Abstract: In one aspect, the invention relates to a peptide that forms a calcium-dependent hydrogel using a rationally engineered beta roll peptide. In the absence of calcium, the peptide is intrinsically disordered. Upon addition of calcium, the peptide forms a corkscrew-like structure. In one embodiment, one face of the beta roll is mutated to comprise leucine residues. In some embodiments, a leucine zipper forming helical domain to the engineered beta roll forms hydrogels by physical cross-linking in calcium rich environments.

Abstract: Protein hydrogel monomers incorporating bio-active proteins and methods for producing the same are provided. In some embodiments, the disclosed subject matter includes a protein hydrogel monomer including a bio-active protein and two alpha helices that are adapted to interact with alpha helices on other monomers to form coiled-coil junctions.

Abstract: Methods and systems for producing a biofuel using genetically modified ammonia-oxidizing bacteria (AOB) are disclosed. In some embodiments, the methods include the following: providing an AOB that have been genetically modified to include a particular metabolic pathway to enable them to generate a particular biofuel or chemical; feeding a first source of ammonia to the AOB; feeding carbon dioxide to the AOB; and producing at least the biofuel or chemical, nitrite, and an AOB biomass. In some embodiments, the methods and systems include the following: a bioreactor including AOB that have been genetically modified to include a particular metabolic pathway to enable them to generate a particular biofuel; a first source of ammonia; a source of carbon dioxide; and a electrochemical reactor that is configured to electrochemically reduce nitrite produced in the bioreactor to a second source of ammonia.

Abstract: Protein hydrogel monomers incorporating bio-active proteins and methods for producing the same are provided. In some embodiments, the disclosed subject matter includes a protein hydrogel monomer including a bio-active protein and two alpha helices that are adapted to interact with alpha helices on other monomers to form coiled-coil junctions.

Abstract: Methods for producing mutant 2,5-diketo-D-gluconic acid reductase enzymes with altered cofactor dependency are provided. Also provided are mutant 2,5-diketo-D-gluconic acid reductase enzymes with altered cofactor dependency, DNA encoding these mutant enzymes, and vectors and host cells expressing these mutant enzymes.