This disclosure provides a new conceptual framework in which orthogonal, new-to-nature carbon and energy conversion pathways facilitate the synthesis of fuels and chemicals from carboxylic acid intermediates (CAis) driven by genetically altered microorganisms. This allows the CAi platform to generate diverse products at ?100% carbon yield while retaining the established high product and energy efficiencies of fermentative metabolism. In another embodiment, a carboxylic acid platform for fuel and chemical production at high carbon and energy efficiency is also provided.

Described are methods for the production of isobutene comprising the enzymatic conversion of 3-methylcrotonic acid into isobutene wherein said 3-methylcrotonic acid is obtained by the enzymatic conversion of 3-methylcrotonyl-CoA into 3-methylcrotonic acid or wherein said 3-methylcrotonic acid is obtained by the enzymatic conversion of 3-hydroxyisovalerate (HIV) into 3-methylcrotonic acid. It is described that the enzymatic conversion of 3-methylcrotonic acid into isobutene can, e.g., be achieved by making use of a 3-methylcrotonic acid decarboxylase, preferably an FMN-dependent decarboxylase associated with an FMN prenyl transferase, an aconitate decarboxylase (EC 4.1.1.6), a methylcrotonyl-CoA carboxylase (EC 6.4.1.4), or a geranoyl-CoA carboxylase (EC 6.4.1.5).

Construction and expression of synthetic pathways to produce (S) or (R)-3-hydroxybutyrate (3HB) as enantiomerically-pure products by genetically engineering cyanobacterium Synechocystis sp. PCC 6803. Under optimized growth conditions, the pathway employing phaA and phaB from R. eutropha was the most effective, producing up to 533.45.5 mg/l (R)-3HB after 21 days photosynthetic cultivation. For the first time, the feasibility and high efficiency of producing 3HB using solar energy and CO.sub.2 as sole energy and carbon sources by engineered cyanobacteria is demonstrated.

The invention relates to a genetically engineered bacterium having an enzyme that converts 3-hydroxyisovaleryl-CoA to 3-hydroxyisovalerate and an enzyme that converts 3-hydroxyisovalerate to isobutylene. Typically, the bacterium is capable of producing isobutylene from a gaseous substrate containing CO, CO.sub.2, and/or H.sub.2, such as syngas or an industrial waste gas.

The invention relates to a genetically engineered bacterium having an enzyme that converts acetyl-CoA to acetoacetyl-CoA, an enzyme that converts acetoacetyl-CoA to 3-hydroxybutyryl-CoA, and an enzyme that converts 3-hydroxybutyryl-CoA to 3-hydroxybutyrate. The bacterium may also have enzymes to produce other downstream products, such as 3-hydroxybutyryaldehyde, and 1,3-butanediol. Typically, the bacterium is capable of producing these products from a gaseous substrate, such as syngas or an industrial waste gas.

The invention relates to a genetically engineered bacterium having an enzyme that converts acetyl-CoA to acetoacetyl-CoA, an enzyme that converts acetoacetyl-CoA to 3-hydroxybutyryl-CoA, and an enzyme that converts 3-hydroxybutyryl-CoA to 3-hydroxybutyrate. The bacterium may also have enzymes to produce other downstream products, such as 3-hydroxybutyryaldehyde, and 1,3-butanediol. Typically, the bacterium is capable of producing these products from a gaseous substrate, such as syngas or an industrial waste gas.

Construction and expression of synthetic pathways to produce (5) or (R)-3-hydroxybutyrate (3HB) as enantiomerically-pure products by genetically engineering cyanobacterium Synechocystis sp. PCC 6803. Under optimized growth conditions, the pathway employing phaA and phaB from R. eutropha was the most effective, producing up to 533.45.5 mg/l (R)-3HB after 21 days photosynthetic cultivation. For the first time, the feasibility and high efficiency of producing 3HB using solar energy and CO.sub.2 as sole energy and carbon sources by engineered cyanobacteria is demonstrated.

Provided herein are microorganisms and methods for fermentative production of -ketoadipate from gaseous substrates such as carbon dioxide (CO.sub.2), carbon monoxide (CO), and/or hydrogen (H.sub.2). Additionally, the processes provided herein are methods for producing polymers containing -ketoadipate, that can potentially enable a circular economy by diverting waste, e.g., plastic waste.

Embodiments of the present invention relate to methods for the biosynthesis of di- or trifunctional C7 alkanes in the presence of isolated enzymes or in the presence of a recombinant host cell expressing those enzymes. The di- or trifunctional C7 alkanes are useful as intermediates in the production of nylon-7, nylon-7,x, nylon-x,7, and polyesters.

The invention relates to a genetically engineered bacterium comprising an energy-generating fermentation pathway and methods related thereto. In particular, the invention provides a bacterium comprising a phosphate butyryltransferase (Ptb) and a butyrate kinase (Buk) (Ptb-Buk) that act on non-native substrates to produce a wide variety of products and intermediates. In certain embodiments, the invention relates to the introduction of Ptb-Buk into a C1-fixing microoorgansim capable of producing products from a gaseous substrate.