AMINOPEPTIDASE ACTIVITIES IN PEPTOSTREPTOCOCCUS SPP. ARE STATISTICALLY CORRELATED TO GELATIN HYDROLYSIS

One hundred Peptostreptococcus isolates from five species were assesse d for their ability to hydrolyze gelatin. Most Peptostreptococcus magn us (95.8%) and Peptostreptococcus micros isolates (79.0%) hydrolyzed g elatin in contrast to Peptostreptococcus asaccharolyticus (8.0%), Pept ostreptococcus anaerobius (10.0%), and Peptostreptococcus prevotii iso lates (16.7%). Gelatin hydrolysis in Peptostreptococcus magnus and Pep tostreptococcus micros isolates correlated (r = 0.80; P = 0.0019) with more aminopeptidases produced than Peptostreptococcus asaccharolyticu s, Peptostreptococcus anaerobius, or Peptostreptococcus prevotii. The five species were further classified into three groups using the exten ded Tukey test (P < 0.0001) based on the mean percentage of aminopepti dases produced by each species with Peptostreptococcus magnus and Pept ostreptococcus micros belonging to group I, Peptostreptococcus asaccha rolyticus and Peptostreptococcus prevotii belonging to group II, and P eptostreptococcus anaerobius forming group III. An analysis of possibl e proteolytic activity of four selected Peptostreptococcus magnus isol ates indicated that only 5 of 11 substrates were hydrolyzed as compare d to a control isolate of Porphyromonas gingivalis W83, which had a st rong proteolytic profile. Therefore, gelatin hydrolysis by Peptostrept ococcus spp., in particular Peptostreptococcus magnus and Peptostrepto coccus micros, is probably due to a variety of aminopeptidases rather than proteinases.