Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
2003-02-26
2003-11-18
Acquah, Samuel A. (Department: 1711)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C528S361000, C528S364000, C528S293000, C524S765000, C435S136000, C435S142000, C435S146000, C435S874000
Reexamination Certificate
active
06649380
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for controlling the molecular weight of a polyhydroxyalkanoate (PHA), a kind of polyester. More specifically, the present invention relates to a method for controlling the molecular weight of the PHA employing a microorganism which is capable of producing and accumulating the PHA in the cell.
2. Related Background Art
Many microorganisms have been reported to produce and accumulate poly-3-hydroxybutyric acid (PHB) or other PHA in the cells (“Seibunkaisei Purasutikku Handobukku (Biodegradable Plastics Handbook)”, Biodegradable plastics Research Group, NTS K. K., pp.178-197 (1995)). These polymers are useful as various articles molded by melt processing or other processing similarly as conventional polymers. Moreover, these polymers, which are biodegradable, are completely degraded by a microorganism in the nature, not causing pollution in natural environment advantageously, differently from conventional synthetic high polymers. Furthermore, these diodegradable polymers are highly adaptable to a living body and are promising also for a medical soft material and other uses.
Such PHAs produced by a microorganism are known to have various compositions and structures depending on the kind of microorganism, culture medium composition, cultivation conditions, and other factors in the production. The control of the composition and structure of PHA has been studied for improvement of the physical properties of PHA.
The PHAs produced by microorganisms are roughly classified into two groups according to the biosynthesis mechanism. One group of PHAs are short-chain-length PHAs (hereinafter referred to as “scl-PHA(s)”) typified by polyhydroxybutyric acid (PHB), polyhydroxyvaleric acid (PHV), and copolymers thereof: the other group of PHAs are medium-chain-length PHAs (hereinafter referred to as “mcl-PHA(s)”) having medium-chain-length 3-hydroxyalkanoic acid of about 6-14 carbons as the units.
The former, scl-PHA, is formed from sugars such as glucose and gluconic acid, or acetyl-CoA which is an in-vivo metabolism product of organic acids such as lactic acid, pyruvic acid, and malic acid as the starting material by enzymatic dimerization and reduction into a polymer.
The latter, mcl-PHA, is formed enzymatically from an alkanoic acid as the starting material by CoA addition, dehydrogenation, and water addition through the &bgr;-oxidation pathway, a fatty acid degradation system, into a polymer.
As mentioned above, the respective groups of PHAs are synthesized through different biosynthesis pathways by action of different enzymes in vivo according to the results of detailed investigation.
Of the microorganisms producing the latter, mcl-PHAs, some microorganisms are known to produce PHAs having various functional groups and residues.
Among them, production of the PHAs having an aromatic ring in the unit is actively investigated in recent years.
Makromol.Chem., 191, 1957-1965 (1990) and Macromolecules, 24, 5256-5260 (1991) describe that
Pseudomonas oleovorans
produces a PHA containing 3-hydroxy-5-phenylvaleric acid as the unit from 5-phenylvaleric acid as the substrate.
Macromolecules, 29, 1762-1766 (1996) describes that
Pseudomonas oleovorans
produces a PHA containing 3-hydroxy-5-(4′-tolyl)valeric acid as the unit from 5-(4′-tolyl)valeric acid as the substrate.
Macromolecules, 32, 2889-2895 (1999) describes that
Pseudomonas oleovorans
produces a PHA containing 3-hydroxy-5-(2′,4′-dinitrophenyl)valeric acid and 3-hydroxy-5-(4′-nitrophenyl)valeric acid as the units from 5-(2′,4′-dinitrophenyl)valeric acid as the substrate.
Macromol.Chem.Phys., 195, 1665-1672 (1994) describes that
Pseudomonas oleovorans
produces a PHA copolymer of 3-hydroxy-5-phenoxyvaleric acid and 3-hydroxy-9-phenoxynonanoic acid from 11-phenoxyundecanoic acid as the substrate.
