DE1643539B2 - Process for the microbiological production of D-pantoic acid from DL-pantoic acid - Google Patents

Description

The invention relates to a method for the microbiological production of D-pantoic acid from DL-pantoic acid by inoculating a culture medium containing DL-pantoic acid with a microorganism, able to assimilate L-panioic acid, but not in is able to assimilate D-pantoic acid, incubation of the culture medium, up to L-pantoic acid in the medium is practically consumed, and recovery of D-pantoic acid from the medium.

Since it is easily possible to convert the acids into their lactones and the lactones into acids Pantoic acid, pantolactone and their mixtures are equivalent to one another so that they are used in the present description and simply referred to as "pantoic acid" in the claim. D-pantoic acid, L-pantoic acid and DL-pantoic acid are hereinafter referred to as the D-isomer, the L-isomer for convenience and denotes the racemate.

D-pantoic acid is very important as an intermediate in the production of D-pantothenic acid.

The D-isomer has so far been most advantageous in practice by converting DL-pantolactone with quinine sulfate in a solution, separation of the D-quinine pantoate thus formed by fractional crystallization and hydrolysis of the D-quinine pantoate. This procedure (hereinafter referred to as However, when it comes to large-scale production, it is inevitably associated with disadvantages is applied:

1) The procedure is quite complicated and cumbersome to carry out.

2) The D-isomer obtained in this worship is not pure and always contaminated with about 5% of the L-isomer so that further purification is sometimes required is.

3) Quinine is very expensive, and so is its production cost after this procedure change with the cost of quinine.

A new, easy to carry out process for the production of the pure D-isomer in the technical Scale is therefore desirable. Such a process, which is a simplification, leads to high yields and lowers the manufacturing cost is the subject of the invention.

The invention accordingly relates to a process for the microbiological production of D-pantoic acid from DL-pantoic acid, which is characterized in that a culture medium containing DL-pantnic acid is mixed with one of the microorganisms Brevibacterium inseptiphilium ATCC-21110, Brevibacterium maus ATCC-21111, Corynebacterium equi ATCC -21107, Corynebacterium humferium ATCC-21108, Arthrobacter tumes-ί cens ATCC-21109, Arthrobacter ureafaciens ATCC-21124 or Bacillus pulvifaciens ATCC-21112, inoculated to a pH of about 5.0 to 10.0, and the temperature between about 15 and 50 ⁰ C until the L-paritoinic acid in the medium is practically consumed.

ίο In the quinine sulphate process, this is used as the starting material used racemate purified before treatment with quinine sulfate, while in the method according to the invention the crude racemate is used as starting material and there is no need that Purify source material. In addition, the process does not require quinine recovery like this is the case with the quinine sulfate process

In general, natural forms are available. Racemates are physiologically active and are believed to be are consumed by microorganisms. Surprisingly, however, it was found that there were three Groups of microorganisms exist, classified according to their ability to assimilate pantoic acid namely the group I, which assimilates the L-isomer but not the D-isomer, the group II, which assimilates the D-isomers but not the L-isomer assimilated, and Group III which has both the D-isomer and the L-isomers assimilated. By using microorganisms of the first group, it is possible that

to isolate jo D-isomers from the racemate.

The microorganisms mentioned, which are able to assimilate the L-isomer without the D-isomer assimilate are suitable for the purposes of the invention. You will be following the usual methods

J) isolated, for the isolation of microorganisms from Soil, sewage and air.

Includes a basal agar plate for isolation e.g. 0.1% urea, 0.1% potassium nitrate, 0.1%

4 (i ammonium nitrate, 0.05% potassium dihydrogen phosphate, 0.05% dipotassium hydrogen phosphate, 0.05% magnesium sulfate, 0.01% yeast extract and agar (about 1.5-2.5%) in water. The main carbon source becomes about 0.5 to 4% of the D-isomer or L-isomer dem

4) Basal medium added. The two types of agar plates (i.e. the medium containing the D-isomer and the medium containing the L-isomer) are mixed with inoculated into the test organisms and incubated for a few days at 27 "C. The microorganisms assimilating the L-isomer

". (I ganisms are selected from the microorganisms those on the plate containing the L isomer but not on the plate containing the D isomer ability to grow.

Determining whether or not there is growth.

")"> must be done with the necessary caution, as certain Microorganisms that are unable to assimilate the L-isomer on the one containing the L-isomer Plate due to assimilation of yeast extract and / or a small amount of impurities in the agar

wi can grow.

