Candida davenportii sp. nov., a potential soft-drinks spoilage yeast isolated from a wasp

Abstract

During a survey of yeast ecology in a soft-drinks production facility, a dead wasp was removed from the sampling tap of an external sugar-syrup storage tank. A yeast isolated from the dead wasp was found to be similar, although not identical, in its physiological characteristics to Candida lactis-condensi and Candida stellata. Sequence analysis of the 26S rDNA D1/D2 variable domain revealed that this isolate was most closely related to C stellata, but differed sufficiently in its D1/D2 sequence to indicate that it belonged to a separate species. The yeast species has been named Candida davenportii sp. nov.; the type strain is NCYC 3013T (= CBS 9069T). C davenportii sp. nov. was osmotolerant, moderately preservative-resistant and able to grow in very acidic conditions, i.e. pH 14. This yeast grew well in fruit-containing soft drinks, cola-type beverages and a synthetic soft drink and is therefore a potential cause of spoilage of soft drinks and other sugary food products. Other related yeast species in the same taxonomic clade as C davenportii sp. nov. are also osmotolerant, growing in < 50% (w/v) sugar. Many of these species are associated with insects, specifically bees, bumblebees and leafcutter bees, and many have been reported as the causative agent of spoilage of sugary foods, such as condensed milk, fruit juices and concentrates. It is proposed that C davenportii sp. nov. and other closely related yeasts are primarily associated with Aculeates (bees and wasps). In turn, bees and wasps are attracted by sugary residues in foods such as fruit juices and concentrates, forming the source of infection of these yeasts and thus instigating spoilage.

Full text

International Journal of Systematic and Evolutionary Microbiology (2002), 52, 1369–1375 DOI: 10.1099/ijs.0.02088-0
Candida davenportii sp. nov., a potential soft-
drinks spoilage yeast isolated from a wasp
1
Microbiology Section,
Unilever R&D, Colworth
House, Sharnbrook,
Bedford MK44 1LQ, UK
2
National Collection of
Yeast Cultures, Food Safety
Science Division, Institute
of Food Research, Colney
Lane, Norwich NR4 7UA,
UK
M. Stratford,
1
C. J. Bond,
2
S. A. James,
2
I. N. Roberts
2
and H. Steels
1
Author for correspondence: Malcolm Stratford. Tel: j44 1234 222 670. Fax: j44 1234 222 777.
e-mail: malcolm.stratford!unilever.com
During a survey of yeast ecology in a soft-drinks production facility, a dead
wasp was removed from the sampling tap of an external sugar-syrup storage
tank. A yeast isolated from the dead wasp was found to be similar, although
not identical, in its physiological characteristics to Candida lactis-condensi and
Candida stellata. Sequence analysis of the 26S rDNA D1/D2 variable domain
revealed that this isolate was most closely related to C. stellata, but differed
sufficiently in its D1/D2 sequence to indicate that it belonged to a separate
species. The yeast species has been named Candida davenportii sp. nov.;
the type strain is NCYC 3013
T
(l CBS 9069
T
). C. davenportii sp. nov. was
osmotolerant, moderately preservative-resistant and able to grow in very
acidic conditions, i.e. pH 14. This yeast grew well in fruit-containing soft
drinks, cola-type beverages and a synthetic soft drink and is therefore a
potential cause of spoilage of soft drinks and other sugary food products.
Other related yeast species in the same taxonomic clade as C. davenportii sp.
nov. are also osmotolerant, growing in T 50% (w/v) sugar. Many of these
species are associated with insects, specifically bees, bumblebees and
leafcutter bees, and many have been reported as the causative agent of
spoilage of sugary foods, such as condensed milk, fruit juices and concentrates.
It is proposed that C. davenportii sp. nov. and other closely related yeasts are
primarily associated with Aculeates (bees and wasps). In turn, bees and wasps
are attracted by sugary residues in foods such as fruit juices and concentrates,
forming the source of infection of these yeasts and thus instigating spoilage.
