The Yeasts || Wickerhamiella van der Walt (1973)

Chapter 79

Wickerhamiella van der Walt (1973)

Marc-Andre Lachance and Cletus P. Kurtzman

DIAGNOSIS OF THE GENUS

Asexual reproduction: Multilateral budding occurs on either a narrow or a broad base. The cells are unusually small, and range from sphericalto ellipsoidal. Neither hyphae nor pseudohyphae are produced.Sexual reproduction: Asci are conjugated and usually form a single, roughened ascospore. The spores are spherical to elongate, and a basalring may be formed. Asci become deliquescent at the terminus, sometimes with a flanged tubular outgrowth.Physiology/biochemistry: Sugars are not fermented. Nitrate is assimilated by most species. Pellicles are not formed on liquid media. The dia-zonium blue B reaction is negative.Phylogenetic placement: Wickerhamiella is a member of a clade that includes Sugiyamaella, Trichomonascus and Zygoascus (Figs 13.1, 79.1).

TYPE SPECIES

Wickerhamiella domercqiae van der Walt

70

100

99

Candida sp. BG01726006A11 / AY242275Candida sp. BG02718027A12 / AY520352

98

100

99

97

10059

Candida sp. BG99818131 / AY242245Candida sp. ST-315 / DQ404498

100

63

71

96

93

100

98

94

100

100

76

52

0.05

Candida sergipensis UFMG R188T / AF397405Candida spandovensis NRRL Y-17761T / U62309

Candida sp. UWO 00-136.3 / AF313356

Candida sp. pb155 / AJ786253

Candida sorbophila NRRL Y-7921T / U45852Candida sp. NRRL Y-17858 / AF017239

Candida versatilis CBS 1752T / U45834

Candida bombiphila CBS 9712T / AJ620185

Wickerhamiella domercqiae CBS 4351T / U45847

Candida sp. UWOPS 00-192.1 / AF313368Candida sp. UWOPS 00-107.1 / AF313369

Candida galacta CBS 6939T / U45820

Wickerhamiella lipophila CBS 8458T / AF046040Wickerhamiella occidentalis CBS 8452T / AF046037Wickerhamiella australiensis CBS 8456T / AF046033

Wickerhamiella cacticola CBS 8454T / AF046035

Candida drosophilae CBS 8459T / AF046039Candida vanderwaltii CBS 5524T / U62313

Candida azyma CBS 8626T / U62312Candida pararugosa CBS 1010T / U62306

Candida sp. UWO(PS)00-102.1 / AF313351

FIGURE 79.1 Phylogram of Wickerhamiella and related species determined from neighbor-joining analysis of D1/D2 LSU rRNA gene sequences.GenBank accession numbers follow strain numbers.

891The Yeasts, a Taxonomic Study© 2011 Elsevier B.V. All rights reserved.

SPECIES ACCEPTED

1. Wickerhamiella australiensis Lachance, Rosa, Starmer, Schlag-Edler, Barker & Bowles (1998)2. Wickerhamiella cacticola Lachance, Rosa, Starmer, Schlag-Edler, Barker & Bowles (1998)3. Wickerhamiella domercqiae van der Walt (1973)4. Wickerhamiella lipophila Lachance, Bowles, Mueller & Starmer (2000)5. Wickerhamiella occidentalis Lachance, Rosa, Starmer, Schlag-Edler, Barker & Bowles (1998)

KEY TO SPECIES

1. a. Citrate is weakly or strongly assimilated..................................................................................................................................................................2b. Citrate is not assimilated ................................................................................................................................................................................................3

2 (1). a. D-Gluconate is assimilated ..................................................................................................................................................................W. domercqiae: p. 894b. D-Gluconate is not assimilated ...............................................................................................................................................................W. cacticola: p. 893

3 (1). a. Nitrate is assimilated .......................................................................................................................................................................................................4b. Nitrate is not assimilated .........................................................................................................................................................................W. lipophila: p. 895

4 (3). a. Glucono-δ-lactone is weakly assimilated .....................................................................................................................................W. occidentalis: p. 896b. Glucono-δ-lactone is not assimilated............................................................................................................................................W. australiensis: p. 892

