[DESCRIPTION] [Invention Title]
METHOD OF EXTRACTION AND YIELD-UP OF TRICYCLO COMPOUNDS BY ADDING A SOLID ADSORBENT RESIN AS THEIR CARRIER IN FERMENTATION MEDIUM [Technical Field]
<1 > The present invention relates to tricyclo compounds, and more particularly to a method of fermenting and purifying FK506 and/or FK520. [Background Art]
<2> The present invention relates to tricyclo compounds, as disclosed in US Patent No. 4,894,366, and more particularly to a method for improving production of tacrolimus (FK506) and ascomycin (FK520) and purifying the same.
<3> In general, tricyclo compounds are biologically active materials that are secondary metabolites produced by microorganisms, particularly actinomyces sp. , and display antifungal activity and immunosupressive activity. The general structure of the tricyclo compound is shown in Chemistry Figure 1. [Chemistry Figure 1]
<4>
<5> (Wherein, Rl is a hydroxyl group or a protected hydroxyl group, R2 is hydrogen, a hydroxyl group or a protected hydroxyl group, R3 is a methyl, ethyl, propyl or al IyI group, n is 1 or 2, the double solid and dotted line represents a single or a double bond.)
<6> Important examples of tricyclo compounds include FK506 and FK520, and rapamycin and the like are known to have a similar structure. Particularly, FK506 has superior immunosuppressive activity to cyclosporin A as reported by Kino et al. in 1987 (Hantanaka, H., M. Iwai , T. Kino. T. Goto, and M. Okuhara. 1988. /. Antibiot. 41: 1586-1591; Kino, T., H. Hantanaka, M. Hashimoto, M. Nishiyama, T. Goto, M. Okuhara, M. Kohsaka, H. Aoki and H. Iminaka. 1987. J. Antibiot. 40: 1249-1255). Further, FK506 is produced by microorganisms such as Streptomyces tsukubaensis 9993, Streptomyces sp. ATCC 55098, Streptomyces sp. ATCC 53770, Streptomyces kanaywyceticus KCC S-043, and the like (Muramatsu, H., S. I. Mokhtar, M. Katsuoka, and M. Ezaki . 2005. Actinomyetelolgoica. 19:33-39, U.S. Patent No. 4,894,366). FK520, a structurally similar analog of FK506, exhibits immunosuppressive activity and antifungal activity, is reported to be produced from Streptomyces hygroscopicus subsp. ascomyceticus ATCC 14891, Streptomyces hygroscopicus subsp. yakusimaensis 7238, Streptomyces tsukubaensis 993, and the like. [Disclosure] [Technical Problem]
<7> FK506 is useful as a medicine for treatment of autoimmune diseases, organ transplant rejection, erythroblastosis, etc. In development of such a medicine, high purity must be ensured. Therefore, it is necessary to establish a microorganism with improved productivity, a fermentation process, and an efficient purification process. An aspect of the present invention is to provide a method of fermenting tricyclo compounds including FK506 and FK520 that ensures an increased yield of tricyclo compounds and permits a simplified process of purifying the same. [Technical Solution]
<8> In accordance with an aspect of the present invention, the method of fermenting tricyclo compounds includes adding a hydrophobic synthetic adsorbent resin capable of adsorbing hydrophobic tricyclo compounds as a carrier to a fermentation medium of actinomyces to prevent the inhibition of production, thereby improving yield of the tricyclo compounds, specifically FK506 and FR520 (Chemistry Figure 2).
<9> In accordance with another aspect of the present invention, a method of purifying tricyclo compounds includes extracting the tricyclo compounds from a resin added to a fermentation medium.
[Advantageous Effects]
<ii> According to exemplary embodiments of the present invention, a hydrophobic synthetic adsorbent resin is added for production and purification of hydrophobic tricyclo compounds, thereby substantially improving yield of tricyclo compounds while simplifying purification thereof. [Description of Drawings]
<i2> The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
<i3> Fig. 1 is a graph depicting HPLC analysis results of tricyclo compounds, FK506 and FK520.
<i4> In an experimental control group to which a resin was not added, analysis was carried out on a whole control culture media, a control supernatant where cells were removed, and control cells that were collected after being centrifuged. In an HP-20 added culture group, analysis was carried out on a whole fermented culture media where an HP-20 synthetic resin was added at 5% (v/v).
<i5> Fig. 2 is a graph depicting LC-Mass analysis results of FK506 and FK520.
