经解除阻遏的酿酒酵母产生改良型胞外β-D-呋喃果糖苷酶果糖水解酶的动力学

Kinetics of improved extracellular beta-d-fructofuranosidase fructohydrolase production by a derepressed Saccharomyces cerevisiae.

作者信息

Ali S, Haq I

机构信息

Institute of Industrial Biotechnology, GC University Lahore, Pakistan.

出版信息

Lett Appl Microbiol. 2007 Aug;45(2):160-7. doi: 10.1111/j.1472-765X.2007.02171.x.

DOI:10.1111/j.1472-765X.2007.02171.x

PMID:17651212

Abstract

AIMS

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.

MATERIALS AND 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.

CONCLUSION

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)).

SIGNIFICANCE AND IMPACT OF THE STUDY

The EMS-II mutant can be exploited for FFH production over a wide range of incubation temperature (26-34 degrees C).

摘要

目的

β - d - 呋喃果糖苷酶果糖水解酶（FFH，EC 3.2.1.26）是一种水解蔗糖的α - 1,4糖苷键并释放单糖的酶。本研究探讨了酿酒酵母在分批培养中提高细胞外FFH产量的动力学。

材料与结果

酿酒酵母菌株在化学限定培养基上生长时可表现出FFH活性增加。在本研究中，野生培养的酿酒酵母GCB - IV用甲磺酸乙酯（EMS）处理进行诱变。在六个酵母突变体中，EMS - II被发现是产生FFH最高的菌株（51.46±2.4 U ml⁻¹）。该2 - 脱氧 - d - 葡萄糖（2dg）抗性突变体（76.20 mg ml⁻¹蛋白质）在培养48小时后获得最大FFH产量（78.46±3.2 U ml⁻¹）。蔗糖的最佳浓度、培养时间和初始pH分别为30.0 g l⁻¹、28℃和6.5。当向SAPY培养基中添加5.0 g l⁻¹尿素作为唯一氮源时，突变体EMS - II的FFH产量有所提高。EMS - II的Q(p)（1.802±0.2 U ml⁻¹ h⁻¹）和Y(p/s)（3.460±1.1 U g⁻¹）值比其他酵母菌株有显著提高。