture - dependent methods, which are generally selective for the component of the community that has to be cultured, can reflect the activities of a broad range of bacteria. In this study the Biolog system was not considered as a culture - dependent method, but rather as a collection of metabolic tests (database) used for the purpose of generating a recognizable pattern for a specific community. Our hypothesis was that microbial community level carbon source utilization could be used to determine diversity and evenness in activated sludge systems.

In our study we used activated sludge systems representative of an environment with a high species diversity and uneven distribution of species, indicated that upon dilution some of the substrates where no longer utilized due to the loss of some of the species.

1999, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Van Heerden J 1999, The determination of microbial species diversity and evenness in activated sludge systems using different biolog systems, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-12072006-152703/ >


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