Abstract
Attempting selective screening procedures for penicillin acylase producing microorganisms, a yeast was isolated from a soil sample using a mineral medium, containing N‐acetyl‐glycine. It was classified as Rhodotorula glutinis var. glutinis. The Rhodotorula cells specifically hydrolyze penicillin V into 6‐APA (6‐amino‐penicillanic acid); other penicillins and penicilloic acids ae not attacked. No β‐lactamase is present. The optimum pH for acylase activity is 6.4–6.6, while at pH 8 only a low activity is found. Next to penicillin V, also different aliphatic and aromatic amides as well as some special di‐ and tripeptides are hydrolyzed, although rather slowly. No resynthesis of penicillins could be detected at any pH value.
The yeast is able to yield biomass on a wide range of “economic” media, always displaying high acylase biosynthesis. Especially, addition of urea to a molasses medium stimulated the acylase biosynthesis. Supplying phenoxyacetic acid, N‐acetylglycine, phenylacetamide or triglycine to the growing cells, yield higher acylase levels.
The penicillin acylase could be partially liberated by ultrasonic treatment and by alumina disruption. A crude enzyme preparation was entrapped in polyacrylamide gel and tested upon its capacity to act as a continuous insoluble enzyme reactor. However, its transformation capacity was rather low.
In many aspects this yeast acylase is comparable with the Erwinia penicillin V‐acylase earlier described by the authors.