Keywords: Candida stellata, Candida lactis-condensi, insects, osmotolerance,
preservative resistance
INTRODUCTION
Due to their low pH, soft drinks constitute a hostile
environment in which the great majority of microbes
die, although Escherichia coli O157 and Salmonella
species can persist for weeks in chilled, fruit juices
(Goverd et al., 1979 ; Zhao et al., 1993). Spoilage of
soft drinks is caused by a limited number of yeasts,
moulds and acid-tolerant bacteria. Spoilage effects
include formation of clouds, particulates, taints and
excessive gas (Stratford et al., 2000). Infection of soft
drinks commonly occurs via raw materials, returned
.................................................................................................................................................
Abbreviation: a
w
, water activity.
The EMBL accession number for the sequence of the 26S rDNA D1/D2
region of NCYC 3013
T
is AJ310447.
bottles or aerial vectors (Sand, 1971 ; Tilbury, 1980;
Byrne, 1994). Insects are increasingly recognized as
a vector for yeasts. Many insects carry yeasts and
insect frass, notably from fruit flies (Drosophila sp.),
is particularly rich in soft-drinks spoilage yeasts
(Lachance et al., 1995; Barnett et al., 2000).
Although many of the 800 or so yeasts discovered
hitherto have been found in soft drinks or fruit juices
(Barnett et al., 2000), relatively few species can grow in
this environment or cause spoilage (Pitt & Hocking,
1997). Soft-drinks factories similarly contain large
numbers of yeast isolates and micro-organisms of
great taxonomic diversity (Sand, 1970, 1973; Sand &
van Grinsven, 1976a, b). In a ‘ forensic approach ’,
Davenport (1996, 1997, 1998) proposed a usable
taxonomy based on the behaviour of microbes, rather
than on specific names. Members of Group 1 were
02088 # 2002 IUMS Printed in Great Britain
1369

M. Stratford and others
defined as spoilage organisms, proliferating in soft
drinks and able to cause spoilage from as few as one
cell per container (van Esch, 1987 ; Davenport, 1996).
Group 1 spoilage yeasts were characteristically osmo-
tolerant and resistant to preservatives, such as acetic,
sorbic or benzoic acids. Molecular taxonomic methods
have shown that most of the Group 1 yeasts are closely
related, clustered around the Zygosaccharomyces sensu
stricto clade (James et al., 1994). Members of Group 2
were described as spoilage\hygiene micro-organisms,
capable of causing spoilage of soft drinks following
mistakes during manufacture. These are opportunistic
spoilage organisms, often present in soft-drinks fac-
tories in small numbers. Group 3 microbes were
hygiene indicators and would not cause spoilage.
In this paper, a novel species of yeast, isolated at a soft-
drinks production facility, is reported and its spoil-
age characteristics are defined. The name Candida
davenportii sp. nov. is proposed for this novel species.
METHODS
Yeast strains. The yeast strains used in this work are listed
in Table 1. These include Zygosaccharomyces bailii and
Zygosaccharomyces rouxii (Group 1; Davenport, 1996),
Candida parapsilosis and Saccharomyces cerevisiae (Group
2) and Rhodotorula glutinis (Group 3). NCYC strains are
available from the National Collection of Yeast Cultures,
Norwich, UK (http:\\www.ncyc.co.uk).
Media and growth conditions. Yeasts were maintained at
4 mC on slopes of YEPD agar. YEPD contained (l
−
"
water):
glucose, 20 g ; bacteriological peptone (Oxoid), 20 g; yeast
extract (Oxoid), 10 g, corrected to pH 4n0 using 10 M HCl.
Starter cultures comprised 10 ml YEPD broth in 30 ml
capped McCartney bottles, cultured at 25 mC for 48 h.
Experimental cultures, similarly 10 ml YEPD in 30 ml
bottles, were inoculated at 1i10
$
cells ml
−
"
and cultured
without shaking at 25 mC for 14 days. Synthetic soft-
drink medium contained (l
−
"
water): glucose, 80 g ; citric
acid, 3n5 g; ammonium sulphate, 0n5 g ; potassium ortho-
phosphate, 0n5 g; yeast extract (Oxoid), 0n5 g. Aliquots
(28 ml) of synthetic soft drink were filled into McCartney
bottles, leaving 2 ml headspace.
