Antonievan Leeuwenhoek 67: 17%179, 1995. 177 © 1995 KluwerAcademicPublishers. Printedin the Netherlands.

Babjevia gen. nov. - a new of the Lipomycetaceae

M.Th. Smith l, J.R van der Walt 2 & W.H. Batenburg-van der Vegte 1 1 Centraalbureau voor Schimmelcultures, Yeast Division and Department of Microbiology & Enzymology, Delft University of Technology, Kluyver Laboratoly, Julianalaan 67, 2628 BC Delft, The Netherlands; 2 Department of Microbiology & Biochemistry, University of the Orange Free State, PO. Box 339, Bloemfontein, 9300, South Africa

Received 9 December 1993; acceptedin revisedform 29 March 1994

Key words: Babjevia anomala, Lipomycetaceae, yeast

Abstract

The species described as anomalus Babjeva & Gorin shows significant genetic and phenotypic divergence from the type species Lipomyces starkeyi Lodder & Kreger-van Rij in terms of rRNA base sequence substitution and ascosporal and septal ultrastructure. The species is consequently reclassified in the new, unispecific genus Babjevia, as Babjevia anomala.

Introduction L. starkeyi were consistently characterized by the fin- gerprint sequence UUA, and L. anomalus by the devi- Babjeva & Gorin (1975), during a study of yeasts asso- ating sequence, UAAUCUA. Given this genetic diver- ciated with podzolic soils of the northern taiga sub- gence, Yamada & Nogawa (1990) concluded that L. zone in Russia, recovered strains of an undescribed anomalus could be assigned to a separate genus. species, which, because of its formation of attached, Re-examination of the three available strains of L. multispored, saccate asci, they regarded as representa- anomalus confirmed that it not only differs significant- tive of the genus Lipomyces Lodder & Kreger-van Rij ly from the type species, L. starkeyi, in its cultural, (1952). Nevertheless, they stressed the fact that the new morphological, reproductive and generative characters species differed from the type species, L. starkeyi Lod- but has many properties in common with species of the der & Kreger-van Rij (1952), by the formation of non- genus Batra & Millner (Batra 1978). encapsulated cells, pseudophyphal cell-aggregates and On solid substrates, L. anomalus, like D. uninucleata pulvinate colonies on solid substrates. The new species (Biggs) Batra & Millner and D. tothii (Zsolt) Batra & also had a lower optimal growth temperature and uti- Millner, forms butyrous, raised, restricted and more or lized relatively few carbon sources. In view of these less pulvinate colonies, unlike the viscous, confluent deviating characters, the species was described as L. growth of L. starkeyi and other members of the genus. anomalus Babjeva & Gorin (1975). The relationship with Dipodascopsis is also supported Comparative rRNA base sequence analysis by by its formation of short hyphal units with open, cen- Yamada & Nogawa (1990) and Kurtzman & Liu (1990) trally located septal pores (Figs la, b, c), different from of the type strains ofL. anomalus, L. kononenkoae, L. the micropores observed in L. starkeyi (Fig. ld) and fur- lip@r, L. starkeyi and L. tetrasporus, have, however, ther by the aspirin-sensitive production of arachidonic established that L. anomalus diverges from the oth- acid metabolites (Kock et al. 1992)- two characters not er four species by disproportionate differences in the observed in Lipomyces. Like the allantoid ascospores nucleotide substitutions in its 18S, 25S and 26S sub- of Dipodascopsis, the globose to ellipsoid ascospores units. Yamada & Nogawa (1990) also reported that of L. anomalus are hyaline, lacking the amber colour in the respective 18S rRNA regions (positions 1451- characteristic of Lipomyces species. 1618), L. kononenkoae, L. lip@r, L. tetrasporus, and 178

Fig. 1. Transmission electron micrographs of septa with open pores Fig. 2. Transmission electron micrographs of a. CBS 6740 L. in a. CBS 6740 L. anomalus; b. CBS 190.37 D. uninucleata: CBS anomalus. Ascopore with single layered wall; b. CBS 6740 and 759.85 D. tothii; and with microspore in d, CBS 1807 L. starkeyi. c. CBS 7606 L anomalus. Ascopores surrounded by endoplasmic Bars represent 0,5/~m (Fixation: 2% KMnO4). membranes (arrows); d. CBS 1807 L. starkeyi. Ascospore wall con- sisting of light inner layer and dark outer layer. Bars represent 0,5 ~m (Fixation 2% KMnO4).

