Paul A. Volz

Effect of various antibiotics on gastrointestinal colonization and dissemination by Candida albicans

Mice were treated orally with various antibiotics to determine which members of the indigenous intestinal microflora normally suppress Candida albicans colonization and dissemination from the gastrointestinal (GI) tract. The mice were given penicillin, clindamycin, vancomycin, erythromycin, or gentamicin for 3 days, and then challenged orally with C. albicans. Penicillin, clindamycin, and vancomycin, but not gentamicin or erythromycin, decreased the total anaerobic bacterial populations in the animals ceca, and increased the enteric bacilli population levels. All three of the former antibiotics allowed C. albicans to proliferate in the gut and, subsequently, disseminate from the GI tract to visceral organs. The ability of C. albicans to associate with intestinal mucosal surfaces was also tested. It was found that antibiotics which reduced anaerobic population levels, but not enteric bacilli or aerobes, also predisposed animals to mucosal association by C. albicans. It is suggested that the strictly anaerobic bacterial populations which predominate in the gut ecosystem are responsible for the inhibition of C. albicans adhesion, colonization and dissemination from the GI tract.

Dissemination of yeasts after gastrointestinal inoculation in antibiotic-treated mice

Mice pretreated with antibiotics were inoculated intragastrically with different yeast isolates to determine whether the resulting disruption of the normal flora ecology would allow certain fungi to colonize and disseminate from the gastrointestinal tract. Antibiotic treatment decreased the total population levels of the indigenous bacterial flora, and predisposed mice to gastrointestinal overgrowth and subsequent dissemination by Candida albicans, C. parapsilosis, C. pseudotropicalis, C. tropicalis, and Torulopsis glabrata. A clinical isolate of Rhodotorula rubra, on the other hand, was unable to maintain a stable population in the gut of similar mice and could not be isolated from systemic organs. Control animals not receiving antibiotic therapy, challenged with C. albicans, showed significantly lower gut population levels of yeasts, and Candida organisms could not be grown from visceral organs. It is suggested that suppression of fungi within the gastrointestinal tract by members of the normal bacterial flora may be an important mechanism whereby fungi are confined to the alimentary tract.

Penetration of Trichophyton terrestre in human hair

The systematic human hair degradation by Trichophyton terrestre was examined by electron and light microscopy. The cuticular and hair shaft regions were readily decomposed by the wild type or parent strain selected for phenotype studies after exposure to spaceflight parameters.

DIVERSITY OF CRYPTOGAMIC PLANTS AND FUNGI IN “EVOLUTION CANYON”, NAHAL OREN, MOUNT CARMEL NATURAL PRESERVE, ISRAEL

ABSTRACT The diversity of cryptogamic plants and fungi has been studied, in the context of a research program of biodiversity across phylogeny, at the “Evolution Canyon” microsite. Lower Nahal Oren, Mount Carmel Natural Preserve, Israel. The opposite slopes of Evolution Canyon display dramatic biotic contrasts due to higher (up to 300%) solar radiation on the south-facing slope (S-slope) which is warmer, drier, and climatically more fluctuating than the north-facing slope (N-slope). Diversity of cryptogamic plants and fungi (198 species and intraspecific taxa) at Evolution Canyon is considerable. The list includes 46 taxa of Cyanophyta, 10 of Chlorophyta, 3 of Euglenophyta, 1 of Bacillariophyta, 29 of lichens, 2 of lichenicolous fungi, 59 of soil micromycetes, 39 of Agaricales s.l., and 9 of mosses. Fifty species and infraspecific taxa are new for the biota of Israel, among them 22 taxa of algae, 9 of micromycetes, 8 of Agaricales s.l., 9 of lichens, and 2 of lichenicolous fungi. Some of them are new for ...