<i6> FK506 [m/z, 822], FK520 [m/z, 810]
<i7> Fig. 3 is a graph depicting yields of FK506 and FK520 when using different kinds of synthetic resins.
<i8> Various kinds of synthetic resins were added each at 5% (v/v) to a culture medium. Then, the medium with the resin was sterilized and fermented for six days to measure a yield of FK506 and a yield of FK520. The control group was an experimental group where a synthetic resin was not added.
<19> Fig. 4 is a graph depicting yields of FK506 and FK520 according to days when the resin was added.
<2o> The resin (HP-20) was used for experiments. The resin was separately sterilized during culturing and added on different days corresponding to a final concentration of 5% (v/v). The medium was fermented for six days to measure a yield of compounds. The control group is an experimental group to which resin was not added. <2i> Fig. 5 is a graph depicting yields of FK506 and FK520 according to culturing days and resin added days. <22> -■-: A yield of FK506 depending on a culturing day with no resin added, obtained by collecting a small amount of the compound on a predetermined day in fermentation. <23> -#-: A yield of FK506 depending on a culturing day with the resin added, obtained from Fig. 4. <24> Fig. 6 is graphs depicting yields of FK506 and FK520 according to an added amount of resin. <25> The added amount of resin is given as a volume ratio. The control group is an experimental group to which resin was not added. <26> Fig. 7 illustrates results of sensibility test of actinomyces to
FK506. <27> In the test, 1: Streptomyces venezuelae, 2'- Streptomyces sp. GT1005,
3: Streptomyces sp. ATCC 55098 were used as the actinomyces, and FK506 with a concentration displayed on the drawing was employed. <28> Fig. 8 is a graph depicting an extraction amount of FK506 and an extraction amount of FK520 according to solvents. <29> A resin was extracted from the medium to which the resin (HP-20) was added, and a solvent was added thereto at a volume ratio twice that of the resin to extract the compounds. The compounds were quantitatively analyzed. <30> Fig. 9 is a graph comparing yields of FK506 obtained from recycled resins. <3i> Resin (HP-20) was added at 5% (v/v). A control group was an experiment to which resin was not added. New resin, once-used resin (Re-
1), and twice-used resin (Re~2), recycled by a method mentioned in Example 7, were used.
[Best Mode]
<32> The present invention provides a fermentation method wherein fermentation is performed after adding a hydrophobic synthetic adsorbent resin capable of adsorbing hydrophobic tricyclo compounds as a carrier to a fermentation medium of actinomyces to prevent the inhibition of production, thereby providing an increased yield of tricyclo compounds, specifically FK506 and FK520 (Chemical Formula 2).
<33> Further, the present invention provides a method of purifying tricyclo compounds by extracting the tricyclo compounds from the resin added to a fermentation medium.
[Chemistry Figure 2]
<35> (wherein the compound i s FK506 in the case of R= C
3H
5 , and FK520 in
the case of R=C
2H
5)
<36> Next, an exemplary embodiment of the present invention will be described in detail .
<37> The microorganism used in the exemplary embodiment of the present invention is Streptomyces sp. GT1005 which produces both FK506 and FK520. However, the present invention is not limited thereto, and can be applied to any microorganism that produces tricyclo compounds, specifically FK506 and/or FK520.
<38> Since tricyclo compounds are hydrophobic, a synthetic hydrophobic adsorbent resin which can be used as a carrier of the tricyclo compounds is added to a fermentation medium to prevent adsorption of the tricyclo compounds to hydrophobic mycelia to overcome low yields due to the inhibition if production and to improve a yield of the tricyclo compounds.
<39> As a carrier, the hydrophobic adsorbent resin may include a synthetic resin comprising styrene/divinylbenzene copolymers or aliphatic ester as a main ingredient, and be one selected from the group consisting of Diaion HP-20, Amberlite XAD-2, Amberlite XAD-4, Amberlite XAD-7, Amber lite XAD-7HP, Amberlite XAD-8, Amberlite XAD-16, Amberlite XAD-16 HP, Amberlite XAD-1180, Amberlite XAD-2000, and Amberlite XAD-2010.
<40> The added amount of synthetic resin is 1-15% (v/v), preferably 3-5% (v/v) , most preferably 5% (v/v). If the synthetic resin is directly added to a culture medium for fermentation, a three-fold or greater increase in yield can be expected.
