Transduction of Lactose Metabolism in Streptococcus lactis C2

Ultraviolet (UV)-induced phage lysates, from lactose-positive (lac + )Streptococcus lactis C2, transduced lactose fermenting ability tolac − recipient cells of this organism. Although the phage titer could not be determined due to the absence of an appropriate indicator strain, the number of transductants was proportional to the amount of phage lysate added. Treatment of the lysate with deoxyribonuclease had no effect on this conversion, indicating the observed genetic change was not mediated by free deoxyribonucleic acid. When thelac + transductants were isolated and exposed to UV irradiation, lysates with higher transducing ability were obtained. The transducing ability of this lysate was about 100-fold higher than that observed in the original lysates. Thelac + transductants were unstable sincelac − segregants occurred at high frequency. The phage lysate fromS. lactis C2 also transduced maltose and mannose metabolism to the respective negative recipient cells. The results demonstrate the transduction of carbohydrate markers by a streptococcal phage and establish a genetic transfer system in group N streptococci.