DE1645691A1 - Process for cultivating yeast and removing straight-chain hydrocarbons from their mixtures with other hydrocarbons - Google Patents

Description

2J, January 1970 Kl / Br,

Britannic House, Moor Lane, London, E.C.2 (England)

Method of cultivating yeast and removing straight-chain hydrocarbons from their mixtures with other hydrocarbons

The invention relates to a method for cultivating Yeasts 1. It also affects the full or partial removal of straight-chain hydrocarbons from their mixtures with other hydrocarbons.

In the Belgian patent specification 623 450 a method is described in which a yeast strain that has been so adapted Is that he is based on straight-chain paraffinic hydrocarbons able to grow in the presence of a petroleum fraction partly consisting of straight-chain hydrocarbons, which has an average molecular weight corresponding to at least 10 carbon atoms in the molecule, and in the presence of one aqueous nutrient medium and in the presence of a gas that contains free oxygen at a p "value in the range of

ft

σ 3 to 6, preferably 4 to 5, grown and from the mixture one

J ₀ separated nerseits yeast and secondly a petroleum fraction

which has a reduced proportion of straight-chain carbon

ο Contains hydrogen or is free of these straight-chain

_ * Is hydrocarbons. It is stated that this

^ drive of particular value for the treatment of gas oil fraction

- * ions from petroleum 1st, the straight-chain hydrocarbons in New documents

In the form of waxes, since the process gives a gas-oil of improved pour point, while the waxes are converted into a valuable product. In the continuous implementation of this method, however, bacterial contamination occurs easily, which adversely affects the yield highly, if not carried out at a relatively low _pH value in the range of about 4 to fifth In this p _H range, however, the amount of phosphate, which is required for maintenance of a reasonable for the economics of the process W growth, far greater than the amount theoretically required.

The invention is now a method in which one a straight-chain yeast consuming hydrocarbons in Presence of a wholly or partially straight-chain hydrocarbons existing petroleum fraction, an aqueous nutrient medium consisting partially of phosphate and in Presence of a free oxygen-containing gas grows, whereby the petroleum fraction and the aqueous medium continuously fed to a fermenter containing the yeast, and in which a first cultivation phase at a Ρττ value of 4 to 5 of the yeast takes place, one the yeast containing product stream continuously to a second fermenter stage supplies, in which the yeast with an aqueous nutrient medium of the second stage at a p "value of about 5.5 is treated, a product stream containing the yeast is continuously withdrawn from the second fermenter stage and subjected to a treatment for the recovery of the yeast, wherein in the first cultivation stage the amount of phosphate in the aqueous phase selected in the first fermenter stage becomes that the growth rate of the yeast is not reduced by lack of phosphate, and in the second stage the amount of phosphate in the aqueous phase of the second fermenter stage is less than the amount required for unhindered growth of the He £ e in the first Ferraenterstufe

9 8 20/1 461

or no phosphate is present in the aqueous phase of the second fermenter stage. _:

The aqueous nutrient medium of the second stage can optionally be used contain the nutrient medium withdrawn from the first fermenter stage or consist entirely or in part thereof. Possibly can the withdrawn from the fermenter of the first stage total liquid product that is formed as a product in suspension Contains yeast, fed into the fermenter of the second stage will. ■ ".... '

In the context of the invention, the yeast and / or hydrocarbon can be used in the first and / or second stage with circulation. According to the invention, however, material withdrawn from a particular stage is returned to the same stage.

The working catalytic converter according to the invention results in good yields of yeast, based on the amount of phosphate used.

"Phosphate" in the sense used here is to be understood as meaning water-soluble ammonium or metal phosphates or a phosphoric acid or mixtures which contain two or more such materials. It is preferred to use phosphates of the type which are usually brought into aqueous nutrient media. Sodium triphosphate and φ orthophosphoric acid are preferred as phosphates. The presence of phosphates other than those mentioned above is not excluded if their * ° presence is desired. However, the simultaneous presence of a "phosphate" is as defined above

■ «<. ■■ -

_"* essential.