SYSTEMATIC DISCUSSION OF THE SPECIES

79.1. Wickerhamiella australiensis Lachance,Rosa, Starmer, Schlag-Edler, Barker & Bowles(1998)

Growth on YM agar: After 3 days at 25�C, colonies are small, convex,glossy, smooth, white, and butyrous.Growth in glucose-yeast extract broth: After 3 days at 25�C, thecells are spherical to ovoid, occur singly or in parent-bud pairs, andmeasure 1�232�3 μm.Dalmau plate culture on corn meal agar: After 1 week at 25�C, nei-ther pseudohyphae nor true hyphae are formed.Formation of ascospores: After 1 day on YCBAS agar, mixtures ofcomplementary mating types form short conjugation tubes and con-jugate in pairs, giving rise to zygotes and asci containing one or,rarely, two ascospores (Fig. 79.2). After 2 days, most asci have releasedtheir ascospores through a flared terminal opening. The ascosporesare spherical. Electron microscopy reveals that the spores have a con-voluted surface and a skirt-like ledge (Lachance et al. 1998).

Fermentation: Absent.

Growth (on Agar Media)

Glucose 1 D-Ribose 2

Inulin 2 Methanol 2

Sucrose 2 Ethanol sRaffinose 2 Glycerol 1/wMelibiose 2 Erythritol 2

Galactose 1/w Ribitol wLactose 2 Galactitol 2

Trehalose 2 Mannitol 1

Maltose 2 Glucitol 1

Melezitose 2 myo-Inositol 2

Methyl-α-D-glucoside 2 DL-Lactate 2

Soluble starch 2 Succinate 1

Cellobiose 2 Citrate 2

Salicin 2 D-Gluconate 2

L-Sorbose 1 D-Glucosamine 2

L-Rhamnose 2 N-Acetyl-D-glucosamine 2

D-Xylose v Hexadecane wL-Arabinose 2 Nitrate 1

D-Arabinose 2 Vitamin-free 2

Additional Growth Tests and Other Characteristics

Xylitol s2-Keto-D-gluconate 2

D-Glucuronate 2

Glucono-δ-lactone 2

Amino acid-free 1

Nitrite 1

Ethylamine vLysine 1

Cadaverine 1

10% NaCl v50% Glucose s

Starch production 2

DBB 2

Gelatin 2

Casein 2

Lipase 1

Acid production 2

Cycloheximide 0.01% 1


1% Acetic acid 2

Growth at 30�C 1

Growth at 37�C v

CoQ: Not determined.Mol% G1C: Not determined.Gene sequence accession numbers, type strain: LSU rRNA (incl. D1/D2)5DQ438232, mitochondrial SSU5DQ442748, cytochrome oxi-dase II5DQ443076.Cell carbohydrates: Not determined.

