CN1351650A - Application of Microemulsion in Fermentation Process - Google Patents

Abstract

The invention relates to the use of oil/water emulsions in fermentation processes, these emulsions containing at least water, an emulsifier and an oil phase, the oil phase being selected from one or more compounds of the group consisting of a) fatty acid alkyl esters and/or b) triglycerides of vegetable origin, wherein the average droplet size of the emulsion is in the range of 1 to 100 nm.

Description

Application of Microemulsion in Fermentation Process

The invention relates to the application of microemulsion in the fermentation process.

Microbiological methods are increasingly being used when synthesizing complex natural substances or other organic compounds such as antibiotics. In the case of microorganisms or parts of microorganisms, especially when bacteria or fungi are involved, it involves the transformation of substances under anaerobic or aerobic conditions. As far as these methods are concerned, the fields of expertise differ and the boundaries are always blurred, eg "biotransformation", "biotransformation" or "fermentation" are used. The latter is also termed within the scope of this application for methods in which microorganisms, mainly bacteria, are used for the conversion or synthesis of chemical compounds.

For the development and optimization of fermentation processes, in particular, the reaction medium in which the transformation of the microorganisms takes place is of interest. Generally speaking, the reaction medium is an aqueous solution or dispersion, which especially affects the yield and efficiency of the process. Microorganisms need carbon, nitrogen and certain trace elements such as calcium, iron, phosphorus or zinc in combined form as nutrients in order to carry out metabolism and try to achieve the required products. In addition, certain, often narrow, temperature and pH ranges must always be maintained. For other detailed plots, please refer to the textbook of W. Crueger/A. Crueger: "Biotechnology-Applied Microbiology Tutorial", 2nd edition in 1984, published by R.Oldenbourg Press. Chapter 5 of the book is devoted to the basics of fermentation technology. Therefore, this document also belongs to the disclosed content of the present application. As food for the microorganisms, besides energy-rich sugars and their derivatives, natural fats and oils, as well as derivatives of such substances, such as glycerol, glycerides, fatty acids or fatty esters, are added in many ways. Of course, there should be no inclusions in the medium, which have a negative impact on the metabolism of microorganisms.

From German patent DE 3738812 A1, for example, a method for the production of α-omega-dicarboxylic acids by microorganisms is known, which converts methyl dodecanoate into the desired dicarboxylic acid using the bacterium Candida tropicalis. The transformation takes place in an aqueous medium at a pH of 6.0 at a temperature of 30°C. In addition to glucose, which supplies energy to the microorganisms, the medium contains ethoxylated sorbitan monooleate as emulsifier, yeast extract, corn steep liquor, and inorganic sources of nitrogen and phosphorus. Then, methyl laurate was dosed to the medium. The literature does not mention the type of emulsion, its formation in the ferment or in which methyl laurate is dosed to the medium. Known from European patent EP0 535 939A1, there is a process for the preparation of omega-9-polyunsaturated fatty acids, wherein, in an aqueous medium, suitable microorganisms are present in the presence of carbohydrates as energy suppliers and with inorganic or organic Nitrogen source, and the presence of fatty acid methyl esters to produce the required polyunsaturated fatty acids.

Also there are methods in which only the above-mentioned prior art fatty substances are used as energy suppliers. This is particularly economical since such fatty substances are generally less expensive than sugars, starches and similar compounds. (Park et al., "Journal of Fermentation and Bioengineering", Vol. 82, No. 2, Pages 183-186, 1996) have described a fermentation process to produce Tylosin (Tylosin ), in which microorganisms of the strain Streptomyces fradiae were used in an aqueous medium, the original amount of rapeseed oil as the sole carbon source contained approximately 60 g/liter.

In addition, the oxygen content in the medium or in the fermented juice plays a decisive role in the fermentation process. Therefore, oxygen has the role of a substrate in aerobic processes. Whether various methods can make the rich oxygen transition from the gas phase to the liquid phase containing microorganisms is the key. An important parameter indicates the specific exchange surface, which is generally determined indirectly by the oxygen transition coefficient kLa (see Kruger's literature, Chapter 5, p. 71). Oxygen supply is usually adjusted to an optimum by agitation of the fermented juice, where oxygen or air is mixed with the liquid to allow gas exchange at the interface. By vigorous agitation, there is a significant input of mechanical energy, as performed by Parker et al., but it can also destroy part of the medium and reduce the yield of this method. In addition, the necrotic microorganisms themselves continue to lyse, and the resulting lysates can lead to poisoning of the culture medium, so that economical production is not possible. Known from the work of Goma and Rols (G. Goma, J.L. Rols, Bioprocess Letters, Vol. 13, No. 1, pp. 7-12, 1991) , When soybean oil is used to produce antibiotics in the fermentation process, the transition coefficient kLa of oxygen can be improved, and the yield of the overall process can be increased under the same energy input (stirring).

