Antibiotic substance

Abstract

A novel antibiotic substance, named "Mycoplanecin", of presently unknown structural formula, is produced by cultivating a Mycoplanecin-producing microorganism of the genus Actinoplanes, especially the Actinoplanes nov. sp. Strain No. 41042, NRRL No. 11462.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a novel antibiotic substance, named Mycoplanecin, to a novel microorganism, Actinoplanes nov. sp. Strain No. 41042 capable of producing Mycoplanecin, and to a process for producing Mycoplanecin by cultivating a Mycoplanecin-producing microorganism of the genus Actinoplanes.

The novel antibiotic substance, Mycoplanecin, can be characterized by the following physical and chemical properties:

1. Colour and state White powder. 2. Melting point 161.degree.-167.degree. C. 3. Specific rotation [.alpha.].sub.D.sup.21 66.degree. (C=0.4, chloroform). 4. Elemental analysis C, 61.78%; H, 8.48%; N, 11.75%. (After drying to constant weight) 5. Ultraviolet absorption spectrum Only terminal absorption as shown in FIG. 1 of the accompanying drawings, when measured at 20 .mu.g/ml in a 50% v/v aqueous methanolic solution. 6. Infrared absorption spectrum The spectrum, measured in a KBr disc, is shown in FIG. 2 of the accompanying drawings. 7. Nuclear magnetic resonance spectrum The spectrum, as measured in deuterochloroform as solvent and with tetramethylsilane (TMS) as internal standard, is shown in FIG. 3 of the accompanying drawings. 8. Solubility Soluble in methanol, ethanol, ethyl acetate, acetone and chloroform. Sparingly soluble in benzene. Insoluble in water. 9. Colour reaction Brown-coloured with 50% v/v aqueous sulphuric acid Positive for iodine and potassium permanganate on silica gel thin layer chromatograms. Negative for ninhydrin and 2,4-dinitrophenylhydrazine. 10. Amino acid composition 1mole each of glycine, proline, leucine, 2-amino-5-methylhexanoic acid, N-methylthreonine, N-methylleucine, methylproline and ethylproline; and 2 moles of N-methylvaline detected after hydrolysis with 6 N hydrochloric acid at 105.degree. C. for 20 hours. 11. Antibacterial activity Strong antibacterial activity against various bacteria of the genus Mycobacterium.

In addition, Mycoplanecin has Rf values (on silica gel thin layer chromatography, F254, 0.25 mm, No. 5715, available from Merck and Co. Inc) of 0.15 when developed with ethyl acetate and 0.64 when developed with a 95:5 by volume mixture of chloroform and methanol.

The novel microorganism of the invention is Actinoplanes nov. sp. Strain No. 41042, which was isolated from a sample of soil collected in Sumoto City, Hyogo Prefecture, Japan. The strain has been deposited under Accession No. FERM-4504 with the Technical Research Institute of the Microbial Industry, Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan. The strain has also been deposited under Accession No. NRRL-11462 with the U.S. Department of Agriculture.

Also provided, as part of the present invention, is a method of producing the new antibiotic substance, Mycoplanecin, which comprises cultivating a Mycoplanecin-producing microorganism of the genus Actinoplanes and then isolating Mycoplanecin from the culture.

DETAILED DESCRIPTION OF INVENTION

Morphological characteristics and physiological properties of Actinoplanes nov. sp. Strain No. 41042 are as described below:

1. Morphological characteristics

When cultivated on medium ISP4 prescribed by the International Streptomyces Project (ISP) at 28.degree. C. for 14 days and observed under a microscope Strain No. 41042 exhibited the following morphological characteristics: spherical to subspherical sporangia with an ordinary diameter of 7-15.mu.; and spores of size 0.8.mu..times.1.3.mu., with flagella and having a motility in a 1/15 M phosphate buffer of pH 7.0 of about 40 minutes. The growth results on various media at 28.degree. C. for 14 days are shown in Table 1.

