Elevated minimum inhibitory concentrations to antifungal drugs prevail in 14 rare species of candidemia-causing Saccharomycotina yeasts.

Antifungal susceptibility profiles of rare Saccharomycotina yeasts remain missing, even though an increase in prevalence of such rare Candida species was reported in candidemia. Majority of these rare yeast species carry intrinsic resistances against at least one antifungal compound. Some species are known to be cross-resistant (against multiple drugs of the same drug class) or even multi-drug resistant (against multiple drugs of different drug classes). We performed antifungal susceptibility testing (AFST) according to EUCAST broth microdilution for 14 rare species (Clavispora lusitaniae, Candida intermedia, Candida auris, Diutina rugosa, Wickerhamiella pararugosa, Yarrowia lipolytica, Pichia norvegensis, Candida nivariensis, Kluyveromyces marxianus, Wickerhamomyces anomalus, Candida palmioleophila, Meyerozyma guilliermondii, Meyerozyma caribbica, and Debaryomyces hansenii) known to cause candidemia. In total, 234 isolates were tested for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, micafungin, and caspofungin. Amphothericin B had the broadest efficiency against the 14 tested rare yeast species, while high minimum inhibitory concentrations (MICs) against azole drugs and echinocandins were common. Voriconazole was the most efficient azole drug. Multidrug resistance was observed for the species C. auris and K. marxianus. Multidrug resistant individual isolates were found for Y. lipolytica and M. caribbica. In conclusion, the observed high MIC values of the rare Saccharomycotina species tested limit antifungal treatment options, complicating the management of such infections.

Saccharomyces eubayanus and Saccharomyces arboricola reside in North Island native New Zealand forests.

Saccharomyces is one of the best-studied microbial genera, but our understanding of the global distributions and evolutionary histories of its members is relatively poor. Recent studies have altered our view of Saccharomyces' origin, but a lack of sampling from the vast majority of the world precludes a holistic perspective. We evaluate alternate Gondwanan and Far East Asian hypotheses concerning the origin of these yeasts. Being part of Gondwana, and only colonized by humans in the last ∼1000 years, New Zealand represents a unique environment for testing these ideas. Genotyping and ribosomal sequencing of samples from North Island native forest parks identified a widespread population of Saccharomyces. Whole genome sequencing identified the presence of S. arboricola and S. eubayanus in New Zealand, which is the first report of S. arboricola outside Far East Asia, and also expands S. eubayanus' known distribution to include the Oceanic region. Phylogenomic approaches place the S. arboricola population as significantly diverged from the only other sequenced Chinese isolate but indicate that S. eubayanus might be a recent migrant from South America. These data tend to support the Far East Asian origin of the Saccharomyces, but the history of this group is still far from clear.

Genetic identification of Saccharomyces bayanus var. uvarum, a cider-fermenting yeast.

Twenty-one Saccharomyces strains isolated from a cider process were analysed in terms of karyotypes, Y' S. cerevisiae sequence occurrence, rDNA structure and cross-fertility with species tester strains. A strong predominance of S. bayanus var. uvarum G. Naumov was found (18 strains vs. three S. cerevisiae). Among the S. bayanus var. uvarum, only three strains proved to contain species-specific Y' S. cerevisiae sequences.

An attempt to use selected strains of bacteria adapted to high concentrations of petroleum oil to increase the effective removal of petroleum products in excess activated sludge in laboratory conditions.

Forty two strains of bacteria were isolated from excess activated sludge from petroleum wastewater treatment plant. The strains were identified and classified to the following groups: Enterobacteriaceae (7 strains), Anitratum (3 strains), Pseudomonas (13 strains), Micrococcus (12 strains), Comamonas (2 strains), Xanthomonas (2 strains), Achromobacter (1 strain) and Vibrio-Aeromonas (1 strain). One of the isolates was found to be a yeast strain. Following preliminary selection ten strains, showing the best growth in medium with oil fraction as sole carbon source, were chosen for further studies. The selected strains belong to Pseudomonas (6 strains), Xanthomonas (2 strains), Micrococcus (1 strain) and Saccharomyces (1 strain). The strains were adapted to high oil concentration (500-2000 mg/L) and an attempt to use them to intensify removal of petroleum products from excess activated sludge was made. The sludge was inoculated with a mixture of the isolated strains. The experiment was carried out three times, each time with a fresh sample of the excess sludge. The obtained results show that the inoculation of activated sludge with the strains active against oil reduced the petroleum products content by 20% in 14 days. The greatest reduction of oil was observed in sludge with the lowest dry weight, that is with the greatest degree of hydration. The dry weight of the excess sludge did not significantly decrease during the course of the experiment, after having been inoculated with the mixture of strains.

Influence of sundrying on the chemical composition, aflatoxin content and fungal counts of two pepper varieties--Capsicum annum and Capsicum frutescens.

Samples of sundried, matured red pepper, Capsicum annum with a moisture content (MC) of 12.7-26.8 percent had on dry weight basis, vitamin C, 5.0-6.4 mg/100 g; crude protein, 0.8-1.2 percent; total soluble solids, 3.3-4.1 percent, and fungal counts of log 4.4-4.5/g. Ordinary matured red C. annum had MC, 75.7-78.2 percent vitamin C, 36.1-38.5 mg/100 g; crude protein, 2.4-2.8 percent; total soluble solids, 9.3-9.9 percent and fungal count of log 3.32-3.39/g. Sundried matured red C. frutescens had corresponding values of 9.4-18.7 percent; 5.8-6.3 mg/100 g; 0.8-1.1 percent; 0.9-2.6 percent and log 3.2-3.4/g. No aflatoxins were detected in sundried, matured red C. frutescens, but aflatoxin B1 values obtained from C. annum varied from non-detectable to 2.2 micrograms/kg. Dominant fungi isolated from C. annum and C. frutescens were Rhizopus oryzaze, Aspergillus niger, A. flavus, Geotrichum candidum and Saccharomyces spp.

New mutant types at the ade3 locus of Saccharomyces cerevisiae.

Six mutants, allelic to ade3, were isolated after mutagenic treatment of a prototrophic strain of yeast. All six grow on medium supplemented with adenine alone and four respond to histidine. Supplementation with adenine plus histidine or methionine inhibits growth, but a mixture of these three is stimulatory. Heteroallelic diploids formed by the new mutants with the standard ade3 can resemble either parent or show an intermediate phenotype. The new mutants, unlike standard ade3, are not fully epistatic to ade2. The activities of three enzymes concerned in tetrahydrofolate metabolism have been assayed in the new and standard ade3 mutants and wild type. The only difference detected between the new and standard ade3 was in the levels of 10-formyltetrahydrofolate synthetase. Activity in the new mutants ranged from 36 to 109% of wild type compared with 10 to 12% in the standard ade3. Possible mechanisms to account for the varied phenotypes at the ade3 locus are discussed.