title: Combination of heterogeneous catalase and superoxide dismutase protects Bifidobacterium longum strain NCC2705 from oxidative stress.
abstract: Bifidobacteria are generally sensitive to oxidative stress caused by reactive oxygen species (ROS). To improve oxidative-stress tolerance, the superoxide dismutase (SOD) gene from Streptococcus thermophilus (StSodA) and the heme-dependent catalase (KAT) gene from Lactobacillus plantarum (LpKatL) were heterologously expressed in Bifidobacterium longum strain NCC2705. Three types of strain NCC2705 transformants were obtained: with transgenic SOD expression, with transgenic KAT expression, and with coexpression of the two genes. Intracellular expression of the genes and their functional role in oxidative-stress resistance were evaluated. In response to oxidative stress, B. longum NCC2705/pDP401-LpKatL (expressing LpKatL) and NCC2705/pDP-Kat-Sod (coexpressing LpKatL and StSodA) rapidly degraded exogenous H2O2 and the peroxides generated as a byproduct of aerobic cultivation, preventing oxidative damage to DNA and RNA. Individual expression of StSodA or LpKatL both improved B. longum NCC2705 cell viability. Survival rate of strain NCC2705 was further improved by combining SOD and KAT expression. The two enzymes played complementary roles in ROS-scavenging pathways, and coexpression led to a synergistic beneficial effect under conditions of intensified oxidative stress. Our results illustrate that heterogeneous expression of heme-dependent KAT and Mn(2+)-dependent SOD is functional in the B. longum oxidative-stress response, and synergistic protection is achieved when their expressions are combined.
authors.affiliation: Key Laboratory of Functional Dairy Science of Chinese Ministry of Education and Municipal Government of Beijing, College of Food Science and Nutritional Engineering, China Agricultural University, 17 Qinghua East Road, Haidian District, Beijing, 100083, China.
authors.forename: Fanglei
authors.initials: F
authors.lastname: Zuo
authors.forename: Rui
authors.initials: R
authors.lastname: Yu
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Feng
authors.forename: Gul Bahar
authors.initials: GB
authors.lastname: Khaskheli
authors.forename: Lili
authors.initials: L
authors.lastname: Chen
authors.forename: Huiqin
authors.initials: H
authors.lastname: Ma
authors.forename: Shangwu
authors.initials: S
authors.lastname: Chen
mesh_terms: D001644:Bifidobacterium / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D048191:Lactiplantibacillus plantarum / Q000201:enzymology / Q000235:genetics; D050296:Microbial Viability / Q000187:drug effects*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010545:Peroxides / Q000378:metabolism / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D048249:Streptococcus thermophilus / Q000201:enzymology / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D010545:Peroxides; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D002374:Catalase; D013482:Superoxide Dismutase