TABLE 1______________________________________Type of Characteristics of strainmedium Item No. 41042______________________________________Yeast . malt agar SM Abundant, dark yellowish orange(ISP 2) (8-7-8) AM Not grown SP Not produced SG Not formedOatmeal . agar SM Abundant, yellowish brown(ISP 3) (10-6-8) AM Trace aerial mycelia SP Pale yellowish brown (4-8-9) SG Not formedStarch . salts SM Moderate, dark yellowishagar (ISP 4) orange (8-7-8) AM Not grown SP Not produced SG AbundantGlycerol . aspar- SM Abundant, pale yellowishagine agar brown (4-8-8)(ISP 5) AM Not grown SP Not produced SG Not formedTyrosine- SM Abundant, light brownagar (ISP 7) (8-6-7) AM Not grown SP Pale yellowish brown SG Not formedNutrient SM Less good, pale orangeagar (4-8-7) AM Not grown SP Not produced SG Not formedEmerson's SM Moderate, pale yellowishagar brown (6-8-8) AM Not grown SP Yellowish brown (10-6-8) SG Not formedWater SM Poor, yellowish grayagar (1-9-10) AM Not grown SP Not produced SG Moderately formedCalcium SM Moderate, pale orangemalate (4-8-7)agar AM Not grown SP Not produced SG Slightly formedHickey- SM Abundant, yellowish brownTresner's (8-8-8)agar AM Slight trace aerial mycelia grown SP Not produced SG Not formedBennett's SM Abundant, dark yellowishagar orange (8-7-8) AM Not grown SP Not produced SG Slightly formedSucrose- SM Less good, pale orangenitrate (4-8-7)agar AM Not grown SP Not produced SG AbundantGlucose . SM Moderate, brownish whiteasparagine (2-9-8)agar AM Not grown SP Not produced SG Slightly formedTomato paste . SM Moderate, pale yellowish brownoatmeal (6-8-9)agar AM Not grown SP Not produced SG Not formedGlycerol . SM Abundant, pale yellowish brownglycin (6-8-8)agar AM Not grown SP Not produced SG Not formedGlucose . SM Moderate, dark yellowishnitrate orange (8-7-8)agar AM Not grown SP Dark yellow (10-7-9) SG Not formed______________________________________ Abbreviations: SM: Substrate mycelium AM: Aerial mycelium SP: Soluble pigment SG: Sporangium Physiological characteristics

The physiological characteristics of Strain No. 41042 are given in Table 2.

TABLE 2______________________________________Tyrosinase reaction Positive (strong)Nitrate reduction Positive (strong)Hydrolysis of starch NegativeGelatin liquefaction Positive (strong)Peptonization of milk26.degree. C. Positive (pH 6.0)Coagulation of milk26.degree. C. PositiveMelanin formation:Medium A PositiveMedium B PositiveTemperature range forgrowth 9.0-32.5.degree. C.(on ISP 2 medium) (Optimum temperature for growth 18.5-29.degree. C.______________________________________

The media used were as follows:

Medium A: Tryptone--yeast extract broth (ISP 1). Medium B: Peptone--yeast extract--iron agar (ISP 5).

The carbon source utilization pattern of Strain No. 41042 on Pridham-Gottlieb's agar medium at 28.degree. C. after 14 days is shown in Table 3.

TABLE 3______________________________________Medium C D Medium C D______________________________________D-Glucose ++ ++ Raffinose - -L-Arabinose ++ ++ Inulin - -D-Xylose ++ ++ Dextrin ++ ++D-Fructose + ++ Starch + +L-Rhamnose + ++ i-Inositol - -D-Galactose ++ ++ D-Mannitol - +D-Mannose ++ ++ Dulcitol - -Sucrose + ++ Salicin - -D-Cellobiose + ++ Sodium acetate - -Melibiose - - Sodium succinate - -.beta.-Lactose - + Glycerol - ++Maltose + + Cellulose - -Trehalose - + Control - -______________________________________ ++: Well utilized +: Utilized -: Not utilized

The following media were used:

Medium C: Pridham-Gottlieb's agar. Medium D: Pridham-Gottlieb's agar plus yeast extract 0.5%. 3. Mycelium components

An acid hydrolyzate of the mycelia was analyzed by paper chromatography according to the methods described by B. Becker et al in Applied Microbiology, 12, 421-423 (1964) and 13, 236-243 (1965) and by M. P. Lechevalier et al in "The Actinomycetales" by H. Prauser, 311-316 (1970). The results are shown in Tables 4 and 5.

