Rhodobacter sphaeroidesからの酵母エキス不感受性5-アミノレブリン酸高生産変異株の取得

概要

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Rhodobacter sphaeroides CR-105,which has one-third the 5-aminolevulinic acid dehydratase(ALAD) activity of the parent strain, was selected by mutation from R. sphaeroides IFO12203. This strain (CR-105) cannot accumulate 5-aminolevulinic acid (ALA) in a medium containing yeast extract. To screen for mutants that can accumulate ALA when the medium contains yeast extract, a new bio-assay system was developed using Escherichia coli ALA auxotrophs. CR-28,which can accumulate ALA in the medium without levulinic acid (LA) was induced from CR-105 by this bio-assay system. CR-286 was induced from CR-28 spontaneously, and in this strain the growth rate was recovered and the ALAD activity was ca.2-fold that of the parent strain. Strain CR-286 did, however, require LA for ALA accumulation. Several organic nutrient sources were tested for ALA formation using CR-286. Yeast extract was most effective, the optimum amount of addition being 1%(w/w). The formation of ALA was very sensitive to the pH of the medium ; ca. 15 mM of ALA was accumulated after 200 h cultivation at pH 6.5 when the medium contained 1% yeast extract.
社団法人日本生物工学会の論文
1994-11-25