Open AccessRole of hydrogen peroxide in competition and cooperation between Streptococcus gordonii and Actinomyces naeslundii
Author(s) -
Jakubovics Nicholas S.,
Gill Steven R.,
Vickerman M.Margaret,
Kolenbrander Paul E.
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00585.x
Subject(s) - streptococcus gordonii , actinomyces naeslundii , microbiology and biotechnology , biology , actinomyces , bacteria , catalase , biochemistry , streptococcaceae , enzyme , genetics , antibiotics
In dental plaque α‐haemolytic streptococci, including Streptococcus gordonii , are considered beneficial for oral health. These organisms produce hydrogen peroxide (H 2 O 2 ) at concentrations sufficient to kill many oral bacteria. Streptococci do not produce catalase yet tolerate H 2 O 2 . We recently demonstrated that coaggregation with Actinomyces naeslundii stabilizes arginine biosynthesis in S. gordonii . Protein arginine residues are sensitive to oxidation by H 2 O 2 . Here, the ability of A. naeslundii to protect S. gordonii against self‐produced H 2 O 2 was investigated. Coaggregation with A. naeslundii enabled S. gordonii to grow in the absence of arginine, and promoted survival of S. gordonii following growth with or without added arginine. Arginine‐replete S. gordonii monocultures contained 20–30 μM H 2 O 2 throughout exponential growth. Actinomyces naeslundii did not produce H 2 O 2 but synthesized catalase, removed H 2 O 2 from coaggregate cultures and decreased protein oxidation in S. gordonii . On solid medium, S. gordonii inhibited growth of A. naeslundii ; exogenous catalase overcame this inhibition. In coaggregate cultures, A. naeslundii cell numbers were >90% lower than in monocultures after 24 h. These results indicate that coaggregation with A. naeslundii protects S. gordonii from oxidative damage. However, high cell densities of S. gordonii inhibit A. naeslundii . Therefore, H 2 O 2 may drive these organisms towards an ecologically balanced community in natural dental plaque.