Development of aggregating ability in cells of Streptococcus mitis ATCC 903 grown under glucose-limiting conditions in continuous culture.

Streptococcus mitis ATCC 903 grown under glucose-limiting conditions in continuous culture did not aggregate upon incubation in 10 mM phosphate buffer at pH 5--7 unless a metabolizable sugar was added. Aggregation started 45--60 min after the addition of glucose or sucrose whereas slowly metabolized sugars as galactose and lactose required several hours to cause aggregation. Active metabolism of the carbohydrate was a prerequisite for aggregation as indicated by acid formation. Chloramphenicol inhibited the development of aggregating ability in the presence of glucose or sucrose. The addition of a source of nitrogen (peptides and amino acids) enhanced aggregation and shortened the time for development of aggregating ability. No aggregation occurred at at 0 degrees C and the ability to aggregate was markedly delayed at 20 degrees C as compared to 30 degrees C and 37 degrees C. Trypsin treatment of the bacteria abolished aggregation, indicating that surface components of protein or glycoprotein nature contributed to the capacity to aggregate.