The object of the present invention is to improve the fermentation process, on the one hand using an inexpensive carbon source, and on the other hand ensuring a sufficient supply of oxygen to the microorganisms without a high mechanical burden on the microorganisms by means of agitation. It is necessary to find a way to minimize the mechanical energy in the fermentation process so as not to reduce the yield. The main reason is that the yield can be increased even if the energy input is reduced.

It has been found that the use of specific, finely divided emulsions of oil suspended in water (oil/water) solves the above-mentioned tasks.

In the first embodiment, when an oil/water emulsion is used in the fermentation process, it is required that the emulsion contains at least water, an emulsifier and an oil phase, and the oil phase contains one or more compounds selected from the group consisting of:

a) fatty acid alkyl esters and/or

b) triglycerides of vegetable origin, and the droplet size of the emulsion is from 1 to 100 nanometers.

The emulsions produced according to the invention have an exceptionally small fineness. It thus concerns so-called microemulsions, which are defined as macroscopically homogeneous, optically transparent, often low-viscosity, thermodynamically stable mixtures consisting of two immiscible liquids and at least There is a nonionic or ionic surfactant, especially containing two hydrophobic groups. The condition for the formation of microemulsion is that the oil-water-interfacial tension is almost zero. Generally speaking, at least one nonionic surfactant and then one cosurfactant must be added to achieve this particular emulsion form. Please refer to the literature "Introduction to Colloid and Surface Chemistry, DJ Shaw, Butferworth, 1992, pages 269 and 270". The emulsion droplets used according to the invention have a size of 1 to 100 nanometers. It is preferably in the range of 10-80 nm, especially in the range of 10-30 nm. The fineness of the oil droplets creates a large surface area between the oil and water phases, allowing for quick contact between the water phase containing microorganisms and the oil phase containing nutrients. The exchange of gases, especially oxygen and CO ₂ , is also simplified by the large surface. The viscosity of the emulsion is also additionally reduced so that the entire fermentation medium is affected. Therefore, it is then possible to significantly reduce the stirring speed of the fermentation medium, thereby expecting to increase the yield of the fermentation process.

According to the invention, microemulsions are aqueous fermentation media which contain microorganisms and, if necessary, other auxiliaries and additives. The details of this method, especially the speed and amount of dosing into the emulsion, are determined by the type of microorganism and the fermentation method chosen, and professionals are able to adapt to the specific situation.

In addition to the water and oil phases, the microemulsion also contains: a) compounds composed of fatty acid alkyl esters or b) natural vegetable oils and their derivatives. This concerns hydrophobic, water-insoluble or only slightly water-soluble compounds of the classes a) and b), which are used both as nutrients and as energy suppliers for the bacteria used in the fermentation process, which also serve as Raw materials (substrates) are biotransformed to produce the desired product.

Suitable methyl esters of type a) are especially methyl esters derived from saturated, unsaturated, straight-chain or branched-chain fatty acids with a total of 7 to 23 carbon atoms. This is represented by the compound of formula (I):

R ¹ -COO-R ² (I) wherein R ¹ represents an alkyl group having 6-22 carbon atoms, R ² represents an alkyl group having 1-4 carbon atoms, preferably methyl and ethyl. Particular preference is given to using methyl esters as constituents of a). Esters or methyl esters of formula (I) are obtained by usual methods, for example by esterification of triglycerides with methanol and subsequent distillation. Suitable fatty acids are: caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecane fatty acid, stearic acid, nonadecanoic acid, arachidic acid and behenic acid. Representative of unsaturated acids are, for example, lauric acid, myristoleic acid, palmitoleic acid, petracenoic acid, oleic acid, elaidic acid, ricinoleic acid, linoleic acid, elaidic acid, linolenic acid, cis-9-eicosenoic acid, arachidonic acid and erucic acid. Also, mixtures of the methyl esters of these acids are also suitable. The use of microemulsions containing methyl esters of methyl oleate, methyl palmitate, methyl stearate and/or methyl nonanoate is particularly preferred. Based on natural fatty acid mixtures, for example from linseed oil, coconut oil, palm oil, palm kernel oil, olive oil, castor oil, rapeseed oil, sesame oil, soybean oil or sunflower oil (rapeseed oil and sunflower oil sometimes have new and old cultivated The methyl ester obtained in the species) can also be used.