Addition of inhibitors. Yeasts were characterized by re-
sistance to preservatives, inhibitors, osmotolerance and low
pH. Resistance was determined by the MIC. All tests were
carried out in YEPD medium at pH 4n0. Acetic acid, NaCl
Table 1. Yeast strains used in this study and their sources
Strain Source
Candida davenportii NCYC 3013
T
Wasp, soft-drinks plant, The Netherlands
Candida parapsilosis strain 69 Spoiled fruit juice (infant formulation), UK
Rhodotorula glutinis strain 92 Soft-drinks factory, Israel
Saccharomyces cerevisiae NCYC 957 X2180-1B
Zygosaccharomyces bailii NCYC 1766 Spoiled blackcurrant and grape juice, UK
Zygosaccharomyces rouxii NCYC 381 Cane sugar
and HCl (pH minimum) were added before sterilization.
High-sugar media were autoclaved in two parts, sugar and
YEPD, to avoid sugar charring.
Scanning electron microscopy. Yeasts were cultured in
YEPD medium pH 4n0 for 5 days at 25 mC. Cells were
harvested by centrifugation for 5 min at 3000 g, washed
three times in citrate buffer (pH 4n0, 50 mM) and
resuspended in cacodylate buffer (pH 7n2, 72n5 mM). Cells
were fixed in 2n5% glutaraldehyde for 1 h, washed twice in
buffer and resuspended in 50 % (v\v) ethanol. Fixed cells
were dehydrated in 60, 70, 80 and 90% ethanol, each for
10 min, followed by 100% ethanol, three times. Cells were
packaged into ethanol-saturated filter paper, placed in
acetone and critical-point dried with carbon dioxide. Cells
were then mounted on tape, sputter coated with platinum
and examined by SEM.
Yeast identification and 26S rDNA sequencing. Yeasts were
identified initially using standard API kits in conjunction
with the yeast identification program of Barnett (1996).
rDNA sequence analysis was subsequently carried out. The
variable D1 and D2 domains of 26S rDNA were PCR-
amplified directly from individual yeast colonies following
the protocol detailed by James et al. (1994) using the
conserved fungal oligonucleotide primers NL1 and NL4
(O’Donnell, 1993). Amplified 26S rDNA D1\D2 PCR
products were purified using a Qiagen QIAquick PCR
purification kit and sequenced directly using a Taq
DyeDeoxy terminator cycle sequencing kit (PE Biosystems)
and an Omnigene thermal cycler (Hybaid). 26S rDNA
sequences were determined using NL1 and NL4 as
sequencing primers. Purified sequence reaction mixtures
were electrophoresed with a PE Biosystems model 373A
automated DNA sequencer.
To determine the species identity of strain NCYC 3013
T
, the
26S rDNA D1\D2 sequence was used to search against
sequences held in both the EMBL and GenBank databases.
A sequence alignment of the 26S rDNA sequences for
NCYC 3013
T
and its closest relatives was created using the
multiple-sequence alignment program  (Feng &
Doolittle, 1987) contained within the GCG software package
(Genetics Computer Group, 1991) version 8.1. Phylogenetic
analyses were performed using  (phylogeny inference
package; Felsenstein, 1993) version 3.572. A distance matrix
was generated using the  program with the Jukes–
Cantor distance measure and a rooted phylogenetic tree
(using Candida blankii as outgroup) was constructed using
the neighbour-joining method (Saitou & Nei, 1987) and the
 program. The stability of individual branches
of the tree was assessed using the bootstrap method
(Felsenstein, 1985) with the programs , ,
1370
International Journal of Systematic and Evolutionary Microbiology 52

Candida davenportii sp. nov.
 and . A total of 488 nt was determined
from the 26S rDNA D1\D2 region of NCYC 3013
T
.