TABLE 4______________________________________Cell wall typeType of diaminopimelicacid Glycine Arabinose Galactose______________________________________Meso LL Hydroxy+ - + + Trace +______________________________________

From these results, it is confirmed that the cell wall type is II.

TABLE 5______________________________________Saccharide components in whole cell______________________________________Glucose Galactose Mannose Arabinose Xylose+ + Trace Trace Trace______________________________________

As can clearly be seen from the properties described above, Strain No. 41042 belongs to the genus Actinoplanes of the family Actinoplanaceae, within the group of actinomycetes. This conclusion is based upon the formation of spherical to subspherical sporangia, motile spores and cell walls of type II; the new strain is therefore named Actinoplanes nov. sp. Strain No. 41042.

As is well-known, the properties of actinomycetes including Actinoplanes, strains are not fixed and they readily undergo mutation both through natural causes and as the result of artificial mutation. Although the invention relates to the production of the new antibiotic Mycoplanecin especially by the cultivation of the above-defined Actinoplanes nov. sp. Strain No. 41042, it also includes within its scope the use of mutants of this organism and generally of any Actinoplanes strain which is capable of producing Mycoplanecin, in order to obtain this antibiotic substance.

The cultivation of the Mycoplanecin-producing microorganism, in accordance with the process of the invention, can be performed under the conditions conventionally employed for the cultivation of Actinoplanes species. Shaken culture or submerged culture with aeration and agitation in a liquid medium are preferred.

The nutrient medium used for the cultivation can be of a composition such as is conventionally used for the cultivation of actinomycetes. Thus, it contains: an assimilable carbon source, e.g. glucose, arabinose, galactose, mannose, sucrose, maltose, dextrin, starch, glycerin, a vegetable fat or oil (such as soybean oil, corn oil or cottenseed oil), an animal fat or oil (such as chicken oil or lard) or fish oil, an assimilable nitrogen source, e.g. soybean meal, peanut oil, cottonseed meal, fish meal, corn steep liquor, oatmeal, skimmed milk, peptone, meat extract, live yeast, yeast extract, casamino acid, sodium nitrate, ammonium nitrate or ammonium sulphate; and an inorganic salt, e.g. sodium chloride, potassium chloride, phosphates, magnesium carbonate, calcium carbonate or calcium chloride. It may also contain minor amounts of various other metal salts, for example ferrous sulphate, copper sulphate, magnesium sulphate, zinc sulphate or cobalt sulphate.

Cultivation in a liquid medium is preferably performed aerobically, with aeration and agitation, in which case an anti-foaming agent may be added to the medium: suitable anti-foaming agents include silicone oils, vegetable oils or surfactants.

The cultivation is suitably performed at a substantially neutral pH value and at a temperature of from 18.degree. to 30.degree. C., preferably about 28.degree. C.

The titre of Mycoplanecin produced in the culture broth as cultivation proceeds can be quantitatively determined by the cup assay method using Mycobacterium smegmatis ATCC 607 as the test microbe. The maximum production of Mycoplanecin is generally achieved after 3-5 days of cultivation.

Mycoplanecin is present in both the liquid portion and the mycelial portion of the culture broth produced by the process of the invention. In order to recover the antibiotic from the culture broth on completion of the cultivation, the mycelium and other solids are first removed from the liquid phase by filtration, for example using diatomaceous earth as a filter aid, or by centrifugation. The Mycoplanecin which is present in the mycelial portion on the filtrate or the supernatant can then be isolated and purified by conventional techniques suited to its physico-chemical properties.

For example, the Mycoplanecin in the mycelial portion can be extracted by the addition of a water-miscible solvent, such as methanol, ethanol, isopropanol or acetone. The solvent is then removed from the extract and the residue is re-extracted with a water-immiscible solvent, such as chloroform, ethyl acetate, methyl isobutyl ketone or methylene chloride. The Mycoplanecin contained in the liquid portion of the culture broth can also be extracted with such a water-immiscible solvent, after which it would normally be combined with the extract from the mycelial portion and concentrated to give a crude Mycoplanecin extract.

Alternatively, Mycoplanecin can be extracted by adding a water-miscible solvent, such as those exemplified above, directly to the culture broth without separating the mycelium from the liquid portion; the resulting extract is filtered and concentrated to remove the solvent and then the residue is re-extracted, as in the procedure described above, with a water-immiscible solvent.