TABLE 79.1 Key Characters of Species Assigned to the Genus Wickerhamiella

Species Growth

Galactose Citrate D-Gluconate 2-Keto-D-gluconate Glucono-δ-lactone Nitrate

W. australiensis 1/w 2 2 2 2 1

W. cacticola w w 2 2 2 1

W. domercqiae v 1 s 1 1 1

W. lipophila 2 2 2 2 2 2

W. occidentalis s 2 2 2 w 1

892 PART | IVB Descriptions of Teleomorphic Ascomycetous Genera and Species

Origin of the strains studied: UWOPS 95-604.3 (CBS 8456, NRRLY-27360) and other strains, isolated from flowers of morning glory(Ipomoea spp., Convolvulaceae); UWOPS 95-631.3 (CBS 8457) and otherstrains, from flowers of Hibiscus spp. (Malvaceae); UWOPS 95-686.3,and other strains, from nitidulid beetles (Aethina spp., Coleoptera:Nitidulidae); UWOPS 95-737.2 and other strains, from a fruit fly(Drosophila hibisci), in New South Wales, Queensland, and NorthernTerritory, Australia, and from Fiji and Rarotonga (Cook Islands); UWOPS05-260.2, and another strain from a nitidulid beetle (Eupuraea gestroi,Coleoptera: Nitidulidae), and UWOPS 05-264.4 from Drosophila sp., inflowers of Ipomoea cairica, Cameron Highlands, Malaysia.Complementary mating types: CBS 8456, mating type h1, and CBS8457, mating type h2.Type strain: CBS 8456.Systematics: Lachance et al. (1998) described W. australiensis toaccommodate many isolates collected in eastern Australia fromephemeral flowers and associated beetles and drosophilids. The hap-loid, heterothallic strains mate rapidly and form ascospores. Matingwith closely related species was not observed. Mating tests provide aquick and simple means of identification. Alternatively, the speciescan be identified from its D1/D2 sequence, which differs from that ofother species by several nucleotide substitutions.Ecology: The distribution of W. australiensis extends across theAustralasia-Pacific biogeographic region, matching to a large extentthe distribution of the genus Aethina, a nitidulid beetle that occupieswith Drosophila species the ephemeral flowers of Hibiscus andIpomoea species. The species is one of a handful in that ecosystem,that is known to span the Wallace line, but it has not been isolatedin Hawai’i where Kodamaea anthophila and a few other South Pacificspecies have apparently been introduced together with Aethina con-color (Lachance et al. 2001e). The absence of W. australiensis may bethe result of competitive exclusion by W. occidentalis and W. lipophila,both of which are abundant in Hawai’i.Biotechnology: Unknown.Agriculture and food: Unknown.Clinical importance: Unknown.

79.2. Wickerhamiella cacticola Lachance, Rosa,Starmer, Schlag-Edler, Barker & Bowles (1998)

Growth on YM agar: After 3 days at 25�C, colonies are small, convex,glossy, smooth, white, and butyrous.Growth in glucose-yeast extract broth: After 3 days at 25�C, thecells are spherical to ovoid, occur singly or in parent�bud pairs, andmeasure 1�232�3 μm. The buds are formed on a short neck.Dalmau plate culture on corn meal agar: After 1 week at 25�C, nei-ther pseudohyphae nor true hyphae are formed.Formation of ascospores: After 1 day on YCBAS agar, mixed matingtypes produce short conjugation tubes, zygotes, and asci containing

one ascospore (Fig. 79.3). After 2 days, most asci have released theirascospore through a flared terminal opening. The ascospores arespherical and smooth with an indistinct basal ledge.



Glucose 1

Inulin 2

Sucrose 2

Raffinose 2

Melibiose 2

Galactose wLactose 2

Trehalose 2

Maltose 2

Melezitose 2

Methyl-α-D-glucoside 2

Soluble starch 2

Cellobiose 2

Salicin 2

L-Sorbose 1

L-Rhamnose 2

D-Xylose 2

L-Arabinose 2

D-Arabinose v

D-Ribose 2

Methanol 2

Ethanol wGlycerol sErythritol 2

Ribitol vGalactitol 2

Mannitol 1

Glucitol 1

myo-Inositol 2

DL-Lactate 2

Succinate 1

Citrate wD-Gluconate 2

D-Glucosamine 2

N-Acetyl-D-glucosamine 2

Hexadecane 2

Nitrate 1

Vitamin-free 2


Xylitol v2-Keto-D-gluconate 2

D-Glucuronate 2


Amino acid-free 1

Nitrite 1

Ethylamine 1

Lysine 1

Cadaverine 1

10% NaCl s50% Glucose 2

Starch production 2

DBB 2

Gelatin 2

Casein 2

Lipase 1

Acid production 2



1% Acetic acid 2

Growth at 30�C 1

Growth at 37�C 1

CoQ: Not determinedMol% G1C: Not determined.Gene sequence accession numbers, type strain: LSU rRNA (incl. D1/D2)5DQ438234, mitochondrial SSU5DQ442750, cytochrome oxi-dase II5DQ443078.Cell carbohydrates: Not determined.

(A) (B) (C)

FIGURE 79.2 Wickerhamiella australiensis CBS 84563CBS 8457.(A) Deliquesced ascus and liberated ascospore with broad ledge.(B) Mature ascus with two ascospores. (C) Empty, deliquesced ascus.After 2 days at 25�C on YCBAS agar. Bar55 μm. Reproduced fromLachance et al. (1998), with permission.

(A) (B) (C)

FIGURE 79.3 Wickerhamiella cacticola CBS 84543CBS 8455.(A) Intact ascus. (B, C) Deliquesced asci. (C) Released ascospore. After2 days at 25�C on YCBAS agar. Bar55 μm. Reproduced fromLachance et al. (1998), with permission.

