Abstract
In an effort to develop a microbial in secticide, B. thdringiensis var. thuringiensis was cultured in the medium composed of cocoon-cooked water from a filature. The results obtained are summarized as followss : (1) Bacillus thuringiensis is a bacterium producing a ${\delta}-endotoxin$ especially toxic to lepidopterous insects and a thermostable exotoxin harmful to dipterous insects. (2) With a view to utilizing the cocoon-cooked water discarded from the filature, as a nutrient source in the B. thuingiensis culture, it was analyzed to contain large amounts of various minerals and protein (7.5 mg/ml) believed to be extracted from the pupae. (3) A large amount of the ${\delta}-endotoxin$ can be obtained most cheeply by using cocoon-cooked water instead of distilled water in preparing GYS and citrate salts media. (4) The largest amount of a mixture of the vegetative cells, spores, and crystals was obtained by addition of 8 gr/l of glucose to the GYS medium. (5) The growth of the bacterium was far better, when leucine, isoleucine, and valine were added all together to the citrate salts medium to the concentration of $1.25{\times}10^{-3}M$. (6) The best growth was observed by addition of Na-glutamate to the citrate salts medium to the concentration of $2.5{\times}10^{-3}M$. (7) The optimal culture time ranged from 9 to 15 days. (8) The highest mortality was shown in Pieris rapae Linne with a pH of the total body extract of 8.4, whereas Dendrolimus spectabilis Butler and Bombyx mori Linne with lower pH's were less susceptible to the ${\delta}-endotoxin$. (9) The presence of the thermo stable exotoxin was confirmed by the fact that the supernatant of the culture was very toxic to the Drosophila melanogaster tested.
공업폐수를 이용하여 미생물 살충제를 생산하기 위하여 배양방법, 배양조건 및 생물학적 검정을 행한 결과는 다음과 같다. (1) B. thuringiensis avr. thuringiensis는 특히 나비목 해충에 유효한 ${\delta}-endotoxin$과 파리목에 유효한 fly-toxin을 생산하는 세균이다. (2) 제사공장에서 폐기되는 자견수를 영양원으로서 본 세균배양에 이용할 목적으로 분석한 결과 많은 량의 무기물과 단백질이 용으로부터 추출되어 나왔음을 알았다. (3) GYS 배지와 citrate salts배지를 만들때 물대신 자견수를 사용하면 가장 경제적으로 많은 량의 ${\delta}-endotoxin$을 얻을 있다. (4) GYS 배지에 8gr/l의 glucose 첨가시 균체와 crystal의 혼합물 생산량이 가장 많았다. (5) 아미노산중 leucine + isoleucine _ valine을 $1.25{\times}10^{-3}M$ 농도로 citrate salts 배지에 첨가시 공시세균의 증식이 훨씬 좋았다. (6) Na-glutamate를 citrate salts배지에 $2.5{\times}10^{-3}M$ 첨가시 가장 좋은 증식을 보였다. (7) 공시 나무목 해충중에서 total body extract의 pH가 가장 높은 Pieris rapae Linne (pH 8.4)에서 가장 좋은 살충효과를 보이고 Dendrolimus spectabilis Bulter와 Bombyx mori Linne에서는 효과가 낮았다. (9) 본 세균의 배양 상등액은 초파리에 대하여 높은 살충률을 보여 열에 안정한 exotoxin의 존재를 확인하였다.
(Dept. of Agricultural Chemistry, Chung Buk National University)
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