Kinetics of an extracellular ?-D-fructofuranosidase fructohydrolase production from a derepressed mutant of Saccharomyces carlsbergensis and parameter significance analysis by 2-factorial design.
Hayyat M. U., Sikander Ali
Author Affiliation: Sustainable Development Study Centre, GC University, Lahore, Pakistan.
Pakistan Journal of Zoology 45 : 1299-1310
Abstract : In the present study, over hundred strains of Saccharomyces carlsbergensis were isolated from various fruits including jaman, plum, peach, date, banana and mango. These isolates were screened for extracellular ?-D-fructofuranosidase fructohydrolase (FFH) production under submerged fermentation (SmF). The strain GCBt-99 isolated from plum gave relatively better enzyme activity and it was exposed to ultraviolet radiations (UV dose ~1.2×102 J/m2/s) to improve its FFH potential. Among 16 UV irradiated mutant strains, UV-dg4 was selected for batch culture optimizations as it exhibited ~17.86 fold higher enzyme activity compared to wild culture. The potential mutant was cultured overnight and plated on YPS-agar medium containing various levels of 2-deoxy-D-glucose (2 dg). The cultural conditions and nutritional requirements were optimized in a stirred fermentor by the selected mutant culture. Over 75% enhancement in enzyme production (38.72 U/ml/min) on the basis of substrate consumption was achieved when the process parameters including sucrose concentration (10 g/l), incubation period (72 h), initial pH (6), inoculum size (12%, v/v) and soybean meal as a nitrogen source (5 mg/ml nitrogen) were further identified using Plackett-Burman design (PBD) and response surface methodology (RSM). On the basis of kinetic variables, notably Qp (0.826 U/ml/h), Yp/s (2.845 U/ml/g) and qp (0.102 U/g yeast cells/h), the mutant UV-dg4 was found to be a hyper FFH producer (p?0.05) indicating a viable utility (HS, LSD-0.031).