To isolate the microorganisms, for example, 0.1 g of a soil sample is added to 5 ml of DLA medium (see Table I) given in a test tube. The incubation takes place either stationary or under

Ίΐ Exercise for about 1 to 2 weeks. The media for isolation are described in Table I. After appropriate dilution, a DLA agar plate is inoculated with the culture and incubated at 28 ° C. for about 2 to 7 days.

The colonies formed are transferred to A, LA, DA and DLA agar slants and kept at 28 ° C. for 7 days incubated. The results are given in Table 2.

Furthermore, a loop with a 7-day culture of the Microorganism added to 5 ml of DLA, LA and SA medium (e.g. solution media) in test tubes and Incubated for 5 days at 28 ° C. The amount of carbon source remaining, i.e. H. D- and L-pantoic acid, in the Media is determined by a customary analytical method. The results are given in Table 3. The sign "+" here means "growth" and the sign "-" means "no growth".

Table 1 A medium

urea

KNO ₃

NH ₄ NO ₃

KH ₂ PO ₄

K ₂ HPO ₄

MgSO ₄ -7H ₂ O

Yeast extract

PH value

in tap water

LA agar plate

Plate of the LA medium containing approximately 2 to 3% agar

DLA medium

1% DL-pantoic acid or DL-pantolactone is administered to the A-Mediui; i and sets the pH value to 7.0 a

0.1%

0.05%

0.05%

0.05%

0.05%

0.05%

0.01%

7.0 LA medium

Add 0.5% L-pantoic acid or L-pantolactone to the Α-medium and adjust the pH to 7.0 a

DA medium

Add 0.5% D-pantoic acid or D-pantolactone to the Α-medium and adjust the pH to 7.0 a

A, LA and DA agar slants

Slanted tubes of A, LA and DA medium with about 2 to 3% agar

Table 2

Group strain no.

Growth on agar slant DLA LA DA

III

LP 216-1 LP 166-3 LP 208 LP 75-1 LP 75-2 LP 106-2 LP 46 S LP 60 S LP 166 F LP 1-11

533
538
539
545
553
603
620
571
628

671
124

Trunk no. Growth on agar slants DLA LA DA LP 50-IY + + LP 54 + + - LP 265 S. + + - LP 270S + + - LP 274 + -t- - LP207S + + - LP 135 S + + - LP 26 S-2 + + - LP 14S + + LP 49-1 + + 210 + - + 205 + - + 362 B ■ f- - + 343 + - + 610 + - + 609 Λ-7 + - + 387 A-I + - + 678 Λ-3 + - + 678 A-5 + - + 468 + + + 171 + 4-4-

Table 3 1643 (ATCC-21109), 539 6th 0 m medium,% I66-3 (ATCC-2I IM). 5 Group strain no. 0 Bacillus pulvifaciens Ip-60-S (ATCC-21112). Remaining amount of carbon i 0 THERE IFO number medium 0 100 1 LP 216-1 DLA LA 0 100 LP 166-3 50 0 100 LP 208 12402 50 0 100 LP 75-1 12403 50 0 100 LP 75-2 12404 50 0 100 LP 106-2 12405 50 0 100 LP 46 S 12406 50 20th 100 LP 60 S 12407 50 0 100 LP 166 F 12408 50 0 100 LP 1-11 12409 50 0 100 LP 50-IY 12410 50 0 ! 00 LP 54 12411 65 0 100 LP 265 S. 12412 60 5 100 LP 270S 12413 50 20th 100 LP 274 12414 55 20th 100 LP 207 S. 12415 55 35 100 LP 135S 12416 50 100 100 LP 26 S-2 12417 60 100 100 LP 14 p 12418 75 ! 00 100 LP 49-1 12419 70 100 0 2,533 12420 80 100 0 538 12421 50 100 0 539 50 100 0 545 50 100 0 553 50 100 0 603 50 100 0 620 50 100 0 571 50 100 0 628 50 100 5 210 50 100 5 205 50 100 5 362 B 55 100 5 343 55 100 0 609 A-7 55 80 0 387 A-I 50 60 0 678 A-3 50 90 0 678 A-5 50 70 75 3 671 50 60 324 70 Arthrobacter urcafacien 80 468 55 (ATCC-21124), 60 171 80 Analysis error + 10%. 45 slp-135-S The obtained in this way
tribes are: Brcvibac'erium inscciiphilium lp-14-S Microorganisms (ATCC-21110). Brevibacteriutn mouse Ip Corynebacteriutn equi Ip-Il I (ATCC-21107), _b -, Coryneba ^ terium humiferum Ip-106-2 (ATCC-2M08), Arthrobactcr tumesecns I -p-75-

Some taxonomic characteristics of these microorganisms differ from those in “Bergey's manual of Determinative Bacteriology, Seventh edition ", but

their main characteristics agree with the first literature references. The morphological and physiological Features are given in Table 4 below.

