Kvasny Prumysl, 1991 (vol. 37), issue 5
Formation and reduction of diacetyl during fermentation and maturation of beer.Peer-reviewed article
P. VOLF
Kvasny Prum. 1991; 37(5): 129-134 | DOI: 10.18832/kp1991015 
Diacetyl is one of the important parameters of the fermentation and maturation processes of beer in the cylindro-conical fermentation vessels. The different procedures of the keeping of low diacetyl concentrations in beer are described in a literature. New selected yeast strains with the incorporated gene of acetolactate decar boxylase - E. C. 4.1.1.5 or with the stimulated diacetyl reductase - E. C. 1.1.1.5 permit a possibility of a strongly lowered diacetyl level. However, the problem remaining with these strains is their stability. Therefore, the parameters affecting the diacetyl formation, i. e. temperature, pressure, wort composition and the yeast...
The results of preservation of microorganisms by lyophilization.Peer-reviewed article
J. FUSKA
Kvasny Prum. 1991; 37(5): 134-137 | DOI: 10.18832/kp1991016
A simplified procedure for preservation of microorganisms by lyophilization was elaborated and put to the tests. The preserved strains were revived after two years and they were able to produce the required metabolites in the original concentrations. This procedure of preservation can be used for preparation of standardized sporal inoculum for the test-methods in pharmaceutical, food and wood research, for the screening methods as well as for direct preparation of vegetative inoculum for processes of biosynthesis of metabolites.(In Slovak, English summary only)
Production of Kluyveromyces marxianus on whey.Peer-reviewed article
M. STREĎANSKÝ, E. ŠTURDIK, M. TOMÁŠKA, T. MALIAR, Ľ KREMNICKÝ
Kvasny Prum. 1991; 37(5): 137-141 | DOI: 10.18832/kp1991017
23 strains Kluyveromyces marxianus was screened for production of biomass and β-galactosidase. Straín CCY 51-1-1 was selected. Optimalized medium for cultivation was deproteinized sweet whey with 1 % ammonium sulfate and 0,2 % yeast extract. Yield coefficient Yxs = 0,19 after 12 h fermentation with oxygen limitation was obtained in 1500 1 fermentor. Increasing of partial pressure to level 15 % improved Yxs on 0,24 and shorted fermentation time on 10 h, but specific activity of β-galactosidase in cells decreased by 24 %.(In Slovak, English summary only)