Suitable compounds of class b) are natural oils of vegetable origin. It is therefore primarily concerned with mixtures of triglycerides in which glycerol is sometimes fully esterified with long-chain fatty acids. Particularly suitable vegetable oils are selected from the group consisting of peanut oil, coconut oil, linseed oil, palm oil, olive oil, palm kernel oil, castor oil, rapeseed oil, sesame oil, soybean oil and sunflower oil.

Peanut oil (based on fatty acids) contains on average 54% by weight oleic acid, 24% by weight linoleic acid, 1% by weight linolenic acid, 1% by weight arachidic acid, 10% by weight palmitic acid acid and 4 (weight) % stearic acid. The melting point is 2-3°C.

Linseed oil generally contains 5% by weight of palmitic acid, 4% by weight of stearic acid, 22% by weight of oleic acid, 17% by weight of linoleic acid and 52% by weight of flax acid. The iodine value is in the range of 155-205. The saponification value is 188-196, and the melting point is about -20°C.

Coconut oil contains about 0.2 to 1 (weight)% caproic acid, 5 to 8 (weight)% caprylic acid, 6 to 9 (weight)% capric acid, 45 to 51 (weight)% lauric acid, 16～19(weight)% of myristic acid, 9～11(weight)% of palmitic acid, 2～3(weight)% of stearic acid, less than 0.5(weight)% of behenic acid, 8～10 % by weight of oleic acid and up to 1 % by weight of linoleic acid. The iodine value is in the range of 7.5-9.5, and the saponification value is 0.88-0.90. The melting point is 20-23°C.

Olive oil mainly contains oleic acid (see Lebensmittelchem. Gerichtl. Chem., 39, 112-114, 1985). Palm oil contains about 2 (weight)% of myristic acid, 42 (weight)% of palmitic acid, 5 (weight)% of stearic acid, 41 (weight)% of oleic acid, 10 (weight)% of linoleic acid. Palm kernel oil, in terms of fatty acid spectrum, generally has the following composition: 9 (weight) % caproic/caprylic/capric acid, 50 (weight) % lauric acid, 15 (weight) % myristic acid, 7 (weight) % ) % of palmitic acid, 2 (weight) % of stearic acid, 15 (weight) % of oleic acid and 1 (weight) % of linoleic acid.

Rapeseed oil generally contains about 48% by weight of erucic acid, 15% by weight of oleic acid, 14% by weight of linoleic acid, 8% by weight of linolenic acid, 5% by weight % eicosenoic acid, 3% by weight palmitic acid, 2% by weight hexadecenoic acid and 1% by weight docosadienoic acid. The rapeseed oil cultivated by the new method is rich in unsaturated components. Usually the components of fatty acid are 0.5 (weight)% of erucic acid, 63 (weight)% of oleic acid, 20 (weight)% of linoleic acid, 9 (weight)% of linolenic acid, 1 (weight)% of eicosenoic acid, palm Acid 4% by weight, hexadecenoic acid 2% by weight and docosadienoic acid 1% by weight.

Castor oil contains 80～85 (weight) % glycerides of ricinoleic acid, in addition also contains about 7 (weight) % glycerides of oleic acid, 3 (weight) % glycerides of linoleic acid and about 2 ( weight) % glycerides of palmitic and stearic acids.

Soybean oil contains 55-65% by weight of the total fatty acids of various unsaturated acids, especially linoleic acid and linolenic acid. Sunflower oil has a similar situation, based on total fatty acids, the usual fatty acid spectrum is: about 1 (weight)% myristic acid, 3-10 (weight)% palmitic acid, 14-65 (weight)% oleic acid and 20-75% (weight) of linoleic acid.

All data on the fatty acid composition of the above triglycerides are known, it depends on the quality of the raw material and therefore the figures may be biased. Particular preference is given to microemulsions containing nutrients of type b) selected from coconut oil, sunflower oil and/or rapeseed oil.

An essential constituent of the microemulsions used according to the invention are the added emulsifiers or emulsifier systems. Firstly used as emulsifiers are nonionic emulsifiers, especially ethoxylated aliphatic alcohols and fatty acids.

