Adaptation of Streptococcus mutans and Enterococcus hirae to acid stress in continuous culture.

摘要: Streptococcus mutans GS-5 and IB1600 adapted to growth in acidic environments continuous culture at slow (generation time = 8.3 h) or fast 2.4 rates of complex medium with a restricted glucose supply. The extent adaptation was indicated by changes minimum pH values attained harvested cells suspended dense suspensions excess increased levels ATPase activity assayed permeabilized cells. Also, better withstood potentially lethal acidification. Cells from cultures growing close 5 reduced suspension lower than maintained 7. 6 were intermediate. strain had higher level constitutive acid resistance the also able adapt acidified media. Both less adaptive capacity Enterococcus hirae ATCC 9790. Adaptation occurred rapidly, mainly within single generation culture, while deadaptation more slowly over multiple generations. S. conditions is likely be important ecology dental plaque for cariogenicity organism.