title: Survival of the anaerobic fungus Orpinomyces sp. strain C1A after prolonged air exposure.
abstract: Anaerobic fungi are efficient plant biomass degraders and represent promising agents for a variety of biotechnological applications. We evaluated the tolerance of an anaerobic fungal isolate, Orpinomyces sp. strain C1A, to air exposure in liquid media using soluble (cellobiose) and insoluble (dried switchgrass) substrates. Strain C1A grown on cellobiose survived for 11, and 13.5 hours following air exposure when grown under planktonic, and immobilized conditions, respectively. When grown on switchgrass media, strain C1A exhibited significantly enhanced air tolerance and survived for 168 hours. The genome of strain C1A lacked a catalase gene, but contained superoxide dismutase and glutathione peroxidase genes. Real time PCR analysis indicated that superoxide dismutase, but not glutathione peroxidase, exhibits a transient increase in expression level post aeration. Interestingly, the C1A superoxide dismutase gene of strain C1A appears to be most closely related to bacterial SODs, which implies its acquisition from a bacterial donor via cross kingdom horizontal gene transfer during Neocallimastigomycota evolution. We conclude that strain C1A utilizes multiple mechanisms to minimize the deleterious effects of air exposure such as physical protection and the production of oxidative stress enzymes.
authors.affiliation: 1] Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074 [2] Department of Biology and Health Sciences, McNeese State University, Lake Charles, Louisiana 70609.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Struchtemeyer
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074.
authors.forename: Abhaya
authors.initials: A
authors.lastname: Ranganathan
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074.
authors.forename: M B
authors.initials: MB
authors.lastname: Couger
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074.
authors.forename: Audra S
authors.initials: AS
authors.lastname: Liggenstoffer
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074.
authors.forename: Noha H
authors.initials: NH
authors.lastname: Youssef
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74074.
authors.forename: Mostafa S
authors.initials: MS
authors.lastname: Elshahed
mesh_terms: D000388:Air; D000693:Anaerobiosis; D002475:Cellobiose / Q000378:metabolism; D003470:Culture Media; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D050296:Microbial Viability; D020085:Neocallimastigales / Q000502:physiology*; D010100:Oxygen / Q000502:physiology; D010802:Phylogeny; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D002475:Cellobiose; D013482:Superoxide Dismutase; D010100:Oxygen