LT3050B - Process for the preparing of coloureless polyhydroxyalkanoate - Google Patents

Abstract

A process is disclosed for preparing dye-free polyhydroxyalkanoates formed in the cells as storage substances during the culture of bacterial biomasses. The dried bacterial biomass is at first exposed for 10 to 120 minutes to a temperature between 80 DEG C and the lower limit of the polyhydroxyalkanoate melting range, and is then extracted with acetic acid; 1 to 10 parts per volume, expressed as a percentage, of an aliphatic carboxylic acid derivate, are added to the extracting agent.

Description

The present invention provides a method of obtaining (PHA). PHA is synthesized by growing bacterial biomass in their cells as a storage medium under certain conditions.

Under certain fermentation conditions, various microorganisms synthesize polymers such as hydroxyalkanoic acids, such as polyhydric butyric acid (PHS) or copolymer polyhydroxy valeric acid, as well as other polyhydro carbonic acids. In addition, cells always contain lipids and dyes that, like lubricants, interfere with the subsequent processing of the resulting PHA. There is a known method for removing lipids and coloring agents with alcohol or acetone (EP 15 123, EP 58 480, EP 124 309). However, when using ducks in this way, some of the colored materials acquire an undesirable hue, i.e. resulting in white

Another option for obtaining a colorless polymer is affected by:; 0 /: j / to /// ::: | HA / 0 // ti; rpikl ^; s / (DD .27 6 304) '. This is solved by growing bacterial biomass. On the other hand, the receipt of large quantities of //: / and various''Ž ir p p /' / h h h ad d d pj / / / / h h h A / / / / ^. Large amounts of solvents and precipitators are possible

PHA.

SUMMARY OF THE INVENTION It is an object of the invention to remove from PHA dyes that result from the cultivation of microorganisms and PHA in cells.

According to the invention, the production of colorless PHA from bacterial biomass by stepwise drying of wet bacterial biomass, extraction of PHA with acetic acid, and precipitation of PHA is contemplated such that the dried bacterial biomass is subjected to heat treatment prior to extraction. biomass in the period from 10 to 120 min. heated at a temperature from, 80 ° C to a lower melting point of polyhydroxyalkanoate. As a result of this temperature effect, the coloring material in the bacterial biomass · acquires a form that no longer does. influence the further processing of the polymer. Acetic acid extraction followed by addition of 1 to 10% by volume of aliphatic carbonic acid combinations. These aliphatic carbonic acid derivatives may be, for example, acetic anhydride or β-butyrolactone.

Extraction is carried out under known conditions. Yes, the extraction means release the light PHA under the appropriate conditions of the invention.

15? . Aliphatic carbonic acid derivatives and coloring matter remain in the extraction preparation.

Most surprisingly, the extraction of PHA with a mixture of acetic acid and acetic anhydride of the invention provides a lighter PHA than with extraction with acetic acid or only with acetic anhydride. It was unexpected that the use of acetic anhydride in an amount of 1 to 10% of the total volume of the extraction preparation resulted in a significant decrease in the amount of coloring agent 2 in the PHA compared to the extract, using only acetic anhydride.

30th

An advantage of the process of the present invention is that no additional solvents are required for pre-extraction of the dried bacterial biomass, which is performed to remove the color material prior to extraction, as is done with 7-step PHA precipitation for substantially higher chain length po-1. . The invention is illustrated by the following examples. / '' ³ -'7.

Example for comparison

The bacterial biomass (luminosity according to HUNTER Lab = 64.5) dried to shine is extracted with acetic acid in a ratio of 1:10 at boiling point and treated in known manner. The resulting luminance of polyhydricbutyric acid (PHB) would be L = 75.3.

Example I

Bacterial biomass dried to shine prior to extraction was subjected to heat drying.spinto j e. . Lower polyhydroxy butyric acid, a melting point was 160 ^cc. This was followed by the extraction of the treated bacterial .15 biomass with acetic acid in a ratio of 1:10 by the addition of acetic anhydride: one at a time of 1% of the total volume of the extraction preparations, otherwise at 10%, of the total volume. Received.? ·· ^: next ;; brightness (based HUNTER) PHB: '// // - .: ⁷⁷⁷ //7į'.7' ⁷ 7 / ^'7 777'<7 ^7/77

-: 2.0 '

Acetic anhydride, //i··/:';///'..'-;·% of total extraction '/,>' · 777 ^: 77 / volume of preparations ·. · / '. ·,. // -:.

Processing 10th 10 ⁷ 120 120 - / 10th 10,120 120 time, min Processing 80 160 80 160 80 160 80 160 temperature ^C ' Brightness, L 91.9 92.0 .92.0 92.2 92.2 92.8 92.8 93.2

////./ /.'/- to .'... ^{7 / 7,./} .- ;;;-·/'.· ⁷⁷ '·'; · '·' ⁷ · '/./' / '' ---- / ⁷ '

Example II to

According to Example I, the bacterial biomass dried to shine was heat treated prior to extraction. acetic .--: .// acid-treated β-butyrolactone: in one case 1% and in another 10% of the total extract. The following luminosity L (by HUNTER) PHB was obtained: β - butyrolactone,% for total extraction preparation

Processing 10th 10th 120 10th 120 120 120 time, min Processing 80 160 80 160 80 160 80 16Q temperature, ° C Brightness. ^ - L 80.8 82, 0 81, 8 82.4 82, 3 86, 7 87.7 90.3

Claims (3)

DEFINITION OF INVENTION A process for the preparation of a colorless' polyhydroxyalkanoate from a microorganism culture MB 126 comprising: drying of wet biomass, extraction of dried biomass with acetic acid, and isolation of polyhydroxyalkanoate, 'ZiF.; / s // kl' / inF / r '// r F / a-Fn F / t FI? / Fs ba crteries. characterized in that _: 10 to 10 ° C, · that after drying for 120 minutes at a temperature between the alkanoate, the 80 ° C and lower polyhydroxy- .and extraction 1 to 10% by volume of a total extract preparation of aliphatic carbonic acid derivatives. Method according to claim 2 in / :; pųhktą, F _(i b: // e //. 'H /; r; Fb ^/': .Z in that the aliphatic carboxylic acid compound is acetic anhydride. 3. A process according to claim I, wherein the aliphatic carbonic acid derivative is β-butyrrolactone. . /? / ?? /? /? '<' /? Fi / F · '. ·?'? / FFF / FF? FFF /