A comparison of streptococcal competence factors produced by strain Challis in chemically defined and complex media.

Abstract

SUMMARY: A comparison was made between streptococcal competence factors (CF) elaborated by strain CHALLIS in a chemically defined medium and in a complex medium (defined medium containing neopeptone and horse serum). The CF preparations acted similarly in that: (i) both CFs maximally activated the normally non-transformable streptococcal strain WICKY to the competent state when the WICKY cells were incubated for 40 to 100 min. in phase 2; (ii) both CF preparations had to react with WICKY cells for about 20 min. before the cells would take up deoxyribonucleic acid (DNA); (iii) the rates of DNA uptake in WICKY populations were identical when either CF preparation was used; (iv) both CFs activated different concentrations of WICKY cells so that a fixed proportion of the total population transformed to dihydro-streptomycin resistance; and (v) upon dilution both CF preparations behaved as if they contained more than a single component. The CF preparations behaved differently in that: (i) WICKY cells activated to the competent state with CF made in the complex medium generally yielded frequencies of transformation two to eight times higher than CF prepared in the defined medium, and (ii) CF prepared in the complex medium occurred in culture filtrates at an apparently higher concentration than CF prepared in the defined medium. This observation may be one reason for the high frequencies of transformation observed with CF made in the complex medium.