Enzymatic biosynthesis of lactones

A method for enzymatically producing a lactone under physiological conditions, the method comprising culturing a recombinant bacterium in the presence of a hydroxy acyl-CoA substrate, thereby producing said lactone, wherein said recombinant bacterium expresses a heterologous acyl-CoA thioesterase and a heterologous acyl-CoA synthetase protein, wherein:

• the acyl-CoA thioesterase comprises a YbgC protein, wherein the YbgC protein has at least 85% amino acid sequence identity to any one of the amino acid sequence of SEQ ID NOs:
• 1-6, and wherein the YbgC protein converts a hydroxy acyl-CoA substrate to a lactone;
• the hydroxy acyl-CoA substrate is a member selected from a 4-hydroxy acyl-CoA, a 5-hydroxy acyl-CoA, and a 6-hydroxy acyl-CoA;
• and
• the YbgC protein converts the 4-hydroxy acyl-CoA to a γ-lactone, the YbgC protein converts the 5-hydroxy acyl-CoA to a δ-lactone, and the YbgC protein converts the 6-hydroxy acyl-CoA to a ε-lactone.