Nutritional studies on species and mutants of Lepista, Cantharellus, Pleurotus and Volvariella

The purpose of this study is to determine the ability of select Agaricales species to utilize various sources of carbon, nitrogen, vitamins, and growth hormones. Fungi selected for the studies include:Cantharellus clavatus Fries,C. cibarius Fries,Lepista nuda (Bull. ex. Fries)Cooke,Pleurotus ostreatus (Jacq. ex. Fries)Kummer, andVolvariella volvacea (Bull. ex. Fries)Singer. Three strains ofC. cibarius and one mutant ofV. volvacea (V135), V134, were employed to determine if nutritional requirement differences occurred. One species,V. volvacea, is grown commercially as a cottage industry in the Orient (Alicbusan &Ela, 1961) while the other species currently have no commercial value. All species studied possess pleasing flavors and have potential use in the mushroom production industry. A literature compilation of the nutritional regulation of basidiocarp formation and vegetative growth of Agaricales was made with specific mention to the named species (Volz &Beneke, 1969). Recent nutritional studies with one or more of the specific species include those byYusef &Allam (1967), andEger (1970).

Gastrointestinal inoculation of Sporothrix schenckii in mice.

Antibiotic-decontaminated and untreated conventional mice were inoculated intragastrically with 107 viable cells of Sporothrix schenckii to compare the incidence of gastrointestinal (GI) colonization. In control mice, S. schenckii was completely eliminated from the GI tract by 12 h post-inoculation. Antibiotictreated mice also failed to become colonized with this fungus, however, higher population levels of Sporothrix cells remained in the GI tract for a longer period of time before being eliminated. The ability of S. schenckii to disseminate from the lumen of the bowel to infect other organs was also tested. Results indicate that the gastrointestinal tract is not a portal of entry into the host for S. schenckii.

Variation in cell surface features of Candida albicans with respect to carbon sources.

Clinical isolates of C. albicans were grown in defined media with various carbon sources then examined by scanning electron microscopy in an attempt to note changes in cell surface features. The mode of budding, bud scar morphology, surface topography, and intercellular matrix varied according to the carbon source.

The sclerotia of Coprinus lagopus

SummarySclerotia of Coprinus lagopus were produced in the laboratory and observed microscopically from initiation to maturity. Isolated bulbous hyphal cells appeared below or on the agar surface as the primary sclerotial initials. Short interhyphal cells had expanded lateral walls and increased in number at their isolated locations, and were surrounded by a thick network of normal mycelium. Increasing in numbers, the bulbous cells developed a tightly compact colony devoid of agar if submerged below the agar surface and lacked normal hyphal filaments. The outer cells thickened formed cell lumina and developed as a protective rind to the mature sclerotium.

Newly Discovered Halophilic Fungi in the Dead Sea (Israel)

Organisms living in extreme environments are called extermophiles because they live under extreme conditions at the edge of life (Madigan and Marrs, 1997). These organisms (thermophiles, alkalophiles, acidophiles, halophiles) do not merely tolerate their extreme living conditions, which are detrimental to most organisms. Remarkably, they do best in these extreme habitats, and in many cases require one or more extremes for reproduction. In other words, they evolved unique adaptive evolutionary strategies to these extreme living conditions, thereby becoming narrow extreme specialists.

SOIL MICROMYCETES OF SELECTED AREAS OF ISRAEL

Species content of soil micromycetes of different areas of Israel (Haifa, Akko, Caesarea, Kafr Kanna, Nazareth, Tiberias, Jordan River shore, Jericho, Jerusalem, Bethlehem, Masada, Dead Sea shore) is given. A total of 83 species belonging to 59 genera were found in 74 soil samples collected in Israel during February—March 1994. Many species belonging to the Deuteromycetes were found as well as a few species belonging to other classes, including Zygomycetes and Ascomycetes. Eighteen species are new or rare for the biota of Israel. Peculiarities of species and genera content of soil micromycetes of different regions of Israel are discussed. General, specific, and dominant taxons are described. The dermatophyte, Microsporium gypseum, and keratinophilic species of the genus Chrysosporium were commonly found.