- * Under the "amount of phosphate" is the weight of the in the aqueous

30 phase of the phosphate inlcns present. to understand.

BATH

In a further aspect, the invention is directed to a Process directed in which one produces a straight-chain hydrocarbon Consuming yeast in the presence of a wholly or partly straight-chain hydrocarbon Petroleum fraction, an aqueous nutrient medium consisting partially of phosphate and in the presence of a free oxygen growing the gas containing, the petroleum fraction and the aqueous medium continuously fed to a fermenter, which contains the yeast, and in which a first cultivation

^ phase of the yeast takes place at a p "value of about 4 to 5, a product stream containing the yeast and aqueous nutrient medium continuously from the fermenter of the first Stage withdraws and into a second fermenter stage, in the the yeast is cultivated at a p "value of about 5.5, introduces, continuously withdrawing a product stream containing the yeast from the fermenter of the second stage, wherein in of the first cultivation stage the amount of phosphate in the aqueous phase of the fermenter of the first stage is chosen that the growth rate of the yeast is not slowed down by phosphate deficiency, and is adjusted so, that in the second stage the amount of phosphate in the aqueous Phase in the second fermenter stage is lower than that

) Amount required for unhindered growth of the yeast ■ is.

If according to any of the above-described aspects of the Invention is worked, is preferably the amount of phosphate ions in the second in a given time Medium fed stage less than 1 part by weight, calculated as elemental phosphorus, per 100 parts by weight of the yeast entering the second fermenter stage during this time (based on dry weight).

The straight-chain hydrocarbons are in the present invention input materials usually used as paraphernalia

009820 / U6 T

BATH

fine present »However, they can also be present as olefins. Mixtures can also be used, the straight chain Contains paraffins and olefins.

Luminous kerosene are suitable as starting materials for the process according to the invention. (Kerosene), gas oils and Lubricating oils. These feedstocks can be unrefined or subjected to some refined treatment but they must usually contain some straight-chain hydrocarbons in order for the Purposes of the invention to be suitable. A Petroleum fraction used, the 3 to 45 wt. ^ Straight-chain Contains hydrocarbons. Petroleum fractions are preferred used in whole or in part from straight-chain Hydrocarbons exist and have an average molecular weight of at least 10 carbon atoms in the molecule is equivalent to. . .

The method according to the invention is of particular value for the treatment of gas oil fractions from petroleum, the straight-chain Contain hydrocarbons in the form of waxes, because in the method according to the invention a gas oil of improved Pour point is obtained while the waxes in a valuable product to be transformed.

The yeasts are classified according to the classification system described in the book "The Yeasts - a Taxonomy Study" by Lodder and Kreger-van RiJj (195 ² ) * published by North Holland Publishing Company (Amsterdam).

If yeast is used, it preferably belongs to the family Cryptococcaceae, in particular to the subfamily 'CryptococGoideae. However, if necessary, for example, ascosporogenic yeasts of the subfamily Saceharomycoideae can be used. The preferred genera of the subfamily 0Q9820 / U61

lie Cryptococcoideae are Torulopsis (also known as Torula), Candida, and Mycoderma. Preferred yeast species become hereinafter referred to as. The use of the following together with the deposit numbers is particularly preferred called tribes. The strains marked with CBS are at the Centraal Bureau vor Schimmelculture, Baarn, Holland, and the strains marked with INRA at the Institut National de la Recherche Agronomique, Paris, - France, deposited.

Preferred tribes

Candida lipolytica CBS 599 Candida pulcherrima CBS 610 Candida utilis CBS 890 Candida utilis, Variati major CBS 841 Candida tropicalis CBS 2517 Candida arborea Torulopsis colliculosa CBS 153 Hansenula abnormal CBS 110 Oidium lactis Neurospora sitophila Mycoderma cancoillote INRA: STV 11

Candida lipolytica particularly preferred.

