This article aims to question the reducing of the process of molecularization of life to its informational dimension from the 1970s and 1980s through reintegration of a chemical ontology of life. The characteristic feature of this chemical ontology is the centrality of production issues and a high proximity with industry. Our paper investigates the visibility and characterization of chemical molecularization of life from the birth and stabilization of a little-known scientific field, namely metabolic engineering. To this end our work combined a scientometric analysis of a corpus of 6,288 scientific papers, archives from a research center and a series of semi-structured interviews with several key figures in metabolic engineering. Through the study of this scientific field, we describe a chemical molecularization of life process, a) based on classical entities in biochemistry (enzymes, metabolic pathways), b) supported by innovation policies inspired from chemical engineering and c) involving scientists highly committed with industry, as in chemical engineering. Chemical molecularization has expanded in the shadow of informational molecularization, which is not ignored, but ‘integrated’ as resources for maintaining the competitiveness of existing industries, innovation policies and scientific practices.