title: The effects of RecO deficiency in Lactococcus lactis NZ9000 on resistance to multiple environmental stresses.
abstract: BACKGROUND
  Multiple stresses could cause damage to DNA and other macromolecules. RecO, belonging to the family of DNA repair proteins, plays an important part in homologous recombination and replication repair. In order to explore the role of RecO in overcoming multiple stresses, a mutant of recO deletion is constructed in Lactococcus lactis ssp. cremoris NZ9000.
  
  
  RESULTS
  Compared with the mutant strain, the original strain L. lactis NZ9000 shows better performance in growth under multiple stresses. The survival rates of the original strain under acid, osmotic and chill stresses are 13.49-, 2.78- and 60.89-fold higher. In our deeper research on fermentation capability under osmotic stress, lactate dehydrogenase activity after 8 h fermentation, maximum lactate acid production, lactate yield and maximum lactate productivity of L. lactis NZ9000 are 1.63-, 1.28-, 1.28- and 1.5-fold higher, respectively.
  
  
  CONCLUSIONS
  Results indicate that RecO has positively improved the survival of L. lactis NZ9000, protected its key enzymes and enhanced its fermentation efficiencies. Our research confirms the role of RecO in enhancing tolerances to multiple stresses of L. lactis NZ9000, and puts forward the suggestion that RecO could be used in other industrial microorganisms as a new anti-stress component to improve their resistance to various stresses.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, People's Republic of China; School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China.
authors.forename: Mengru
authors.initials: M
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
mesh_terms: D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D004777:Environment; D005285:Fermentation; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D013294:Lactococcus lactis / Q000737:chemistry* / Q000254:growth & development / Q000502:physiology*; D016296:Mutagenesis; D009997:Osmotic Pressure; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase
keywords: DNA repair proteins; Lactococcus lactis NZ9000; RecO; anti-stress component