BioChem - DOS

Formic acid triggers the acid crash of acetone-butanol-ethanol fermentation by Clostridium acetobutylicum

Applied and environmental microbiology

Wang, Shaohua; Zhang, Yanping; Dong, Hongjun; Mao, Shaoming; Zhu, Yan; Wang, Runjiang; Luan, Guodong; Li, Yin

<P><B>ABSTRACT</B><P> Solvent production by <I>Clostridium acetobutylicum</I> collapses when cells are grown in pH-uncontrolled glucose medium, the so-called &ldquo;acid crash&rdquo; phenomenon. It is generally accepted that the fast accumulation of acetic acid and butyric acid triggers the acid crash. We found that addition of 1 mM formic acid into corn mash medium could trigger acid crash, suggesting that formic acid might be related to acid crash. When it was grown in pH-uncontrolled glucose medium or glucose-rich medium, <I>C. acetobutylicum</I> DSM 1731 containing the empty plasmid pIMP1 failed to produce solvents and was found to accumulate 0.5 to 1.24 mM formic acid intracellularly. In contrast, recombinant strain DSM 1731 with formate dehydrogenase activity did not accumulate formic acid intracellularly and could produce solvent as usual. We therefore conclude that the accumulation of formic acid, rather than acetic acid and butyric acid, is responsible for the acid crash of acetone-butanol-ethanol fermentation. </P></P>

2011

American Society for Microbiology

0099-2240

1098-5336

77

5

pp.1674-1680

10.1128/aem.01835-10

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