Free-living amoebae promote Candida auris survival and proliferation in water

Candida auris is an emerging species responsible for life-threatening infections. Its ability to be resistant to most systemic antifungal classes and its capacity to persist in a hospital environment have led to health concerns. Currently, data about environmental reservoirs are limited but remain essential in control of C. auris spread. The aim of our study was to explore the interactions between C. auris and two free-living amoeba (FLA) species, Vermamoeba vermiformis and Acanthamoeba castellanii, potentially found in the same water environment. Candida auris was incubated with FLA trophozoites or their culture supernatants. The number of FLA and yeasts was determined at different times and transmission electron microscopy (TEM) was performed. Supernatants of FLAs promoted yeast survival and proliferation. Internalization of viable C. auris within both FLA species was also evidenced by TEM. A water environmental reservoir of C. auris can therefore be considered through FLAs and contamination of the hospital water networks would consequently be possible.     

Autism-Misregulated eIF4G Microexons Control Synaptic Translation and Higher Order Cognitive Functions

1. Download : Download high-res image (173KB)
2. Download : Download full-size image

     

Biotyping of pathogenic fungi by the killer system and with monoclonal antibodies

Biotyping of pathogenic yeasts and hyphomycetes based on their suceptibility to selected killer yeasts and their reactivity with monoclonal antibodies are described. Both methods were used to differentiate fungi isolated from patients providing valuable epidemiological information on mycotic infections. The functional biotyping obtained with the two systems and the conventional auxenographic biocoding approaches commercially available for opportunistic yeasts are comparatively evaluated. The potential for biotyping of industrial fungal isolates is also discussed.     

Formation and physiological role of biosurfactants produced by hydrocarbon-utilizing microorganisms

Microbial growth on water-insoluble carbon sources such as hydrocarbons is accompanied by metabolic and structural alterations of the cell. The appearance of surface-active compounds (biosurfactants) in the culture medium or attached to the cell boundaries is often regarded as a prerequisite for initial interactions of hydrocarbons with the microbial cell. Under this point of view, biosurfactants produced by hydrocarbon-utilizing microorganisms, their structures and physico-chemical properties are reviewed. The production of such compounds is mostly connected with growth limitation in the late logarithmic and the stationary growth phase, in which specific enzymes are induced or derepressed. Addition of purified biosurfactants to microbial cultures resulted in inhibitory as well as in stimulatory effects on growth. Therefore, a more differentiated view of microbial production of surface-active compounds is proposed. Biosurfactants should not only be regarded as prerequisites of hydrocarbon uptake, but also as secondary metabolic products.     

Constitutive appearance of peroxisomes in a regulatory mutant of the methylotrophic yeast Hansenula polymorpha

Summary A selection by glucosamine for mutants of Hansenula polymorpha insensitive to glucose repression of methanol assimilation is described. Constitutive synthesis of enzymes is established in standard batch cultures of glucosegrown cells. Upon prolonged glucose metabolism the phenotype is masked by catabolite inactivation and degradation of enzymes. Addition of the substrate methanol remarkably improves constitutive synthesis by preventing catabolite inactivation and delaying degradation. Regular peroxisomes of reduced number are formed in mutant cells under repressed conditions. No constitutive synthesis is detectable using ethanol as a carbon source. In addition, this alcohol is detrimental to growth of the mutants, indicating that H. polymorpha is constrained to repress synthesis of enzymes involved in the C₁-metabolism when ethanol is present as a substrate.     

The vectoring of cactophilic yeasts by Drosophila

Summary At two locations in the Sonoran Desert, yeasts were sampled from species of Drosophila, the flies' cactus hosts, and other neighboring sources of cactophilic yeasts to determine the relation between the yeasts vectored by the fly and the yeasts found in their breeding sites. D. mojavensis, D. nigrospiracula, and D. mettleri vectored yeast assemblages significantly more similar to the yeast species found on the rot from which the flies were collected than to the yeasts found on other rots from the flies host cactus or other rotting cactus at the same site. Rots with Drosophila had fewer yeast species than those without flies, suggesting that flies were associated with younger rots. Rots with flies and the Drosophila also had more yeast species with the capability to produce ethyl acetate than rots without flies. The results support the contention that cactophilic Drosophila feed on a subset of the yeasts available in an area, and may act to maintain differences among the yeast communities found on different species of cactus.     

酵母的不同显色法的研究

在多年采集分离酵母菌的基础上,本文报道其中43属的600多株主要与担子菌有关的酵母及其他酵母的DBB反应,其中某些菌以往尚未测定过,从而广泛比较了担子菌酵母、子囊菌酵母与某些类酵母的区别。此外在方法上,摸索了其他未见报道的重氮盐的显色效果,发现固红B盐对布掷孢酵母(Bulleta Derx)的反应比DBB更灵敏。同时试验了热碱·乙醇处理细胞的快速DBB测试法,用此法测定某些疑难菌株,结果稳定,可大大缩短测试周期,并适用于多毛有气生菌丝的菌类。     

Neotypification of the genusTrichosporon

The currently accepted type species of the genusTrichosporon Behrend isT. beigelii. This species has formerly been regarded as identical toT. cutaneum. However, these fungi are now known to represent separate species with different ecology. The first species described inTrichosporon wasT. ovoides, an agent of human white piedra. A neotype strain is designated for this species, while a lectotype strain is indicated forT. cutaneum. The nameT. beigelii is considered as doubtful and consequently cannot be maintained.     

CUG codons inCandida spp.

Codon CUG is used for serine instead of for leucine, its usual assignment, in several yeasts of the genusCandida. We propose a series of steps for the reassignment, including disappearance of leucine CUG and its anticodon CAG, formation of a new serine tRNA, with anticodon CAG, from a duplication of the gene for serine tRNA (IGA), and then production of CUG codons by mutation at sites that are mostly nonessential.