Cyniclomyces guttulatus (Saccharomycopsis guttulata)--culture, ultrastructure and physiology

An Investigation of the Relationship between Cyniclomyces guttulatus and Rabbit Diarrhoea

Cyniclomyces guttulatus is usually recognised as an inhabitant of the gastrointestinal (GI) tract in rabbits. However, large numbers of C. guttulatus are often detected in the faeces of diarrhoeic rabbits. The relationship of C. guttulatus with rabbit diarrhoea needs to be clearly identified. In this study, a C. guttulatus Zhejiang strain was isolated from a New Zealand White rabbit with severe diarrhoea and then inoculated into SPF New Zealand white rabbits alone or co-inoculated with Eimeriaintestinalis, another kind of pathogen in rabbits. Our results showed that the optimal culture medium pH and temperature for this yeast were pH 4.5 and 40-42 °C, respectively. The sequence lengths of the 18S and 26S ribosomal DNA fragments were 1559 bp and 632 bp, respectively, and showed 99.8% homology with the 18S ribosomal sequence of the NRRL Y-17561 isolate from dogs and 100% homology with the 26S ribosomal sequence of DPA-CGR1 and CGDPA-GP1 isolates from rabbits and guinea pigs, respectively. In animal experiments, the C. guttulatus Zhejiang strain was not pathogenic to healthy rabbits, even when 1 × 10⁸ vegetative cells were used per rabbit. Surprisingly, rabbits inoculated with yeast showed a slightly better body weight gain and higher food intake. However, SPF rabbits co-inoculated with C. guttulatus and E. intestinalis developed more severe coccidiosis than rabbits inoculated with C. guttulatus or E. intestinalis alone. In addition, we surveyed the prevalence of C. guttulatus in rabbits and found that the positive rate was 83% in Zhejiang Province. In summary, the results indicated that C. guttulatus alone is not pathogenic to healthy rabbits, although might be an opportunistic pathogen when the digestive tract is damaged by other pathogens, such as coccidia.

Deaths Due to Mixed Infections with Passalurus ambiguus, Eimeria spp. and Cyniclomyces guttulatus in an Industrial Rabbit Farm in Greece

Domestic rabbits are commercially farmed for their meat whilst gastrointestinal diseases can hinder their production. Passalurusambiguus and Eimeria spp. are two common rabbit intestinal parasites that can cause diarrhoea, among other symptoms, and in severe cases, death. C. guttulatus is a commensal yeast of the rabbits’ stomach that is considered apathogenic but can worsen symptoms in rabbits suffering from coccidiosis. In the present case report, we describe an outbreak of deaths in three different age groups (A: lactating does, B: 58 days old and C: 80 days old) in an industrial rabbit farm in Greece. Symptoms included depression, diarrhoea, inappetence, weight loss, dehydration and ruffled furs. Using a faecal flotation technique, sick rabbits were found to be moderately to heavily infected with P. ambiguus, Eimeria spp. and C. guttulatus. Treatment with fenbendazole and oregano oil combined with hygiene control measures successfully controlled the infections and resolved clinical symptoms. A faecal flotation method or other reliable diagnostic technique should be used regularly in industrial rabbit farms to screen for gastrointestinal parasitic infections. Early diagnosis and control will help to maintain production levels and, therefore, limit financial losses for the farmer while ensuring animal welfare.

Sphingolipidomics of Thermotolerant Yeasts

Mass spectrometry-based shotgun lipidomics was applied to the analysis of sphingolipids of 11 yeast strains belonging to four genera, that is Cryptococcus, Saccharomyces, Schizosaccharomyces, and Wickerhamomyces. The analysis yielded comprehensive results on both qualitative and quantitative representation of complex sphingolipids of three classes-phosphoinositol ceramide (PtdInsCer), mannosyl inositol phosphoceramide (MInsPCer), and mannosyl diinositol phosphoceramide (M(InsP)₂ Cer). In total, nearly 150 molecular species of complex sphingolipids were identified. Individual strains were cultured at five different temperatures, that is 5, 10, 20, 30, and 40 °C (Wickerhamomyces genus only up to 30 °C), and the change in the culture temperature was found to affect the representation of both the sphingolipid classes and the length of the long-chain bases (LCB). Individual classes of sphingolipids differing in polar heads differed in the temperature response. The relative content of PtdInsCer increased with increasing temperature, whereas that of M(InsP)₂ Cer decreased. Molecular species having C18-LCB were associated with low cultivation temperature, and a higher proportion of C20-LCB molecular species was produced at higher temperatures regardless of the type of polar head. On the other hand, the influence of temperature on the representation of very long-chain fatty acids (VLCFA) was less noticeable, the effect of the taxonomic affiliation of the strains being more pronounced than the cultivation temperature. For example, lignoceric and 2-hydrocylo-lignoceric acids were characteristic of the genera Cryptococcus and Schizosaccharomyces, and of Saccharomyces genus cultivated at high temperatures.

