%0 Journal Article %A Nilsson, Martin %A Jakobsen, Tim Holm %A Givskov, Michael %A Twetman, Svante %A Tolker-Nielsen, Tim %T Oxidative stress response plays a role in antibiotic tolerance of Streptococcus mutans biofilms %D 2019 %J Microbiology, %V 165 %N 3 %P 334-342 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.000773 %K antimicrobial tolerance %K oxidative stress %K Streptococcus mutans %K biofilm %I Microbiology Society, %X Knowledge about biofilm-associated antibiotic tolerance mechanisms is warranted in order to develop effective treatments against biofilm infections. We performed a screen of a Streptococcus mutans transposon mutant library for mutants with reduced biofilm-associated antimicrobial tolerance, and found that the spxA1 gene plays a role in tolerance towards gentamicin and other antibiotics such as vancomycin and linezolid. SpxA1 is a regulator of genes involved in the oxidative stress response in S. mutans . The oxidative stress response genes gor and ahpC were found to be up-regulated upon antibiotic treatment of S. mutans wild-type biofilms, but not spxA1 mutant biofilms. The gor gene product catalyses the formation of glutathione which functions as an important antioxidant during oxidative stress, and accordingly biofilm-associated antibiotic tolerance of the spxA1 mutant could be restored by exogenous addition of glutathione. Our results indicate that the oxidative stress response plays a role in biofilm-associated antibiotic tolerance of S. mutans , and add to the on-going debate on the role of reactive oxygen species in antibiotic mediated killing of bacteria. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000773