title: Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.
abstract: Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric) for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells). In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i) the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii) the thiol-molecules (cysteine + coenzyme M-SH + sulfide) and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days) of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Jasso-Chávez
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: M Geovanni
authors.initials: MG
authors.lastname: Santiago-Martínez
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lira-Silva
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Erika
authors.initials: E
authors.lastname: Pineda
authors.affiliation: Facultad de Medicina, UNAM, Mexico City, Mexico.
authors.forename: Armando
authors.initials: A
authors.lastname: Zepeda-Rodríguez
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Belmont-Díaz
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Rusely
authors.initials: R
authors.lastname: Encalada
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Emma
authors.initials: E
authors.lastname: Saavedra
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico.
authors.forename: Rafael
authors.initials: R
authors.lastname: Moreno-Sánchez
mesh_terms: D000388:Air; D064349:Genome, Microbial; D008697:Methane / Q000096:biosynthesis* / Q000378:metabolism; D017020:Methanosarcina / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D009195:Peroxidase / Q000235:genetics; D011122:Polyphosphates / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D011122:Polyphosphates; D017382:Reactive Oxygen Species; D009195:Peroxidase; D008697:Methane; D010100:Oxygen