If necessary, mushrooms can be used as yeast. A a suitable strain is PenieiHium expansum.

For the growth of the yeast is besides the hydrocarbon feed an aqueous nutrient medium and the supply of oxygen, preferably in the form of air, are required.

A suitable nutrient medium for yeast (and fungi) has the following Composition:

0098 20 / U.6 1

■■ --- 7 -

^(NH 4) ₂ HPO ₄ 2 G KCl 1.15 G MgSO ₄ -7H ₂ O 0.65 ε ZnSO ₄ -H ₂ O ■ 0.17 ε MnSO ₄ -H ₃ O 0.045 ε FeSO ₄ '7H ₂ O 0.068 G tap water 200 G Yeast extract 0.025 ε

"Distilled water (to make up to 10Qd ml).

The growth of the yeasts used is favored if a very small amount of a yeast extract is added to the culture medium (an industrial product obtained by hydrolysis of yeast and rich in essential nutrilites or growth factors) or in general adding essential nutrilites. The essential nutrients include biotin, pantothenic acid, Nicotinic acid, thiamine, inositol and pyridoxine. The amount of yeast extract added is preferably of the order of magnitude of 25 parts * per million. The. required amount each Nutrillts varies between about 0.1 parts per million for biqtin and about 10 parts per million for inositol.

The aqueous nutrient medium in each fermenter is preferably maintained by stepwise or continuous addition of an aqueous medium of high powert at a desired _pH value.

The optimal temperature of the nutrient medium is different depending

used
depending on the type of yeast and is usually in the range from 25 ° to 35 ° C. When using Candida lipolytica, a temperature range of 28 ° to J> 2 ^G C is preferred.

The uptake of oxygen is essential for yeast growth essential. The oxygen is usually supplied as air.

009820/1461

1545691

A product stream is generated from the second stage permeator subtracted, which contains yeast and unassimilated hydrocarbons in a closed aqueous phase .. The larger one Part of the closed aqueous phase is separated off first. This is preferably done by centrifugation. The separated aqueous phase usually contains a higher concentration of ions of substances that are not nutrients and can be tolerated in the recycle stream. If this is the case, only part of the aqueous phase obtained can be recycled. So it is usually MÖg-1 borrowed, about 96 wt .- ^. of the aqueous present in the product Phase separated from which on the same percentage basis about 20 wt .- # are discarded. Be the circulatory stream supplementary amounts of the necessary nutrients added where * - r. is traced back to the Permenter. The complementary Substances can optionally be fed to the permeator as a separate stream.

The method, when applied to the cultivation of yeast, may have the product separation steps described below include. First of all it is usually possible to use the yeast with a certain amount of the unassimilated Feed material and aqueous nutrient medium is contaminated, from the main mass of the non-assimilated feed fraction to separate.

The fraction of yeast that is usually in the form of a paste or cream is present and contains hydrocarbons as impurities, is with an aqueous solution of a surface-active Washed smock. To do this, it is preferably vigorous with the aqueous surfactant mixed and without another growth period of the yeast a further separation, preferably by centrifugation, subjected, a fraction consisting of the yeast and recovering an aqueous phase which has been removed from the yeast and which contains contaminating hydrocarbons. 009820 / U81. -

Palls can be used to control the washing and separation stages repeated one or more times using an aqueous surfactant in the washing step will. After washing with the surfactant, it must be washed with an aqueous medium other than contains surfactant. ' Preferably water is used as this medium. Here too, if necessary worked with a series of washing and separation stages will.

Washing is preferably carried out until the hydrocarbon content of the yeast is below 7 % , based on the weight of the yeast (calculated in the dry state). This hydrocarbon content is preferably below 5 %

As surface-active substances for washing are suitable cation-active surface-active substances, e.g. stearyltrimethylammonium chloride, non-ionic surface-active substances, e.g. the condensates of oleic acid and ethylene oxide, or anionic surfactants such as sodium alkyl sulfates. .