<4i> The synthetic resin can be added to the culture medium at any time from the beginning of culturing to the end of culturing, preferably within three days (0-72 hours) from the beginning of the culture, which is closely related to production characteristics of the tricyclo compounds. That is, in an experiment in which the resin was not added, a yield of FK506 starts to increase from the second day and reaches a peak on the fifth or sixth day. Thus, the synthetic resin is preferably added at the beginning of culturing to improve the yield of tricyclo compounds.
<42> The tricyclo compounds, specifically FK506 and FK520, are collected from a fermentation medium that has been cultured for four to seven days after addition of the synthetic resin. Most of the tricyclo compounds produced are adsorbed to the synthetic hydrophobic adsorbent resin added as the carrier (90~98%). Thus, it is more preferable to collect the compounds from the synthetic resin after separating the synthetic resin from the mycelial cake or the culture medium.
<43> The synthetic resins are collected by centrifugal separation or filtration. More preferably, a fiber or wire sieve with a smaller pore size than the size of the synthetic resin (average 250mm) is used, and most preferably, a wire sieve (with a pore size of 60-250mm) is used.
<44> A solvent for eluting the tricyclo compounds from the synthetic resin is one selected from the group consisting of methanol, ethanol , acetone, acetonitri Ie, butanol , isopropanol, ethyl acetate, chloroform, dichloromethane, and hexane. Preferably, the solvent is one selected from methanol, ethanol, acetone, and acetonitri Ie, which can be mixed with water, and most preferably is one selected from acetone and an acetone aqueous solution (40-100%).
<45>
[Mode for Invention]
<46> Next, examples of the present invention will be described in detail. However, it is apparent to those skilled in the art that the present invention is not limited to these examples of the present invention disclosed below but can be worked in various ways.
<47>
<48> Example I'- Fermentation for production of tricyclo compounds <49> To produce tricyclo compounds, a pre-culture medium (1% soluble starch, 1% glycerol, 2% soy bean flour, 0.2% CaCO3, and 0.05% GE-304) was inoculated with a mycelial solution of streptomyces sp. GT 1005 and cultured at 27~30°C for 24 hours. A main culture medium (7% soluble
starch, 0.5% soy bean flour, 1.7% yeast extract, 0.1% (NH4) 2S04, 0.5% corn steep liquor, 0.1% CaCO3, and 0.05% GE-304) was inoculated with 1-5% of the resultant product and cultured at 27-30"C for six days. In Erlenmeyer- flask culturing, both pre-culturing and main culturing were carried out in a 50Om-C, flask with 30m£ of the medium by shaking at 230 rpm. In 51 jar fermentor culturing, 3 £ of the main-culture medium was used and the culturing was performed at a ventilation rate of 1.5 wm and 600-900 rpm, and a solid hydrophobic adsorbent resin selected from diaion HP-20, Amberlite XAD4, Amberlite XAD7H, and Amberlite XAD16 was added as a carrier at different times and in different amounts for each example.
<50>
<5i> Example 2: Identification and quantitative analysis of tricyclo compounds
<52> FK506 and FK520 were identified and quantitatively analyzed. FK506 and FK520 standards were purchased from A.G. Scientific, Inc. Molecular weights of FK506 and FK520 standards and the fermented product were identified by LC-ESI-MS/MS (FK506 M/Z, 822; FK520 M/Z, 810). As needed, FK506 and FK520 were identified by a process wherein samples and standards were injected at the same time to examine the same retention times (FK506, 34 minutes; FK520, 33 minutes) (see Figs. 1 and 2). For the quantitative analysis, high performance liquid chromatography (HPLC) was conducted under the conditions listed in Table 1, and samples dissolved in a 50% acetone aqueous solution and having an amount within an effective range (0.1-1 mg) of the quantitative standard calibration curve were used.
<53> [Table 1]
<54>
<55> Example 3: Increase in yield according to solid resins used as carrier
<56> Most of the tricyclo compounds (FK506 and FK520) which were produced were present in mycelia (see Fig. 1). It is assumed that such characteristics of the tricyclo compounds are related with hydrophobic properties of the tricyclo compounds. The biosynthesized hydrophobic tricyclo compounds were adsorbed to a hydrophobic mycelial cake. It was considered that the excessive accumulation of the tricyclo compounds ultimately stops or reduces production of the tricyclo compounds via growth inhibition or feedback inhibition. Therefore, if a hydrophobic solid material having similar properties to those of the mycelial cake were to be added to a fermentation medium, it would serve as a carrier for the tricyclo compounds instead of the mycelial cake. That is, the inventors considered that the produced tricyclo compounds were adsorbed to the hydrophobic solid synthetic resin instead of the mycelial cake when the hydrophobic solid synthetic resin was added to the fermentation medium during fermentation.
