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UV mutagenesis of Cupriavidus necator for extracellular production of ( R )‐3‐hydroxybutyric acid
Author(s) -
Ugwu C.U.,
Tokiwa Y.,
Aoyagi H.,
Uchiyama H.,
Tanaka H.
Publication year - 2008
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2008.03774.x
Subject(s) - cupriavidus necator , mutagenesis , extracellular , microbiology and biotechnology , chemistry , biochemistry , bacteria , polyhydroxyalkanoates , biology , mutant , genetics , gene
Aim: Ultraviolet (UV) mutagenesis was carried out to obtain mutant strains of Cupriavidus necator that could produce ( R )‐3‐hydroxybutyric acid [( R )‐3‐HB] in the culture supernatant. Methods and Results: C. necator (formerly known as Ralstonia eutropha ) was subjected to UV radiation to generate mutants that are capable of producing ( R )‐3‐HB in the culture supernatant. Results indicated that UV mutagen disrupted the phbB ( phbB knock‐out) and thus, promoted production of ( R )‐3‐HB in mutant strains. Inclusion of acetoacetate esters (carbonyl compounds) in the culture broth led to increased production of ( R )‐3‐HB. Thus, acetoacetyl‐CoA (an intermediate of the PHB synthetic pathway) might have been converted to acetoacetate, which in the presence of ( R )‐3‐HB dehydrogenase and NADPH/NADP + , resulted in extracellular production of ( R )‐3‐HB. Conclusions: UV mutagenesis proved to be a satisfactory method in generating interesting mutants for extracellular production of ( R )‐3‐HB. Extracellular production of ( R )‐3‐HB upon addition of acetoacetate esters would suggest a likely ( R )‐3‐HB biosynthetic pathway in C. necator . Significance and Impact of the Study: Mutants obtained in this study are very useful for production of ( R )‐3‐HB. For the first time, the production of ( R )‐3‐HB by C. necator via acetoacetate is reported.