| Congresso Brasileiro de Microbiologia 2023 | Resumo: 283-1 | ||||
Resumo:Biotechnological processes carried out at biorefineries are considered as one of the most attractive alternatives for valorization of biomasses, by converting them into bioproducts, biofuels, and bioenergy. Biodiesel is obtained from alcohols and fatty acids, both renewable, but its manufacture generates glycerol as byproduct. Glycerol can be reused as carbon source by several Clostridium species as carbon source for its conversion to 1,3-propanediol (1,3-PDO), a high added value product. The clostridial metabolism of glycerol occurs via two routes: the oxidative one, by glycerol dehydrogenase and dihydroxyacetone kinase; and the reductive one, by glycerol dehydratase (GDHt) and 1,3-propanediol dehydrogenase (PDODH). In this work, the isolate Clostridium beijerinckii Br21 was transformed by increasing gene expression of glycerol reduction pathway, to improve 1,3-PDO biosynthesis. C. beijerinckii Br21 transformation was performed using pMTL83251, containing the genes coding for GDHt, cobalamin adenosyltransferase, and PDODH, under control of the promoter phosphotransacetylase/acetate kinase (pta-ack). We have modified an electroporation transformation protocol, to promote overexpression of GDHt, cobalamin adenosyltransferase and PDODH (1,3-PDO cluster). The main changes of the transformation protocol were at the cell regeneration time after transformation; and the number of cells in the electrocompetent cells aliquots. Overall, the overexpression of 1,3-PDO cluster enhanced the specific growth rate for the transformed strain, compared to the wild strain: 0.022 and 0.015 h-1, respectively. Although the final concentration of 1,3-PDO was similar in C. beijerinckii Br21 [pMTL83251_Ppta-ack_1,3-PDO_cluster] and wild strain, the 1,3-PDO productivity was increased in the transformed one. Both, wild and transformed strains generated ca. 35 mmol L-1 1,3-PDO, at 167 and 119 h, respectively, i.e., the 1,3-PDO production rate was improved by 1.4 times. This work contributed to improve a transformation protocol for the isolated strain as well as to better understanding of the metabolic pathways of glycerol conversion to 1,3-PDO by a C. beijerinckii isolate. Palavras-chave: Glycerol dehydratase, 1,3-propanediol dehydrogenase, Electroporation, Overexpression, pMTL83251 Agência de fomento:FAPESP (Research Grant 2020/03168-3 and 2021/06757-2) | |||||