The Mycoplanecin thus obtained may be further purified by any of the methods well-known for the purification of compounds having similar physico-chemical properties; however, we prefer to use purification techniques employing an adsorbent or a counter-current distribution method. Suitable adsorbents include alumina, silica gel, Sephadex (a Trade Mark for a range of polysaccharide-derived organic compounds) or cellulose. We particularly prefer a column chromatography separation method employing silica gel as carrier and methanol, ethyl acetate or chloroform or any mixture thereof as eluent. Preparative thin layer chromatography employing silica gel is also effective for producing more highly purified Mycoplanecin.

The purified Mycoplanecin thus obtained shows single spots in coloration reactions with sulphuric acid, potassium permanganate or iodine on a silica gel thin layer chromatogram and also has the physical and chemical properties heretofor described.

The minimal inhibitory concentrations (MIC) of Mycoplanecin against various microorganisms is shown in Table 6. The evaluation was made as follows: for mycobacteria, after incubation for 5 weeks at 37.degree. C. by a dilution method employing a 1% bovine serum-containing Dubos liquid medium; on general bacteria, after incubation for 24 hours at 37.degree. C. by an agar dilution method, employing a heart infusion agar medium; and on fungi and yeasts, after incubation for 48 hours at 26.degree. C. by an agar dilution method employing Sabouraud's agar medium.

TABLE 6______________________________________ MICTest organism Medium (.mu.g/ml)______________________________________Mycobacterium kansasii IFM 2069 DM 0.025Mycobacterium fortuitum IFM 2079 DM 1.56Mycobacterium intracellulare IFM 2073 DM 0.39Mycobacterium intracellulate IFM 2083 DM 0.39Mycobacterium tuberculosis IFM 2026 DM 0.135MatsodoMycobacterium tuberculosis IFM 2027 DM 0.39MaruMycobacterium tuberculosis IFM 2028 DM 0.78H.sub.37Mycobacterium tuberculosis IFM 2029 DM 0.39H.sub.37 R.sub.vMycobacterium tuberculosis IFM 2030 DM 0.78H.sub.2Mycobacterium bovis BCC IFM 2031 DM 0.78Mycobacterium bovis ushi-10 IFM 2032 DM 0.1Mycobacterium tuberculosis(Streptomycin-resistant) IFM 2033 DM 0.1Mycobacterium smegmatis ATCC 607 DM 0.08Mycobacterium phlei DM 0.01Micrococcus luteus PCI 1001 H 0.0125Staphylococcus aureus 209P 3C-1 H >400Bacillus subtilis PCI 219 H >400Escherichia coli NOHO OC-2 H >400Klebsiella pneumoniae PCI 602 H >400Proteus vulgaris OX 19 H >400Proteus mirabilis 1331 H >400Pseudomonas aeruginosa SANK 73860 H >400Candida albicans Yu 1200 S >400Aspergillus oryzae SANK 11262 S >400Penicillium chrysogenum SANK 12768 S >400Trichophyton mentagrophytes SANK 22374 S >400Pyricularia oryzae SANK 16975 S >400______________________________________ *Medium DM: Dubos medium, except that 10% of bovine serum was added other than for the two strains Mycobacterium smegmatis ATCC 607 and Mycobacterium phlei. Medium H: Heart infusion agar medium. Medium S: Sabouraud's agar medium.

The toxicity of the antibiotic substance, Mycoplanecin, was investigated by administering it intraperitoneally to mice at a dose of 100 mg/kg body weight; no mice died.

The preparation of Mycoplanecin is illustrated by the following non-limiting Examples.

EXAMPLE 1

To a 500 ml Sakaguchi flash were added 100 ml of a seed culture medium having a pH of 7.0 before sterilization and the following composition (percentages are w/v):

______________________________________Glucose 1%Glycerine 1%Oatmeal 0.5%Sucrose 1%Soybean meal 2%Casamino acid 0.5%Live yeast 1%Calcium carbonate 0.1%Water q.s.______________________________________

This medium was inoculated with a culture of Actinoplanes nov. sp. Strain No. 41042 and reciprocal shaking culture was carried out at 28.degree. C. for 96 hours. The resulting culture broth was divided into 5 ml portions and each portion was inoculated into a Sakaguchi flask each flask containing 100 ml of a production medium having a pH of 7.0 before sterilization and having the following composition (percentages are w/v):

______________________________________Glycerine 0.5%Sucrose 2%Soybean meal 1%Live yeast 1%Corn steepliquor 0.5%COCl.sub.2 . 6H.sub.2 O 0.001%Water q.s.______________________________________

Reciprocal shaking culture was then carried out at 28.degree. C. for 96 hours. The resulting culture broths were combined.