<57> As an adsorbent resin to be added to the fermentation medium, HP-20 (Yiryoong Chemicals Co., Ltd.), Amberlite XAD-4 (Rohm & Hass), Amber lite XAD-7H (Rohm & Hass), or Amberlite XAD-16 (Rohm & Hass) was added at 5% (v/v) to a main-culture medium, and cultured in a 500-ml Erlenmeyer flask containing 30 ml of a medium for six days as in Example 1. Then, the
contents of tricyclo compounds, specifically FK506 and FK520, were analyzed as in Example 2.
<58> Table 2 shows yields of tricyclo compounds depending on resins provided as a carrier.
<59> [Table 2]
<60> <62>
<63> As can be seen in Table 2 and Fig. 3, in the experimental group where the resin was added to the medium, the yields of the tricyclo compounds, FK506 and FK520, were at least 2.5 times those of the tricyclo compounds in the control group to which the resin was not added. It is considered that FK506 and FK520 are similar in physical and structural properties and in presumed biosynthetic process so that they increase in yield at a similar rate.
<64> <65> Example 4: Increase of yield according to addition of solid synthetic resin by time in fermentation
<66> To determine proper time in adding a solid synthetic resin, an HP-20 resin, as adopted in Example 3, was added at 5% (v/v) to the culture medium at intervals of one day from the beginning of fermentation to one day before the end of fermentation, followed by fermentation and culturing for six days as in Example 1. The contents of tricyclo compounds (FK506 and FK520) were analyzed as in Example 2.
Table 3 illustrates a yield of the compounds according to the addition time of the resin. [Table 3]
<69> <7Φ>
<72> As can be seen from Table 3 and Fig. 4, the compounds in the experimental group where the resin was added at the beginning of cultivation showed the highest increase in yield. That is, the yield of the compounds in the experimental groups to which the resin was added within two days (48 hours) from the day of the fermentation increased by about three times. The yield began to exponentially decrease after third day. In the experimental group to which the resin was added one day before the end of the fermentation, i.e., fifth day from the beginning of fermentation, the yield of the compounds hardly increased. This was inversely proportional to the yield curve of FK506 in the control group without the resin added (see Fig. 5). For an increasing yield, in other words, it was effective to add the resin within three days at an initial stage where the production started, but it was useless to add the resin at the stage where the production was completed. Therefore, it was very critical to add a synthetic resin at an initial stage of fermentation. In the following experimental groups of Examples 5 and 6 to which the resin was added, a fermentation medium to which the resin was added was prepared and sterilized, followed by inoculation with mycelia to ensure fermentation starts simultaneous with the addition of a synthetic resin.
<73> <74> Example 5: Increase of yield according to amount of solid resin used as carrier
<75> One of synthetic resins, HP20, used in Example 3 was adopted and added to a fermentation medium at 3%, 5%, 7%, and 10% (v/v) as in Example
4, followed by culturing for six days as in Example 1. Tricyclo compounds were extracted by the method of Example 2 and quantities thereof were determined using HPLC.
<76> Table 4 shows a yield according to an added amount of resin.
<77> [Table 4]
<78> <SΘ>
<81 > As can be seen from Table 4 and FIG. 6, FK506 and FK520 had the highest yield in the experimental groups where HP20 was added at 3% and 5%, and tended to slightly decrease in yield as the synthetic resin was added at a higher ratio. It is considered that excessive addition of resin has a negative effect upon growth of microorganism.
<82> <83> Example 6: Cause of increase in yield of tricyclo compound by synthetic resin
<84> To explain the increase in yield of the compounds by the synthetic resin in detail, the synthetic resin was enclosed with Miracloth (Calbiochem) , through which mycelia cannot pass but the medium easily passes, and was added to a fermentation medium, followed by fermentation as in Example 1. As a result, an increase in yield due to the resin did not occur in the experimental group where the synthetic resin was separated and added (Table 5).
<85> [Table 5] <86>
<87> The results show that contact of mycelia with the synthetic resin was important in adsorption of the tricyclo compounds to the synthetic resin. Further, the mechanism of increasing the yield of the tricyclo compounds by the synthetic resin was determined by the fact that tricyclo compounds which would normally adsorbed by the mycelium were transferred instead adsorbed by the synthetic hydrophobic resin, so that toxicity or feedback inhibition of the tricyclo compound to the mycelia could be solved, thereby leading to an increase in yield of the tricyclo compounds.