RESULTS AND DISCUSSION
Isolation and identification of a novel yeast species
A dead wasp, tentatively identified as Vespula vulgaris,
was found beside a few drops of sugar syrup at the
sampling tap of an external sugar-syrup tank at a
European soft-drinks production facility. Several
other wasps were seen in the area, attracted by the
sugar. A yeast isolated from the wasp could not be
identified using standard methods (API kit) and was
termed isolate 220
T
. Microscope examination of isolate
220
T
(C. davenportii sp. nov. NCYC 3013
T
) showed
that the cells were small and ovoid, approximately
2–3 µm in length and 1n2–1n5 µm in diameter. Cell
division occurred by budding (Fig. 1). Standard
biochemical assimilation tests were carried out on
isolate 220
T
. Results are shown in Table 2. Isolate 220
T
fermented glucose only and grew on glucose, sucrose
and raffinose.
The 26S rDNA D1\D2 nucleotide sequence of isolate
220
T
was used to search the EMBL and GenBank
databases to establish the identity of this yeast isolate
at the species level. Results from the search revealed
that the 26S rDNA D1\D2 sequence was most similar
to that of Candida stellata, displaying 94n1% sequence
identity. However, such a level of sequence divergence
(5n9%) indicated that isolate 220
T
belonged to a
separate and hitherto undescribed yeast species;
conspecific strains typically differ by less than 1% in
this region (Kurtzman & Blanz, 1998).
(a)
(b)
.................................................................................................................................................................................................................................................................................................................
Fig. 1. (a) Photomicrograph of C. davenportii sp. nov. NCYC 3013
T
grown in yeast nitrogen base medium (25 mM glucose)
for 1 day at 25 mC. Bar, 10 µm. (b) Scanning electron micrograph of a small cluster of cells of C. davenportii sp. nov. NCYC
3013
T
grown for 5 days in YEPD medium pH 4n0at25mC. Bar, 1 µm.
To establish the taxonomic position of this novel
species, 26S rDNA D1\D2 sequences of NCYC 3013
T
,
C. stellata and a number of related Candida species
(Kurtzman & Robnett, 1998) were aligned and used to
generate a phylogenetic tree using the neighbour-
joining method (Saitou & Nei, 1987). Fig. 2 depicts the
phylogenetic placement of NCYC 3013
T
in relation to
C. stellata and other Candida species. C. davenportii
NCYC 3013
T
, along with Candida apicola, Candida
bombi, Candida etchellsii, Candida floricola, Candida
lactis-condensi, C. stellata, Candida batistae, Can-
dida powellii and Starmerella bombicola (Candida
bombicola), formed a statistically significant species
group (bootstrap value of 100%).
Bee/wasp association of C. davenportii and related
species
C. davenportii NCYC 3013
T
was isolated from V.
vulgaris, the common wasp (Else, 1994). This finding in
isolation does not prove that C. davenportii is wasp-
associated. Isolation of a strain from a particular
location may or may not indicate the normal en-
vironment of that strain. However, when the origin of
species most closely related to C. davenportii was
examined, a more convincing picture emerged. Of the
18 species listed in Fig. 2, 11 have been isolated from
insects, with ten records of isolation from bees. Besides
C. davenportii NCYC 3013
T
, species in this group
noted for having been isolated from insects are
C. bombi (bumblebees; Montrocher, 1967), C. apicola
(bees; Hajsig, 1958), C. stellata (fruit fly; Spencer et
al., 1992), Candida magnoliae (bees ; Deak & Beuchat,
1993), Candida gropengiesseri (cockroach cocoon ;
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1371

M. Stratford and others
Table 2. Standard physiological and biochemical characteristics of C. davenportii sp. nov. NCYC 3013
T
Character Result Character Result
Fermentation of carbohydrates: Assimilation of carbon compounds: (cont.)
