title: Biochemical analysis of respiratory metabolism in the heterofermentative Lactobacillus spicheri and Lactobacillus reuteri.
abstract: OBJECTIVE
  This study evaluated the aerobic and respiratory metabolism in Lactobacillus reuteri and Lactobacillus spicheri, two heterofermentative species used in sourdough fermentation.
  
  
  RESULTS
  In silico genome analysis, production of metabolites and gene expression of pyruvate oxidase, pyruvate dehydrogenase and cytochrome oxidase were assessed in anaerobic and aerobic cultures of Lact. reuteri and Lact. spicheri. Respiring homofermentative Lactobacillus casei N87 and Lact. rhamnosus N132 were used for comparison. Aerobiosis and respiration increased the biomass production of heterofermentative strains compared to anaerobic cultivation. Respiration led to acetoin production by Lact. rhamnosus and Lact. casei, but not in heterofermentative strains, in which lactate and acetate were the major end-products. Lactobacillus spicheri LP38 showed the highest oxygen uptake. Pyruvate oxidase, respiratory cytochromes, NADH oxidase and NADH peroxidase were present in the genome of Lact. spicheri LP38. Both Lact. spicheri LP38 and Lact. rhamnosus N132 overexpressed pox in aerobic cultures, while cydA was up-regulated only when haeme was supplied; pdh was repressed during aerobic growth.
  
  
  CONCLUSIONS
  Aerobic and respiratory growth provided physiological and metabolic advantages also in heterofermentative lactobacilli.
  
  
  CONCLUSIONS
  The exploitation of oxygen-tolerant phenotypes of Lact. spicheri may be useful for the development of improved starter cultures.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.|Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali, Università degli Studi della Basilicata, Potenza, Italy.
authors.forename: R G
authors.initials: RG
authors.lastname: Ianniello
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: J
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Istituto di Scienze dell'Alimentazione-CNR, Avellino, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Zotta
authors.affiliation: Scuola di Scienze Agrarie, Forestali, Alimentari e Ambientali, Università degli Studi della Basilicata, Potenza, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ricciardi
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Gänzle
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D007778:Lactobacillus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D052200:Limosilactobacillus reuteri / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism; D011771:Pyruvate Oxidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D010544:Peroxidases; C021845:NAD+ peroxidase; D011771:Pyruvate Oxidase; D010100:Oxygen
keywords: Lactobacillus reuteri; Lactobacillus spicheri; genome analysis; metabolism; respiration