| 摘要 |
A micro-organism capable of growing on a feedstock consisting wholly or in part of straight chain hydrocarbons with formation of lipids is cultivated in the presence of the feedstock, a fraction comprising the micro-organism is separated from the product and the fraction is extracted by means of a solvent. The micro-organism may be a yeast, particularly Candida lipolytica though many other yeasts are particularly mentioned, a mould such as Penicillium expansum, or a bacterium, particularly Bacillus megaterium, Bacillus subtilis and Pseudomonas aeruginosa, though many other species and strains of bacteria are particularly mentioned. The feedstock may be a petroleum faction, consisting in part of straight chain hydrocarbons, or a wax-containing petroleum gas oil, whereby there is recovered from the product of the growth of the micro-organism a petroleum fraction having a reduced proportion of straight chain hydrocarbons (or free from straight chain hydrocarbons) or a gas oil of reduced content of wax, as the case may be. The solvent extraction may be carried out in two stages, the first in the presence of a polar solvent and the second in the presence of a mixed solvent consisting of an azeotropic mixture of a hydrocarbon solvent and a polar solvent. Preferred solvents are ethanol, iso-propanol, benzene, light platformate fractions, n-hexane, ethyl ether, acetone, chlorinated solvents and liquefied petroleum gases such as butane and propane. Preferably, the solvent is fed to the extractor at a periodically varying rate to create pulsations in the flow of the liquid stream. Pulses at a rate of between 1 and 60 per minute may be produced by an alternating pump from which the valves have been removed. According to an example, Candida lipolytica was cultivated under continuous operation with vortex aeration in the presence of a heavy gas oil of petroleum origin containing 20% by weight of normal paraffins, an aqueous mineral medium including tribasic sodium phosphate, potassium chloride, magnesium sulphate, ammonium sulphate and trace elements, and a minute amount of yeast extract; the temperature was maintained at 30 DEG C. and the pH of the medium regulated to pH 4 by the addition of aqueous ammonia. The cultivation mash was centrifuged to give three fractions: (a) an oil phase containing the yeast cells, (b) an aqueous mineral medium phase (which may contain traces of oil and yeast), and (c) a yeast cream. The yeast cream together with an aqueous solution of a surface-active agent, e.g. a non-ionic detergent having in the molecule a condensed ethylene oxide chain, was mixed and then further centrifuged to obtain three further fractions: (a) an oil phase, (b) an aqueous phase containing the surfactant product which is recycled to the mixer, and (c) a second yeast cream. This second yeast cream was passed with water to a mixer and was then yet further centrifuged to obtain the following three fractions: (a) an oil phase, (b) an aqueous phase and (c) a thick yeast cream containing 20% by weight of yeast. This thick yeast contained 44% by weight of proteins and 18.5% of lipids, and possessed a sharp and rancid taste. The lipids with residual oil were extracted from the yeast by solvent extraction using a mixture of 80% hexane and 20% ethyl alcohol. After evaporating the solvent, there was obtained a yeast of neutral taste, containing 52% of proteins and 3% of lipids. The extract consisted principally of oxidized and unoxidized fatty acids, esters and sterols. In a further example, the thick yeast cream was extracted in a horizontally rotating filtration drum first with ethanol and then with a solvent mixture consisting of 80% n-hexane and 20% ethanol. In a third example, the thick yeast cream was extracted in a vertical filtration drum furnished with a paddle stirrer rotated at 10 r.p.m. with (a) ethanol, (b) ethanol followed by n-hexane, or (c) iso-propanol. Specifications 1,049,066 and 1,049,067 divided from the present Specification have identical subject-matter but differing claims.ALSO:A micro-organism capable of growing on a feedstock consisting wholly or in part of straight chain hydrocarbons with formation of lipids is cultivated in the presence of the feedstock, a fraction comprising the micro-organism is separated from the product and the fraction is extracted by means of a solvent. The micro-organism may be a yeast, particulary Candida lipolytica though many other yeasts are particularly mentioned, a mould such as Penicillium expansum, or a bacterium, particularly Bacillus megaterium, Bacillus subtilis and Pseudomonas aeruginosa, though many other species and strains of bacteria are particularly mentioned. The feedstock may be a petroleum fraction, consisting in part of straight chain hydrocarbons, or a wax-containing petroleum gas oil, whereby there is recovered from the product of the growth of the micro-organism a petroleum fraction having a reduced proportion of straight chain hydrocarbons (or free from straight chain hydrocarbons) or a gas oil reduced content of wax, as the case may be. The solvent extraction may be carried out in two stages, the first in the presence of a polar solvent and the second in the presence of a mixed solvent consisting of a azeotropic mixture of a hydrocarbon solvent and a polar solvent. Preferred solvents are ethanol, iso-propanol, benzene, light platformate fractions, n-hexane, ethyl ether, acetone, chlorinated solvents and liquefied petroleum gases such as butane and propane. Preferably the solvent is fed to the extractor at a periodically varying rate to create pulsations in the flow of the liquid stream. Pulses at a rate of between 1 and 60 per minute may be produced by an alternating pump from which the valves have been removed. According to an example, Candida lipolytica was cultivated under continuous operation with vortex aeration in the presence of a heavy gas oil of petroleum origin containing 20% by weight of normal paraffins, an aqueous mineral medium including tribasic sodium phosphate, potassium chloride, magnesium sulphate, ammonium sulphate and trace elements, and a minute amount of yeast extract; the temperature was maintained at 30 DEG C. and the pH of the medium regulated to pH4 by the addition of aqueous ammonia. The cultivation mash was centrifuged to give three fractions: (a) an oil phase containing the yeast cells, (b) an aqueous mineral medium phase (which may contain traces of oil and yeast), and (c) a yeast cream. The yeast cream together with an aqueous solution of a surface-active agent, e.g. a non-ionic detergent having in the molecule a condensed ethylene oxide chain, was mixed and then further centrifuged to obtain three further fractions: (a) an oil phase, (b) an aqueous phase containing the surfactant product which is recycled to the mixer, and (c) a second yeast cream. This second yeast cream was passed with water to a mixer and was then yet further centrifuged to obtain the following three fractions: (a) an oil phase, (b) an aqueous phase and (c) a thick yeast cream containing 20% by weight of yeast. This thick yeast contained 44% by weight of proteins and 18.5% of lipids, and possessed a sharp and rancid taste. The lipids with residual oil were extracted from the yeast by solvent extraction using a mixture of 80% hexane and 20% ethyl alcohol. After evaporating the solvent, there was obtained a yeast of neutral taste, containing 52% of proteins and 3% of lipids. The extract consisted principally of oxidized and unoxidized fatty acids, esters and sterols. In a further example, the thick yeast cream was extracted in a horizontally rotating filtration drum first with ethanol and then with a solvent mixture consisting of 80% n-hexane and 20% ethanol. In a third example the thick yeast cream was extracted in a vertical filtration drum furnished with a paddle stirrer rotated at 10 r.p.m. with (a) ethanol (b) ethanol followed by n-hexane, or (c) iso-propanol. Specifications 1,049,066 and 1,049,067 divided from the present Specification have identical subject-matter but differing claims.
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