893Chapter | 79 Wickerhamiella van der Walt (1973)

Origin of the strains studied: UFMG 96-267 (CBS 8454, NRRLY-27362), UFMG 96-381 (CBS 8455), and one other strain, isolatedfrom flowers of columnar cactus (Cereus pernambucensis); UFMG 95-343.2, from a flower of columnar cactus (Pilosocereus arrabidae);UFMG 96-LS32 and UFMG LS-34, from flowers of Cereus calcirupicola,all from the states of Rio de Janeiro and Minas Gerais, Brazil.Complementary mating types: CBS 8454, mating type h1, and CBS8455, mating type h2.Type strain: CBS 8454.Systematics: Wickerhamiella cacticola was described from five strainsisolated from flowers of columnar cacti in Brazil (Lachance et al.1998). The species was circumscribed based on the formation of asciby pairs of compatible haploid strains. Mating with related specieshas not been observed. The D1/D2 LSU rRNA gene sequence differsby several substitutions from the closest known relatives and pro-vides rapid and convenient identification, as does mixing withstrains of known mating types. Growth characteristics are lessdiscriminatory.Ecology: The original isolates of W. cacticola came from flowers ofcolumnar cacti where they were ostensibly vectored by drosophilidsor beetles. Later isolations demonstrated that they occur in nitidulidbeetles found in the flowers (Lachance et al. 2001e). The species maybe endemic to South America.Biotechnology: Unknown.Agriculture and food: Unknown.Clinical importance: Unknown.

79.3. Wickerhamiella domercqiae van derWalt (van der Walt and Liebenberg 1973a)

Anamorph: Candida domercqiae (van der Walt & van Kerken) S.A.Meyer & YarrowSynonyms:

Torulopsis domercqiae (as T. domercqii) van der Walt & van Kerken(1960)

Candida domercqiae (van der Walt & van Kerken) S.A. Meyer &Yarrow (Yarrow and Meyer 1978)

Torulopsis saccharum Shehata (1960) nom. nud.1

Growth on YM agar: After 3 days at 25�C, the cells are spherical toellipsoidal, 1�331�4 μm, and occur singly, in pairs, or in small clus-ters. CBS 4351 has quite small cells that tend to be at the lower endof the size range given, whereas CBS 4733 has noticeably larger cells.Growth is butyrous and light tannish-white in color.Growth in glucose-yeast extract broth: Pellicles are not formed.Dalmau plate culture on corn meal agar: After 1 week at 25�C,pseudohyphae and true hyphae are not formed.Formation of ascospores: Asci are conjugated and each produces asingle elongated spore which is released at maturity (Fig. 79.4).Because of the small size of cells and spores, van der Walt andLiebenberg (1973a) examined the process of ascosporulation bytransmission electron microscopy. They demonstrated that asci arisefrom conjugation between independent cells rather than conjugationbetween a cell and its bud. The elongated ascospores were shown tobe somewhat roughened and irregular in shape. Following dissolu-tion of a terminal portion of the ascus wall, van der Walt andLiebenberg (1973a) stated that the spores are ejected. Empty ascioften have a corrugated appearance. Heat treatment of sporulatingcultures gave only sporogenous colonies, thus indicating the speciesto be homothallic. However, because just one spore is formed perascus, it is not certain that they are haploid. Ascospores were

observed in PDA cultures of CBS 4733 after two weeks at 15�C.Sporulation was not detected in CBS 4351, the type strain.



