Penicillin Acylase Activity Research Articles

Penicillin Acylase Activity of Penicillium chrysogenum1

The penicillin acylase activity of Penicillium chrysogenum was studied. Washed mycelial suspensions of a high penicillin-producing and a nonproducing strain were found to be similar in respect to relative acylase activity on benzylpenicillin, 2-pentenylpenicillin, heptylpenicillin, and phenoxymethylpenicillin. The relative rates for both strains, as determined by 6-aminopenicillanic acid formation, were approximately 1.0, 2.5, 3.5, and 6.0 on the penicillins in the order given. The high producing strain formed both 6-aminopenicillanic acid and "natural" penicillins in fermentations to which no side-chain precursor had been added. Therefore, its demonstrated ability to cleave the natural penicillins, 2-pentenylpenicillin and heptylpenicillin, suggests that at least some of the 6-aminopenicillanic acid produced during such fermentations arises from the hydrolysis of the natural penicillins. At pH 8.5, the mycelial acylase activity of the nonproducing strain was about three times that at pH 6.0; at 35 C, it was about 1.5 times as active as it was at 30 C. When tested on penicillin G or V, no differences in either total or specific penicillin acylase activity were observed among mycelia harvested from cultures of the nonproducer to which penicillin G, penicillin V, or no penicillin had been added. Acetone-dried mycelium from both strains displayed acylase activity, but considerably less than that shown by viable mycelium. Culture filtrates were essentially inactive, although a very low order of activity was detected when culture filtrate from the nonproducer was treated with acetone and the acetone-precipitated material was assayed in a minimal amount of buffer.

Continuous cultivation of Escherichia coli possessing high penicillin–acylase activity

AbstractThe authors describe continuous cultivations of Escherichia coli possessing high penicillin‐acylase activity in corn‐steep liquor, peptone, and ammonium phenylacetate containing nutrient medium. If the cultivation is performed in the absence of ammonium phenylacetate the enzymic activities of cells from the batch as well as the continuous cultures are very low. The enzymic activity of cells in the batch process was considerably increased by the addition of 0.015% ammonium phenylacetate to the nutrient medium. Further increase of ammonium phenylacetate concentration did not result in any further increase of acylase activity. Continuous cultivation of the bacteria at the above ammonium phenyl‐acetate concentration was unsuccessful, as the enzymic activity of the bacteria constantly decreased during the process. On increasing the concentration of ammonium phenylacetate in the medium to 0.15% the authors succeeded in maintaining the enzymic activity of the bacteria at the same level as in the batch process performed at 0.015% concentration, throughout the whole continuous cultivation. At the dilution rate D = 0.5 hr.−1 the concentration of cells in the culture effluent from the fermentor at the steady state was equal to cell concentration at the end of batch cultivation. In relation to the cultivation time the output of cells in continuous cultivation is almost seven times higher as compared with the batch process.

Microbial resistance to penicillin as related to penicillinase or penicillin acylase activity.

Summary1. The penicillin moiety, 6-aminopenicillanic acid, has antibacterial activity but is considerably less active than penicillin. 2. Resistance to penicillin in one group of bacteria could be explained logically by presence of penicillinase activity, i.e., conversion of penicillin to the inactive penicilloic acid. 3. Resistance to penicillin in a second group of bacteria could be explained logically by presence of penicillin acylase activity, i.e., conversion of penicillin to the relatively inactive 6-aminopenicillanic acid. 4. In a third group of bacteria resistant to penicillin, neither penicillinase nor penicillin acylase activity could be detected. Still another metabolic mechanism other than penicillinase or penicillin acylase activity must be present in selected bacteria.