Summary auto-generated
Researchers isolated a novel yeast species, Candida davenportii sp. nov., from a dead wasp found at a soft-drinks production facility. Using 26S rDNA D1/D2 sequencing, they determined the isolate was most closely related to Candida stellata but sufficiently divergent (94.1% identity) to represent a separate species. C. davenportii exhibits several characteristics of soft-drink spoilage yeasts: osmotolerance (growing in up to 59.4% glucose), moderate resistance to preservatives like sorbic and benzoic acids, and exceptional tolerance to acidic conditions (growing at pH 1.4). The yeast grew well in fruit-containing soft drinks, cola beverages, and synthetic soft-drink media. Phylogenetic analysis revealed C. davenportii clusters with other osmotolerant Candida species, many of which have been isolated from bees and wasps. This association suggests these yeasts are primarily linked to Aculeates (bees and wasps), which may serve as vectors for contaminating sugary foods. The findings support a model where bees and wasps attracted to sugary residues in food products inadvertently transmit these spoilage yeasts to beverages and other high-sugar commodities.
Key findings
- Candida davenportii sp. nov. is a novel yeast species isolated from a wasp at a soft-drinks facility, differentiated from C. stellata by 5.9% sequence divergence in 26S rDNA D1/D2 domain
- C. davenportii is osmotolerant, preservative-resistant, and notably acid-tolerant (growth at pH 1.4), making it a potential spoilage agent in soft drinks, fruit juices, and other sugary products
- The species clusters phylogenetically with other Candida species predominantly associated with bees and wasps, suggesting these insects are natural vectors for transmitting yeast contamination to high-sugar foods
- C. davenportii demonstrates exceptional resistance to acetic acid (MIC 190 mM) compared to most spoilage yeasts, though lower salt tolerance than related osmotolerant species
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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 3013(T) (=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 <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.