Glucose 1

Inulin 2

Sucrose vRaffinose 2

Melibiose 2

Galactose vLactose 2

Trehalose 2

Maltose 2

Melezitose 2


Soluble starch 2

Cellobiose 2

Salicin 2

L-Sorbose 1

L-Rhamnose 2

D-Xylose vL-Arabinose 2

D-Arabinose 2

D-Ribose vMethanol 2

Ethanol 1

Glycerol sErythritol 2

Ribitol vGalactitol 2

Mannitol 1

Glucitol vmyo-Inositol 2

DL-Lactate 2

Succinate 1

Citrate 1

D-Gluconate sD-Glucosamine 2


Hexadecane 2

Nitrate 1

Vitamin-free 2


Xylitol v2-Keto-D-gluconate 1

D-Glucuronate 2


Amino acid-free 1

Nitrite 1

Ethylamine 1

Lysine 1

Cadaverine 1

10% NaCl 1

50% Glucose v

Starch production 2

DBB 2

Gelatin 2

Casein 2

Lipase 1

Acid production 2



1% Acetic acid 2

Growth at 30�C 1

Growth at 37�C v

FIGURE 79.4 Wickerhamiella domercqiae CBS 4733. Budding cellsand an ascus with a single ascospore (arrow), after 2 weeks on PDA,15�C. A cluster of four free ascospores is located on the left of thephotomicrograph. Bar55 μm. Inset: An enlarged view of an ascuswith an ascospore. Bar51 μm.

1 Synonymy determined from multigene sequence analysis (Kurtzman andRobnett 2007).


CoQ: Not determined.Mol% G1C: 48.6, CBS 4351 (BD: Stenderup et al. 1972).Gene sequence accession numbers, type strain: LSU rRNA (incl. D1/D2)5DQ438240, SSU rRNA5AB018157, mitochondrial SSU5

DQ442756, cytochrome oxidase II5DQ443084.Cell carbohydrates: Glucose, mannose, and galactose are present incell hydrolysates (Suzuki and Nakase 1998).Origin of the strains studied: NRRL Y-6692 (CBS 4351), type strainof Torulopsis domercqiae, isolated from a wine vat, South Africa;NRRL Y-6698 (CBS 4733), type strain of Torulopsis saccharum,from effluent from a sugar cane factory, Brazil.Type strain: CBS 4351.Systematics: Van der Walt and van Kerken (1960) describedTorulopsis domercqii on the basis of a strain isolated from a wine vat.They commented on the small cell size and the similarity withCandida (Torulopsis) magnoliae, a member of the Starmerella clade.Later, van der Walt and Liebenberg (1973a) erected the genusWickerhamiella after having examined two additional strains andobserving conjugation and ascospore formation in two of the threeavailable strains. From phenotypic characterizations, one of thestrains of W. domercqiae had been previously identified as Candida(Torulopsis) magnoliae, a member of the Starmerella clade.Ecology: The species is rare, making ecological generalizationsuncertain.Biotechnology: Chen et al. (2006) reported the production of asophorolipid by W. domercqiae that induces apoptosis in human can-cer cells. Few details were given on the identification of the strain(based on a Biolog profile), its deposition, or the chemical similaritybetween the sophorolipid in question and that known to occur inStarmerella bombicola. The Wickerhamiella and Starmerella clades doshare a number of similarities. A better knowledge of the taxonomicrange of organisms able to produce these intriguing substances couldgreatly enhance the prospection of a broader diversity of potentialanti-cancer agents.Agriculture and food: Unknown.Clinical importance: Unknown.Additional comments: Unknown.

79.4. Wickerhamiella lipophila Lachance,Bowles, Mueller & Starmer (2000a)

Anamorph: Candida lipophila Lachance, Rosa, Starmer, Schlag-Edler,Barker & BowlesSynonym:

Candida lipophila Lachance, Rosa, Starmer, Schlag-Edler, Barker &Bowles (1998).

Growth on YM agar: After 3 days at 25�C, the colonies are small,convex, glossy, smooth, white and butyrous.Growth in glucose-yeast extract broth: After 3 days at 25�C, thecells are spherical to ovoid, occur singly or in parent�bud pairs, andmeasure 1�232�3 μm. A pellicle is not formed.Dalmau plate culture on corn meal agar: After 1 week at 25�C,pseudohyphae and true hyphae are not formed.Formation of ascospores: Zygotes are formed in mixed culturesof complementary mating types after 1�3 days incubation(Fig. 79.5). A single ascospore with an indistinct ledge is formedand liberated after 3 days by apical ascus deliquescence.Conjugation was observed in fresh isolates on YCBAS agar. Matingand ascus formation in older cultures was unpredictable, butoccurred best on dilute (25%) V8 juice agar after 3 or more daysat 25�C.


