炭化水素資化性酵母Candida sp. Y-191の培養条件(炭化水素資化性酵母に関する研究(第2報),自然科学)

前報で,同定株,未同定株合せて309株を供試菌として炭化水素資化性酵母の検索を行い,26株の酵母を選択した。その中でも赤木が四日市市の油浸土壌から分離したCandida sp. Y-191号菌は増殖速度,菌体収量などの点ですぐれていることを認めたので,本報ではCandida sp. Y-191についてその生育におよぼすn-Hexadecane濃度の影響,種種の天然、栄養源添加の効果および本菌の各種n-Alkaneの資化性について検討した。n-Hexadecane濃度は低い程菌体収率が高く0.5%濃度では90.5%に達した。また,最高生育量を得たのは2.0%であった。本菌は天然栄養源の添加なしでもよく生育したが,Yeast extract, Corn steep liquor, Meat extract, Peptone等の添加によって生育速度が増大した。Yeast extractは0.01%で効果的であった。11種類のn-Alkane(C_8～C_)の資化性は,炭素数の増大とともに酵母量が増大する傾向がみられた。特にC_～C_のn-Alkaneを基質とした場合酵母収量が多かった。In the previous paper, screening of yeast that assimilate hydrocarbons and the effects of various nitrogen sources and surfactants on the growth of hydrocarbon assimilating yeast, Candida sp. Y-191, which had been isolated from oily soil by M. Akaki, one of the authors, were investigated. The basal medium containing 1% n-Hexadecane as carbon source was used. In this report, the effects of concentration of n-Hexadecane in the medium and the addition of natural nutrients to the basal medium such as yeast extract, meat extract, koji extract, corn . steep liquor and peptone, on the growth of Candida sp. Y-191, were investigated in shaking culture, using the basal medium (n-Alkane, (NH_2)_2CO 1.4g, KH_2PO_4 2.5g, MgSO_4・7H_2O 0.1g, FeSO_4・7H_2O 0.01g, Yeast extract 0.2g, Span 85 0.005g, Distilled water 1000ml, pH5.5～6.0). Also the ability of assimilation of individual pure n-Alkanes (n-C_8～n-C_) by the yeast were investigated. Following results were obtained. As shown in Table 2, the yield of the yeast cell on the basis of added n-Hexadecane increased, together with the decrease of n-Hexadecane concentration in the medium. The yield reached 90.5% with the medium containing 0.5% n-Hexadecane. The yield of the yeast cell on the basis of a definite amount of the medium was maximum, with the medium containing 2% n-Hexadecane. This yeast strain was able to grow comparatively well in the n-Hexadecane containing synthetic medium without addition of natural nutrients. However, by the addition of natural nutrients such as yeast extrct, meat extract and corn steep liquor, the yeast grew abundantly. The addition of 0.01% yeast extract to the medium was effective for the yeast growth. As shown in Table 3, the yeast assimilated hydrocarbons of n-Alkanes, n-C_9 to n-C_ and especially n-C_, n-C_ and n-C_ with good cell production. The yield of yeast cell generally tended to increase with increment of carbon number of n-Alkanes tested

炭化水素資化性酵母の検索と培養条件(炭化水素資化性酵母に関する研究(第1報),自然科学編)

各種の炭化水素を炭素源とした培地を用いて,309株の供試菌(同定株133株,未同定の分離株176株)から炭化水素資化性の強い菌株を選択した。その結果,M.japanica 316, M.japonica 6226, M.japonica 6229, C.tropicalis 6019, C.tropicalis 6263, C. trioucakus 6264,土壌からの分離母Y191株の7菌株を得た。Y191株, M.japonica 316はCetaneを炭素源とする培地でとくによい生育をしたが,窒素源として硫酸アンモニウムを使用したばあいは培地のpHが極端に低下した。硫酸アンモニウムのかわりに尿素を用いると,培養によるpHの極端な低下が防止でき,生育量も増大した。Y191株においてとくに生育量の増大が顕著であった。つぎに,赤木によって四日市市の油浸土壌から分離された炭化水素資化性の強いY191号菌(Candida sp.に属する)の生育におよぼす種種の窒素源,界面活性剤などの影響を検討した。窒素源としては尿素が適当であり,その濃度は0.2～0.8%が良好であった。供試した10種類の界面活性剤のうち,Candida sp. Y191株の生育に効果があったものは,Span 40, Span 80, Span 85であった。中でもSpan 85がもっとも効果的であり,その適量は0.005～0.01%であった。また,培養フラスコ中の培養液量の増加とともに,一定量の培地からの菌体収量は減少した。しかし,Span 85の添加により,収量の減少は大幅に防止できた。We attempted to obtain yeast strains which utilize hydrocarbon as carbon source. In this report, three hundred and nine strains of yeast were employed. These strains included one hundred and thirty-three strains of identified yeast, i.e., forty-four strains of Pichia, fifty-four strains of Hansenula, six strains of Saccharomyces, ten strains of Candida, three strains of Mycotorula, five strains of Rhodotorula and eleven strains of Debaryomyces, and one hundred and seventy-six strains of unidentified yeast. Seven strains of yeast, Mycotorula japonica 316, Mycotorula japonica 6226, Mycotorula japonica 6229, Candida tropicalis 6019, Candida tropicalis 6263, Candida tropicalis 6264 and unidentified strain Y 191, utilizing hydrocarbon as carbon source were selected. Among these seven strains of yeast, Mycotorula japonica 316 and Y 191 strain, which had been isolated from oily soil by M. Akaki, one of the authors, grew abundantly, especially in the medium containing cetane as carbon source. When ammonium sulphate was used as nitrogen source, the pH of culture media depressed extremely during cultivation. In the culture with media, which used urea instead of ammonium sulphate as nitrogen source, these yeast cultures were prevented from depression of pH during cultivation, and gave high yield of the yeast cell, particularly Y 191 strain. Since Y 191 strain is capable of utilizing various hydrocarbon sources and making rapid growth in the media containing hydrocarbon, it would seem to be a promising strain for cell production from hydrocarbons. The effects of various nitrogen sources and surfactants on the growth of hydrocarbon utilizing yeast Y 191, which identified as Candida sp, by M. Akaki, were investigated in shaking culture on the basal medium B(Table 2) containing 1 per cent cetane as carbon source, Following results were obtained. Four kinds of nitrogen source, i,e., urea, ammonium sulfate, ammonium chloride and ammonium nitrate, were tested. Among these four, urea was most fitted for the growth of the yeast, and gave higher yeast cell yield than the other nitrogen sources tested. Optimal concentration of urea as a nutrient for the yeast growth in the medium containing 1 per cent cetane as carbon source was between 0.2 and 0.8 per cent. Ten kinds of surfactant shown in Table 10 were tested. Among them, Span 40, Span 80, Span 85 gave good effects on the growth of the yeast in the basal medium. Especially, Span 85 was most effective for the yeast growth. Optimal concentration of Span 85 for the growth of the yeast in the medium was between 0.005 and 0.01 per cent. The yeast cell yield on the basis of a definite amount of the medium decreased with the increase of the volume of medium in a culture flask. However, the addition of Span 85 to the basal medium greatly prevented the yeast cell yield on the basis of a definite amount of the medium from decreasing

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