Fatty alcohol ethoxylates within the meaning of the invention have the general formula (II):

R ³ -O-(CH ₂ CH ₂ O) _n -H (II) wherein R ³ represents a linear or branched, saturated or unsaturated alkyl group having 6 to 24 carbon atoms, and n represents 1 A value of ~50. Particular preference is given to those compounds in which n in formula (II) has a value from 1 to 35, especially from 1 to 15. Furthermore, particular preference is given to those compounds in formula (II) in which R ³ is an alkyl group having 16 to 22 carbon atoms.

The compounds of formula (II) are obtained according to known methods by conversion of aliphatic alcohols and ethylene oxide under pressure, if necessary in the presence of acidic or basic catalysts. Representative examples are hexane alcohol, octanol, 2-ethylhexyl alcohol, decanol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isotridecyl alcohol, Stearyl alcohol, oleyl alcohol, elaidic alcohol, petracel alcohol, linoleyl alcohol, linolenyl alcohol, tungyl alcohol, arachidyl alcohol, cis-9-eicosenol, behenyl alcohol, ericyl alcohol, and braziene Alcohols and their industrial mixtures are produced, for example, in the high-pressure hydrogenation of oil-based industrial methyl esters or in the production of aldehydes by the Roelen hydroxyl synthesis and in monomer fractionation in the dimerization of unsaturated aliphatic alcohols. Preference is given to technical aliphatic alcohols having 12 to 18 carbon atoms, such as coconut alcohol, palmityl alcohol, palm kernel alcohol or stearyl alcohol.

Fatty acid ethoxylates can also be considered as emulsifiers or emulsifier ingredients, which are mainly of formula (III):

R ⁴ CO ₂ (CH ₂ CH ₂ O) _m H (III) wherein R ⁴ represents a linear or branched chain alkyl group with 12 to 22 carbon atoms, and m represents a number from 5 to 50, preferably 15 to 50 35. A typical example is composed of 20 to 30 moles of ethylene oxide and lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, Addition products of petroselinic acid, linoleic acid, linolenic acid, erucic acid, arachidic acid, eicosenoic acid, behenic acid and erucic acid and their industrial mixtures, for example in the pressure cracking of natural fats and oils or Produced during the synthesis of reduced aldehydes by Rorent's carbonylation. Preference is given to addition products of 20-30 moles of ethylene oxide and fatty acids having 16-18 carbon atoms.

其中COR⁵代表有12～22个碳原子的直链或支链的酰基，x、y和z的总和表示0或者从1～50的数字，特别是15～35。对本发明含义的合适偏甘油酯的实例有：月桂酸单甘油酯、椰子脂肪酸单甘油酯、棕榈酸单甘油酯、硬脂酸单甘油酯、异硬脂酸单甘油酯、油酸单甘油酯和硬脂酸单甘油酯以及其和5～50特别是20～30摩尔的环氧乙烷的加成产物。首先是使用单甘油酯或工业的单甘油/二甘油酯的混合物和过量的式(IV)的单甘油酯的组份，其中COR⁵代表有16～18个碳原子的直链酰基。Partial glycerides can be considered as emulsifiers, mainly of formula (IV):

Wherein COR ⁵ represents a linear or branched acyl group with 12-22 carbon atoms, and the sum of x, y and z represents 0 or a number from 1-50, especially 15-35. Examples of suitable partial glycerides within the meaning of the present invention are: monoglyceride laurate, monoglyceride coconut fatty acid, monoglyceride palmitate, monoglyceride stearate, monoglyceride isostearate, monoglyceride oleate And stearic acid monoglyceride and its addition product with 5-50, especially 20-30 moles of ethylene oxide. The first is the use of monoglycerides or commercial monoglyceride/diglyceride mixtures and excess monoglyceride components of formula (IV), in which COR ⁵ represents a linear acyl group having 16-18 carbon atoms.

As other suitable emulsifiers, nonionic surfactants can be selected from, for example, the following:

(1) The addition product of 2～30 moles of oxirane and/or 0～5 moles of propylene oxide and the linear aliphatic alcohol of 8～22 carbon atoms;

(II) Monoglycerides and diglycerides of saturated and unsaturated fatty acids having 6 to 22 carbon atoms, as well as sorbitan monoesters and sorbitan diesters and their addition products of ethylene oxide;

(III) Alkyl monoglycosides and alkyl oligoglycosides with 8 to 22 carbon atoms in the alkyl group and their ethoxylated analogues;

(IV) addition products of 15-60 moles of ethylene oxide and castor oil and/or hardened castor oil;

(V) Polyoleyl esters, especially polyglycerol esters such as polyglycerol polyricinoleate or polyglycerol poly-12-hydroxystearate. Also suitable are mixtures of compounds consisting of several of these substances:

(VI) addition products of 2 to 15 moles of ethylene oxide and castor oil and/or hardened castor oil;

(VII) Based on linear, branched, unsaturated or saturated C _12/22 -fatty acids, ricinoleic acid and 12-hydroxystearic acid and glycerol, polyglycerol, pentaerythritol, dipentaerythritol, sugar alcohols (such as sorbitol) and partial esters of polyglycosides (such as cellulose);

(VIII) wool wax alcohol;

(IX) Polyalkylene glycols.

