In this study, the effects of bioprocess design parameters on & / #946 / -lactamase
production were systematically investigated using wild type Bacillus species. For
this purpose, the research programme was carried out in mainly four parts.
Initially, potential & / #946 / -lactamase producers were screened and Bacillus
licheniformis ATCC 25972, a constitutive & / #946 / -lactamase producer, was selected.
Next, the effects of bioprocess medium components, i.e., carbon sources
(glucose, fructose, sucrose, citric acid and glycerol), inorganic nitrogen sources
((NH4)2HPO4 and NH4Cl) and organic nitrogen sources (yeast extract, peptone
and casamino acids), were investigated in agitation and heating rate controlled
laboratory scale bioreactors. Thereafter, by using the designed medium, the
effects of bioprocess operation parameters, i.e., pH and temperature, on & / #946 / -
lactamase activity were investigated in order to achieve a higher & / #946 / -lactamase
production. Among the investigated bioprocess conditions, the highest & / #946 / -
lactamase activity was obtained as 275 U cm-3, in the medium with 10.0 kg m-3
glucose, 1.2 kg m-3 (NH4)2HPO4, 8.0 kg m-3 yeast extract and the salt solution, at
pH0=6.0, T=32° / C, N=200 min-1, which was 7.9 fold higher than the activity
obtained in the reference medium. Finally, using the optimum bioprocess
parameters obtained in laboratory scale experiments, the fermentation and
oxygen transfer characteristics of the bioprocess were investigated in 3.0 dm3
pilot scale bioreactor, having temperature, pH, foam and stirring rate controls, at
Q0/V=0.5 vvm and N=500 min-1 oxygen transfer conditions. The variations in & / #946 / -
lactamase activity, cell, glucose, amino acid and organic acid concentrations with
the cultivation time / the oxygen uptake rate and the liquid phase mass transfer
coefficient values were determined. Throughout the bioprocess, overall oxygen
transfer coefficient (KLa) varied between 0.008-0.016 s-1 / oxygen uptake rate
varied between 0.001-0.003 mol m-3 s-1. Furthermore, rate limiting step analysis
was performed / the yield and maintenance coefficients for the bioprocess as well
as the kinetic parameters for & / #946 / -lactamase were determined.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/1121029/index.pdf |
| Date | 01 September 2003 |
| Creators | Celik, Eda |
| Contributors | Calik, Pinar |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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