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Glucoamylase isoenzymes tailoring through medium composition.

J G Silva¹, H J Nascimento, V F Soares

¹Instituto de Quimíca, Universidade Federal do Rio de Janeiro, CT, Bloco A, Ilha do Fundão, Rio de Janeiro, RJ, Brasil CEP:21949-900.

Applied Biochemistry and Biotechnology

|April 1, 1997

Summary

This study analyzed glucoamylase isoenzymes (GAI and GAII) from Aspergillus awamori. Different carbon-to-nitrogen ratios in fermentation media influenced the proportion of GAI and GAII produced, impacting enzyme characteristics.

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Area of Science:

Biochemistry
Enzymology
Microbial Biotechnology

Background:

Two major glucoamylase isoenzymes (GAI and GAII) exist in Aspergillus awamori culture supernatants.
Isoenzyme formation is hypothesized to result from enzyme degradation during fermentation.
These isoenzymes exhibit distinct substrate specificities and stability profiles.

Purpose of the Study:

To analyze glucoamylase isoenzymes (GAI and GAII) produced by Aspergillus awamori under varying C/N ratios.
To characterize the hydrolitic activities, molecular weight, and isoelectric points of GAI and GAII.
To investigate the influence of fermentation media C/N ratios on the proportion of GAI and GAII.

Main Methods:

Culturing Aspergillus awamori in liquid media with different C/N ratios (10 and 26).
Analysis of glucoamylase isoenzymes using HPLC gel filtration and FPLC chromatofocusing.
Characterization through gel electrophoresis, amino acid analysis, and structural data.

Main Results:

GAI exhibited a molecular weight of 110,000 Da and pI 3.45; GAII showed a molecular weight of 86,000 Da and pI 3.65.
Lower C/N ratio (10) favored GAI production, while higher C/N ratio (26) favored GAII production.
Both GAI and GAII preparations demonstrated high homogeneity.

Conclusions:

Fermentation C/N ratios significantly affect the relative proportions of Aspergillus awamori glucoamylase isoenzymes.
The characterized GAI and GAII isoenzymes are distinct molecular entities with different physicochemical properties.
This study provides insights into the regulation of glucoamylase isoenzyme production in Aspergillus awamori.