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.

Under the optimal conditions, 10 U/ml of glucoamylase was produced by the marine yeast Aureobasidium pullulans N13d. It was noticed that the crude glucoamylase actively hydrolyzed potato starch granules, but poorly digested raw corn starch and sweet potato starch, resulting in conversion of 68.5, 19 and 22% of them into glucose within 6 h of incubation in the presence of 40 g/l of potato starch granules and 20 U/ml of the crude enzyme. When potato starch granules concentration was increased from 10 to 80 g/l, hydrolysis extent was decreased from 85.6 to 60%, while potato starch granules concentration was increased from 80 to 360 g/l, hydrolysis extent was decreased from 60 to 56%. Ratio of hydrolysis extent of potato starch granules to hydrolysis extent of gelatinized potato starch was 86.0% and the hydrolysis extent of potato starch granules by action of the crude glucoamylase (1.0 U/ml) was 18.5% within 30 min at 60 8C. Only glucose was detected during the hydrolysis, indicating that the crude enzyme could hydrolyze both a-1,4 and a-1,6 linkages of starch molecule in the potato starch.

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.