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KMID : 0545120030130010090
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Journal of Microbiology and Biotechnology
2003 Volume.13 No. 1 p.90 ~ p.98
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^31P Nuclear Magnetic Resonance Studies of Acetic Acid Inhibition of Ethanol Production by Strains of Zymomonas mobilis
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KIM, IN SEOP
BARROW, KEVIN D/ROGERS, PETER L.
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Abstract
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In vivo^31P Nuclear Magnetic Resonance(^32P NMR) and metabolic studies were carried out in an acetic acid tolerant mutant, Zymomonas mobilis ZM4/Ac^R, and compared to those of the parent strain, Z. mobilis ZM4, to evaluate possible mechanism of acetic acid resistance. This investigation was initiated to determine whether or not the mutant strain might be used as a suitable recombinant host for ethanol production from lignocellulose hydrolysates containing various inhibitory compounds. ZM4/Ac^R showed multiple resistance to other lignocellulose toxic compounds such as syringaldehyde, furfural, hydroxymethyl furfural, vanillin, and vanillic acid. The mutant strain was resistance to higher concentrations of ethanol or lower pH in the presence of sodium acetate, compared to ZM4 which showed more additive inhibition. In vivo^31P NMR studies revealed that intracellular acidification and de-energization were two mechanisms by which acetic acid exerted its inhibitory effect. For ZM4/Ac^R, the internal pH and the energy states were less affected by sodium acetate compared to the parent strain. This resistance to pH change and de-energization caused by acetic acid id a possible explanation for the development of resistance by this strain.
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