-Glucose j Glycerol k
Sucrose k Erythritol k
Maltose k Ribitol k
-Galactose k Xylitol k
Lactose k -Glucitol k
Cellobiose k -Mannitol k
α,α-Trehalose k Galactitol k
Melibiose k Inositol k
Melezitose k -Glucono-1,5-lactone k
Raffinose  -Lactate k
Methyl α--glucoside k Succinate k
Inulin k Citrate k
Soluble starch k Methanol k
Assimilation of carbon compounds: Assimilation of nitrogen compounds:
-Glucose j Nitrate k
-Galactose k Ethylamine k
-Sorbose k Cadaverine k
-Glucosamine k -Lysine j
-Ribose k Growth in :
-Xylose k 10% NaCl\5% glucose j
-Arabinose k 15% NaCl\5% glucose k
-Arabinose k 20% NaCl\5% glucose k
-Rhamnose k -Glucose (50 %) j
Sucrose j -Glucose (60 %) k
Maltose k Cycloheximide (0n01 %) k
α,α-Trehalose k Cycloheximide (0n1%) k
Methyl α--glucoside k Acetic acid (1%) k
Cellobiose k Urease activity k
Salicin k Lipolytic activity k
Melibiose k Acid production k
Lactose k Arbutin hydrolysis k
Ethanol k Starch formation k
Raffinose j Growth at :
Melezitose k 37 mC k
Inulin k 40 mC k
Starch k Pseudohyphae k
, Not tested.
Harrison, 1928, quoted by Barnett et al., 2000),
Candida apis (bees; Lavie, 1954, quoted by Barnett et
al., 2000), C. batistae (solitary nesting digger bees ;
Rosa et al., 1999), C. powellii and Candida tilneyi (bees
and nitidulid beetles ; Lachance et al., 2001a) and S.
bombicola as C. bombicola (bumblebees and alfalfa
leaf-cutter bees ; Spencer et al., 1970; Inglis et al., 1993;
Rosa & Lachance, 1998). Three novel species related
to C. etchellsii were also isolated from bees and beetles
(Lachance et al., 2001b). This evidence suggests
strongly that the majority of yeasts in this clade,
possibly all species, are primarily associated with
Aculeates (bees and wasps). It may be speculated that
insects may form the normal environment for these
yeasts. Limited data, from C. bombicola (Inglis et al.,
1993), suggest that these yeasts are not carried within
the insect digestive system, as has been reported for
fruit flies (Lachance et al., 1995), but associated with
nectar and pollen.
Physiology of C. davenportii sp. nov. NCYC 3013
T
C. davenportii NCYC 3013
T
grew well in a fruit-juice-
containing soft drink (pH 3n3), a synthetic soft drink
(pH 3n3) and a cola-type beverage (pH 2n65) and was
therefore shown to have the potential to cause spoilage
of soft drinks. Spoilage yeasts are characteristically
resistant to preservatives and osmotolerant. The pre-
servative resistance of NCYC 3013
T
was therefore
determined and compared with other, more notorious
1372
International Journal of Systematic and Evolutionary Microbiology 52

Candida davenportii sp. nov.
.................................................................................................................................................................................................................................................................................................................
Fig. 2. Dendrogram showing the phylogenetic relationship of C. davenportii sp. nov. NCYC 3013
T
(isolate 220
T
) to other
related Candida species (Kurtzman & Robnett, 1998; Lachance et al., 2001a) based on 26S rDNA D1/D2 sequences. The
tree was constructed using the neighbour-joining method (Saitou & Nei, 1987). Bootstrap values, expressed as
percentages of 100 replications, are given at branch points (only values  50% are shown). Bar, 3 estimated base
substitutions per 100 nucleotides. EMBL/GenBank accession numbers are shown in parentheses.
Table 3. Preservative resistance in C. davenportii sp. nov. compared with that of other spoilage yeasts
.................................................................................................................................................................................................................................................................................................................
Values are means of at least two determinations of MIC, measured in YEPD, at pH 4n0, following incubation at 25 mC for
14 days.
Preservative C. davenportii
NCYC 3013
T
C. parapsilosis
strain 69
R. glutinis
strain 92
S. cerevisiae
NCYC 957
Z. bailii
NCYC 1766
Z. rouxii
NCYC 381
Sorbic acid (mM) 1n82n40n33n37n61n8
Benzoic acid (mM) 2n43n11n23n38n73n4
Acetic acid (mM) 190 85 45 125 470 135
Ethanol (M) 1n55 1n20 0n60 2n00 1n80 1n60
spoilage yeasts. Results are shown in Table 3. Z. bailii
showed phenomenal resistance to all acidic pre-
servatives. C. davenportii NCYC 3013
T
was mod-
erately resistant to sorbic and benzoic acids, but less
resistant than C. parapsilosis, S. cerevisiae or Z. rouxii.