The fraction containing the yeast then preferably becomes one Subject to solvent extraction, which is preferably carried out with a solvent that consists of a Is or contains hydrocarbons. Hydrocarbons with 4 to 7 carbon atoms in the molecule are preferred, especially paraffins, of which in turn are straight-chain © Paraffins are preferred. Suitable solvents are n-pentane and η-hexane. If necessary, before the extraction of the hydrocarbons with a hydrocarbon solvent, an extraction with an alcohol is preferred Ethanol. If necessary, an extraction stage can be used in which a solvent is used Mixture of a hydrocarbon for example with ethanol used w ^ gd ^ gG ^ gfygjpe ^ jjst for example a solution

INSPECTED

1645697

- ίο -

medium, which consists of 80 wt .-% hexane and 20 wt .- % ethanol. The hydrocarbons recovered in the extract phase by solvent extraction can, if they can be used by the yeast, be returned to the yeast cultivation stage. A yeast which has been completely or partially freed from its lipids and contaminating hydrocarbons by one of the methods described above and whose taste has been improved is a valuable industrial product for human consumption.

In a preferred feature, the invention is directed to a Process directed in which a yeast in the manner described above in the presence of a petroleum fraction, which partly consists of straight-chain hydrocarbons and has an average molecular weight corresponding to at least 10 carbon atoms in the molecule, and in the presence of an aqueous Nutrient medium and a gas containing free oxygen breeds and from (far mixture on the one hand the yeast and on the other hand separating a petroleum fraction which contains a reduced proportion of straight-chain hydrocarbons or is free of straight chain hydrocarbons, and then the yeast in the manner described above worked up.

Preferred methods that can be used in the cultivation of the yeast and in the recovery of the product, are in British patents 9l4 567 and 9JA 568, described in UK patent application 49052/62 and the following UK patents:

0 0 98 207 U6.1

16A 5691

- li -

British patents:

1 017 584 1 009 882

1 021 697 1 059 883

1 021 698 1 059 884

1 059 891 1 059 885

1 049 065 - ■■. ■ 1 059 886 1 059 890 1 095 183

1 059 881 1 059 887

1 059 088 1 153 292

1,059,889 1,017,583.

1 O85 282. 1 154 163

1 089 093 1 049 929

The invention is illustrated by the following experiment and examples 1 and 2 illustrate «The experiment is merely described for comparison purposes.

attempt

The yeast Candida tropicalis was produced in a continuous operated first fermenter of 60 m capacity in Presence of an aqueous nutrient medium of the following composition bred:

S / l (NH ^) ₂ HPO ₄ 2.0

KCl 1.15

MgSO ₄ .7 H ₂ O 0.65

Mn SO ₄ * 4 H ₂ O 0.068

FeS0 ₄ * 7 H ₂ O 0.124

ZnSO ₄ '7 H ₂ O 0.308

Yeast extract 0.03

Here, air was used in an amount of 30 clearing parts / room part / hour fed by vortex aeration. A gas oil made from Iraqi crude oil was used as the carbon source and had the following bacterial counts:

009820/1461 -

164569t

Specific gravity 0.870

Pour point + 15 ° C

Boiling range from 300 ° to

A mixture of gas oil and aqueous nutrient medium in a volume ratio of 1.5 * 10 was fed to the permenter in an amount of 200 l / nr fermenter / hour (corresponding to 12,000 l / hour). The fermenter was at J50. C and kept _{at ρ Η} 4 by the continuous addition of aqueous ammonia.

A product flow of .1 ^ * 000 l / h. was continuously withdrawn from the fermenter of the first stage and passed into a decanter, in the 2.Ö00 l / h. an aqueous yeast paste »separated and continuously returned to the fermenter of the first stage. The rest of about 12,000 l / h. was withdrawn from the decanter and continuously fed into a second fermenter of JO nr capacity.