Growth (on Liquid Media)

Glucose 1

Inulin 2

Sucrose 2

Raffinose 2

Melibiose 2

Galactose 2

Lactose 2

Trehalose 2

Maltose 2

Melezitose 2


Soluble starch 2

Cellobiose 2

Salicin 2

L-Sorbose 1/sL-Rhamnose 2

D-Xylose 2

L-Arabinose 2

D-Arabinose 2

D-Ribose 2

Methanol 2

Ethanol 2

Glycerol 2

Erythritol 2

Ribitol 2

Galactitol 2

Mannitol sGlucitol smyo-Inositol 2

DL-Lactate 2

Succinate sCitrate 2

D-Gluconate 2

D-Glucosamine 2


Hexadecane sNitrate 2

Vitamin-free 2


Xylitol 2

2-Keto-D-gluconate 2

D-Glucuronate 2


Amino acid-free 1

Nitrite 2

Ethylamine 2

Lysine 1

Cadaverine s10% NaCl s50% Glucose w

Starch production 2

DBB 2

Gelatin 2

Casein 2

Lipase 1

Acid production 2

Cycloheximide 0.01% vCycloheximide 0.1% v1% Acetic acid 2

Growth at 30�C wGrowth at 37�C 2

(A) (B)

(C) (D) (E)

FIGURE 79.5 Wickerhamiella lipophila CBS 84583CBS 8812.(A) Budding cells. (B�E) Asci . After 3 days at 25�C on 25% V8 juiceagar. Bar55 μm. Reproduced from Lachance et al. (2000), withpermission.


CoQ: Not determined.Mol% G1C: Not determined.Gene sequence accession numbers, type strain: LSU rRNA (incl. D1/D2)5DQ438231, mitochondrial SSU5DQ442747, cytochrome oxi-dase II5DQ443075.Cell carbohydrates: Not determined.Origin of the strains studied: UWOPS 91-681.3 (CBS 8458, NRRLY-27367) and other strains, isolated from flowers of morning glory(Ipomoea spp., Convolvulaceace); UWOPS 00-340.1 (CBS 8812) andother strains, from a fruit fly (Drosophila floricola); UWOPS 87-2199.1and other strains, from an endemic drosophilid (Exaloscaptomyza cal-liginosa, Diptera: Drosophilidae); UWOPS 00-710.3, from a nitidulidbeetle (Conotelus mexicanus, Coleoptera: Nitidulidae); UWOPS 00-657.3, from a nitidulid beetle (Prosopeus subaeneus, Coleoptera:Nitidulidae), Hawai’i.Complementary mating types: CBS 8458, mating type h1, and CBS8812, mating type h2.Type strain: CBS 8458.Systematics: Lachance et al. (1998) described Candida lipophila toaccommodate many strains isolated in morning glory flowers andassociated insects in Hawai’i. Conjugation and ascospore formationwere observed later (Lachance et al. 2000a) when fresh isolates weremixed and examined soon after return from the field to the labora-tory. All strains formed zygotes when mated with at least one partneron dilute V8 agar. Although not all pair-wise mixtures of complemen-tary strains mated, it was possible to assign all strains to one of twomating types, suggesting that a multiallelic mating system is not pres-ent. The D1/D2 LSU rRNA gene sequence differs by five substitutionsfor that of the sister species W. occidentalis. Although the two speciesform a sister pair (Fig. 79.1), they are clearly separable on ascus mor-phology and nitrate utilization as well as mating incompatibility.Ecology: The species stands out by its narrow range of growth abilitiescontrasted with strong hydrolysis of Tween 80. Most strains reportedas “Candida species L” by Lachance et al. (1988) were later identified asW. lipophila, and a few as W. occidentalis. The distribution data clearlysuggested a strong association between the two species and drosophi-lids found in morning glories, in contrast to Metschnikowia and relatedspecies, which appeared to be associated with another substrate, laterfound to be the nitidulid beetles that visit the same flowers (Lachanceet al. 2001e). Unlike W. occidentalis, W. lipophila has hitherto been iso-lated only in Hawai’i, and is abundant there. The possibility exists thatit is endemic to Hawai’i in association with endemic drosophilids suchas Exalloscaptomyza calliginosa. The yeasts may be involved in enrich-ing the flies’ diet by converting flower lipids into a nutritionally richerbiomass consumed by the flies.Biotechnology: Unknown.Agriculture and food: Unknown.Clinical importance: Unknown.

