DD204942A1 - PROCESS FOR SEMICONDUCTORY PRODUCT SYNTHESIS - Google Patents

Abstract

The invention relates to a microbial process for semicontinuous product synthesis. The aim of the solution according to the invention is to reduce the specific substance requirements and to increase the product formation rates in the microbial transformation into certain products or product mixtures, such as citric acid / isocitric acid. The invention is therefore based on the object to develop a method that allows on the way over the control of the use of energy and carbon source by the microorganisms, the goal, lowering the specific material and energy consumption and increasing the space-time To achieve yields with high stability of the biological system and use of high cell densities. The object is achieved according to the invention by controlling the exchange of fermentation medium in the semicontinuous product synthesis according to the state of the microorganisms, so that the exchange preferably half of the fermentation medium after passing through a biomass formation phase under optimal growth conditions and a product formation phase under favorable conditions for product formation upon reaching a certain product concentration or when the product formation rate decreases and that fermentation solutions with high cell densities are used.

Description

title

Process for this continuous product synthesis

Field of application of the invention

The invention relates to a process for microbial semi-continuous product synthesis, e.g. for the synthesis of organic acids such as citric acid, and must be classified in the IPK C 12 Ii

Characteristic of the known technical solutions

For semi-continuous product synthesis, predominantly methods are used in which the / most of the Perraentationsmediums is discharged after discontinuing the discontinuous rate. The proportion of the fermentation medium remaining in the reactor, preferably 1/10 of the total contents, serves as the inoculating material for the following set, DD-WP 130 046 *

Disadvantage of this and other known discontinuous and semicontinuous' method for microbial citric acid synthesis (DE-OS 20 50 361, DE-OS 22 15 141, DE-OS 21 15 514, US-PS 3,902,965) is the high residence time of the organisms in the reactor system from about 5 to 7 days, associated with low space-time yields (<1.2 g acid / kg, h), high specific substance and energy consumption due to the storage of essential nutrients and Reo-servestoffbildung and increased Kuhlkos -th "

The known technical solutions for continuous citric acid synthesis (PR-PS 2 209 840, GB-PS 14 18-561, DE-OS 23 23 106, DE-OS 23 60 091, 5 ¹ R-PS 14 28 440) has the disadvantage reason that 2 or more process stages '5' are required, which require an increased Inve tauf wall and high operating costs require, or that in the Palle of 1-stage process control a continuous process duration ·· of ca «200 h due to lack of stability of the microbiological System can not be exceeded "Another disadvantage of the known technical solutions is the use of low cell densities *

Object of the invention

The aim of the invention is the reduction of the specific material and energy consumption and the increase of the specific product formation rate while maintaining the micro-physical stability of the permentation process and the increase of the space-time yield by using high cell densities.

Essence of the invention

The invention is therefore based on the object to develop a method that it allows on the way to control the use of energy and carbon source by the microorganisms, the goal, reducing the specific material and energy consumption and increase the space-time Yields with high stability of the biological system and use of high cell densities. The object is achieved according to the invention by the synchronization of the microorganism population, wherein the synchronization of the microorganism population is achieved by exchanging half of the permentation medium for an equivalent amount of fresh nutrient solution, which enables a doubling of the cell count.

The solution according to the invention is that first the biomass growth under the conditions of the optimal growth process, with continuous supply of the carbon source, is led 'After reaching an optimal for the subsequent product formation process cell concentration, the' growth process on the nitrogen supply or other except carbon and Oxygen for growth essential nutrient limited * At the end of the growth phase, marked by the transition of the cells from the growth state to the single cell state, carbon and energy sources are continuously added according to the production rate to be achieved. When the production rate decreases or »when a certain desired product concentration in the medium is reached, the contents of the reactor are exchanged. In this case, preferably half of the contents of the reactor are exchanged for a curing medium which enables a doubling of the cell mass and cell number. The transition of cells from growth to single cell state can be determined by microscopic tracking of the growth process.

The method is also applicable when multiple carbon and energy sources are used for biological conversion corresponding to an optimum carbon energy ratio,

The invention is illustrated by the following examples:

example 1

In a laboratory fermenter of 12 1 gross volume 5 1 of a medium of the following composition are given (accounted for 20 g of organism growth)

6 g / l M ₄ Cl 1.4 g / l KH ₂ PO ₄

0.7 g / l MgSO ₄ . 7H ₂ O

0.09 g / l CuSO,. 5H ₂ O

0.042 g / l ZnCl ₂ ..