■ ... "ν

The second fermenter was kept at 30 ^° C. Air in one «

r be

an amount of 30 V / v / hour. was distributed by ventilation. No fresh source of carbon was supplied, rather the carbon was replaced by the remaining hydrocarbons delivered from the first to the second fermenter arrived. From the second fermenter was continuous withdrawn a product stream and subjected to decantation. Then 66 wt .- ^ of the aqueous phase were drawn off and replaced with 66 wt .- ^ tap water.

The nr of the mixture of yeast, remaining oil and water were 0.5 kg of a non-ionic detergent> as the product of the condensation of a mixture of lauric and. Myristic alcohol with xethylene oxide (trade name "NI 29") was added. This mixture turned out fine stirred and in a centrifuge (Sharpies Autojector DG 2) centrifuged, the following separated products being

■: '009820 / UB1 ■. = .-. ".

were kept: a yeast paste, an aqueous phase and a gas oil phase.

The yeast paste was then mixed again with tap water in a ratio of 1 part by weight of dry substance per 5 parts by weight of water, stirred well and. centrifuged again. The yeast paste obtained contained 65 to 70 # water. A portion of the water was removed in such an amount that a cream consisting of 50 wt .-% yeast (dry weight) and 50 wt .-% water was obtained.

This wet yeast was pumped into an extractor which was in the form of a filter drum that rotated about its horizontal axis. A solvent mixture of 50% by weight each of hexane and isopropanol was added to the wet yeast in an amount of 8 parts by weight of mixture per part by weight of yeast (dry weight). 5 NC minutes at 50 ⁰ C held; was the mixture of yeast, water and solvent. Then the solvent, which contained most of the yeast impurities, was stripped off.

The remaining wet yeast product was again in a second extraction stage with the solvent in a ratio of 1 part by weight of dry yeast per part by weight of water per 4 parts by weight of a mixture of 50% by weight each of hexane and isopropanol Treated for 30 minutes at 50 ° C. On disconnecting · the laden with some contaminating yeast solvent filter was the remaining product in a third extract ionsstufe with 2 parts by weight of a solvent agent mixture comprising 80 wt .- # η-hexane and 20 wt -. $> Isopropanol treated. The mixture was held for 10 minutes at 5O ⁰ * C, the solvent was removed under vacuum at the end * The washing with this solvent mixture was repeated four times. Finally the yeast product was dried with superheated steam.

009820 / U6 1 · ·

645691

The operating data and the results obtained are in in the following table.

009820/1 46

- ■ 15-

example 1

The procedure used in the previous experiment was with a different phosphate concentration in the media, which were fed to the two permers, repeated.

a) The medium fed to the first fermenter was. durch Dilution of the aqueous nutrient medium described in the experiment obtained with the same volume of water. The yeast extract was adjusted to 0.03 g / l.

b) Circuit of yeast cream was not used.

The working conditions and the results obtained are mentioned in the following table.

Example 2

The yeast Hansenula suaveolens was produced in a continuous operated first fermenter of 60 1 capacity in an aqueous nutrient medium of the following composition cultivated:

KCl

MgSO ₄ ¹ TH ₂ O MnSO ₄ * 4 H ₂ O ZnSO ₄ * 7 H ₂ O. FeSO ₄ 'TH ₂ O yeast extract

1.0 0.58 0.52 0.034 0.15 0.061 0.15

Air was supplied in an amount of 30 v / v / hr. through eddies ventilation supplied.

A gas oil was used as the carbon substrate Iraq crude oil had been received and had the following codes: Specific weight at 15.6 / i5.6 ° C 0.867

Refractive index n ~ cloud point

20th

1.484 +13 ⁰ G

Ö09820 / 1 46 1

Pour point + 11 ° C

Total sulfur 1.59

A mixture of gas oil and aqueous nutrient medium in proportion from 1.5 parts by volume to 10 parts by volume was in an amount of 12 l / hour introduced into the fermenter. The fermenter was at.30 C and by continuously adding aqueous Ammonia kept at p "4.

