title: Cloning and functional expression of the mitochondrial alternative oxidase gene (aox1) of Aspergillus niger in Lactococcus lactis and its induction by oxidizing conditions.
abstract: Lactococcus lactis is a widely used food bacterium mainly known for its fermentation metabolism. An important, and for long time overlooked, trait of this species is its ability to perform respiratory metabolism in the presence of heme and under aerobic conditions. There is no evidence however for the presence of an alternative respiration pathway and AOX activity. In this study, a cDNA fragment encoding the mitochondrial alternative oxidase, the enzyme responsible for alternative respiration, from a citric acid producing Aspergillus niger strain was cloned and expressed in L. lactis as a host strain. Expression of aox1 conferred on this organism cyanide-resistant and salicylhydroxamate-sensitive growth. Bioreactor cultures under fully aerobic conditions of the transformed L. lactis showed that the alternative respiratory pathway operates and improves significantly the microorganism's response to oxidizing stress conditions as it enhances biomass production, suppresses lactate formation, and leads to accumulation of large amounts of nisin.
authors: Department of Hygiene and Technology of Food of Animal Origin, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece. mp2000@vet.auth.gr
authors: Maria
authors: M
authors: Papagianni
authors: Nicholaos
authors: N
authors: Avramidis
mesh_terms: D000332:Aerobiosis; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics*; D001483:Base Sequence; D019149:Bioreactors / Q000382:microbiology; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D050259:Genes, Mitochondrial; D013294:Lactococcus lactis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism*; D009561:Nisin / Q000096:biosynthesis; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D000099188:Alternative Oxidase
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D009561:Nisin; D010088:Oxidoreductases; D010940:Plant Proteins; D011994:Recombinant Proteins; D000099188:Alternative Oxidase