A yeast strain, Aureobasidium pullulans, which could produce the high yield of protease was isolated from sediment of saltern in Qingdao, China. Maximum production of enzyme (623.1 U/mg protein; 7.2U/ml) was obtained in a medium containing 2.5 g soluble starch and 2.0 g NaNO3, 100ml seawater, initial pH 6.0, after fermentation at 24.5℃ for 30 h. The protease had the highest activity at pH 9.0 and 45℃.

Marine yeast strain 1, isolated from the surface of a marine alga, was found to secrete a large amount of inulinase into the medium. This marine yeast was identiWed as a strain of Pichia guilliermondii according to the results of routine yeast identiWcation and molecular methods. The crude inulinase produced by this marine yeast worked optimally at pH 6.0 and 60

UNESCO Chinese Center of Marine Biotechnology, Ocean University of China, Qiangdao 266003, P.R.China The terrestrial yeasts have been receiving great attention in science and industry for over one hundred years because they can produce many kinds of bioactive substances. However, little is known about the bioactive substances of marine yeasts. In recent years, it has been found that marine yeasts have wide applications in mariculture and other fields. Tive substances they produced are reviewed in this paper.

In this study, the effects of inositol addition on expression of the MAL gene encoding maltase and phosphatidylinositol (PI) biosynthesis in Schizosaccharomyces pombe (a naturally inositol-requiring strain) were examined. We found that specific maltase activity was at its maximum when the concentration of added inositol reached 6 ug ml1 in a synthetic medium containing 2.0% (w/v) glucose. When the concentration of added inositol was 1 ugml1 in the medium, repression of MAL gene expression occurred at glucose concentration higher than 0.2% (w/v). However, when S. pombe was cultured in the synthetic medium containing 6 ug ml1, repression of maltase gene expression occurred only at initial glucose concentration above 1.0% (w/v). More mRNA encoding maltase was detected in the cells grown in the medium with 6 ug ml1 inositol than in those grown in the same medium with 1 ug ml1 inositol. These results demonstrate that higher inositol concentrations in the synthetic medium could derepress MAL gene expression in S. pombe. PI content of the yeast cells grown in the synthetic medium with 6 ug ml1 of inositol was higher than that of the yeast cells grown in the same medium with 1 ug ml1 of inositol. This means that PI may be involved in the derepression of MAL gene expression in S. pombe.

The marine yeast strain G7a isolated from sediment of China South Sea was found to secrete a large amount of inulinase into the medium. This marine yeast strain was identified to be a strain of Cryptococcus aureus according to the results of routine yeast identification and molecular methods. The crude inulinase produced by this marine yeast showed the highest activity at pH 5.0 and 50 8C. The optimal medium for inulinase production was artificial seawater containing inulin 4.0% (w/v), K2HPO4 0.3% (w/v), yeast extract 0.5% (w/v), KCl 0.5% (w/v), CaCl2 0.12% (w/v), NaCl 4.0% (w/v) and MgCl2