Furfural inhibits growth by limiting XXXX assimilation in ethanologenic @entity526 LY180.

@entity2226 @entity1522 @entity2125 @entity462 @entity8962 @entity3793 @entity2569 @entity9735 @entity1853 @entity39208 @entity1110 @entity563 @entity599 @entity369 @entity3363 @entity526
A wide variety of commercial products can be potentially made from monomeric @entity3363 produced by the dilute acid hydrolysis of lignocellulosic biomass. However, this process is accompanied by side products such as furfural that hinder microbial growth and fermentation. To investigate the mechanism of furfural inhibition, mRNA microarrays of an ethanologenic strain of @entity526 (LY180) were compared immediately prior to and 15 min after a moderate furfural challenge. Expression of genes and regulators associated with the biosynthesis of @entity462 and @entity1853 was increased by furfural, consistent with a limitation of these critical metabolites. This was in contrast to a general stringent response and decreased expression of many other biosynthetic genes. Of the 20 @entity1522 individually tested as supplements (100 microM each), @entity462 and @entity1853 were the most effective in increasing furfural tolerance with @entity563 (precursor of @entity462 ), @entity3793 , and @entity369 of lesser benefit. Supplementation with other reduced @entity599 sources such as @entity39208 and @entity8962 also increased furfural tolerance. In contrast, supplementation with @entity2226 , a @entity599 source that requires 3 molecules of @entity1110 for @entity599 assimilation, was of no benefit. Furfural tolerance was also increased by inserting a plasmid encoding pntAB, a cytoplasmic @entity2125 / @entity1110 transhydrogenase. Based on these results, a model is proposed for the inhibition of growth in which the reduction of furfural by YqhD, an enzyme with a low K(m) for @entity1110 , depletes @entity1110 sufficiently to limit the assimilation of @entity599 into @entity1522 ( @entity462 and @entity1853 ) by @entity2569 IJ ( @entity9735 reductase).
