Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
2000-12-26
2003-02-18
Weber, Jon P. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C428S361000
Reexamination Certificate
active
06521429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel polyhydroxyalkanoate (PHA), as well as a method of producing such a novel PHA by utilizing microorganisms.
2. Related Background Art
Synthetic polymers derived from petroleum have been used as plastics etc. for a long time. Recently, the treatment of the used plastics has become one of serious social problems. These synthetic polymers have advantages of hard-to-decompose have been used in the place of metal or glass materials. On mass consumption and mass disposal, however, this feature of hard-to-decompose makes them accumulated in waste-disposal facilities, or when they are burned, it causes increased carbon dioxide exhaust, and harmful substances such as dioxin and endocrine-disruptors may be generated to cause environmental pollution.
On the other hand, polyesters produced by microorganisms (hereinafter referred to as “microbial polyesters”) can be biologically degraded to be incorporated in a natural recycling system. Thus they would not remain in natural environment without causing pollution, in contrast to the numerous usual synthetic polymer compounds. Furthermore, since the biodegradability dispenses with incinerating treatment, microbial polyesters are effective from the standpoint of the prevention of air pollution and global warming, and usable as plastics to maintain the environment. In addition, their potential as soft materials for medical use has been investigated (Japanese Patent Application Laid-Open No. 5-159, Nos. 6-169980, 6-169988, 6-225921, etc.).
Heretofore, various bacteria have been reported to produce and accumulate PHB or copolymers of other hydroxyalkanoic acids in the cells (Handbook of Biodegradable Plastics, ed. by Biodegradable Plastics Society, published by N.T.S., p. 178-197 (1995)). Microbial PHA thus obtained is known to have various compositions and structures depending on the class of microorganisms used, medium composition, culture conditions, etc. during production, and many studies related to the control of composition and structure of PHA products have been conducted to improve PHA properties.
For example,
Alcaligenes eutropus
H16 ATCC No. 17699 and its mutants can produce copolymers of 3-hydroxybutyric acid (3HB) and 3-hydroxyvaleric acid (3HV) at a various composition ratio by varying carbon sources during culture (Published Japanese Translation of PCT International Publication Nos. 6-15604, 7-14352, 8-19227, etc.).
Japanese Patent No. 2642937 discloses that
Pseudomonas oleovorans
ATCC29347, when given acyclic aliphatic hydrocarbons as a carbon source, produces PHA having a monomer unit of 3-hydroxyalkanoate of 6 to 12 carbon atoms.
Japanese Patent Application Laid-Open No. 5-74492 discloses the method comprising contacting a microorganism of Methylobacterium sp., Paracoccus sp., Alcaligenes sp., or Pseudomonas sp. with a primary alcohol of 3 to 7 carbon atoms, thereby allowing to produce a copolymer of 3HB and 3HV.
Japanese Patent Application Laid-Open Nos. 5-93049 and 7-265065 disclose that
Aeromonas caviae
can produce, by using oleic acid and olive oil as carbon sources, a binary copolymer of 3HB and 3-hydroxyhexanoic acid (3HHx).
Japanese Patent Application Laid-Open No. 9-191893 discloses that
Comamonas acidovorans
IFO13852 can produce, by using gluconic acid and 1,4-butanediol as a carbon source, a polyester having monomer units of 3HB and 4-hydroxybutyric acid.
Furthermore, certain microorganisms has been reported to produce PHA having various substituents such as groups derived from unsaturated hydrocarbons, ester group, allyl group, cyano group, nitro group, groups derived from halogenated hydrocarbon, and epoxide. Thus, there have been started several attempts to improve the properties of microbial PHA by using such a technique. Examples of microbial polyester having such substituents are described in FEMS Microbiology Letters, 128 (1995) p.219-228, in detail. Makromol. Chem., 191, 1957-1965, 1990, Macromolecules, 24, 5256-5260, 1991, and Chirality, 3, 492-494, 1991 report that
Pseudomonas oleovorans
produces PHA comprising a monomer unit of 3-hydroxy-5-phenylvaleric acid (3HPV), and changes in polymer properties probably due to the presence of the monomer unit of 3HPV.
