PHA-producing microorganism in which glycerol kinase activity is enhanced, and PHA production method using same
Provided are a PHA-producing microorganism producing a higher molecular weight PHA and a PHA production method using the PHA-producing microorganism. A PHA-producing microorganism including a gene encoding a PHA synthase derived from genus Aeromonas , in which at least a portion of a PHA degrading enzyme gene is altered by substitution, deletion, insertion, and/or addition to reduce or eliminate activity of a PHA degrading enzyme encoded by the gene, and further a glycerol kinase activity is enhanced.
1. A microorganism capable of producing a polyhydroxyalkanoate (PHA), comprising a gene encoding a PHA synthase derived from Aeromonas caviae,
wherein at least a portion of a PHA degrading enzyme gene of the microorganism is altered by substitution, deletion, insertion, and/or addition of at least one nucleotide such that an activity of a PHA degrading enzyme encoded by the PHA degrading enzyme gene is eliminated or reduced as compared to an activity of the PHA degrading enzyme of a host of the microorganism, and
a glycerol kinase activity of the microorganism is enhanced by introducing a gene encoding exogenous glycerol kinase as compared to a glycerol kinase activity of a host of the microorganism, wherein the gene encoding exogenous glycerol kinase is derived from Escherichia coli.
2. The microorganism according to claim 1 , wherein the microorganism does not have an enhanced activity to uptake glycerol into cells as compared to a glycerol uptake activity of the host.
3. The microorganism according to claim 1 , wherein the microorganism is a transformant of a microorganism belonging to genus Cupriavidus.
4. The microorganism according to claim 3 , wherein the microorganism belonging to genus Cupriavidus is Cupriavidus necator.
5. A method for producing PHA, comprising culturing the microorganism according to claim 1 .
6. The method according to claim 5 , wherein in the culturing, the microorganism is cultured in the presence of a carbon source comprising glycerol and/or a compound having a glycerol skeleton.
7. The method according to claim 5 , wherein the PHA is a copolymerized PHA comprising a structural unit derived from 3-hydroxybutyric acid.
8. The method according to claim 7 , wherein the copolymerized PHA comprises a structural unit derived from 3-hydroxybutyric acid and 3-hydroxyhexanoic acid.
9. The microorganism according to claim 1 , wherein the activity of the PHA degrading enzyme of the microorganism is reduced to 20% or lower of an activity of the PHA degrading enzyme of the host which does not have the substitution, deletion, insertion, and/or addition.
10. The microorganism according to claim 1 , wherein the activity of the PHA degrading enzyme of the microorganism is eliminated by the substitution, deletion, insertion, and/or addition.
11. The microorganism according to claim 1 , which is capable of producing a copolymerized PHA comprising a structural unit derived from 3-hydroxybutyric acid.
12. The microorganism according to claim 1 , wherein the PHA produced by the microorganism has a weight average molecular weight of from 300,000 to 4,000,000.
13. The microorganism according to claim 1 , wherein the PHA produced by the microorganism has a weight average molecular weight of 160×10 4 or higher.
14. The microorganism according to claim 1 , wherein the PHA degrading enzyme gene is a phaZ gene.