Methods and systems for production of polyhydroxyalkanoate
Several embodiments of the invention relate generally to a system and methods for the treatment of gaseous emissions comprising methane and one or more non-methane compounds that can influence the metabolism of methane-oxidizing microorganisms. In several embodiments, there is provided a system and methods for the treatment of methane emissions through the use of methanotrophic microorganisms to generate functionally consistent and harvestable products. Certain embodiments of the invention are particularly advantageous because they reduce environmentally-destructive methane emissions and produce harvestable end-products.
1. A method for producing a polyhydroxyalkanoate (PHA) in a culture of methanotrophic microorganisms, the method comprising:
a) providing a gas comprising methane and one or more non-methane substances;
b) providing a culture of methanotrophic microorganisms;
c) providing a microorganism culture medium comprising at least a first essential nutrient and a second essential nutrient;
d) exposing said culture to said gas;
e) controlling the concentration of said first essential nutrient in said culture medium to a concentration sufficient to induce said methanotrophic microorganisms to produce particulate methane monooxygenase (pMMO) or soluble methane monooxygenase (sMMO); and
f) controlling the concentration of said second essential nutrient, wherein said control of said second essential nutrient causes said methanotrophic microorganisms to produce said PHA.
2. The method of claim 1 , wherein said PHA is selected from the group consisting of polyhydroxybutyrate, polyhydroxybutyrate-covalerate (PHBV), poly-4-hydroxybutyrate (P4HB), polyhydroxyhexanoate (PHHx), and polyhydroxyoctanoate (PHO).
3. The method of claim 1 , wherein said step e) is followed by said step f), and wherein step e) followed by step f) comprises a production cycle.
4. The method of claim 3 , further comprising repeating step e) followed by step f) one or more times, thereby resulting in at least a first production cycle and a second production cycle.
5. The method of claim 4 , wherein the molecular weight of said PHA produced in said first production cycle differs from the molecular weight of said PHA produced in said second production cycle by less than 50%.
6. The method of claim 5 , wherein said molecular weight ranges from about 100 to about 5,000,000 Daltons.
7. The method of claim 5 , wherein said molecular weight distribution ranges from about 100,000 to about 2,500,000 Daltons.
8. The method of claim 4 , wherein the polydispersity of said PHA produced in said first production cycle differs from the polydispersity of said PHA produced in said second production cycle by less than 75%.
9. The method of claim 4 , wherein the polydispersity of said PHA produced in said first production cycle differs from the polydispersity of said PHA produced in said second production cycle by less than 50%.
10. The method of claim 8 , wherein said polydispersity ranges from about 0.1 to about 5.0.
11. The method of claim 1 , wherein said one or more non-methane substances are selected from the group consisting of methanol, acetone, acetate, formate, formaldehyde, hydroxyalkanoates, hydroxybutyrate, octanoic acid, octanol, carbon dioxide, nitrogen, oxygen, di-oxygen, di-nitrogen, water, water vapor, argon, ethane, propane, butyrate, butyric acid, hexanoic acid, hexanol, heptanoic acid, heptanol, pentane, pentanoic acid, and volatile organic compounds.
12. The method of claim 1 , wherein said culture comprises two or more species of methanotrophic microorganisms.
13. The method of claim 1 , wherein said first and said second essential nutrients comprise one or more of carbon, hydrogen, nitrogen, oxygen, phosphorus, potassium, calcium, sodium, chlorine, methane, carbon dioxide, magnesium, iron, copper, sulfate, manganese, boron, zinc, aluminum, nickel, chromium, cobalt, or molybdenum.
14. The method of claim 4 , wherein the concentration of said pMMO and said sMMO produced in said microorganisms in said first production cycle differs by less than 75% from the total concentration of said pMMO and said sMMO produced in said microorganisms in said second production cycle.
15. The method of claim 1 , wherein said controlling of said first essential nutrient or of said second essential nutrient comprises increasing the concentration of first essential nutrient or of said second essential nutrient.
16. The method of claim 1 , wherein said controlling of said first essential nutrient or of said second essential nutrient comprises decreasing the concentration of first essential nutrient or of said second essential nutrient.
17. The method of claim 1 , wherein the gas comprising methane is produced from a landfill, wherein the polyhydroxyalkanoate produced is PHB, wherein the culture of microorganisms are exposed to said gas comprising methane in a bioreactor, and wherein the culture of methanotrophic microorganisms comprises a non-specified consortium of methanotrophic microorganisms.