A product flow of 12 l / hour was continuously drawn off and fed to a second fermenter with a capacity of 30 l. This second fermenter was kept at 30 ^° C. Air in an amount of 30 V / V / hour was fed to it by vortex aeration. No fresh carbon source was supplied, rather the remaining hydrocarbons that were transferred from the first to the second fermenter served as the carbon source.

A stream of product was continuously withdrawn from the second fermenter and subjected to decantation. Then, 70 wt were -. Withdrawn% of aqueous phase and 70 weight -% replaced tap water..

1 g of an oxyethylated lauric alcohol (non-ionic detergent, Trade designation "NI 29") was added per liter of the mixture of yeast, residual oil and water. This mixture was stirred well and centrifuged in a Sharples supercentrifuge, using a yeast paste, an aqueous phase and a gas oil phase were obtained.

The yeast paste was then mixed again with tap water in an amount of 1 part by weight of dry substance per 5 parts by weight of water, stirred well and centrifuged again. The 'water content of the yeast was then heated to 50 wt -% set.. This moist yeast was then pumped into an extractor, which had the shape of a filter drum with horizontally lying

0 0 9820/1461

ϊ 64.5691

the axis was rotated. A mixed solvent of 50% by weight of hexane and 50% by weight of isopropanol was added to the wet yeast in an amount of 8 parts by weight of the mixture per part by weight of yeast (dry basis). The mixture of yeast, water and solvent was kept at 80 ° C. for one hour, after which the solvent, which contained the greater part of the impurities in the yeast, was removed. The remaining yeast was subjected to a second solvent treatment on the same basis as described above. After removing the solvent laden with the impurities of the yeast, the remaining wet yeast product was treated with solvent in a second extraction stage, on the basis of 1 part by weight of dry yeast per 4 parts of isopropanol for a period of 50 minutes and a temperature of 60 ⁰ C. The solvent was removed and the yeast product was finally dried with superheated steam.

The working conditions and the results obtained are summarized in the following table.

Experiment example 1 example 2

Fermenter fermenter fermenter fermenter fermenter fermenter

dilution V / V / h It 0.2 0.4 0.2 0.4 0.2 0.4 p _H value Il 4th 5.5 4th 5.5 4th 5.5 temperature ⁰ C Ii 30th 30th 30th 30th 30th 30th Supply of fresh
Gas oil g / l 120 _ 120 120 SX Air supply V / V / h 30th 30th 30th 30th 30th 30th (O
m
O
^ * Circular performance
of yeast cream
Fresh nutrient medium % of the dean
tied cream 50 - - - - - Phosphorus (1) g / l 0.44 0.23 0.26 0.11 0.26 0.10 σ> Cell density g / l 9.8 13.0 8.4 11.0 8.5 11.8 ' Used medium 00 Phosphorus (1) g / l 0.23 0.17 0.11 0.07 0.10 0.03 ' Dewaxing Bump point d. Gas oil ⁰ C +3 -7 -2 -6, +2 Hefeanalyse wt -.% (Dry basis) Total lipids 0.5 0.5 0.3 0.4 0.8 0.7 nitrogen 8.4 8.6 9.2 10.2 8.2 '10.5 Phosphorus content (1) 2.1 2.0 1.8 1.5 2.0

(1) calculated as elemental phosphorus - not determined

.es cn co

CD

Claims (1)

