Molecular heterogeneity of the bdellovibrios: metallo and serine proteases unique to each species.

Abstract

1. Bdellovibrio bacteriovorus, B. starrii, andB. stolpii each produce at least two or three extracellular proteolytic enzymes. One enzyme (metallo enzyme) is inhibited by 10 mM EDTA and the other (serine protease) is inhibited by 1 mM phenylmethyl sulfonylfluoride. Separation of the two major enzymes was achieved only by polyacrylamide gel electrophoresis. 2. Bands of protease activity were developed on casein agar and each species produced a unique zymogram. Under standard growth and assay conditions, the decreasing order of enzyme units was:B. starrii>B. stolpii>B. bacteriovorus in about a 10∶5∶1 ratio. Each species produced its own unique amount of metallo- and serine proteases. 3. Knowledge of the enzyme units/109 PFU appears to be a useful criterion for classifying newBdellovibrio isolates to the species level.