Ultrastructurally, as revealed by transmission elec- tron microscopy, the ascospores of L. anomalus differ cellulis zymoticis multilateraliter gemmatantibus, con- fundamentally from those of Lipomyces and Dipodas- stans. Asci affixi, saccati, uni- vel multispori. Ascospo- copsis. The spores of L. anomalus appear glabrous, rae hyalinea, globosae vell ellipsoideae, glabrae, pari- but the ascosporal wall is atypical in consisting of a ete unistratoso. Imidazolo pro fonte nitrogeni utens. single, dark, electron-opaque layer (Fig. 2a), lacking Colonies butyrous, pulvinate, restricted. Vegetative the lighter, electron-translucent inner layer which, as state dimorphic, composed of short, septate hyphae a rule, characterizes the ascosporal wall of ascomyce- with single, open, central pores, and multilaterally tous yeasts (Fig. 2d). These unusual ascospores may budding yeast cells. Asci saccate, attached, one- to sometimes be surrounded by a membrane, possibly multispored. Ascospores hyaline, globose to ellipsoid, of endoplasmic origin (Figs 2b, c). This phenomenon smooth with a single-layered wall. Imidazole is utilized could account for the report by Babjeva & Gorin (1975) as source of nitrogen. that the spores of this species are associated with an Typus: Babjevia anomala (Babjeva & Gorin) Van 'exosporium'. der Walt & M.Th. Smith comb. nov. (Basionym: Given the genetic divergence and phenotypic dif- Lipomyces anomalus Babjeva & Gorin in Antonie van ferences that distinguish L. anomalus from the type Leeuwenhoek 41: 186: 1975). species of Lipomyces and Dipodascopsis, the proposal The genus is named for Prof. Dr. Inna R Babjeva, of Yamada & Nogawa (1990) is followed by classify- in recognition of her services to yeast systematics. ing L. anomalus in a new genus: Although Yamada & Nogawa (1990) and Kurtzman Babjevia Van der Walt & M.Th. Smith, gen. nov. & Liu (1990) did not include Dipodascopsis species (Lipomycetaceae) in their studies, it can be anticipated that rRNA base Coloniae butyrosae pulvinatae restrictae. Status sequence analyses will confirm the postulated con- vegetativus dimorphus, ex hyphis brevibus septatis nexion between Babjevia and Dipodascopsis. While poris septalibus singulis apertis centralibus praeditis, et the segregation Babjevia imparts greater homogeneity 179 to Lipomyces, it also calls for a re-evaluation of the References genus Waltomyces Yamada & Nakase (1985) based on L. lipofer. Since, (a) the comparative data of Yamada BabjevaIP & Gorin SE (1975)Lipomycesanomalus sp. nov. Antonie van Leeuwenhoek41: 185-191 & Nogawa (1990) and Kurtzman & Liu (1990) estab- Batra LR (1978) Taxonomy and systematics of the Hemias- lished that the type strain ofL. lipofer shows no dispro- comycetes. In: SubramanianCV (Ed) Taxonomyof Fungi. Proc. portionate differences in its rRNA base substitutions, Int. Symp. Madras, India (pp 187-214)Madras University,1973 and (b) the criteria originally adopted for the demarca- Kock JLE Coetzee DJ, Dijk MS van, Truscott M, Botha A & Augustyn OPH (1992) Evidence for, and taxonomic value of, tion of the genus (differences in ascosporal topography an arachidonicacid cascade in the Lipomycetaceae.Antonie van and ubiquinone isoprenelogue composition) no longer Leeuwenhoek 62:251-259 serve for generic differentiation in the Lipomycetaceae Kurtzman CP & Liu Z (1990) Evolutionary affinities of species (Van der Walt 1992), the segregation of Waltomyces assigned to Lipomyces and Myxozymaestimated from ribosomal RNA sequencedivergence. Current Microbiol.21: 387-393 from Lipomyces does not seem justified. Lodder J & Kreger-vanRij NJW (1952) The yeasts, a taxonomic The more recently described species, L. japonicus study. North Holland Publ. Co., Amsterdam Van der Walt et al. (1989), not dealt with by either Walt JP van der (1992) The Lipomycetaceae, a model family for Yamada & Nogawa (1990) or Kurtzman & Liu (1990), phylogeneticstudies. Antonie van Leeuwenhoek62:247-250 Walt JP van der, SmithMTh, Yamada Y, Nakase T & Richards PDG is excluded from Babjevia in terms of its (a) typical- (1989) Lipomycesjaponicussp. nov. from Japanese soil. System. ly double-layered, ascomycetous ascosporal wall (Van Appl. Microbiol. 11 : 302-304 der Walt et al. 1989), and (b) characteristic 18S rRNA Yamada Y & Nakase T (1985) Waltomyces,a new ascesporogenous UUA fingerprint sequence in the 1488-1491 position yeast genus for the Q10-equipped, slime producing organisms whose asexualreproduction is by multilateralbudding and whose (Y. Yamada, 1994; personal communication). ascospores have smooth surfaces. J. Gen. Appl. MicrobioLTokyo Lipomyces consequently comprises the currently 31:491-492 known species, L. japonicus, L. kononenkoae, L. Yamada Y & Nogawa C (1990) The molecular phylogeny of the lipofer, L. starkeyi and L. tetrasporus. lipomycetaceous yeasts based on partial sequences of 18S and 26S ribosomalribonucleic acids. In: Reisinger A & BresinskyA (Eds) Abstracts 4th Int. Mycol. Congress Regensburg(p. 63)