Cyniclomyces guttulatus Infection in Dogs: 19 Cases (2006-2013)

Cyniclomyces guttulatus, a gastrointestinal yeast of rabbits, is considered an uncommon, nonpathogenic, "pass through" organism and possible opportunistic pathogen in dogs that consume rabbit feces. This retrospective study aimed to characterize the presenting complaint, clinical findings, location of organisms, and final diagnosis of dogs in which yeast morphologically consistent with C. guttulatus were identified at a veterinary teaching hospital from 2006-2013. The prevalence of C. guttulatus infection in a general population of dogs from a regional animal shelter was also determined. Nineteen dogs were retrospectively identified as diagnosed with C. guttulatus infection. Among these, 79% presented with a chief complaint and/or clinical signs consistent with gastrointestinal tract disease. The most common clinical sign was chronic diarrhea. The majority of dogs had C. guttulatus identified cytologically within samples obtained from the gastrointestinal tract; however, four dogs had C. guttulatus identified in non-gastrointestinal tract samples, including a nasal biopsy (one dog) and urine (three dogs). C. guttulatus was not identified in any of 105 shelter dogs evaluated, suggesting low prevalence of C. guttulatus in our region. These findings suggest that additional studies to determine if C. guttulatus is a potential cause or consequence of gastrointestinal illness in dogs may be warranted.

The clinical significance of Cyniclomyces guttulatus in dogs with chronic diarrhoea, a survey and a prospective treatment study

This study surveyed the prevalence of massive numbers of Cyniclomyces guttulatus in faecal samples from healthy dogs (18%) and dogs with chronic diarrhoea (14%) suggesting that this yeast has no clinical significance. Subsequently, a total of 57 referred dogs with chronic diarrhoea were selected because they excreted massive numbers of C. guttulatus and their initial diagnostic work-up yielded no other direct clues explaining their diarrhoea. Treatment with nystatin did not result in any clinical response in 36 out of these 57 dogs (63%), although they no longer shed the yeast. However, a response was noted in the remaining 21 (37%) dogs: 13 were 'responders', in that their diarrhoea subsided for more than two weeks and the faeces were cleared of the yeast. However, three of these dogs relapsed repeatedly, with signs of diarrhoea and massive shedding of the yeast. The other eight dogs were 'incomplete responders', whereby faecal quality initially normalised, but diarrhoea relapsed within two weeks, whilst still not shedding the yeast. In these cases, further diagnostic work up revealed other co-causes of diarrhoea. It was concluded that there was no direct evidence that C. guttulatus is a primary pathogen. However, the results of the prospective treatment study suggest that a possible role in a minority of cases, perhaps as an opportunist, cannot be ruled out.

Engineering the rabbit digestive ecosystem to improve digestive health and efficacy

In rabbits, the bacterial and archaeal community of caecal ecosystem is composed mostly of species not yet described and very specific to that species. In mammals, the digestive ecosystem plays important physiological roles: hydrolysis and fermentation of nutrients, immune system regulation, angiogenesis, gut development and acting as a barrier against pathogens. Understanding the functioning of the digestive ecosystem and how to control its functional and specific diversity is a priority, as this could provide new strategies to improve the resistance of the young rabbit to digestive disorders and improve feed efficiency. This review first recalls some facts about the specificity of rabbit digestive microbiota composition in the main fermentation compartment, and its variability with some new insights based on recent molecular approaches. The main functions of the digestive microbiota will then be explained. Finally, some possible ways to control rabbit caecal microbiota will be proposed and a suitable timing for action will be defined.

Isolation and characterization of Cyniclomyces guttulatus (Robin) Van Der Walt and Scott, 1971 in dogs in Brazil

Vegetative cells of an ascomycetous yeast, morphologically consistent with published descriptions of Cyniclomyces guttulatus, were observed in large numbers in the feces and stomach washes of three dogs with a recurrent medical history characterized by vomiting and diarrhea. Nucleotide sequence analysis of an approximately 600 base pair fragment of the variable D1/D2 domain of large subunit (26S) ribosomal DNA of a pure culture, isolated from a Siberian Husky, revealed 98-99 % homology to sequences deposited in the GenBank as C. guttulatus. These data represent the first observation of C. guttulatus in association with canine gastrointestinal illness in the southern hemisphere and add weight to the hypothesis that this yeast may act as an opportunistic pathogen of dogs. An extended examination of wet mounts and smears prepared from feces collected from 63 dogs with no clinical symptoms of gastrointestinal illness, identified C. gluttulatus in 14 (22.2 %) of the animals, albeit at lower numbers than in diseased dogs, indicating that this yeast species is widely distributed as a component of the normal microflora of the canine gastrointestinal tract.

Carbonic anhydrase (Nce103p): an essential biosynthetic enzyme for growth of Saccharomyces cerevisiae at atmospheric carbon dioxide pressure

The NCE103 gene of the yeast Saccharomyces cerevisiae encodes a CA (carbonic anhydrase) that catalyses the interconversion of CO2 and bicarbonate. It has previously been reported that nce103 null mutants require elevated CO2 concentrations for growth in batch cultures. To discriminate between 'sparking' effects of CO2 and a CO2 requirement for steady-state fermentative growth, we switched glucose-limited anaerobic chemostat cultures of an nce103 null mutant from sparging with pure CO2 to sparging with nitrogen gas. This switch resulted in wash-out of the biomass, demonstrating that elevated CO2 concentrations are required even under conditions where CO2 is produced at high rates by fermentative sugar metabolism. Nutritional analysis of the nce103 null mutant demonstrated that growth on glucose under a non-CO2-enriched nitrogen atmosphere was possible when the culture medium was provided with L-aspartate, fatty acids, uracil and L-argininine. Thus the main physiological role of CA during growth of S. cerevisiae on glucose-ammonium salts media is the provision of inorganic carbon for the bicarbonate-dependent carboxylation reactions catalysed by pyruvate carboxylase, acetyl-CoA carboxylase and CPSase (carbamoyl-phosphate synthetase). To our knowledge, the present study represents the first full determination of the nutritional requirements of a CA-negative organism to date.