However, C. davenportii NCYC 3013
T
was un-
expectedly resistant to acetic acid, with an MIC value
of 190 mM. While not approaching the resistance of
Z. bailii to acetic acid (Table 3), NCYC 3013
T
was
more resistant to acetic acid than almost all other
spoilage yeasts.
C. davenportii NCYC 3013
T
was osmotolerant and
capable of growth in up to 3n3 M glucose (59n4%,
w\v). This is comparable with other spoilage yeasts,
with the exception of Z. rouxii and Z. bailii. C.
davenportii NCYC 3013
T
was, however, substantially
less salt tolerant than other spoilage yeasts, being
inhibited by 1n7 M NaCl (10%, w\v). Almost all
species related to NCYC 3013
T
are also sugar tolerant,
most species being able to grow in 60% (w\v) glucose
(Barnett et al., 2000). Recognized osmotolerant yeasts
in this clade include C. apicola, C. etchellsii, C. lactis-
condensi and C. magnoliae, with a minimum water
activity (a
w
) for growth of 0n70 in sucrose\glycerol
syrups (Tilbury, 1980). It is possible that osmo-
tolerance may aid survival of these yeasts in low-a
w
habitats associated with bee\wasp nectar or honey.
Unusual tolerance to low pH was shown by C.
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M. Stratford and others
davenportii NCYC 3013
T
. Z. bailii NCYC 1766 and Z.
rouxii NCYC 381 failed to grow in media at pH 2n0,
whereas C. davenportii NCYC 3013
T
grew well in
YEPD media down to an initial pH of 1n4. While
growth of most yeasts is impaired at pH 3n0, C.
davenportii NCYC 3013
T
grew almost as well at pH 2n0
as at pH 3n0, suggesting that growth at pH 1n8–2n0 was,
unusually, not stressful to this species. Other related
species showed only average resistance to low pH: C.
stellata NCYC 486, pH minimum 2n1; C. etchellsii
NCYC 2432, pH minimum 1n9.
Spoilage significance of C. davenportii NCYC 3013
T
and related species
Many of the yeasts related to C. davenportii NCYC
3013
T
have been implicated in spoilage of foods,
particularly sugary, low-a
w
foods. Spoilage of high-
sugar commodities has been reported by C. apicola
(blackcurrant drink, sugar syrups; Hajsig, 1958 ; Scarr
& Rose, 1966), C. bombicola (concentrated grape juice,
high-sugar vegetables ; Spencer et al., 1970; Ok &
Hashinaga, 1997), C. etchellsii (concentrated citrus
juice; Recca & Mrak, 1952), C. lactis-condensi
(condensed milk, sugar syrups; Hammer, 1919; Scarr
& Rose, 1966), C. stellata (soft drinks, fruit juices and
concentrates, tomato sauce ; Pitt & Richardson, 1973;
Sand & van Grinsven, 1976a, b ; Spencer et al., 1992;
Deak & Beuchat, 1993) and C. magnoliae (concen-
trated fruit juice ; Deak & Beuchat, 1993). Spoilage of
high-salt commodities by C. etchellsii, C. apicola and
C. lactis-condensi has been reported (Tilbury, 1976,
1980; Barnett et al., 2000). Spoilage by these yeasts is
relatively uncommon and, in the context of spoilage
significance, they are probably Group 2, opportunist
spoilage microbes (Davenport, 1996). Pitt & Hocking
(1997) do not list these yeasts as responsible for
spoilage of foods processed and packaged according to
normal standards of good manufacturing practice.
The high-sugar commodities spoiled by these yeasts
include condensed milk, concentrated fruit juices and
sugary syrups, all likely to attract bees and wasps.
