Open AccessEnvironmental Influences on Competitive Hydrogen Peroxide Production in Streptococcus gordonii
Author(s) -
Lan Zheng,
Andreas Itzek,
Zhiyun Chen,
Jens Kreth
Publication year - 2011
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.00309-11
Subject(s) - ccpa , catabolite repression , streptococcus gordonii , biochemistry , biology , biofilm , chemistry , mutant , microbiology and biotechnology , bacteria , gene , genetics
Streptococcus gordonii is an important member of the oral biofilm. One of its phenotypic traits is the production of hydrogen peroxide (H2 O2 ). H2 O2 is an antimicrobial component produced byS. gordonii that is able to antagonize the growth of cariogenicStreptococcus mutans . Strategies that modulate H2 O2 production in the oral cavity may be useful as a simple therapeutic mechanism to improve oral health, but little is known about the regulation of H2 O2 production. The enzyme responsible for H2 O2 production is pyruvate oxidase, encoded byspxB . The functional studies ofspxB expression and SpxB abundance presented in this report demonstrate a strong dependence on environmental oxygen tension and carbohydrate availability. Carbon catabolite repression (CCR) modulatesspxB expression carbohydrate dependently. Catabolite control protein A (CcpA) repressesspxB expression by direct binding to thespxB promoter, as shown by electrophoretic mobility shift assays (EMSA). Promoter mutation studies revealed the requirement of two catabolite-responsive elements (CRE) for CcpA-dependentspxB regulation, as evaluated byspxB expression and phenotypic H2 O2 production assays. Thus, molecular mechanisms for the control ofS. gordonii spx B expression are presented for the first time, demonstrating the possibility of manipulating H2 O2 production for increased competitive fitness.