Effect of acetate on molecular and physiological aspects of Clostridium beijerinckii NCIMB 8052 solvent production and strain degeneration

The addition of sodium acetate to chemically defined MP2 medium was found t o increase and stabilize solvent production and also increase glucose utili zation by Clostridium beijerinckii NCIMB 8052. RNA and enzyme analyses indi cated that coenzyme A (CoA) transferase was highly expressed and has higher activity in C. beijerinckii NCIMB 8052 grown in MP2 medium containing adde d sodium acetate than in the microorganism grown without sodium acetate. RN A analysis suggested the existence of a sol operon and confirmed the presen ce of a ptb-buk operon in C. beijerinckii NCIMB 8052. In addition to CoA tr ansferase. C. beijerinckii NCIMB 8052 grown in MP2 medium containing added acetate demonstrated higher acetate kinase- and butyrate kinase-specific ac tivity than whew the culture was grown in MP2 medium containing no added ac etate. Southern blot analysis with chromosomal DNA isolated from solventoge nic and degenerated C. beijerinckii NCIMB 8052 indicated that C. beijerinck ii NCIMB 8052 strain degeneration does not involve loss of the CoA transfer ase genes. The addition of acetate to MP2 medium may induce the expression of the sol operon, which ensures solvent production and prevents strain deg eneration in C beijerinckii NCIMB 8052.