title: Metabolic engineering of Clostridium acetobutylicum for the industrial production of 1,3-propanediol from glycerol.
abstract: Clostridium butyricum is to our knowledge the best natural 1,3-propanediol producer from glycerol and the only microorganism identified so far to use a coenzyme B12-independent glycerol dehydratase. However, to develop an economical process of 1,3-propanediol production, it would be necessary to improve the strain by a metabolic engineering approach. Unfortunately, no genetic tools are currently available for C. butyricum and all our efforts to develop them have been so far unsuccessful. To obtain a better "vitamin B12-free" biological process, we developed a metabolic engineering strategy with Clostridium acetobutylicum. The 1,3-propanediol pathway from C. butyricum was introduced on a plasmid in several mutants of C. acetobutylicum altered in product formation. The DG1(pSPD5) recombinant strain was the most efficient strain and was further characterized from a physiological and biotechnological point of view. Chemostat cultures of this strain grown on glucose alone produced only acids (acetate, butyrate and lactate) and a high level of hydrogen. In contrast, when glycerol was metabolized in chemostat culture, 1,3-propanediol became the major product, the specific rate of acid formation decreased and a very low level of hydrogen was observed. In a fed-batch culture, the DG1(pSPD5) strain was able to produce 1,3-propanediol at a higher concentration (1104 mM) and productivity than the natural producer C. butyricum VPI 3266. Furthermore, this strain was also successfully used for very long term continuous production of 1,3-propanediol at high volumetric productivity (3 g L-1 h-1) and titer (788 mM).
authors.affiliation: Escola Superior Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
authors.forename: María
authors.initials: M
authors.lastname: González-Pajuelo
authors.forename: Isabelle
authors.initials: I
authors.lastname: Meynial-Salles
authors.forename: Filipa
authors.initials: F
authors.lastname: Mendes
authors.forename: Jose Carlos
authors.initials: JC
authors.lastname: Andrade
authors.forename: Isabel
authors.initials: I
authors.lastname: Vasconcelos
authors.forename: Philippe
authors.initials: P
authors.lastname: Soucaille
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods; D046969:Clostridium acetobutylicum / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D024861:Genetic Enhancement / Q000379:methods*; D005990:Glycerol / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D011409:Propylene Glycols / Q000378:metabolism*
chemical_list: D011409:Propylene Glycols; C041787:1,3-propanediol; D005990:Glycerol