<88> To specifically determine the cause of the increase in yield of the tricyclo compounds, distribution of FK506 and FK520 in the culture broth was examined. HP-20 resin, mycelia, and culture supernatant used for cultivation were separated to analyze the content of tricyclo compounds. As a result, most of the tricyclo compounds (95~99%) were adsorbed to the HP-20 resin, whereas a very small amount of tricyclo compounds (1-5%) were present in the mycelia and the supernatant (Table 6).
<89> [Table 6] <90>
<91> Further, actinomyces were tolerant to an excess (1 mg/m-O of FK506 and growth thereof was not inhibited (see Fig. 7). This result verified reports that the tricyclo compounds have antifungal activity and do not have antibacterial activity. It proved that the increase in yield of FK506 and FK520 by the synthetic resin was not obtained by elimination of their own toxicity. Considering the facts that growth of bacteria was not affected by an excessive amount of tricyclo compounds and that growth rates or weights of cells were not increased by the addition of the resin, it is assumed that yield was not increased by improvement in growth of
bacteria via reduction in toxicity of the tricyclo compounds or other secondary metabolites. Therefore, it is one of the reason of tricyclo compounds yield up that the removal of feedback inhibition material, it could be candidate that tricyclo compounds and other hydrophobic secondary metabolites, by the added synthetic resin which entrapped of them. Conclusively, in the present invention where the synthetic resin was added for fermentative cultivation, the tricyclo compounds, specifically FK506 and FK520, adsorbed to mycelia were transferred to an added synthetic resin to prevent feedback inhibition, thereby achieving an increased yield. The present invention enables high tricyclo compound production from a microorganism by overcoming the problems of the conventional technique wherein limited adsorption quantity of tricyclo compounds to mycelia causes the obstacle of development of a microorganism for high tricyclo compound production.
<92> Example T- Collection of solid resin, extraction of FK506 from solid resin, and recycling of resin
<93> The synthetic resin, to which most of the tricyclo compounds identified in Example 6 were adsorbed, was separated to extract FK506 and FK520 therefrom and to purify the same. Because the synthetic resin (HP- 20) has an average size of 250 mm or more, a copper sieve having a pore diameter of 250 mm or less was used to collect the synthetic resin from the culture broth (5-2) after completion of fermentation. The collected synthetic resin was washed with distilled water and filled in a proper- size column. Tricyclo compounds were then extracted from the synthetic resin using various organic solvents, but acetone, methanol, ethanol, and acetonitri Ie, which can be easily mixed with water, were preferable (Table 7). For acetone, a 50% or more acetone aqueous solution could collect the tricyclo compounds and a 70-75% acetone aqueous solution could collect tricyclo compounds with less impurities and a good yield (see Fig. 8). In extraction with 75% acetone, the resin was washed with a 40% acetone
aqueous solution acetone at a volume of three times that of the resin, and the compounds were extracted with a 75% acetone aqueous solution at a volume of three times that of the resin. Here, the yield was 94% or more (Table 8). Thus, the fermentation broth with the HP-20 resin added was very effective since the synthetic resin was separated from the culture broth for extraction with an extraction solvent to reduce the amount of extraction solvent while enabling the most of tricyclo compounds to be extracted.
<94> Table 7 shows an yield of the compounds from the resin by extraction with a solvent .
<95> [Table 7]
<99> Table 8 shows an yield of the compounds from the resin by extraction with an acetone aqueous solution.
<100> [Table 8]
<101>
<102>
<103> Table 9 shows adsorption efficiency of recycled resin. <104> [Table 9]
<105>
<106>
<108> It is shown that the adsorption efficiencies of the recycled resins are 90% of the new resin, the collected synthetic resin (HP-20) having been washed with the mixture of 50% isopropyl alcohol and a 50% IN NaOH aqueous solution, a 4% NaOCl aqueous solution, and distilled water at a quadruple volume ratio each in order (see Fig. 9 and Table 9).
<109> Although the present invention has been described with reference to the embodiments and the accompanying drawings, the present invention is not limited to these embodiments and the drawings. It should be understood that various modifications, additions and substitutions can be made by a person having ordinary knowledge in the art without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
<1 10>
[Industrial Applicability]
< i l l > According to the present invention, hydrophobic tricycle compounds such as FK506 and FK520 can be yield up by hydrophobic adsorbent resin which acts as a carrier of them during fermentation, and the resin can be easily harvesting and the compounds can be efficiently extracted from the resin. Therefore, the present invention is useful for efficient production of hydrophobic tricycle compounds.