Image analysis of Bacillus thuringiensis

 

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dc.contributor.advisor Harrison, STL en_ZA
dc.contributor.author Dickason, Gregory John en_ZA
dc.date.accessioned 2016-08-22T12:27:07Z
dc.date.available 2016-08-22T12:27:07Z
dc.date.issued 1998 en_ZA
dc.identifier.citation Dickason, G. 1998. Image analysis of Bacillus thuringiensis. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/21432
dc.description.abstract This thesis concerns the development of a method to quantify the morphology of the bacterium Bacillus thuringiensis, and to automatically count the bacteria. The need to quantify the bacterial morphology arose out of the possibility of controlling a fermentation based on the morphology of the observed bacteria. Automatic counting of bacteria was considered necessary to reduce the inaccuracies that resulted in manual counts performed by different people. Bacillus thuringiensis is a spore forming, gram-positive bacterium, which produces both intracellular spores and insecticidal protein crystals. The production of the insecticidal protein crystal makes Bacillus thuringiensis important as a producer of biological insecticides. Automatic counting was developed in a Thoma counting chamber (Webber Scientific) at 200x magnification under dark field illumination. It was found that at this magnification the problem of out of focus cells was eliminated. The use of a thick coverslip, which reduces variability in slide preparation, was also possible at 200xmagnification as the focal depth of the 20x objective lens was considerably larger than the 1 00x objective lens and thus the 20x objective lens could focus through the thick coverslip (20x objective lens with 1 Ox magnification in eyepiece = 200xmagnification). An automatic algorithm to acquire images was developed and 5images per sample were acquired. Processing of the images involved automatically thresholding and then counting the number of bright objects in the image. Processing was thus rapid and the processing of the five images took no more than a few seconds. Results showed that the correlation between the automatic and manual counts was good and that the use of a thick coverslip reduced variability in slide preparation. It was shown that the manual -counting procedure, which necessarily used a thin coverslip at 1000x magnification, underestimated the volume of the Thoma counting chamber. This was a result of warping in the thin coverslip. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Bioprocess Engineering en_ZA
dc.title Image analysis of Bacillus thuringiensis en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering & the Built Environment en_ZA
dc.publisher.department Centre for Bioprocess Engineering Research en_ZA
dc.type.qualificationlevel Masters en_ZA
dc.type.qualificationname MSc (Eng) en_ZA
uct.type.filetype Text
uct.type.filetype Image


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