Please use this identifier to cite or link to this item: https://hdl.handle.net/11147/2100
Title: Effect of various process parameters on morphology, rheology, and polygalacturonase production by Aspergillus sojae in a batch bioreactor
Authors: Öncü, Şelale
Tarı, Canan
Ünlütürk, Sevcan
Öncü, Şelale
Tarı, Canan
Ünlütürk, Sevcan
Izmir Institute of Technology. Food Engineering
Keywords: Enzymes
Bacteria
Biomass
Bioreactors
Agitation rate
Dissolved oxygen tension
Issue Date: Jul-2007
Publisher: American Institute of Chemical Engineers
Source: Öncü, Ş., Tarı, C., and Ünlütürk, S. (2007). Effect of various process parameters on morphology, rheology, and polygalacturonase production by Aspergillus sojae in a batch bioreactor. Biotechnology Progress, 23(4), 836-845. doi:10.1021/bp070079c
Abstract: The effects of pH, agitation speed, and dissolved oxygen tension (DOT), significant in common fungal fermentations, on the production of polygalacturonase (PG) enzyme and their relation to morphology and broth rheology were investigated using Aspergillus sojae in a batch bioreactor. All three factors were effective on the response parameters under study. An uncontrolled pH increased biomass and PG activity by 27% and 38%, respectively, compared to controlled pH (pH 6) with an average pellet size of 1.69 ± 0.48 mm. pH did not significantly affect the broth rheology but created an impact on the pellet morphology. Similarly, at constant agitation speed the maximum biomass obtained at 500 rpm and at 30 h was 3.27 and 3.67 times more than at 200 and 350 rpm, respectively, with an average pellet size of 1.08 ± 0.42 mm. The maximum enzyme productivity of 0.149 U mL-1 h-1 was obtained at 200 rpm with an average pellet size of 0.71 ± 0.35 mm. Non-Newtonian and pseudoplastic broth rheology was observed at 500 rpm agitation speed, broth rheology exhibited dilatant behavior at the lower agitation rate (200 rpm), and at the medium agitation speed (350 rpm) the broth was close to Newtonian. Furthermore, a DOT range of 30-50% was essential for maximum biomass formation, whereas only 10% DOT was required for maximum PG synthesis. Non-Newtonian shear thickening behavior (n > 1.0) was depicted at DOT levels of 10% and 30%, whereas non-Newtonian shear thinning behavior (n < 1.0) was dominant at 50% DOT. The overall fermentation duration (50-70 h) was considerably shorter compared to common fungal fermentations, revealing the economic feasibility of this particular process. As a result this study not only introduced a new strain with a potential of producing a highly commercially significant enzyme but also provided certain parameters significant in the design and mathematical modeling of fungal bioprocesses.
URI: http://doi.org/10.1021/bp070079c
http://hdl.handle.net/11147/2100
ISSN: 8756-7938
8756-7938
Appears in Collections:Food Engineering / Gıda Mühendisliği
Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

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