Proteases from actinomycetes interfere in solid media plate assays of hyaluronidase activity

Four hundred and fifteen actinomycete strains were screened for hyaluronida se activity in two plate assays media. In the first one, using hyaluronic a cid as substrate and bovine serum albumin (BSA) to help precipitation of th e nondegraded substrate, only strain 594 and hyaluronidase control were pos itive. In the second assay, plates with hyaluronic acid, but not BSA, gave the same results. For plates containing only BSA, proteinase activity was d etected in strain 594. When hyaluronic acid was treated with pronase, the o nly clear zones, in the second assay without BSA, were those around hyaluro nidase controls. Protease activity, commonly found in actinomycetes, was de tected only in strain 594, among the 415 studied, when tested in hyaluronid ase assay using hyaluronate plus BSA. This may be due to the composition of the growth medium, since media with different composition gave different r esults for protease activity in each of the 15 strains analyzed. These data suggest that proteases can affect an accurate detection of hyaluronidase i n media containing proteins, not only from hyaluronate preparations, but al so from other medium ingredients. Thus, for a correct interpretation of the method, they must be excluded. Commercial Hyaluronidase used as controls m ust be also tested for the presence of protease contamination. (C) 2001 Els evier Science B.V. All rights reserved.