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Transglutaminase (TGase) was produced by a locally isolated Streptomyces sp. strain using solid fermentation with wheat bran as substrate. The highest product yield was obtained with 70% moisture content; 15% inoculum size (volume per mass) and incubation period of 6 days. Among different carbon sources, starch (4%) resulted in maximum enzyme production followed by glycerol and glucose. The best nitrogen source was peptone (3%) followed by yeast extract. The highest TGase activity was observed at 45 °C and pH 6.5 with a good activity in the range of 6-7.5. The enzyme was stable at 40 to 45°C. It was found to be highly stable within the range of 5-8.5 pH values.

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The present study was undertaken to evaluate the characteristics of pectin methylesterase produced from Aspergillus niger. The enzyme had a molecular weight of 59.668 kDa. The enzyme exhibited maximum activity at 45°C. The enzyme lost most of its initial activity after 20 min of incubation at 75°C. Optimal activity and stability of the enzyme occurred at pH 4, with more than 90 % of retained activity after 10 min at pH 5. Michaelis constant (Km) was found equal to (1) mg/ml, whereas, maximum velocity (Vmax) was (1000) μmol/min. The catalyzed reaction by pectin methylesterase had activation energy equal to 9.66 Kcal/mol. The enzyme lost 24% and 13% of its initial activity during two months of storage at4°C and -20 °C, respectively. The enzyme was activated by NaCl, KCl and CaCl2 at concentration of 25 mM and inhibited by MgSO4, polygalacturonic acid, methanol, IAA and EDTA.