title: Glutathione protects Lactococcus lactis against acid stress.
abstract: Previously we showed that glutathione (GSH) can protect Lactococcus lactis against oxidative stress (Y. Li et al., Appl. Environ. Microbiol. 69:5739-5745, 2003). In the present study, we show that the GSH imported by L. lactis subsp. cremoris SK11 or produced by engineered L. lactis subsp. cremoris NZ9000 can protect both strains against a long-term mild acid challenge (pH 4.0) and a short-term severe acid challenge (pH 2.5). This shows for the first time that GSH can protect a gram-positive bacterium against acid stress. During acid challenge, strain SK11 containing imported GSH and strain NZ9000 containing self-produced GSH exhibited significantly higher intracellular pHs than the control. Furthermore, strain SK11 containing imported GSH had a significantly higher activity of glyceraldehyde-3-phosphate dehydrogenase than the control. These results suggest that the acid stress resistance of starter culture can be improved by selecting L. lactis strains capable of producing or importing GSH.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Rui-Yan
authors.initials: RY
authors.lastname: Fu
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hugenholtz
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000143:Acids / Q000378:metabolism / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism / Q000494:pharmacology* / Q000502:physiology; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013997:Time Factors
chemical_list: D000143:Acids; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005978:Glutathione