Kinetics of improved extracellular beta-d-fructofuranosidase fructohydrolase production by a derepressed Saccharomyces cerevisiae.
OBJECTIVE
beta-d-fructofuranosidase fructohydrolase (FFH, EC 3.2.1.26) is an enzyme which hydrolyses the alpha-1,4 glycosidic bonds of sucrose and releases monosaccharides. The present study deals with the kinetics of improved extracellular FFH production by Saccharomyces cerevisiae in batch culture.


RESULTS
Strains of S. cerevisiae can show increased FFH activity when grown on chemically defined medium. In the present study, wild-culture S. cerevisiae GCB-IV was mutated by treatment with ethyl methane sulfonate (EMS). Among six yeast mutants, EMS-II was found to be the highest FFH-producing strain (51.46 +/- 2.4 U ml(-1)). Maximum FFH production (78.46 +/- 3.2 U ml(-1)) was obtained 48 h after incubation by this 2-deoxy-d-glucose (2dg)-resistant mutant (76.20 mg ml(-1) protein). The optimal concentration of sucrose, incubation period and initial pH were 30.0 g l(-1), 28 degrees C and 6.5, respectively. The mutant EMS-II showed improvement in FFH production when 5.0 g l(-1) urea was added as a sole nitrogen source into SAPY medium. Values for Q(p) (1.802 +/- 0.2 U ml(-1) h(-1)) and Y(p/s) (3.460 +/- 1.1 U g(-1)) of EMS-II were significantly improved over the other yeast strains.


CONCLUSIONS
The E(a) value (40.28 +/- 3.5 kJ mol(-1)) of EMS-II was significant (P <or= 0.05) when compared with its wild-culture progenitor GCB-IV. In addition, thermodynamic studies revealed that the cell system exerts protection against thermal inactivation of FFH (33.55 +/- 4.2 kJ mol(-1)).


CONCLUSIONS
The EMS-II mutant can be exploited for FFH production over a wide range of incubation temperature (26-34 degrees C).
Ali
S
S
Institute of Industrial Biotechnology, GC University Lahore, Pakistan.
Haq
I
I
D001709:Biotechnology / Q000379:methods; D003470:Culture Media / Q000737:chemistry; D015966:Gene Expression Regulation, Fungal; D006867:Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D007700:Kinetics; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D013395:Sucrose / Q000378:metabolism; D013816:Thermodynamics; D014508:Urea / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000378:metabolism*
D003470:Culture Media; D013395:Sucrose; D014508:Urea; D006867:Hydrolases; D043324:beta-Fructofuranosidase