Table 4

Taxonomic name

Coryne-

bacterium

equi

Trunk no.
t n- i-ii

Coryne-

bacterium

humiferum

lp-IO6-2

Arthral

bacter

tumescens

lp-75-1

Arihro-

bactcr

ureafaciens

lp-135-S

Brcvi

bacterium

inscctiphilium

Ip-I4-S

Brevi

bacterium

malis

lp-16 () - 3

Bacillus pulvifiiciens

lp-60-S

Taxonomic cocci to cocci to cocci to cocci to

ι :: ~~., .- ~ *. ~ γ «« ,, cijjK ^ u ^ n Stiihchen Si ^{; i} -bch * 'n S! i * N * h? n

I-orni of cells 0.5 x 0.5 to 0.5 to 0.4 to 0.6 to

2 ■). 0.7 x 0.7 to 0.6 x 0.7 to 0.8 X 0.8 to

5 μ 3 μ 2.5 μ

pleomorphic pleomorphic pleomorphic branched,

pleomorphic

Mobility immobile immobile immobile immobile

(meaning no no no no

Kur / rod cocci to rod

0.8 to
1.0 x 1.5 to
3 ί.
pleomorphic

immovable immovable moveable none none available

Stiihrn 0.4 until 0.5 to 0.6 x 3 to 0.6 x 0.6 to 8 ■ /. 1.2 μ pleomorphic

Spore formation no no no no no no ellipsoid. 0.7-1.0 x 1.0-1.5 ■>. Sporangia swollen Gram stain positive positive positive positive positive positive positive (14 hours) (14 hours (14 hours (14 hours) (14 hours (14 hours) (14 hours) changeable 4 days) 4 days) changeable 4 days) changeable changeable (4 days) (4 days) (4 days) (5 days) Oxygen demand aerobic aerobic aerobic aerobic aerobic aerobic aerobic Growth good good good growth good growth good temperature growth growth growth at 7-25 C. growth at 25-37 C. growth at 25-37 C. at 25 C. none at 20-37 (. no at 7-25 C. no at 25-48 C, no growth core growth weak growth no growth at 7 I 'or growth at 37 C growth at 7 C or growth at 48 C. at 37 C " at 7 C or at 37 C ". none at 48 C. at 7 C 48 C growth at 48 C. Agar slant thread-like. thread-like. thread-like. thread-like. thread-like. thread-like. thread-like. opaque, cream opaque. opaque, cream opaque. yellow. opaque. yellow. opaque, cream opalescent. Colours. glittering. Colours. glittering glittering Colours, White shiny glittering white damp glittering. wet wet glittering wet wet wet Agar plate circular. circular. circular circular circular circular circular 1-1.5 mm less than with 0.5-2mm with 1.5 mm with 0.5-1 mm with with Diameter. 0.5 mm Diameter. Diameter. Diameter. 0.7-2.5 mm 0.2-1.5mm closed Diameter. closed. closed. closed. Diameter, Diameter, increased, white. auricular. increased, opali raised, yellow. raised, yellow, closed, closed, opalescent. umbilical. sating, white moist, opaque opaque, moist raised, pale pale yellow, wet opaque, dry. until cream yellow, damp. moist, opali far Colours opaque sating KartofTel- growth good wax cream colored. strong strong weak Growth, Weird culture very good. tum, yellowish wet Growth, Growth. growth pale yellow cream colored. Brown. glittering pale yellow, pale yellow. wet dry dry dry glittering Litmus milk no alkaline no alkaline easy no no change change alkaline, change change curdled, Peptonization Acid formation from no no no Acid formation Acid formation no no Carbohydrate from sucrose from sucrose

ίο

continued / uni:

