Masahiko Natori

Effect of culture temperature shift on the cellular sugar accumulation of Chlorella vulgaris SO-26

Abstract We investigated the effect of culture temperature on the maximum specific growth rate and cellular sugar accumulation, and the effect of a temperature shift on the sugar accumulation of cells of an Antarctic green alga, Chlorella vulgaris SO-26, in a batch culture system. Decreases in temperature appeared to correlate with decreases in the maximum specific growth rate; on the other hand, the cellular sugar content showed a reverse tendency against temperature. We attempted to use this tendency to improve sugar productivity in Chlorella. First, we cultured Chlorella at 20°C during the logarithmic growth phase to obtain a high specific growth rate. The culture temperature was then shifted from 20°C to 14°C during the stationary growth phase to increase the cellular sugar content. As a result, we obtained a 25% increase in sugar production over that obtained by culture at 20°C throughout the culture.

'One for all scales' methods for plasmid, phagemid and bacteriophage DNAs preparation

We have established two simple, reliable, economical and time-saving methods, one for plasmid and phagemid DNAs another for bacteriophage DNAs, that can be applied for any desired scale of vector and its recombinant DNAs preparation. The methods require neither toxic chemicals nor expensive enzymes or chemical reagents. In case of the small-scale preparation, the entire procedure can be done in one microfuge tube. The A260/A280 values for isolated DNAs were constantly between 1.60 and 1.85. The isolated plasmid or phagemid DNA can be used for restriction digestion, religation, transformation, construction of deletion mutants, sequencing, PCR and in vitro transcription. The double-stranded and single-stranded phage DNAs prepared from the present method have the quality to serve as good templates for PCR and site-directed mutagenesis experiments.