0.01 g / l CoSO ₄ . 7 H ₉ O 0.08 g / l MnS0 _A , 4 HpO

O, 11g / l H ₃ BO ₃ 0.09 g / l CaCl ₂ ♦ 6H ₂ O 0.007 g / l PeCl ₂ . 2.5 g / l CaCO ₃ 5 g / l yeast extract

10 g / l paraffin (range C ₁₀ to C ₂₀ )

It is sterilized in a customary manner for 30 minutes at 128 ° C. After cooling of the reactor system, it is inoculated with 200 ml of culture solution of Candida lipolytica EH 59 and the growth process is carried out under the following conditions:

pH 4.2 (control with 30% NaOH) Temperature 31 ° C Stirrer speed 2,000 rpm

Air flow rate 100 l / kg ·· h

The dosage of the paraffin is carried out according to the growth process, so that the residual concentration in the medium is> 1 g / l »

After a process time of 16 h, the growth process at 20 g Biotrockensubstanz / l, due to nitrogen limitation, completed and the product formation process with a productivity of 2.2 g acid / 1 »h begins * STach 48 hours of process time is reached when a product concentration of 105 g acid / 1 the .Produktakkumulationsprozeß interrupted by exchange of 50% of the perforation medium and initiated a new growth phase, which occurs after cell doubling nitrogen-limited again in the product formation phase.

Carbon and energy sources are continuously metered according to the product formation rate while maintaining a residual concentration during the product formation process

The specific yield coefficients amount

XZ. = 0.75 g Parex / g acid and P

The exchange process can be repeated *

J%

Example 2

Process conditions and reactor system as Example 1 "nutrient medium for 50 g organism gain. After inoculation with 500 ml of a 1.0% culture solution of Candida lipoytica EH 59, the growth phase begins over a period of 28 h. After reaching the cell concentration of 50 g / l, triggered by nitrogen imitation, the porogen formation process begins with a productivity of 3. 1 g acid / 1 h. After a production time of 35 hours, 108 g of acid / 1 are analogously to Example 1 of the 1 »exchange process *

Yield coefficients:

O ^ · ** = 0.81 g Parex / g acid P

r ⁰ P

-C = 3.2 g 0 ₂ / g acid

Example 3

Process conditions and reactor system analogously to Example 1, the nutrient medium Example 1, glucose is added in the proportion of 40 g / l and maintained the Paraffindosierung in the specified residual concentration limits. After inoculation of the medium analogously to Example 1, the growth process begins, which is completed after about 14 h at a concentration of 20 g of EIS / 1. The productivity of the subsequent product formation process is 2.9 g of acid / l, h. After 40 h of production, the exchange process begins at a product concentration of 116 g of acid / l *

Yield coefficients:

j ^ = 0.65 g substrate / g acid ρ

χ ° 2 = 2.90 g 0 ₂ / g acid

Claims (1)

Claim of invention 1. A method for semi-continuous product recovery, such as for the recovery of organic acids on all microbially usable substrates and substrate combinations, characterized in that the lährmedium is added at intervals equal to the duration of the growth phase and product formation phase * 2 «method according to point 1, characterized that the carbon and energy source is added sufficiently for the necessary biomass growth when replacing the fermentation medium and is metered continuously at the beginning of the product formation phase according to the product formation rate to be achieved until the product formation rate decreases " Method according to items 1 and 2, characterized in that the growth process is limited by the nitrogen source or another suitable nutrient and the carbon and energy source for biomass growth is balanced in a slight excess. 4 * Method according to items 1 to 3 hereby in that the nitrogen source added in the exchange of the fermentation medium is sufficient for one to three, preferably for a doubling of the number of cells, 5 "method according to item 1 to 4, characterized in that when replacing the Fermentationsmediuins half or more than half preferably half of the 9rrn: tion medium is drained and a entspДnde amount of nutrient medium, the necessary for growth! Annual substances contains, supplements v / ird, 6 «method according to item 1 to 5 characterized. that the amount of product remaining after replacement of the fermentation medium is removed by dialysis or precipitation when growth inhibition occurs due to high product concentration » 7 * Method according to item 1 to 5, characterized in that cell densities greater than or equal to 50 g / l are used »