Microbial strains and methods of making and using
Microbial strains are provided, as are methods of making and using such microbial strains.
1. A mutant heterodisulfide reductase-like protein subunit B (HdrB) polypeptide, wherein the mutant HdrB polypeptide comprises an amino acid sequence with at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 3, wherein methionine at the amino acid corresponding to position 249 of SEQ ID NO: 3 is substituted with valine in the mutant HdrB polypeptide, and wherein when the mutant HdrB polypeptide is combined with a heterodisulfide reductase-like protein subunit A (HdrA) polypeptide and a heterodisulfide reductase-like protein subunit C (HdrC) polypeptide forms an HdrABC enzyme that has heterodisulfide reductase activity.
2. The mutant HdrB polypeptide of claim 1 , wherein the mutant HdrB polypeptide comprises the amino acid sequence of SEQ ID NO:6.
3. A nucleic acid molecule comprising a polynucleotide encoding the mutant HdrB polypeptide of claim 1 .
4. The nucleic acid molecule of claim 3 , wherein the polynucleotide comprises the nucleotide sequence of SEQ ID NO: 5.
5. The nucleic acid molecule of claim 3 , wherein the mutant HdrB polypeptide comprises the amino acid sequence of SEQ ID NO: 6.
6. The nucleic acid molecule of claim 1 , further comprising a polynucleotide encoding a heterodisulfide reductase-like protein subunit A (HdrA) polypeptide and a polynucleotide encoding a heterodisulfide reductase-like protein subunit C (HdrC) polypeptide.
7. A microorganism comprising the nucleic acid molecule of claim 3 .
8. The microorganism of claim 7 , wherein the microorganism is a methanogen.
9. The microorganism of claim 8 , wherein the microorganism is Methanosarcina acetivorans.
10. The microorganism of claim 7 , wherein the nucleic acid molecule is expressed in the microorganism via an expression vector.
11. A microorganism comprising the nucleic acid molecule of claim 6 .
12. The microorganism of claim 11 , wherein the microorganism is a methanogen.
13. The microorganism of claim 12 , wherein the microorganism is Methanosarcina acetivorans.
14. The microorganism of claim 11 , wherein the nucleic acid molecule is expressed in the microorganism via an expression vector.
15. A method of producing methane, comprising culturing the microorganism of claim 11 under appropriate conditions to express the HdrA polypeptide, the mutant HdrB polypeptide, and the HdrC polypeptide and produce methane.