title: Characterization of nitrite degradation by Lactobacillus casei subsp. rhamnosus LCR 6013.
abstract: Nitrites are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. The nitrite degradation capacity of Lactobacillus casei subsp. rhamnosus LCR 6013 was investigated in pickle fermentation. After LCR 6013 fermentation for 120 h at 37°C, the nitrite concentration in the fermentation system was significantly lower than that in the control sample without the LCR 6013 strain. The effects of NaCl and Vc on nitrite degradation by LCR 6013 in the De Man, Rogosa and Sharpe (MRS) medium were also investigated. The highest nitrite degradations, 9.29 mg/L and 9.89 mg/L, were observed when NaCl and Vc concentrations were 0.75% and 0.02%, respectively in the MRS medium, which was significantly higher than the control group (p ≤ 0.01). Electron capture/gas chromatography and indophenol blue staining were used to study the nitrite degradation pathway of LCR 6013. The nitrite degradation products contained N2O, but no NH4(+). The LCR 6013 strain completely degraded all NaNO2 (50.00 mg/L) after 16 h of fermentation. The enzyme activity of NiR in the periplasmic space was 2.5 times of that in the cytoplasm. Our results demonstrated that L. casei subsp. rhamnosus LCR 6013 can effectively degrade nitrites in both the pickle fermentation system and in MRS medium by NiR. Nitrites are degraded by the LCR 6013 strain, likely via the nitrate respiration pathway (NO2(-)>NO->N2O->N2), rather than the aammonium formation pathway (dissimilatory nitrate reduction to ammonium, DNRA), because the degradation products contain N2O, but not NH4(+).
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Dong-mei
authors.initials: DM
authors.lastname: Liu
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Wang
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Xin-yue
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Xi-lin
authors.initials: XL
authors.lastname: Xu
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wu
authors.affiliation: College of Light Industry and Food Science, South China University of Technology, Guangzhou, Guangdong, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects; D002849:Chromatography, Gas; D003470:Culture Media / Q000494:pharmacology; D005285:Fermentation / Q000187:drug effects; D007780:Lacticaseibacillus casei / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000032:analysis; D012965:Sodium Chloride / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014675:Vegetables / Q000378:metabolism
chemical_list: D003470:Culture Media; D009573:Nitrites; D012965:Sodium Chloride; D009572:Nitrite Reductases; D009609:Nitrous Oxide
references.citation: J Biol Chem. 2002 Jun 28;277(26):23664-9
references.pmid: 11960983
references.citation: FEMS Microbiol Ecol. 2002 Mar 1;39(3):175-81
references.pmid: 19709197
references.citation: Free Radic Biol Med. 2000 Apr 1;28(7):1039-50
references.pmid: 10832065
references.citation: J Bacteriol. 1990 May;172(5):2558-62
references.pmid: 2158973
references.citation: Arch Microbiol. 1986;145:202-8
references.pmid: 11540874
references.citation: Appl Environ Microbiol. 2005 Aug;71(8):4427-36
references.pmid: 16085833
references.citation: Int J Food Microbiol. 2006 Oct 1;111(3):191-6
references.pmid: 16928406
references.citation: Arch Microbiol. 1984 Jan;137(1):79-84
references.pmid: 6712419
references.citation: J Agric Food Chem. 2001 Apr;49(4):2096-103
references.pmid: 11308373