1.) A method for cultivating straight-chain hydrocarbons-consuming yeast on straight-chain hydrocarbons containing hydrocarbon mixtures, characterized in that the yeast is contained in the presence of a petroleum fraction consisting entirely or partly of straight-chain hydrocarbons, an aqueous nutrient medium partly consisting of phosphate and in the presence of free oxygen gas grows to give the crude oil fraction and the aqueous medium are fed continuously to a fermentor, which contains the yeast, and in which a first cultivation phase of the yeast takes place at a _pH value of about 4 to 5, a yeast-containing product stream continuously to a second Feeds perment stage, in which the yeast is treated with an aqueous nutrient medium of the second stage at a Pjj value of about 5.5, continuously withdraws a product stream containing the yeast from the second perment stage, the Ph Amount of osphat in the aqueous phase in the first fermenter stage is chosen so that the growth rate of the yeast is not reduced by phosphate deficiency, and in the second stage the amount of phosphate in the aqueous phase of the second fermenter stage is less than the amount required for unhindered growth of the yeast is required in the fermenter of the first stage, or no phosphate is present in the aqueous phase of the second fermenter stage. 2.) The method according to claim 1, characterized in that the aqueous nutrient medium of the second stage ^{contains the nutrient medium withdrawn from 1} 'of the first fermenter stage or consists entirely or in part thereof. 00 9 8 20 / VAT New documents ιαλ.7 §iabs.2 ι * λ saus desÄnderunesges.v.4.9.1S6ZI >.) Process according to claim 1 and 2, characterized in that straight-chain hydrocarbon-consuming yeast is cultured in the presence of a petroleum fraction consisting entirely or partially of straight-chain hydrocarbons, an aqueous nutrient medium consisting partially of phosphate and in the presence of a gas containing free oxygen, the petroleum fraction and continuously feeding the aqueous medium to a fermenter which contains the yeast, and in which a first phase of cultivation of the yeast takes place at a p n value of about 4 to 5, a product stream containing the yeast and aqueous nutrient medium continuously from the fermenter of the first stage withdrawing and introducing into a second fermenter stage in which gezüch- the yeast at a _pH value of about 5 * 5, tet, continuously withdrawing a yeast containing Pröduktstrom from the fermenter of the second stage, wherein in the first stage of cultivation, the amount of phosphate in the aqueous phase of the first stage fermenter e is chosen so that the growth rate of the yeast is not slowed down by phosphate deficiency, and is set so that in the second stage the amount of phosphate in the aqueous phase in the second fermenter stage is less than the amount required for unhindered growth of the yeast in the first fermenter stage is required, 4.) Method according to any one of the preceding claims 1 to 3, characterized in that the entire from the Liquid product withdrawn from the first stage fermenter, which contains the yeast formed as a product in suspension, is fed into the fermenter of the second stage. 5.) Method according to any of the preceding Ai, prüche- 1 to Λ, characterized in that er .-. e ·. step part of the yeast and / or at least part of the G 0 9 8 2 0 / U 6 1 BAD ϊ64569T Hydrocarbon withdrawn from this stage has, returns in the cycle, 6.) Method according to any one of the preceding claims 1 to 5, characterized in that part of the yeast is returned to the second stage in the cycle. 7.) Process according to any one of the preceding claims 1 to 6, characterized in that a yeast is used, the straight-chain paraffinic hydrocarbons consumed. . 8.) The method according to claim 1 to T, characterized in that the yeast used is one which belongs to the family of the Cryptococcaceae, in particular to the subfamily of the Cryptococcoideae. 9.) Method according to claim 1 to 7 »characterized in that that a yeast of the Torulopsis or Candida tribe is used as the yeast. 10.) The method according to claim 1 to 7> characterized in that the yeast is Candida lipolytiea or Candida, tropicalis begins. 11.) Method according to any one of the preceding claims 1 to 10, characterized in that one, petroleum fraction used, which consists wholly or partially of straight-chain hydrocarbons and a medium Has molecular weight that is at least Io carbon atoms per molecule. :,: ..> 12.) A method according to any one of claims vorsteheiiden '.1 to 11 "characterized in that one uses" ^v as a petroleum fraction _Öasöl: · 13.) The method according to any one of the preceding claims 1 to 12, characterized in that the aqueous nutrient medium supplied in a given time of the second stage less than 1 part by weight of phosphate, calculated as .elementarer phosphorus, per 100 parts by weight of the while
contains yeast introduced into this fermenter at this time on a dry basis. 069820/1461