Abstract

The biobased economy establishment will require material resources to the synthesis of different bioproducts. Biorefeneries are industrial complexes, with some similarities to petrochemical refineries, where carbon sources (biomass) are converted to biofuels, energy and chemicals. The sugarcane mills in Brazil represent biorefenery embryos currently producing sugar, ethanol and electricity, but offering the possibility to integrate the production of several other bioproducts. These could be produced from resources available in the sugarcane mill (sucrose, bagasse, etc) though other carbon sources could be integrated like glycerol (derived from biodiesel production process), plant oils and agricultural residues, like soybean or eucalyptus molasses. Soybean molasses is a by-product from soybean processing for the production of soybean protein. A proper destination for soybean molasses could alleviate disposal problems in industries processing soybean. Soybean molasses could be a good resource for polyhydroxyalkanoates (PHA) production however bacterial strains able to use sugars like raffinose and stachyose should be selected. In this work, the capability of PHA production from soybean molasses was evaluated in a collection of bacterial isolates. The soybean molasses was analyzed by HPLC and the sugars raffinose, sucrose, glucose and fructose were detected. After acid-hydrolysis, galactose was detecte and the amounts of glucose and fructose were increased probably derived from the hydrolys of raffinose and sucrose present in the soybean molasses. Nine bacterial isolates were cultured (30 oC, 150 rpm, 72 hours) in mineral salts medium containing soybean molasses (20 g/L) as the sole carbon source. The best performance was reached by the isolate DCL8 (3,4 g/L of cell dry weight containg 16% of poli-3-hydroxybutyrate).