Taxonomic name

Coryne- Coryne- Arthro-

bacterium bacterium bacter

equi humiferum tumescens

Arthro-Brevi-Brevi-Bacillus

baths bacterium bacterium pulvifaciens

ureafaciens insectiphilium malis

Trunk no. lp-106-2 lp-75-1 Ip-1.VS-S lp-14-S Ip-166-3 lp-60-S Ip-I-Il no positive no no positive no Nitrite formation positive from nitrate no no liquefaction liquefaction no liquefaction Gelatin- liquefaction liquefaction liquefaction liquefaction (gradually) Stitch culture no no positive positive no no Hydrolysis of no Strength positive positive positive positive positive positive FljS-Bilciiing positive no no no no no no Indole formation no ricir. ricir: r.i: r. ne :. ". no no VwKCS-PfOiiiSüCr- no reaction positive positive positive positive positive positive K.iüilase education positive no no no no no no Cellulase no education no no no no no no Assimilation no by D-Pantoin- acid positive positive positive positive positive positive Assimilation positive by L-Pantoin- acid positive positive positive - - - \ ssimilation - of citrate good P / «iges growth Glucose agar strong Soybean agar

For the large-scale production of the D-isomer by the microorganisms assimilating the L-isomer according to According to the invention, it is expedient to use a liquid culture medium. Cultivation is carried out in the generally carried out stationary or in shaking culture or submerged culture.

The medium usually contains the racemate as the main source of carbon. As carbon sources you can use in addition to the L-isomer, for example glucose, Sucrose, dextrin, starch, glycerin or sorbitol can be used alone or in combination.

Organic nitrogenous materials, for example, are suitable as a source of usable nitrogen, like urea, peptone. Meat extract, casein, edamin, casein hydrolyzate, soybean meal, corn steep liquor, Yeast, yeast extract, and inorganic nitrogen compounds such as ammonium nitrate, ammonium chloride. Ammonium phosphate, Ammonium sulfate and sodium nitrate

In general, an addition of other organic salts (e.g. potassium monohydrogen phosphate is sodium chloride or magnesium sulfate) and vitamins (e.g. thiamine, nicotinic acid, biotin, p-aminobenzoic acid, Pyridoxine) required for good growth.

The racemate used as starting material can be in the form of salts, e.g. B. of sodium salts, potassium salts, Calcium salts or ammonium salts can be used. These salts are appropriate to the medium added in an amount of more than 0.5%. The usual concentration in the medium varies depending on the Culture conditions of about 5 to 30%. The starting racemat is before cultivation all at once or growth

added intermittently in several portions or continuously during cultivation.

in The starting material is in the form of the free acid or of the salt, e.g. B. the sodium salt, Kaliums..Izes or calcium salt, or in the form of the lactone powder, optionally after prior dissolution or emulsification fed in water.

For cultivation, the pH of the culture medium is adjusted to about 5.0 to about! 0.0, expediently to 6.5 to 8.5, and the cultivation ^{temperature to about 15 to 50 °} C., expediently to 25 to 35 ° C held. Ventilation is essential for growth. Expedient

Vi Big uses suitable antifoam agents.

The cultivation is continued until the L-isomer in the medium is practically consumed. The cultivation time is different depending on certain Factors e.g. B. microorganism, temperature, ventilation. Movement and composition of the medium.

It is also possible to degrade the L-isomer in an aqueous solution by combining it with enzymes extracted from the cells of the microorganisms. The desired D-isomer

to remains unchanged in the medium.

The D-isomer is separated off by simple, customary methods, e.g. B. by adsorption chromatography on activated carbon or alumina or by partition chromatography with one with water

immiscible solvents such as ethyl ether, benzene and chloroform or allyl acetate or by distillation. These methods can be used alone or in combination.

In the following examples, the yields are calculated based on the D-sodium pantoate in the starting materials. The percentages in Table 3 and the yields in the examples relate to weight / weight and in the other cases to weight / volume. The ATCC numbers indicated for the strains of the microorganisms are the Deposit ^nl jmmern of the microorganisms deposited with the American Type; Culture Collection. Maryland, USA.

, HIS example 1 Sodium Dl. pantoate, In 200 ml Erlenmeyer flasks. the 100 nile one Urea, Nutrient solution KNO ,. 7.9 ¹ Vo NH ₄ NO ₁ , 0.2% MgSO ₄ · 7 H, O. 0.1% KH ₂ PO ₄ . 0.1% K ₂ HPO ₄ , 0.05% lleefy extract 0.05% 0.05% 0.1%

was sterilized by autoclaving and, after cooling, with a suspension of Brevibacterium mouse Ip 166-3 (ATCC-21111) by rinsing an agar slant with physiological saline solution.