79.5. Wickerhamiella occidentalis Lachance,Rosa, Starmer, Schlag-Edler, Barker & Bowles(1998)

Growth on YM agar: After 3 days at 25�C, the colonies are small,convex, glossy, smooth, white and butyrous.Growth in glucose-yeast extract broth: After 3 days at 25�C, thecells are spherical to ovoid, occur singly or in parent�bud pairs, andmeasure 1�232�3 μm. The buds are formed on a short neck. A pel-licle is not formed.Dalmau plate culture on corn meal agar: After 1 week at 25�C,pseudohyphae and true hyphae are not formed.Formation of ascospores: After 1 day on YCBAS agar, mixed matingtypes give rise to short conjugation tubes, zygotes, and asci contain-ing one ascospore located at the extremity of a protuberance that

grows from one of the conjugated cells. After 2 days, most asci havereleased their ascospore through a flanged terminal opening(Fig. 79.6). The ascospores are spherical with a slightly convolutedsurface. Two or more basal ledges are visible in the electron micro-scope (Lachance et al. 1998).



Glucose 1

Inulin 2

Sucrose 2

Raffinose 2

Melibiose 2

Galactose sLactose 2

Trehalose 2

Maltose 2

Melezitose 2


Soluble starch 2

Cellobiose 2

Salicin 2

L-Sorbose 1

L-Rhamnose 2

D-Xylose 2

L-Arabinose 2

D-Arabinose 2

D-Ribose 2

Methanol 2

Ethanol sGlycerol 1

Erythritol 2

Ribitol sGalactitol 2

Mannitol sGlucitol 1

myo-Inositol 2

DL-Lactate 2

Succinate 1

Citrate 2

D-Gluconate 2

D-Glucosamine 2


Hexadecane sNitrate 1

Vitamin-free 2

(A) (B) (C)

(D)

(E)

FIGURE 79.6 Asci of Wickerhamiella occidentalis CBS 84523UFMG96-197. (A, B). Immature asci. (C) Mature ascus with ledged spore. (D,E) Deliquesced asci. After 3 days at 25�C on YCBAS agar. Bar55 μm.Reproduced from Lachance et al. (1998), with permission.



Xylitol w2-Keto-D-gluconate 2

D-Glucuronate 2

Glucono-δ-lactone wAmino acid-free 1

Nitrite 1

Ethylamine sLysine 1

Cadaverine 1

10% NaCl w50% Glucose 1

Starch production 2

DBB 2

Gelatin 2

Casein 2

Lipase 1

Acid production 2



1% Acetic acid 2

Growth at 30�C 1

Growth at 37�C s

CoQ: Not determined.Mol% G1C: Not determined.Gene sequence accession numbers, type strain: LSU rRNA (incl. D1/D2)5DQ438233, mitochondrial SSU5DQ442749, cytochrome oxi-dase II5DQ443077.Cell carbohydrates: Not determined.Origin of the strains studied: SUB99-201.4 and other strains,isolated from nitidulid beetle (Conotelus obscurus, Coleoptera,Nitidulidae) collected in morning glory (Ipomoea pandurata,Convolvulaceae), Tennessee, USA; UFMG95-401.2, from a flower ofIpomoea cairica; UFMG96-197, from Conotelus sp.; UFMG96-212 (CBS8453), from a flower of Ipomoea carnea var. fistulosa, Minas Gerais,Brazil; UWOPS 91-698.4 (CBS 8452, NRRL Y-27364), isolated from aflower of Ipomoea indica, Island of Hawai’i, and other strains fromflowers of various morning glories (Ipomoea spp.); UWOPS 87-2197.2and other strains, from Drosophila floricola; UWOPS 00-355.4, andother strains from Conotelus spp. (Coleoptera: Nitidulidae); UWOPS00-618.2, and other strains from nitidulid beetle (Aethina concolor,Coleoptera, Nitidulidae); UWOPS 00-623c2, from a bee, Hawaii;UWOPS 99-323.1 and other strains, from Conotelus sp. from flowers ofa Bignonaceous vine; UWOPS 01-114.2 and other strains, from nitidu-lid beetle (Carpophilus sp., Coleoptera, Nitidulidae); UWOPS 01-141c1,from a dipter collected on Ipomoea indica; UWOPS 01-142c2, fromConotelus sp., Guanacaste Province, Costa Rica.Complementary mating types: CBS 8452, mating type h1, andUFMG96-197, mating type h2.Type strain: CBS 8452.Systematics: Several strains isolated from Hawaiian morning gloryflowers and associated drosophilids were referred to as “Candida sp.L” by Lachance et al. (1988). Of these, a few were later assigned tothe genus Wickerhamiella based on the formation of typical asci, thegrowth profile, and some similarities in the D1/D2 LSU rRNA genesequence (Lachance et al. 2000a). Strain UFMG 96-212 was originallydeposited at the Centraalbureau voor Schimmelcultures as CBS 8453to serve as allotype. However, the two strains are the same matingtype. UFMG 96-197 was selected to serve as a replacement allotype.Many more strains of W. occidentalis have since been isolated indiverse localities on the American continent. Identification of thespecies based on morphology is possible due to the unusual appear-ance of the ascus.Ecology: Wickerhamiella occidentalis is the most widespread ofWickerhamiella species, having been isolated from morning glories

