Three polygalacturonases constitutively synthesized by Aspergillus alliaceus

Of three molecular forms of polygalacturonases synthesized by Aspergillus alliaceus on glucose media, two were exopolygalacturonases (exoPG₁ and exoPG₂) and one was an endopolygalacturonase (endoPG). Low-methoxylated beet pectin was the preferred substrate for the endoPG and exoPG₂ whereas pectic acid was the optimal substrate for exoPG₁. The highest activities of endoPG, exoPG₁ and exoPG₂ were at pH 5.5, 3.5, and 6.0 and at 35, 45 to 50 and 35°C, respectively. Disks of potato-tuber tissue were macerated by endoPG, but not by exoPG₁ or exoPG₂.The authors are with the Institute of Microbiology, Belarus Academy of Sciences, Zhodinskaya 2, 220141, Minsk, Belarus;