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Title: Investigating a novel high pressure homogenizer for producing cell disruption
Author: Coss, G. M.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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A new cell homogenizer, the Constant Systems UHPD disrupter was investigated as to its ability for cell disruption. The unique feature of the homogenizer is its ability to safely operate at very high pressure (276 MPa). This project reports investigation of the production of cell disruption bacteria and yeasts. After a methodology was established for the measurement of cell disruption using soluble protein release, a general survey involving 3 bacteria (including E. coli) and 6 yeasts was performed. This showed that the homogenizer was capable of efficiently disrupting most microbial cells with a single pass. Two yeasts, Saccharomyces cerevisea (Baker's yeast) and Pichia pastoris were then used for further studies. These cell disruption studies were sub-divided into two major groups, those influenced by the biological based factors and those influenced the mechanical design of the disrupter. The results showed that in the range of cell concentration used (up to 25 g/l cell dry weight) disruption was independent of cell concentration. Stationary cells were significantly more resistant to disruption, for example stationary grown cells required 150MPa for 50% while exponential cells required 75 MPa to achieve the same result. Growth media that produce slow-growing cells were more difficult to disrupt. Reducing the osmoticum significantly improved disruption. There was some evidence that specific ions and chelating agents may influence susceptibility of yeast disruption, for example to achieve 50% disruption when 30 mM CaCl2 was added to the disruption medium, the disruption pressure had to be increased from 75 to 150 MPa. This work showed that yeast physiology and the environment around cell disruption can significantly alter disruption performance and should be a major consideration when designing a disruption process.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available