清酒麹から分離した<i>Pichia angusta</i> Y-11393の亜硝酸消失能

Abstract

KIMOTO SHUBO is a traditional seed mash producing method in sake brewing. Yeast is cultivated vigorously in open systems without contamination by bacteria or wild yeast. In the process, contaminated microorganisms are inhibited from growing by a nitrite/nitrate system in the mother water and lactic acid produced by lactic acid bacteria. Finally, under the low pH condition, the sake yeast is grown predominantly in the mash. However, in the brewer's house, there is a phenomenon in which the nitrite is not eliminated in the mash. This factor was researched using model mash by sake koji obtained from sake brewer's houses. The microorganisms in the koji eliminated the nitrite in mash. Y-11393 strain was identified as Pichia angusta. The strain oxidized nitrite to eliminate it from the mash. It is believed that the yeast assimilated nitrate, which is a low toxic substance for yeast. The strain had tolerance against nitrite and could grow under 1-5mM nitrite conditions. It also eliminated nitrite up to 6-16% for 4 days. Moreover, the strain had acid tolerance and ethanol tolerance up to 5% ethanol and 1.1% lactic acid. The yeast eliminated nitrite in the model moto-mash. Also, the yeast cells between the mid-log phase and late-log phase thoroughly eliminated nitrite. It is obvious that the yeast has the ability to remove nitrite in the KIMOTO method.