SUMMARYTransformable streptococci produce an exocellular factor provoking competence under certain conditions. Non-competent cultures become competent upon addition of this factor. The kinetics of conversion is concomitant with an enzymic reaction ; the process is time and temperature dependent and the factor itself is heat sensitive. The action of the hypothetical enzyme on cells of a non-transformable streptococcus results in provocation of competence.
SUMMARY:The heat-stability of the T antigen of strains of Streptococcus pyogenes grown in Pope & Smith (1932) broth (containing maltose and yeast) with added pancreatic extract varied considerably from strain to strain; with several strains 30 minutes' boiling was insufficient to eliminate all T agglutinability.By heating suspensions of streptococci to 80' for 30 min. and then treating the heated suspensions with trypsin-containing pancreatic extract for a few hours, T antigen was obtained in solution and could be demonstrated by precipitin tests with appropriate type-specific sera.It is well known that streptococci of Lancefield's Group A (Streptococcus pyogenes) have two type-specific antigens, known as M and T (Lancefield, 1940-1). Both these antigens may be concerned in type identification by the slide agglutination method but the suspensions of streptococci that have to be used for this test are frequently unstable and the method commonly used for stabilizing them comprises digestion with trypsin-a process that destroys the M but not the T antigen. Consequently, in practical slide agglutination typing, one often has to rely on the T antigen alone, which may be confusing owing to the sharing of T antigens by streptococci of different types (Stewart, Lancefield, Wilson & Swift, 1944). For the precise study of the T antigen content of streptococci it would therefore be useful to be able to destroy this antigen in the cells without affecting the M antigen.It would also be of great value if the T antigen could be extracted from the cocci and demonstrated by a precipitin method similar to that used for the M antigen. Elliott (1943) and Lancefield & Dole (1946) selectively destroyed the T antigen by heating the streptococcal suspension to 100' for 30 min.; and Lancefield & Dole demonstrated that a T-containing extract could be obtained by prolonged pepsin or trypsin digestion of the cocci. The present paper reports some extensions of this work.
EXPERIMENTALThe antisera used were prepared at various times in this laboratory, usually by repeated intravenous inoculation of formalin-killed streptococci into rabbits, and were absorbed with heterologous strains to remove Group antibodies. The strains of streptococci used were all 'classical' strains, stored in the laboratory in the dried state. for 18-24 hr. a t 3 7 ' ; small samples of the cultures were boiled for varying times and then tested with dilutions of a Type 4 antiserum. Control tests were made with saline and with heterologous type-specific sera, and were in all cases negative. There was considerable variation in the duration of heating necessary to eliminate the T-agglutination (Table I), and in three cases agglutination still occurred after 30 min. heating. Similar tests were carried out with other types, but in these cases the sera were used a t one dilution only (1/5). The sera used included those of heterologous types thought to share a T antigen with the strain under test, because any agglutination thus observed would almost certainly be due to...
Production of competence-provoking factor and transformation of a group H streptococcus were achieved in the absence of serum or albumin in media sterilized by filtration through Millipore filters.No significant transformation was found when the medium was heated more than 40–50 minutes at 115°−117 °C. This suggests that the medium contained a heat-labile factor necessary for transformation. The factor was found in yeast extract, one of the ingredients of the medium.Addition of serum to heated medium allowed production of the competence-provoking factor and of transformation. Serum albumin, claimed to be an adequate substitute for serum, was less active in this respect. It is concluded that serum contains, in addition to albumin, another factor enhancing transformation.
The Wicky Streptococcus was rendered competent for deoxyribonucleic acid (DNA) uptake with the competence factor (CF) derived from a related strain. Initiation of competence resulted in an almost immediate decline of the rate of cell proliferation and of incorporation of 14C-uracil into acid-insoluble material. DNA synthesis was affected in the later stage of competence development. The competent cells were penicillin resistant.
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