Marine fungi are known to originate from a wide variety of habitats within the marine environment. Marine sediment represents one environmental niche, with most fungi occurring in these sediments being facultative marine fungi with terrestrial origins. It has not been proven whether these fungi merely survive the harsh environmental conditions presented by the ocean sediment, as opposed to playing an active role in this ecological niche. During this study, marine sediment was collected from St. Helena Bay, on the west coast of the Western Cape, South Africa. Using dilution, enrichment, and repetitive culturing techniques, 59 fungal isolates were obtained from marine sediments and identified to at least genus level using morphological and molecular methods. Moreover, a series of tests were performed to characterize the physical and physicochemical attributes of the isolates. Results showed that the isolates not only survived but also had the potential to grow in the natural conditions present in this environment. Extracellular cellulase was produced by the filamentous fungal isolates indicating their probable role in detrital decay processes and therefore the carbon cycle on the ocean bed. Also, denitrification patterns were observed when isolates were grown in liquid media amended with NaNO(2), NaNO(3), and (NH(4))SO(4), implicating that these fungi have the potential to play an active role in denitrification, co-denitrification, and ammonification phases of nitrogen cycles occurring in the marine sediments.

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ABSTRACT:A female southern right whale (Eubalaena australis) neonate was found stranded on the Western Cape coast of southern Africa. Skin samples were taken the same day from three different locations on the animal's body and stored at 220 C. Isolation through repetitive culture of these skin sections yielded a single yeast species, Candida zeylanoides. Total genomic DNA also was isolated directly from skin samples. Polymerase chain reaction analysis of the internal transcribed spacer region of the fungal ribosomal gene cluster revealed the presence of Filobasidiella neoformans var. neoformans, the teleomorphic state of Cryptococcus neoformans. Fungal infections in cetaceans seem to be limited when compared to infections caused by bacteria, viruses and parasites. However, Candida species appear to be the most common type of fungal infection associated with cetaceans. To our knowledge this is the first report of a C. zeylanoides infection in a mysticete, as well as the first report of a dual infection involving two opportunistic pathogenic yeast species in a cetacean.

The yeast-like fungus Coniochaeta pulveracea was studied with regard to its novel lignocellulolytic activities and the possible effect thereof on yeasts from the woody phylloplane. An enrichment procedure was used to isolate C. pulveracea from a decaying Acacia tree, and the identity of the isolate was confirmed using morphology, as well as molecular and phylogenetic techniques. This isolate, as well as strains representing C. pulveracea from different geographical regions, were compared with regard to optimum growth temperature and enzyme activity to representatives of closely related species. These include strains of Coniochaeta boothii, Coniochaeta rhopalochaeta, and Coniochaeta subcorticalis. Plate assays for cellulase and xylanase activity indicated that all representatives of the above-mentioned species were able to produce extracellular hydrolytic enzymes and were also able to degrade birchwood toothpicks during a 50-day incubation period at 30°C. To test the ability of these fungi and their enzymes to release simple sugars from complex cellulosic substrates, filtrates obtained from liquid cultures of Coniochaeta, cultivated on carboxymethyl cellulose (CMC) as sole carbon source, were analyzed using high-performance liquid chromatography analysis. Consequently, the presence of mono- and disaccharides such as glucose and cellobiose was confirmed in these culture filtrates. Two subsequent experiments were conducted to determine whether these simple sugars released from woody material by Coniochaeta may enhance growth of phylloplane yeasts. In the first experiment, representatives of Coniochaeta were co-cultured with selected yeasts suspended in agar plates containing birchwood toothpicks, followed by examination of plates for colony formation. Results indicated that Coniochaeta growth on the toothpicks enhanced growth of nearby yeast colonies in the agar plates. In the second experiment, representatives of selected yeasts and Coniochaeta species were co-cultured on CMC and xylan-containing plates where after yeast colony formation was recorded on the plates. Saccharomyces cerevisiae strains, engineered to utilize specific wood degradation products, i.e., cellobiose or xylose, as sole carbon source were used as positive controls. While it was found that cellobiose released from CMC was assimilated by the yeasts, no evidence could be obtained that xylose released from xylan was used as carbon source by the yeasts. These ambiguous results could be ascribed to secretion of nutritious metabolic end products, other than the products of fungal xylanases.

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