Aspergillus niger production of pectinase and α-galactosidase for enzymatic soy processing
| Autor: | Nicholas V. Callow, Qian Li, S. M. M. Islam, Lu-Kwang Ju, Christopher S. Ray, Abdullah Al Loman |
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| Rok vydání: | 2019 |
| Předmět: |
0106 biological sciences
0301 basic medicine food.ingredient Pectin Bioengineering Cellulase 01 natural sciences Applied Microbiology and Biotechnology Biochemistry Sucrase 03 medical and health sciences food 010608 biotechnology Food science Pectinase Soy protein biology Chemistry Hydrolysis Aspergillus niger Temperature biology.organism_classification 030104 developmental biology Polygalacturonase Biofuels alpha-Galactosidase Fermentation biology.protein Xylanase Soybean Proteins Soybeans Biotechnology |
| Zdroj: | Enzyme and microbial technology. 134 |
| ISSN: | 1879-0909 |
| Popis: | Soybean is a most promising sustainable protein source for feed and food to help meet the protein demand of the rapidly rising global population. To enrich soy protein, the environment-friendly enzymatic processing requires multiple carbohydrases including cellulase, xylanase, pectinase, α-galactosidase and sucrase. Besides enriched protein, the processing adds value by generating monosaccharides that are ready feedstock for biofuel/bioproducts. Aspergillus could produce the required carbohydrases, but with deficient pectinase and α-galactosidase. Here we address this critical technological gap by focused evaluation of the suboptimal productivity of pectinase and α-galactosidase. A carbohydrases-productive strain A. niger (NRRL 322) was used with soybean hull as inducing substrate. Temperatures at 20 °C, 25 °C and 30 °C were found to affect cell growth on sucrose with an Arrhenius-law activation energy of 28.7 kcal/mol. The 30 °C promoted the fastest cell growth (doubling time = 2.1 h) and earliest enzyme production, but it gave lower final enzyme yield due to earlier carbon-source exhaustion. The 25 °C gave the highest enzyme yield. pH conditions also strongly affected enzyme production. Fermentations made with initial pH of 6 or 7 were most productive, e.g., giving 1.9- to 2.3-fold higher pectinase and 2.2- to 2.3-fold higher α-galactosidase after 72 h, compared to the fermentation with a constant pH 4. Further, pH must be kept above 2.6 to avoid limitation in pectinase production and, in the later substrate-limiting stage, kept below 5.5 to avoid pectinase degradation. α-Galactosidase production always followed the pectinase production with a 16-24 h lag; presumably, the former relied on pectin hydrolysis for inducers generation. Optimal enzyme production requires controlling the transient availability of inducers. |
| Databáze: | OpenAIRE |
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