Geobacillus thermoleovorans: growth and lipase production
| dc.contributor.advisor | Litthauer, D. | |
| dc.contributor.advisor | Van Heerden, E. | |
| dc.contributor.advisor | Du Preez, J. C. | |
| dc.contributor.author | Knoesen, Shaun | |
| dc.date.accessioned | 2017-03-15T07:20:23Z | |
| dc.date.available | 2017-03-15T07:20:23Z | |
| dc.date.issued | 2004-01 | |
| dc.description.abstract | English: The aim of this study was to elucidate factors, specifically media composition and growth conditions that would improve the thermophilic lipase production by Geobacillus thermoleovorans. A semi-starved state where carbon and or nitrogen becomes limiting was found not to be conducive to optimum lipase production. Instead, the notion that lipase activity peaks at these limiting conditions, normally during stationary phase was disproved as we could get a 25% increase in biomass obtained under optimized conditions, yielding a 100% increase in lipase production. This showed that the availability of specific nutrients has a direct positive effect on the amount of enzyme produced. The occurrence of free fatty acids (products of lipolysis) under these conditions was found to be the main signal for the commencement of lipase production. This was shown by the almost immediate production of lipase once free fatty acids were present at the initial point of inoculation (stearic acid induction), showing that the presence of free fatty acids does not repress the production of inducible lipases by Geobacillus thermoleovorans but that it rather acts as a signal for lipase induction. The presence of glucose as a second utilizable carbon source at inoculation was not inhibitory to lipase production. The consumption of glucose and stearic acid occurred simultaneously, with the consumption of free fatty acids being enhanced by the presence of glucose. The pH of the media also had a noticeable effect on the physiology surrounding lipase production, specifically effecting the rate of uptake of free fatty acids. This indicated that not only the presence but also the rate of uptake of free fatty acids probably plays a direct role in the regulation and/or secretion of lipases. The optimum temperature for lipase production and the optimum for growth differed. The optimum temperature for lipase production was found to be 55ºC with little or no lipase production occurring at 65ºC, which is the optimum growth temperature. The addition of NaCl increased lipase yield and/or activity further. It is however not clear whether the presence of NaCl has an effect on lipase production or merely acts as a stabilizer of lipase activity. We propose that the presence of free fatty acids in the culture media is the primary signal for lipase production, possibly by inducing the transcription of an inducible lipase gene. | en_ZA |
| dc.description.abstract | Afrikaans: Die doel van hierdie studie was om die faktore, meer spesifiek die kwekingsmedium samestelling en groei kondisies te onder soek wat die maksimale produksie van die termofiele lipase van Geobacillus thermoleovorans sal lewer. Dis is gevind dat `n semi-uitgehongerde toestand waar koolstof en stikstof beperkend is nie optimale produksie van lipase bevorder nie. Die opvatting dat lipase poduksie gewoonlik tydens die stasionêre groeifase geskied is as verkeerd bewys. ‘n Verhoging van 25% in biomassaopbrengs is gekry onder die optimum toestande met `n 100% verhoging in die totale lipase opbrengs. Dit dui daarop dat die beskikbaarheid van spesifieke media komponente `n direkte, positiewe invloed het op die hoeveelheid ensiem wat geproduseer word. Die teenwoordigheid van vrye vetsure (die produk van lipolise) was as die hoofoorsaak van lipase produksie geïdentifiseer. Daar is aangetoon dat daar ‘n byna onmiddelike produksie van lipase plaasvind as vrye vetsure by die aanvang van groei teenwoordig was (steariensuur induksie). Ons kon ook aandui dat die teenwoordigheid van vrye vetsure nie `n onderdrukker van lipase produksie deur Geobacillus thermoleovorans is nie. Daar is ook aangedui dat die aanwesigheid van glukose as `n tweede koolstofbron by die aanvang van groei nie `n onderdrukker van lipase produksie blyk te wees nie. Glukose en steariensuur is gelyktydig verbruik en die teenwoordigheid van glukose het die opname van steariensuur versnel. Die pH van die kweking het ook `n effek gehad op die fisiologie van lipase produksie, meer spesifiek op die verbruik van vrye vetsure. Daar is aangetoon dat die teenwoordigheid van vetsure asook hulle verbruik `n direkte rol speel in die regulering van lipase produksie of -sekresie. Die optimum temperatuur vir lipase produksie en die optimum temperatuur vir groei het verskil. Vir lipase produksie was die optimum temperatuur 55ºC, met min of geen lipase produksie by 65ºC, wat die optimum vir groei is. Die bevoeging van NaCl het die lipase opbrengs en/of aktiwiteit verder verhoog. Dit is nie seker of die teenwoordigheid van NaCl `n effek het op die produksie van die lipase en of dit net optree as `n stabiliseerder van lipase aktiwiteit nie. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/5821 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Dissertation (M.Sc.Agric. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2004 | en_ZA |
| dc.subject | Thermophilic bacteria | en_ZA |
| dc.subject | Lipase | en_ZA |
| dc.title | Geobacillus thermoleovorans: growth and lipase production | en_ZA |
| dc.type | Dissertation | en_ZA |