Microfiltration using activated carbon

Details Microfiltration using activated carbon Microfiltration using activated carbon

2001-05-18

2003-06-24

Drodge, Joseph (Department: 1723)

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

C210S651000, C210S652000, C210S774000, C435S183000, C530S412000

Reexamination Certificate

active

06582606

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a method of increasing process capacity when microfiltrating a fermentation-derived product.
BACKGROUND ART
Microfiltration has been the target for much research and development over the last years. Especially developments in hardware and membranes have been at focus. However two issues still limit the use of microfiltration within recovery of fermented biomolecules. Low fluxes and often also low transmission are the limiting factors for success. Often a process can be developed based on microfiltration for harvest of such products, however in many cases the process will not be able to compete with the more traditional solid liquid separation techniques like centrifugations and drum-filtrations. This is especially the case in continuous large scale processes where fouling necessitates frequent CIP (cleaning-in-place) for maintaining high transmission and flux.
Especially within the biotechnology industry fouling has been an almost unsolvable problem regarding microfiltration of fermentation broths. This is due to the fact that fermentation broths contain besides the product of interest numerous impurities like other intracellular and extracellular metabolites, lysed cells, substrate components, nucleic acids, defoaming agents etc.
Much focus has therefore been allocated to development of hydrophilic membranes and of improved microfiltration hardware with technologies such as back wash/back shock and mechanical induced shear as the more successful developments.
On the operational side focus has been on precise control of trans-membrane pressure and of control of maximum permeate flow rate, as these parameters also are important for limiting membrane fouling. Furthermore, optimisation of process temperature and of pH has also been identified as important parameters for improving the microfiltration performance.
However, even though much development has been going on over the years regarding membranes, hardware and operational parameters, fouling is still today considered the one largest culprit to overcome for developing a successful microfiltration. This is in particular the case for microfiltration of products originating from fermentation broths.
The purpose of this invention is therefore to minimize fouling within microfiltration of fermented products.
SUMMARY OF THE INVENTION
It has surprisingly been found that activated carbon and elevated temperature may increase process capacity when microfiltrating a fermentation-derived product.
Therefore, the present invention provides:
A microfiltration process of a fermentation-derived product comprising adding activated carbon to a solution of the fermentation-derived product prior to or during the microfiltration process at a microfiltration process temperature of from 25° C. to 65° C.
DETAILED DISCLOSURE OF THE INVENTION
The present invention deals with a new and surprisingly effective way of reducing fouling in microfiltration processes of fermentation-derived products.
It has surprisingly been found that fouling can be efficiently minimized in microfiltration processes when activated carbon is added prior to or during the microfiltration step.
It has also been found that a synergy exists between addition of activated carbon and the use of high temperature processing. The performance enhancement by carbon is found to be well suited for the modern microfiltration systems with back wash/back shock and systems with mechanical induced shear.
The use of activated carbon in relation to microfiltration is known from wastewater treatment and also from production of casein hydrolyzate where activated carbon in both cases is used for removing soluble impurities with the aim of improving product quality (WO 93/08702).
However, use of activated carbon with the purpose of minimizing fouling in microfiltration processes has not previously been applied within the biotechnology field.
An added advantage of introducing activated carbon for enhancement of microfiltration performance is that the added carbon in many cases bind unwanted impurities influencing the subsequent concentration or that otherwise needs to be removed by an added purification step for achieving acceptable product quality.
According to the present invention any fermentation-derived product of interest may be microfiltrated as described herein. Especially the method of the invention can be applied to purification of a protein.
In a preferred embodiment, the method is applied to enzymes, in particular to hydrolases (class EC 3 according to Enzyme Nomenclature; Recommendations of the Nomenclature Committee of the International Union of Biochemistry).
In a particular preferred embodiment the following hydrolases are preferred: Proteases: Suitable proteases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. The protease may be a serine protease or a metallo protease, preferably an alkaline microbial protease or a trypsin-like protease. Examples of alkaline proteases are subtilisins, especially those derived from Bacillus, e.g., subtilisin Novo, subtilisin Carlsberg, subtilisin 309, subtilisin 147 and subtilisin 168 (described in WO 89/06279). Examples of trypsin-like proteases are trypsin (e.g. of porcine or bovine origin) and the Fusarium protease described in WO 89/06270 and WO 94/25583.
Examples of useful proteases are the variants described in WO 92/19729, WO 98/20115, WO 98/20116, and WO 98/34946, especially the variants with substitutions in one or more of the following positions: 27, 36, 57, 76, 87, 97, 101, 104, 120, 123, 167, 170, 194, 206, 218, 222, 224, 235 and 274.
Preferred commercially available protease enzymes include Alcalase™, Savinase™, Primase™, Duralase™, Esperase™, and Kannase™ (Novozymes A/S), Maxatase™, Maxacal™, Maxapem™, Properase™, Purafect™, Purafect OxP™, FN2™, and FN3™ (Genencor International Inc.).
Lipases: Suitable lipases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Examples of useful lipases include lipases from Humicola (synonym Thermomyces), e.g. from
H. lanuginosa
(
T. lanuginosus
) as described in EP 258 068 and EP 305 216 or from
H. insolens
as described in WO 96/13580, a Pseudomonas lipase, e.g. from
P. alcaligenes
or
P. pseudoalcaligenes
(EP 218 272),
P. cepacia
(EP 331 376),
P. stutzeri
(GB 1,372,034),
P. fluorescens
, Pseudomonas sp. strain SD 705 (WO 95/06720 and WO 96/27002), P. wisconsinensis (WO 96/12012), a Bacillus lipase, e.g. from
B. subtilis
(Dartois et al. (1993), Biochemica et Biophysica Acta, 1131, 253-360), B. stearothermophilus (JP 64/744992) or
B. pumilus
(WO 91/16422).
Other examples are lipase variants such as those described in WO 92/05249, WO 94/01541, EP 407 225, EP 260 105, WO 95/35381, WO 96/00292, WO 95/30744, WO 94/25578, WO 95/14783, WO 95/22615, WO 97/04079 and WO 97/07202.
Preferred commercially available lipase enzymes include Lipolase™ and Lipolase Ultra™ (Novozymes A/S). Amylases: Suitable amylases (&agr; and/or &bgr;) include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Amylases include, for example, &agr;-amylases obtained from Bacillus, e.g. a special strain of
B. licheniformis
, described in more detail in GB 1,296,839.
Examples of useful amylases are the variants described in WO 94/02597, WO 94/18314, WO 96/23873, and WO 97/43424, especially the variants with substitutions in one or more of the following positions: 15, 23, 105, 106, 124, 128, 133, 154, 156, 181, 188, 190, 197, 202, 208, 209, 243, 264, 304, 305, 391, 408, and 444.
Commercially available amylases are Duramyl™, Termamyl™, Fungamyl™ and BANT™ (Novozymes A/S), Rapidase™ and Purastar™ (from Genencor International Inc.).
Cellulases: Suitable cellulases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Suitable cellulases include cellulases from the genera Bacillus, Pseudomonas, Humicola, Fusarium, Thielavia, Acremonium, e.g. the fungal cellulase

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