Abstract: The disclosure relates to methods for the production of natural lactones by bacteria under physiological conditions. The methods employ ybgC proteins having lactonizing activity.

Abstract: The disclosure relates to the field of specialty chemicals and methods for their synthesis. In embodiments, the disclosure provides viable bacterial cells which comprise heterologous dual 3-hydroxy-acyl-ACP dehydratase/isomerases, etc. The disclosure further provides monounsaturated fatty acid derivative molecules produced by the viable bacterial cells which are non-native to the bacterial cells. The disclosure further provides methods for the preparation and production of non-native monounsaturated fatty acid derivative molecules such as e.g., an ?3-monounsaturated fatty acid derivative, an ?5-monounsaturated fatty acid derivative, an ?9-monounsaturated fatty acid derivative, an ?11-monounsaturated fatty acid fatty acid derivative, etc.