Bw. Senior, Investigation of the types and characteristics of the proteolytic enzymes formed by diverse strains of Proteus species, J MED MICRO, 48(7), 1999, pp. 623-628
Many diverse clinical isolates of Proteus mirabilis (48 strains), E. penner
i (25), P. vulgaris biogroup 2 (48) and P. vulgaris biogroup 3 (21) from ma
n were examined for their ability to produce proteolytic enzymes and the na
ture and characteristics of the proteases were studied. All the P. penneri
isolates, most (94-90%) of the P. mirabilis and P. vulgaris biogroup 2 isol
ates, but only 71% of the P. vulgaris biogroup 3 isolates, secreted proteol
ytic enzymes. These were detected most readily at pH 8 with gelatin as subs
trate. A strong correlation was found between the ability of a strain to fo
rm swarming growth and its ability to secrete proteases. Non-swarming isola
tes invariably appeared to be non-proteolytic. However, some isolates, part
icularly of P. vulgaris biogroup 3, were non-proteolytic even when they for
med swarming growth. Analysis of the secreted enzymes of the different Prot
eus spp. on polyacrylamide-gelatin gels under various constraints of pH and
other factors showed that they were all EDTA-sensitive metalloproteinases.
Analysis of the kinetics of production of the proteases revealed the forma
tion of an additional protease of undefined type and function that was cell
-associated and formed before the others were secreted. The secreted protea
se was subsequently modified to two isoforms whose mass (53-46 kDa) varied
with the Proteus spp. and the strain. There was no evidence that the secret
ed proteases of strains of Proteus spp. were of types other than metallopro
teinases.