The preculture was incubated for 3 days at 28 ³ C with shaking, after which I ml of the culture was inoculated into five 200 ml cooking flasks, each containing 100 ml of the same nutrient solution. These flasks were shaken for 4 days at 28 ° C. The combined Kullurfiltrate of all flasks was adjusted to pH 1 and repeatedly extracted with ethyl acetate, after which the remaining D-pantoic acid in the filtrate was lactonized by autoclaving under a pressure of 1.177 bar for a period of 10 minutes The solvent was distilled off and the residue obtained was purified by further distillation and condensation, giving 2.5 g (yield 83%) of D-pantolactone as white needles.

Melting point 91 to 92 ° C
[»] -50.5" (H ₂ O)
NMR: OP? " ¹ (in CDCI ₂ )

1.08 (CH ₃ ) 1.22 (CH ₃ )

4.00 (CH ₂ ) 4.07.4.20 (CHOH)

Example 2

A 200 ml Erlenmeyer flask containing 100 ml of a nutrient solution containing 5.24% was sterilized DL sodium pantantoate removed, and then vaccinated with one Suspension of Brevibacterium insectiphilium lp-14-S (ATCC-21110) obtained by rinsing a slant culture with physiological saline solution. The preculture was shaken for 3 days at 28 ° C and then inoculated with 1 ml of the culture five 200 ml fermentation flasks, each containing 100 ml of the same nutrient solution. The flasks were shaken for 4 days at 28 ° C. combined culture filtrate of all flasks to pH 1 and extracted the filtrate repeatedly with ethyl acetate, after the remaining D-pantoic acid in the filtrate by autoclaving under a pressure of 1.177 bar had been lactonized for a period of 10 minutes.

The solvent was distilled off and the residue obtained was purified by further destination and condensation. 76 g (yield 88%) of D-pantolactone were obtained as white needles.
Optical rotation, «£ [>] = -50.7" (H ₂ O)
Example 3

A 200 ml Erlenmeyer flask containing K) OmI of the same nutrient solution as in Example 2 was sterilized and then inoculated with a suspension of Arthrobacter lumescens Ip 75-1 (ATCC-21109), obtained by rinsing an agar slant with physiological saline.

The culture was agitated for 3 days at 28 C ^1. whereupon 1 ml of the culture was inoculated into five 200 ml fermentation flasks containing the same nutrient solution. The flasks were shaken at 28 "C for 4 days.

The combined culture of all the pistons was adjusted to pH 1 and extracted repeatedly with Äthylaceiat after it was lactonized the remaining D-pantoic acid in the filtrate by autoclaving at a pressure \ o) 1,177 bar for a period of 10 minutes. The solvent was distilled off and the residue obtained was purified by further distillation and condensation. 1.81 g (yield 90%) of D-pantolactone were obtained as white needles which had an optical rotation [■■ *] of -50.4 "C (HjO).

Example 4

A 200 ml Erlenmeyer flask containing 100 ml of the same nutrient solution as in Example 2 was sterilized and then inoculated with a suspension of Arthrobacter ureafaciens Ip 1J5-S (ATCC-2Ü24) obtained by rinsing a slant culture with physiological saline had been received. The pre-culture was shaken for 2 days at 28 ⁰ C, after which the culture I ml in five 200-ml Gärkolben containing the same nutrient solution was changed inoculated. The flasks were shaken at 28 "C for 4 days.

The combined culture filtrate from all flasks was adjusted to pH 1 and repeated with ethyl acetate extracted after the remaining D-pantoic acid in the filtrate by autoclaving under a pressure of 1.177 bar for a period of 10 minutes', actonized had been. The solvent was distilled off and the residue obtained by further distillation and Condensation cleaned.

1.64 g (yield 85%) of D-pantolactone were obtained as white needles which _{showed an optical rotation [λ] = -50.6 "C (H 2} O).

Example5

A 200 ml Erlenmeyer flask. containing 100 ml of the same nutrient solution as in Example 2 was sterilized and then inoculated with a suspension of Corynebacterium equi Ip 1-11 (ATCC-21107), obtained by rinsing an agar slant with physiological saline. The preculture was shaken for 2 days at 28 ° C, whereupon 1 ml of the culture in five 200 ml fermentation flasks containing the same Containing nutrient solution, was vaccinated. The flasks were shaken at 28 ° C for 4 days.