Addition products of ethylene oxide and/or propylene oxide and mono- and diglycerides and sorbitan mono- and diesters of fatty acids or castor oil are known and commercially available Products of. These are thus homologous mixtures, the average degree of alkoxylation of which corresponds to the ratio of the amount of substance to ethylene oxide and/or propylene oxide and the substrate which undergoes an addition reaction therewith.

Particular preference is given to the co-use of emulsifiers of class (III), ie alkyl glycosides. Alkyl oligosides and alkenyl oligosides are known nonionic surfactants of formula (V)

R ⁶ O-[G] _p (V) wherein R ⁶ represents an alkyl and/or alkenyl group with 4 to 22 carbon atoms, G represents a sugar group with 5 to 6 carbon atoms, and P represents 1 to 6 Numbers between 10. They can be prepared according to the relevant methods of organic chemical preparations. Some representative documents are listed here from many references: Biermann et al. "Starch/Starke" 45, 281 (1993), B. Salka in "Cosmetics" 108, 89 (1993) and J. Kahre et al. in SOFW magazine , Volume 8, 598 (1995).

Alkyl and/or alkenyl oligosides can be derived from aldoses and ketoses having 5 or 6 carbon atoms, especially glucose. Preferred alkyl and/or alkenyl oligosides are alkyl and/or alkenyl oligoglucosides. The index P in the general formula (V) is the degree of oligomerization (DP), that is to say, the distribution of monoglycosides and oligoglycosides, and represents a number between 1 and 10. In the listed compounds, P must be an integer, and here at first it can be assumed that the P value=1 to 6. For a certain alkyl oligoglycoside, the P value is the calculated average value after analysis, so most of them are fractions. In particular the average degree of oligomerization P of the alkyl and/or alkenyl oligosides is from 1.1 to 3.0. From an applied technical point of view, such alkyl and/or alkenyl oligosides are preferred with a degree of oligomerization of less than 1.7, especially between 1.2 and 1.4. Alkyl or alkenyl ^R6 is derived from a primary alcohol having 4 to 11 carbon atoms, preferably 8 to 10 carbon atoms. Representative examples are butanol, hexanol, octanol, decanol, undecanol and industrial mixtures thereof, as obtained, for example, during the hydrogenation of industrial fatty acid methyl esters or during the hydrogenation of aldehydes in the Lorenzo hydroxyl synthesis. Alkyl oligosides with a chain length of C ₈ -C ₁₀ (DP=1~3) are preferred, which are produced as foreruns during the distillation and separation of industrial C ₈ -C ₁₀ coconut oil alcohols, and can be doped There are less than 6% by weight of C ₁₂ -alcohols, and alkyl oligosides based on industrial C _9/11 -carbonyl alcohols (DP=1-3). Alkyl or alkenyl R ⁶ may also be further derived from primary alcohols having 12 to 22 carbon atoms, especially 12 to 14 carbon atoms. Representative examples are lauryl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidic alcohol, petracel alcohol, arachidyl alcohol, cis-9-eicosene Alcohol, Behenyl Alcohol, Behenyl Alcohol, Bascenyl Alcohol, and industrial mixtures thereof, all of which are obtainable as described above. Preference is given to alkyl oligosides based on hardened C _12/14 coconut alcohols with a DP of 1-3. If the alkylglycosides of the formula (V) are used as emulsifiers, it has the advantage of using small amounts of polyhydroxycarboxylic acids, especially citric acid, as formulation aids. Generally speaking, the amount of polyhydroxy acid used at this time is 0.1-3.0% by weight, preferably 0.1-1.0% by weight.