As stated above, microbial PHA of various compositions/structures can be obtained by varying the microorganism, medium composition, culture conditions, etc. for polymer production. Their physical properties, however, are still insufficient for plastics. In order to further extend the application field, it is important to investigate more extensively the improvement of properties, and it is, therefore, essential to develop and search PHA made of structurally various monomer units, methods of producing them, as well as microorganisms capable of efficiently producing the desired PHA.
On the other hand, those PHA having introduced substituents in the side chains as described above, can be expected to be developed as “functional polymer” having useful functions and properties by selecting the substituent to be introduced according to the desired properties, etc. It is also important to develop and search PHA satisfying both functionality and biodegradability, methods of producing them, as well as microorganisms capable of efficiently producing desired PHA.
One example of such PHA having a substituent introduced in side chains is PHA having phenoxy in side chains.
For example, Macromol. Chem. Phys., 195, 1655-1672 (1994) reports that
Pseudomonas oleovorans
produces PHA containing units of 3-hydroxy-5-phenoxyvaleric acid and 3-hydroxy-9-phenoxynonanoic acid, from 11-phenoxyundecanoic acid.
Macromolecules, 29, 3432-3435 (1996) also reports that
Pseudomonas oleovorans
can be used to produce PHA containing 3-hydroxy-4-phenoxyburyric acid and
3‘-hydroxy-
6-phenoxyhexanoic acid units from 6-phenoxyhexanoic acid, PHA containing 3-hydroxy-6-phenoxyhexanoic acid and 3-hydroxy-8-phenoxyoctanoic acid units from 8-phenoxyoctanoic acid, and PHA containing 3-hydroxy-5-phenoxyvaleric acid and 3-hydroxy-7-phenoxyheptanoic acid units from 11-phenoxyunndecanoic acid. The polymer yield is as follows.
Furthermore, Can. J. Microbiol., 41, 32-43 (1995) reports that when given octanoic acid and p-cyanophenoxyhexanoic acid or p-nitrophenoxyhexanoic acid as substrates,
Pseudomonas oleovorans
ATCC29347 or
Pseudomonas putida
KT2442 can produce PHA containing a monomer unit of 3-hydroxy-p-cyanophenoxyhexanoic acid or 3-hydroxy-p-nitrophenoxyhexanoic acid.
Japanese Patent No. 2989175 describes a homopolymer consisting of 3-hydroxy-5-(monofluorophenoxy)pentanoate (3H5(MFP)P) unit or 3-hydroxy-5-(difluorophenoxy)pentanoate (3H5(DFP)P) unit, a copolymer containing at least one of 3H5(MFP)P unit and 3H5(DFP)P unit,
Pseudomonas putida
which can produce such polymers; and a method of producing the above polymers by using a Pseudomonas sp.
Such productions are conducted by “2-step culture” described below. Culture period: step 1 - 24 hours; step 2 - 96 hours.
Substrates in each step and polymers obtained are as follows.
(1) Polymer obtained: 3H5(MFP)P homopolymer
Substrates in step 1: citric acid, yeast extract
Substrates in step 2: monofluorophenoxyundecanoic acid
(2) Polymer obtained: 3H5(DFP)P homopolymer
Substrates in step 1: citric acid, yeast extract
Substrates in step 2: difluorophenoxyundecanoic acid
(3) Polymer obtained: 3H5(MFP)P copolymer
Substrates in step 1: octanoic or nonanoic acid, yeast extract
Substrates in step 2: monofluorophenoxyundecanoic acid
(4) Polymer obtained: 3H5(MFP)P homopolymer
Substrates in step 1: octanoic or nonanoic acid, yeast extract
Substrates in step 2: difluorophenoxyundecanoic acid
It describes that the microorganism can assimilate substituted aliphatic acids of a medium chain length to produce a polymer having phenoxy group substituted with 1 to 2 fluorine atoms at the end of a side chain, and such a polymer has stereoregularity and water repellency while keeping a high melting point and a good processibility.
It has been reported a PHA contain
Honma Tsutomu
Imamura Takeshi
Kenmoku Takashi
Kobayashi Shin
Kobayashi Toyoko
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