The combined culture filtrate from all flasks was adjusted to pH 1 and repeated with ethyl acetate extracted after the remaining D-pantoic acid in the filtrate by autoclaving under a pressure of 1.177 bar had been lactonized for a period of 10 minutes. The solution center! was distilled off and the residue obtained was purified by further distillation and condensation. 1.71 g (ex

loot 85%) D-pantolactone was obtained as white needles which had an optical rotation f \] = - 50.6 ⁰ C (H2O).

B e i s ρ i e 1 6

F. in 200 ml Erlenmeyer flasks containing 100 ml of a Nutrient solution containing the same composition as in Example 2 was sterilized and then with a Suspension of Corynebacterium humiferum Ip 106-2 (ATCC-21108) vaccinated by rinsing an oblique 1 » Agarkuitur obtained with physiological saline solution had been. The preculture was shaken for 2 days at 28 "C, after which I ml of the culture in five 200 ml fermentation flasks. which contained the same nutrient solution. U; Ti vaccinated became. The flasks were shaken at 28 ° C for 4 days.

The combined refrigerant filtrate from all flasks was adjusted to pill and repeatedly exiiaim with ethyl acetate. by autoclaving under a pressure of: n 1,177 Dar for a period of 10 minutes. The solvent was distilled off and the residue obtained was purified by further distillation and condensation. This gave 1.69 g (84% yield) of D-pantolactone as white needles, which had an optical three Mg [\] of -50.7 "C (U ₂ O) .

Example 7

A 200 ml Erlenmeyer flask. containing 100 ml of a nutrient solution containing 2.62% DL sodium pantoate was sterilized and then inoculated with a suspension of Bacillus pulvifaciens IP60-S (ATCC-21112) obtained by rinsing an agar slant with physiological saline. The preculture was shaken for 2 days at 28 ° C., after which 1 ml of the culture was inoculated into five 200 ml fermentation flasks, which all contained the same nutrient solution. The flasks were ^{shaken at 28 °} C. for 4 days.

The combined culture filtrate from all flasks was adjusted to pH I and repeated with ethyl acetate extracted after the remaining D-Pantoinsäu, e in the filtrate by autoclaving under a pressure of 1.177 bar lactonized for a period of 10 minutes had been. The solvent was distilled off and the residue obtained is purified by further distillation and condensation. This gave 0.87 g (yield 85%) D-pantolactone obtained as white needles, which have an optical rotation [λ] of -50.4 ° C ^; 2O) had.

Example 8

A 200 ml Lrlenmcycr flask containing 100 ml of the same nutrient solution as in Example 1. wuhL and then inoculated with a suspension of Brevibacterium maliz Ip 166-3 (ATCC-21111) obtained by rinsing an agar slant with physiological saline. The preculture wuiiic 2 Tilge uci 28 ° v. gc ^ cnuiien, wuiaui uie gestiinie culture was transferred to a conventional 2-i fermenter equipped with a device for moving the fermenter, aeration, a temperature control device. a pH analyzer, etc., and contained 1 L of the same nutrient solution. The culture was incubated at 28 "C with aeration and agitation. After a cultivation period of i? Hours 53g NatriunvDL-pantoate were added to the medium. At this time, L Pantoinsäurc was practically consumed in the output medium. The Kultivieruiig was continued for about 30 hours .

The culture filtrate was adjusted to pH 1 and extracted repeatedly with ethyl acetate after the remaining D-pantoic acid in the filtrate had been lactonized by autoclaving under a pressure of 1,177 bar for a period of 10 minutes. The solvent was distilled off and the residue obtained was purified by further distillation and condensation. This gave 86 g of D-pantolactone (yield 86%) as white needles. the one optical rotation [λ]
of -50.6 "C (H ₂ O).

Claims (1)

Claim: Process for the microbiological production of D-pantoic acid from DL-pantoic acid, characterized in that a culture medium containing DL-pantoic acid is mixed with one of the microorganism strains Brevibacterium insectiphilium ATCC-21U0, Brevibacterium maus ATCC-21111, Corynebacterium equi ATCC-21107, Corynebacterium equi ATCC-21107, 21108, Arthrobacter tumescens ATCC-21109, Arthrobacter ureafaciens ATCC-21124 or Bacillus pulvifaciens ATCC-21112, adjusts to a pH of about 5.0 to 10.0, and ^{keeps the temperature between about 15 and 50 0} C until the L-pantoic acid in the medium is practically consumed