The microemulsion used according to the present invention mainly contains 20-90 (weight) %, especially 30-80 (weight) % of water, and the most preferred is 30-60 (weight) % of water, 100 % by weight The rest is the oil phase and emulsifier, and other auxiliary agents and additives if necessary. The preferred content of the oil phase itself is 10-80% by weight, especially 20-70% by weight, and particularly preferably 25-55% by weight. The oily phase mainly contains ingredients a) or b) and mixtures of these ingredients. It is particularly preferred to use these emulsions with a weight ratio of oil phase to water phase of 1:1. The preferred content of emulsifier or emulsifying system is 10-50% by weight, preferably 15-45% by weight, and particularly preferred content is 20-40% by weight.

The microemulsion of the present invention can be used in various fermentation processes. Furthermore, it can be used in all process arrangements familiar to the skilled person, such as batch or fed-batch fermentation, as well as continuous fermentation. Any fermentation system familiar to professionals can be used. For details, see the individual sections of Crueger, pp. 50-70. The use of microemulsions is not limited to certain microorganisms, all compounds familiar to professionals through fermentation can be produced or transformed using emulsions. In addition to the classical fermentation methods used mainly for the synthesis of antibiotics (see Crueger, pp. 197-242), the above emulsions are also suitable for microbial transformations ("biotransformations"), such as steroids and sterols , the conversion of antibiotics and pesticides, or the manufacture of vitamins (see Kruger, pp. 254-273). Rather, it is preferably a fermentation process for the manufacture of antibiotics, such as cephalosporins, telosin or erythromycin.

Usually microemulsions are aqueous fermented juices which contain microorganisms as well as nitrogen sources and trace elements and, if necessary, other auxiliaries, especially defoamers, and are formulated in an appropriate manner. Examples of nitrogen sources are: peptone, yeast extract or malt extract, corn steep liquor, urea or lecithin. Trace elements can be used in the form of inorganic salts such as sodium or potassium nitrate, ammonium nitrate, ammonium sulfate, iron sulfate, and the like. Another advantage is that the microemulsion itself can be added with additional additives such as defoamers or nitrogen sources.

Example

Different microemulsions are made by mixing raw materials. The composition is listed in Table 1. Droplet size can be measured with a Malvern Mastersizer 2000. The emulsion is suitable as an independent nutrient source in the fermentation process, and can also be directly mixed into the aqueous fermentation juice.

Table 1a weight% weight% weight% weight% methyl oleate 32.44 Methyl laurate 30.95 Methyl nonanoate 29.61 Rapeseed Fatty Acid Methyl Esters 32.35 water 34.27 32.04 30.24 34.18 Alkyl glycosides 25.22 31.55 30.95 25.3 Glyceryl Oleate 7.91 6.55 7.62 7.84 citric acid 0.25 0.24 0.24 0.24 Exterior clarify clarify clarify clarify droplet size <80nm <80nm <80nm <80nm

Claims (10)

1. The application of oil/water emulsion, it contains water, emulsifying agent at least, and oil phase, and this oil phase contains one or more selected from following compounds: a) fatty acid alkyl esters and/or b) triglycerides of vegetable origin, It is characterized in that the droplet size range of the emulsion in the fermentation process is 1-100 nanometers. 2. Use according to claim 1, characterized in that fatty acid methyl esters are used as component a). 3. Use according to claim 1 or 2, characterized in that the average droplet size of the emulsion used is in the range of 10 to 80 nm, preferably in the range of 10 to 50 nm. 4. According to the application in claims 1 to 3, it is characterized in that the water content of the emulsion used is 20-90 (weight) %, preferably 30-80 (weight) %, and particularly preferably 30-60 (weight) %. 5. Use according to claims 1 to 4, characterized in that the emulsion used has an oil phase content of 10-80% by weight, preferably 20-70% by weight and particularly preferably 25-55% by weight. 6. According to the application of claims 1 to 5, it is characterized in that the fatty acid methyl ester of formula (I) is contained in the oil phase of the emulsion used: R ¹ -COO-R ² (I) Wherein R ¹ represents an alkyl group having 6 to 22 carbon atoms, and R ² represents a methyl group. 7. According to the application in claims 1 to 6, it is characterized in that the oil phase of the emulsion used contains methyl oleate, methyl palmitate, methyl stearate and/or methyl nonanoate. 8. Use according to claims 1 to 7, characterized in that the oily phase of the emulsion used contains coconut oil, sunflower oil and/or rapeseed oil. 9. Use according to claims 1 to 8, characterized in that the emulsion used contains alkyl oligoglycosides as emulsifiers. 10. Use according to claims 1 to 9, characterized in that the emulsifier used in the emulsion contains 10-50% by weight, preferably 15-40% by weight, particularly preferably 20-35% by weight.