and their insects in Hawai’i as well as South, Central and NorthAmerica. The distribution to some extent parallels that of Drosophilafloricola, which is known to occur in warmer parts of the Americasand to have been introduced to the Hawaiian archipelago in the 20thcentury (Montague and Kaneshiro 1982). The northernmost samplescame from localities in Tennessee, USA, where drosophilids can beobserved in flowers. However, samples taken from Convolvulaceaeand their beetles in the Great Lakes (USA/Canada) area, as well ascoastal Maine, USA, and Southern Québec, Canada, where drosophi-lids are absent from the flowers, did not yield members of theWickerhamiella clade.Biotechnology: Unknown.Agriculture and food: Unknown.Clinical importance: Unknown.

COMMENTS ON THE GENUS

The cells of Wickerhamiella species are among the smallest knownfor yeasts. Equally unusual is the shape of the asci, which dissolveterminally for ascospore release. The number of chromosomes maybe as low as two in some of the six species examined by Lachanceet al. (1998).

Wickerhamiella species are highly specialized nutritionally andecologically. The restricted physiology and the strong associationwith floricolous insects seems to be characteristic of most othermembers of the clade (Fig. 79.1), which includes a number ofCandida species that may eventually be found to form ascospores. Interms of biogeography, the clade provides examples of species thatmay be endemic (W. australiensis, W. cacticola, W. lipophila), spreadacross a small number of regions (W. occidentalis, Candida drosophi-lae) or cosmopolitan (Candida azyma). Other members of the cladeare less frequently isolated, precluding biogeographic inferences atthis time.

Phylogenetic analysis of D1/D2 LSU rRNA gene sequences forWickerhamiella and related species of Candida placed W. domercqiaein a clade basal to and somewhat separated from the four morerecently described species of the genus (Fig. 79.1). A similar phylog-eny was seen from SSU rRNA gene sequence analysis (Suzuki et al.1999), as well as from analysis of the entire LSU gene sequence com-bined with those of the mitochondrial SSU rRNA and cytochromeoxidase II (Kurtzman and Robnett 2007), although these analysesgave 100% bootstrap support for the whole clade.

Further support for retaining the existing species of Wickerhamiellain a single genus comes from their biology, characterized by muchmor-phological and physiological homogeneity. Although the ecology of W.domercqiae in the wild is unknown, the recent isolation from ephem-eral flowers and associated insects of representatives of a related pairof sister species also indicates biological cohesion. These isolatesinclude strains UWOPS 00-192.1 and UWOPS 00-107.1 (Lachance et al.2001e), as well as Candida bombiphila (Brysch-Herzberg and Lachance2004). In spite of their clear relatedness to W. domercqiae, the new iso-lates differ by as much as 12% in the D1/D2 sequences, again showing ahigh degrees of sequence divergence among described species of theclade, which suggests that there might be many unknown species yetto be discovered in this clade.


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The Yeasts || Wickerhamiella van der Walt (1973)