To 4 liters of the combined culture broths (pH 7.2) were added 5% w/v of Celite 545 (a Trade Mark for a filter aid available from Johns Manville Product Corporation, U.S.A.) and the broth was filtered to separate the liquor from the mycelia-containing filter cake. The filtrate was extracted with 2 liters of ethyl acetate to recover its Mycoplanecin content, whilst the mycelial cake was extracted with 2 liters of acetone containing 20% v/v water; the acetone was distilled off under reduced pressure and the residue was extracted with 2 liters of ethyl acetate. The ethyl acetate extracts from the filtrate and the mycelial cake were combined, to give 4 liters of combined extracts.

These combined extracts were washed twice, each time with 1 liter of a saturated aqueous solution of sodium chloride. The washed extracts were dehydrated over anhydrous sodium sulphate and then concentrated by evaporation under reduced pressure to give 1.07 g of an oily substance.

This oily substance was dissolved in a small volume of chloroform and adsorbed on a column containing 20 g of silica gel which had previously been prepared with chloroform. The column was then washed with chloroform and impurities were eluted away using a 1:1 by volume mixture of chloroform and ethyl acetate and then ethyl acetate alone. The desired Mycoplanecin was then eluted with a mixed solvent containing 95% by volume ethyl acetate and 5% by volume methanol. One liter of an active fraction was separated from the eluted fractions and concentrated by evaporation under reduced pressure to give 130 mg of a white powder.

110 mg of this white powder were dissolved in a small volume of chloroform and the resulting solution was passed into a 200 ml column containing Sephadex LH-20 (available from Pharmacia Co. Limited, Sweden) packed with chloroform, and which was then eluted with chloroform. Active fractions thus collected were concentrated by evaporation under reduced pressure to give 90 mg of Mycoplanecin as a white powder. This purified product showed single spots with iodine, sulphuric acid and potassium permanganate on a silica gel thin layer chromatograph.

EXAMPLE 2

Ten 500 ml Sakaguchi flasks, each containing 100 ml of a seed culture medium having the same composition as that described in Example 1, were inoculated with a culture of Actinoplanes nov. sp. Strain No. 41042, and reciprocal shaking culture was conducted at 28.degree. C. for 96 hours.

A 30 liter jar fermenter, which contained 15 liters of a production medium having the same composition as that described in Example 1, was inoculated with 750 ml of the culture broth produced as described above and then this was subjected to shaking culture with agitation and aeration at 250 rpm, a temperature of 28.degree. C. and an aeration of 15 liters/minute for 80 hours.

To the resulting culture broth were added 15 liters of acetone, the mixture was stirred and the product was filtered with the aid of 500 g of Celite. 25 liters of the filtrate were concentrated by evaporation under reduced pressure to distill off the acetone. To the residual liquid (15 liters) were added 7 liters of methylene chloride and extraction was carried out with shaking and agitation. The residue was further extracted with another 7 liters of methylene chloride and the extracts were combined, after which the solvent was evaporated off to give 1.8 g of an oily substance.

A solution of this oily substance in a small volume of chloroform was adsorbed on a column containing 50 g silica gel and packed with chloroform, from which Mycoplanecin was eluted with a solvent system comprising 99% by volume chloroform and 1% by volume methanol.

400 ml of active fraction were collected and concentrated by evaporation under reduced pressure to give 390 mg of a white powder. A solution of this white powder in a small volume of chloroform was then subjected to preparative thin layer chromatography employing a silica gel plate (5717, available from Merck and Co. Inc.) developed with a 95:5 by volume mixture of chloroform and methanol. The active bands were extracted with ethyl acetate to give 250 mg of Mycoplanecin as a white powder having a purity of about 90% (by bioassay).

Claims

1. A biologically pure culture of Actinoplanes nov. sp. Strain No. 41042, NRRL-11462, said culture being capable of producing Mycoplanecin.