Evolutionary relationships of the two basal fungal phyla Chytridiomycota and Zygomycota are reviewed in light of recent molecular phylogenetic investigation based on rDNA (nSSU, nLSU rDNA), entire mitochondrial genomes, and nuclear protein coding gene sequences (e.g., EF-1α, RPB1). Accumulated molecular evidence strongly suggests that the two basal fungal phyla are not monophyletic. For example, the chytridiomycete order Blastocladiales appears to be closely related to the zygomycete order Entomophthorales. Within the Zygomycota, a monophyletic clade, consisting of the Dimargaritales, Harpellales, and Kickxellales, which is characterized by a shared unique septal ultrastructure, was identified. Moreover, evidence for the exclusion of zygomycete orders Amoebidiales and Eccrinales from the Fungi, and their placement at the Animal-Fungi boundary has been clearly documented. Microsporidia, a group of amitochondriate organisms currently under intensive study, is not supported as derived within the Fungi, but a fungal affinity cannot be ruled out. Taking these molecular phylogenetic studies into account, we proposed a hypothetical evolutionary framework of basal fungi.
Three strains of xylose-lacking and ubiquinone-10-having ballistoconidium-forming yeasts isolated from plant leaves collected in Taiwan were found to represent respective new species. In phylogenetic trees constructed based on the nucleotide sequences of 18S rDNA and D1/D2 domain of 26S rDNA, they were located in the Agaricostilbum lineage (Agaricostilbum/Bensingtonia cluster). Since the taxonomic properties of these species coincide with those of the genus Sporobolomyces, they are described as Sporobolomyces diospyroris sp. nov., Sporobolomyces lophatheri sp. nov. and Sporobolomyces pyrrosiae sp. nov., respectively.
Phylogenetic analysis based on 16S rDNA sequences was performed on all type strains of the 14 validly described Methylobacterium species to ascertain the genealogic relationships among these species. The results showed that type strains of Methylobacterium were divided into two monophyletic groups whose members were distinct species with sequence similarity values greater than 97.0% between any two of the members in the same group. Only M. organophilum JCM 2833T and ATCC 27886T were not divided into those two groups. In particular, strains of M. dichloromethanicum and M. chloromethanicum exhibited extremely high similarity values (99.9 and 100%, respectively) with the type strain of M. extorquens. To clarify the relationships among Methylobacterium species in more detail, phylogenetic analysis based on the 5′ end hyper-variable region of 16S rDNA (HV region), ribotyping analysis, fatty acid analysis, G+C content analysis and DNA-DNA hybridization experiments was performed on 58 strains of Methylobacterium species. Results of the ribotyping analysis and the phylogenetic analysis based on HV region sequences indicated that many Methylobacterium strains, including M. ‘organophilum’ DSM 760T, have been erroneously identified. The DNA G+C content of Methylobacterium strains were between 68.1 and 71.3%. Results of whole-cell fatty-acid profiles showed that all strains contained 18 : 1ω7c as the primary fatty acid component (82.8–90.1%), with 16 : 0 and 18 : 0 as minor components. M. dichloromethanicum DSM 6343T, M. chloromethanicum NCIMB 13688T, and M. extorquens IAM 12631T exhibited high DNA-DNA relatedness values between each other (69–80%). M. lusitanum NCIMB 13779T also showed a close relationship with M. rhodesianum DSM 5687T at DNA-DNA relatedness levels of 89–92%. According to these results, many Methylobacterium strains should be reclassified, with M. dichloromethanicum and M. chloromethanicum regarded as a synonym of M. extorquens, and M. lusitanum a synonym for M. rhodesianum.
An acetic acid bacterium, designated as isolate AC28T, was isolated from a flower of red ginger (khing daeng in Thai; Alpinia purpurata) collected in Chiang Mai, Thailand, at pH 3.5 by use of a glucose/ethanol/acetic acid (0.3%, w/v) medium. A phylogenetic tree based on 16S rRNA gene sequences for 1,376 bases showed that isolate AC28T constituted a cluster along with the type strain of Kozakia baliensis. However, the isolate formed an independent cluster in a phylogenetic tree based on 16S-23S rDNA internal transcribed spacer (ITS) region sequences for 586 bases. Pair-wise sequence similarities of the isolate in 16S rRNA gene sequences for 1,457 bases were 93.0–88.3% to the type strains of Asaia, Kozakia, Swaminathania, Acetobacter, Gluconobacter, Gluconacetobacter, Acidomonas, and Saccharibacter species. Restriction analysis of 16S-23S rDNA ITS regions discriminated isolate AC28T from the type strains of Asaia and Kozakia species. Cells were non-motile. Colonies were pink, shiny, and smooth. The isolate produced acetic acid from ethanol. Oxidation of acetate and lactate was negative. The isolate grew on glutamate agar and mannitol agar. Growth was positive on 30% D-glucose (w/v) and in the presence of 0.35% acetic acid (w/v), but not in the presence of 1.0% KNO3 (w/v). Ammoniac nitrogen was hardly assimilated on a glucose medium or a mannitol medium. Production of dihydroxyacetone from glycerol was weakly positive. The isolate did not produce a levan-like polysaccharide on a sucrose medium. Major isoprenoid quinone was Q-10. DNA base composition was 63.1 mol% G+C. On the basis of the results obtained, Neoasaia gen. nov. was proposed with Neoasaia chiangmaiensis sp. nov. The type strain was isolate AC28T (=BCC 15763T =NBRC 101099T).
Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)