Workers of the common wasp, V. vulgaris, are com-
monly a great nuisance in late summer in various food
factories, confectionery shops, greengrocers, fish
shops, at picnics and wherever sugary foodstuffs are
exposed (Else, 1994). It is therefore a distinct possi-
bility that spoilage of sugary foods by C. davenportii
and related species occurs when bees and wasps carry
the yeast infection to the food, bees and wasps thus
being the direct source of infection of these spoilage
yeasts.
The novel yeast species is named C. davenportii sp.
nov. in honour of Professor Bob Davenport, whose
work with spoilage yeasts in the soft-drinks production
environment is legendary. It was with deep sadness
that the authors learned of the death of Professor
Davenport in 2001, shortly after he had been informed
of the discovery and naming of this novel yeast species.
Latin diagnosis of Candida davenportii Stratford,
Bond, James, Roberts & Steels sp. nov.
Cultura in agaro morphologico (Difco) post 48 horas
ad 24 mC: cellulae ovoideae (2n0–3n0i1n0–1n5 µm),
singulae, binae, adhaerentes, per gemmationem multi-
polarem reproducentes. Ascomata nulla post 20 dies
24 mC seu in agaro farina maydis confecto se PDA seu
medio Gorodkowae. In agaro farinae Zea mays post dies
14 pseudomycelium non formatur. Glucosum fermen-
tantur at non sucrosum maltosum, galactosum, lac-
tosum, cellobiosum, trehalosum, melibiosum, melezi-
tosum, raffinosum, methyl α--glucosidum, inulinum
nec amylum. Glucosum, sucrosum, raffinosum et
lysinum assimilantur at non galactosum, -sorbosum,
maltosum, cellobiosum, trehalosum, lactosum, melibi-
osum, inulinum, amylum, -xylosum, -arabinosum,
-arabinosum, -ribosum, -rhamnosum, galactitolum,
methyl α--glucosidum, melezitosum, erythritolum,
ribitolum, -mannitolum, -glucitolum, salicinum,
acidum succinicum, acidum citricum, glucono--lacto-
num, glycerinum, xylitolum, nitrus kalicus, ethyl-
aminum, acidum lacticum, inositolum, -glucosaminum,
cadaverinum, methanolum nec alcohol aethylicum.
Crescit in medio cum 50% glucoso. Non crescit in medio
1% acido acetico addito et in medio 0n01% cyclo-
heximido addito. Typus depositus in zymotica collec-
tionis National Collection of Yeast Cultures,
Norwich, UK (NCYC 3013
T
) et Centraalbureau voor
Schimmelcultures, Utrecht, The Netherlands (CBS
9069
T
).
Description of Candida davenportii Stratford, Bond,
James, Roberts & Steels sp. nov.
Candida davenportii (L. gen. sing. masc. n. davenportii
of Davenport, referring to Robert R. Davenport, in
recognition of his life-long work on spoilage yeasts in
the soft-drinks environment).
On morphology agar, after 48 h at 24 mC, cells are
spherical to ovoid (2n0–3n0i1n0–1n5 µm) and occur
singly, in pairs or in groups (Fig. 1). Budding is
multilateral. No ascosporulation is observed after
incubation for 3 weeks at 24 mC, on corn-meal agar,
potato-dextrose agar or Gorodkowa agar. Pseudo-
hyphae are not formed. A summary of the physio-
logical and other growth characteristics of Candida
davenportii sp. nov. NCYC 3013
T
is given in Table 2.
Cultures of the type strain, strain 220
T
, have been
deposited with the National Collection of Yeast
Cultures, Norwich, UK (NCYC 3013
T
), and the
Centraalbureau voor Schimmelcultures, Utrecht, The
Netherlands (CBS 9069
T
).
ACKNOWLEDGEMENTS
We gratefully acknowledge Dr James Barnett, School of
Biological Sciences, University of East Anglia, and Linda
Barnett in the preparation of photomicrographs and Mark
Kirkland at Unilever Research, Colworth House, for the
scanning electron micrograph. The assistance of Barbara C.
1374
International Journal of Systematic and Evolutionary Microbiology 52

Candida davenportii sp. nov.
Last is gratefully acknowledged in the taxonomy and
identification of wasps.
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