Journal
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
Volume 98, Issue 17, Pages 7523-7534Publisher
SPRINGER
DOI: 10.1007/s00253-014-5851-z
Keywords
Bifidobacteria; Oxidative stress; Reactive oxygen species; Catalase; Superoxide dismutase
Categories
Funding
- National Natural Science Foundation of China [31071507]
- National High Technology Research and Development Program (863 Program) [2008AA10Z310]
- National Science and Technology Support Program of Ministry of Science and Technology of China [2012BAD28B07]
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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 Mn2+-dependent SOD is functional in the B. longum oxidative-stress response, and synergistic protection is achieved when their expressions are combined.
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