• Journal of Microbiology and Biotechnology
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• v.9 no.1
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• pp.70-77
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• 1999

An extremely cadmium-tolerant budding yeast, Hansenula anomala B-7 underwent a morphological switch in response to either heat shock treatment or cadmium stress, respectively. It exhibited a morphological transition from a unicellular yeast form to a pseudohyphae-like coagulation when subjected to prolonged heat shock treatment. In contrast, the yeast cells showed an irregularity in surface morphology when given thermal stress for a short time. Patterns of proteins expressed in the pseudohyphae-like cells demonstrated that several proteins were overexpressed while others were underexpressed in comparison with those prepared from the cells in the yeast form. It was a striking feature, however, that nearly 40％ of the proteins extracted from the cells in the pseudohyphae form appeared to be composed of a single polypeptide. This polypeptide was apparently overexpressed during the pseudohyphae phase and its molecular weight was estimated to be 58 kDa according to SDS-PAGE analysis. However, a significant level of the protein was not observed in the cells before transition to pseudohyphae. The architecture of the cell shape was also damaged when incubated in a medium containing more than 1,000 ppm (8.9mM) of cadmium ions, although able to proliferate at a slow rate. However, the irregularity in the cell morphology exerted either by the brief heat shock treatment or by the cadmium stress with the high concentrations of the metal ions was not repaired, even though the damaged cells were allowed to grow for sufficient time in fresh, cadmium-free medium.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.75-81
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• 1998

The yeast strain 504D, isolated from salted shrimp soup, showed the best proteolytic activity under alkaline condition. The yeast formed vegetative cells in almost optimal media for yeasts, but formed only pseudohyphae in the MM medium containing citric acid and true hyphae in the MM medium containing N-acetylglucosamin and ${\beta}$-D-glucose. The yeast was classified as hemiascomycetes to form ascospores by sexual reproduction, and formed blastospores and athrospores by asexual reproduction. The yeast strain did not assimilate almost of the carbon sources, nitrate and nitrite, but some organic acids and alcohols. The fatty acids of whole cells were composed of 53.67% unsaturated fatty acids and 14.58% saturated, and, especially, C17:1 was observed in this strain but not in two control yeasts. However, almost of all results were very similar to the morphological and physiological characteristics of Yarrowia lipolytica KCCM 12495 and KCCM 35426, except for a little differences which are the composition of fatty acids and the manner of mycellium formation. Therefore, the isolated yeast strain 504D is identified as a Yarrowia lipolytica.