Japanese Patent Publication No. 2989175 discloses homopolymers having a 3-hydroxy-5-(monofluorophenoxy)pentanoate (3H
5
(MHP)P) unit or a 3-hydroxy-5-(difluorophenoxy)pentanoate (3H
5
(DHP)P) unit, and copolymers having at least the 3H
5
(MFP)P unit or 3H
5
(DFP)P unit synthesized by
Psudomonas putida
(Pseudomanas Genus); and a process for synthesis of the above polymers. Thereby, a polymer having a mono- or di-fluorine-substituted phenoxy group at side chain ends can be synthesized by assimilation of a substituted long-chain fatty acid, the polymer having stereoregularity and water repellency with retention of the high melting point and high processability.
Cyano- or nitro-substituted polymers are investigated besides the above fluorine-substituted polymers.
Can.J.Microbiol., 41, 32-43 (1995), and Polymer International, 39, 205-213 (1996) describe production of PHAs containing 3-hydroxy-p-cyanophenoxyhexanoic acid or 3-hydroxy-p-nitrophenoxyhexanoic acid as the monomer unit from octanoic acid and p-cyanophenoxyhexanoic acid or p-nitrophenoxyhexanoic acid as the substrate by employing
Pseudomonas oleovorans
ATCC29347 strain and
Pseudomonas putida
KT2442 strain.
Macromolecules, 32, 8315-8318 (1999) and Polymer Preprints, Japan, 49(5), 1034 (2000) describe capability of
Pseudomonas putida
27N01 strain to produce PHA copolymers containing 3-hydroxy-5-thiophenoxyvaleric acid and 3-hydroxy-7-thiophenoxyheptanoic acid from 11-thiophenoxyvaleric acid as the substrate.
For practical application of the PHAs, control of the molecular weight is attempted to broaden the application field thereof.
U.S. Pat. No. 6,156,852 discloses the decrease of the number-average molecular weight in biosynthesis of PHB by employing
Ralstonia eutropha, Ralstonia latus
, and
Comamonas testosteroni
as the producing microorganism strain by addition of a diol such as ethylene glycol, neopentyl glycol, propylene glycol, butanediol, hexanediol, and octanediol; butanetriol, polypropylene glycol, glycerol, hydroquinone, benzene-dimethanol, pentaerithritol, and derivatives thereof; or a sugar alcohol such as sorbitol and mannitol to the culture medium. These items are described in detail as chemical reports in Biotechnology and Bioengineering, 62, 106-113 (1999), and International Journal of Biological Macromolecules, 25, 43-53 (1999).
These techniques have merits of controlling the molecular weight in the PHA biosynthesis process without using a chemical substance such as an acid or a base. The PHAs having a functional group such as the phenyl group described above are also required to be controlled in the molecular weight for broadening the practical application field. However, no technique therefore has been developed yet.
SUMMARY OF THE INVENTION
The present invention provide a method for controlling the molecular weight of a polyhydroxyalkanoate having units of a residue containing a phenyl-, thienyl-, or cyclohexyl-structure in the side chain of the molecule.
After comprehensive study to solve the above problems, the inventors of the present invention achieved the invention described below.
The present invention provides a method for controlling the molecular weight of a polyhydroxyalkanoate containing at least one of 3-hydroxy-&ohgr;-substituted alkanoic acid units represented by Chemical Formula (1):
(in the above formula, m is an integer selected from the numerical range shown with the Chemical Formula;
R
1
is a residue having a ring structure of any one selected from the group consisting of a phenyl structure and a thienyl structure; and in the presence of plural units, m and R
1
are selected independently for the respective units), and 3-hydroxy-&ohgr;-cyclohexylalkanoic acid units represented by Chemical Formula (2):
(in the above formula, R
2
denotes a substituent on the cyclohexyl group selected from the group consisting of H atom, CN, NO
2
, halogen atom, CH
3
, C
2
H
5
, C
3
H
7
, CF
3
, C
2
F
5
and C
3
F
7
; k is an integer selected from the numerical range shown with the Chemical Formula;
and in the presence of plural units, k and R
2
are selected independently for the respective units), wherein a microorganism is
Fukui Tatsuki
Honma Tsutomu
Imamura Takeshi
Kenmoku Takashi
Sugawa Etsuko
Acquah Samuel A.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
LandOfFree
Method for controlling molecular weight of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling molecular weight of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling molecular weight of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3152718