title: Phylogenetic analysis identifies the 'megabacterium' of birds as a novel anamorphic ascomycetous yeast, Macrorhabdus ornithogaster gen. nov., sp. nov.
abstract: An organism commonly referred to as 'megabacterium' colonizes the gastric isthmus of many species of birds. It is weakly gram-positive and periodic acid-Schiff-positive and stains with silver stains. Previous studies have shown that it has a nucleus and a cell wall similar to those seen in fungi. Calcofluor white M2R staining suggests that the cell wall contains chitin, a eukaryote-specific substance, and rRNA in situ hybridization demonstrates that it is a eukaryote. To characterize this organism phylogenetically, DNA was extracted from purified cells. rDNA was readily amplified by PCR with pan-fungal DNA primer sets and primer sets derived from the newly determined sequence, but not with bacteria-specific primer sets. Specific primer sets amplified rDNA from isthmus scrapings from an infected bird, but not from a non-infected bird or other control DNA. The sequence was confirmed to derive from the purified organism by in situ rRNA hybridization using a specific probe. Phylogenetic analysis of sequences of the 18S rDNA and domain D1/D2 of 26S rDNA showed the organism to be a previously undescribed anamorphic ascomycetous yeast representing a new genus. The name Macrorhabdus ornithogaster gen. nov., sp. nov. is proposed for this organism. The type material is CBS 9251T (= NRRL Y-27487T).
authors.affiliation: Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Tomaszewski
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Logan
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Karen F
authors.initials: KF
authors.lastname: Snowden
authors.affiliation: Microbial Genomics and Bioprocessing Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL 61604-3999, USA.
authors.forename: Cletus P
authors.initials: CP
authors.lastname: Kurtzman
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.|Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Phalen
mesh_terms: D000818:Animals; D001203:Ascomycota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D001717:Birds / Q000382:microbiology*; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D012331:RNA, Fungal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D009626:Terminology as Topic
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S