Preferred hexoses influence long-term memory and induction of lactose catabolism by Streptococcus mutans.

Preferred hexoses influence long-term memory and induction of lactose catabolism by Streptococcus mutans. Appl Environ Microbiol. 2018 May 11;: Authors: Zeng L, Chen L, Burne RA Abstract Bacteria prioritize sugar metabolism via carbohydrate catabolite repression, which regulates global gene expression to optimize the catabolism of preferred substrates. Here, we report an unusual long-term memory effect in certain Streptococcus mutans strains that alters adaptation to growth on lactose after prior exposure to glucose or fructose. In strain GS-5, cells that were first cultured on fructose then transferred to lactose displayed an exceptionally long lag (>11 h) and slower growth, compared to cells first cultured on glucose or cellobiose, which displayed a reduction in lag phase by as much as 10 h. Mutants lacking the cellobiose-PTS or phospho-β-glucosidase lost the accelerated growth on lactose associated with prior culturing on glucose. The memory effects of glucose or fructose on lactose catabolism were not as profound in strain UA159, but the lag phase was considerably shorter in mutants lacking the glucose-PTS EIIMan Interestingly, when S. mutans was cultivated on lactose, significant quantities of free glucose accumulated in the medium, with higher levels found in the cultures of strains lacking EIIMan, glucokinase, or both. Free glucose was also detected in cultures that were utilizing cellobiose or trehalose, albeit at lower l...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research