Effects of a novel variant of the yeast gamma-glutamyl kinase Pro1 on its enzymatic activity and sake brewing
JOURNAL OF INDUSTRIAL MICROBIOLOGY & BIOTECHNOLOGY
Authors: Murakami, Naoyuki; Kotaka, Atsushi; Isogai, Shota; Ashida, Keiko; Nishimura, Akira; Matsumura, Kengo; Hata, Yoji; Ishida, Hiroki; Takagi, Hiroshi
Sake is a traditional Japanese alcoholic beverage brewed with the yeastSaccharomyces cerevisiae. Sake taste is affected by sugars, organic acids, and amino acids. We previously isolated mutants resistant to the proline analogue azetidine-2-carboxylate derived from a diploid sake yeast strain. Some of the mutants produced a greater amount of proline in the brewed sake. One of them (strain K-9-AZC) carried a novel mutation in thePRO1gene encoding the Gln79His variant of the gamma-glutamyl kinase Pro1, a key enzyme in proline biosynthesis inS. cerevisiae. This mutation resulted in extreme desensitization to feedback inhibition by proline, leading to proline overproduction. Interestingly, sake brewed with K-9-AZC contained 3.7-fold more proline, but only 25% less succinate than sake brewed with the parent strain. Metabolome analysis suggests that the decrease in succinate was attributable to a lower level of 2-oxoglutarate, which is converted into glutamate. The approach here could be a practical method for breeding of yeast strains involved in the diversity of sake taste.
Effects of photoperiod on development and demographic parameters of the predatory thripsScolothrips longicornisfed onTetranychus urticae
BULLETIN OF ENTOMOLOGICAL RESEARCH
Authors: Pakyari, Hajar; McNeill, Mark R.
The effect of five photoperiods (0:24, 6:18; 12:12, 18:6, and 24:0 light:dark (L:D)) on the development, reproduction, and survival of the predatory thripsScolothrips longicornisPriesner fed on the two-spotted spider mite,Tetranychus urticaeKoch, was tested under laboratory conditions at 60% RH and 25 degrees C. Development time of almost all immature stages inS. longicorniswas the shortest under long day lengths (18:6 and 24:0 L:D). The adult duration of both sexes decreased with increasing light length from 6 to 24 h. The longevity of male and female decreased with increasing light length. Under a 12:12 L:D photoperiod,S. longicornisfemales had the longest oviposition period and longevity, highest net reproductive rate (R-0= 15.37), intrinsic rate of natural increase (r= 0.141), and finite rate of increase (lambda= 1.151). Life table parameters showed a significant difference with various photoperiods. The consequences of the present research demonstrated that a 12:12 L:D photoperiod is the most favorable for the reproduction and development ofS. longicornisfed onT. urticae, and that for mas rearing for augmentative biological control programs, would be the ideal photoperiod to maximize production.