SUMMARY: Strains of belonging to Types 2 and 4 elaborated an amylolytic enzyme which was not usually a product of other serological Types though it was occasionally produced by members of Types 1, 9, 22 and Types related to 4, 5 and 25. Sixty-six % of amylolytic strains were untypable by M precipitin tests.

The enzyme was produced by variants. Amylolytic organisms were generated by matt and large opaque colonies of the parent strains; small and glossy variants generated relatively fewer enzyme-positive cocci, and had often lost the amylolytic property. When studied as a single character in serial subcultures on starch agar, the property was transmissible, in some instances to 80 % of the progeny for many generations (forty or more subcultures). Other strains readily lost the property in subculture on starch agar but recovered amylolytic power during passage on plasma agar in the absence of substrate. Certain amylolytic strains contained a trypsin-resistant, serologically active substance which precipitated in anti-M, anti-T and anti-proteinase precursor serum. A similar substance diffused into the medium when strains were grown on agar containing the substrate. While serologically related to the cell antigen, the free substance was trypsin-sensitive.


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