Some aspects of the penicillin V-acylase produced by Rhodotorula glutinis var. glutinis.

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.