A study of the enzymatic profile of soil isolates of Nocardia asteroides

In this study, using the API-ZYM system, we have reported the enzyme profil e of 42 soil strains and 2 clinical strains of Nocardia asteroides isolated locally. Of the 19 enzymes tested, only 7 were demonstrable in over 90% of the soil isolates. These included alkaline phosphatase, esterase Lipase, l eucine arylamidase, acid phosphatase, phosphohydrolase, alpha-glucosidase a nd beta-glucosidase. In addition, beta-galactosidase activity was demonstra ted in all the strains by the O-nitrophenyl-beta-D-galactopyranoside (ONPG) test. The enzymes which were not demonstrable in >95% of the strains inclu ded valine arylamidase, cystine arylamidase, trypsin, chymotrypsin, alpha-g alactosidase, beta-glucoronidase, N-acetyl-beta-glucosaminidase, alpha-mann osidase and alpha-fucosidase. With the exception of valine arylamidase, whi ch was lacking in all but one isolate, the enzyme profiles of the soil isol ates were comparable with the clinical isolates of N. asteroides reported i n previous studies. The reasons for this difference in the two sets of isol ates is not clear. The study reinforces the view that specific differences in the enzymatic profiles of Nocardia species could be used for their rapid identification. However, more extensive studies are needed to establish th e reproducibility of this method. To the best of our knowledge, this is the first study of the enzymatic profile of soil isolates of N. asteroides ori ginating from a single geographic region.