より良いバイオ製品のための分子の謎を解く(Solving a molecular mystery for better bioproducts)

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2025-03-25 オークリッジ国立研究所(ORNL)

オークリッジ国立研究所(ORNL)とシンシナティ大学の研究チームは、植物バイオマスの発酵中に微生物が生産するブタノールの毒性メカニズムを解明しました。中性子散乱と分子動力学シミュレーションにより、ブタノールが微生物の細胞膜内の膜ドメインに偏在し、膜を薄くしストレスを引き起こすことを発見。これは、発酵効率を低下させる要因でした。この知見は、耐性の高い微生物の開発や膜構造の強化による生産性向上に貢献し、再生可能バイオ燃料や化学品の持続可能な製造に道を開くものです。

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細胞膜平面におけるブタノールの毒性効果 Toxic Effects of Butanol in the Plane of the Cell Membrane

Luoxi Tan,Haden L. Scott,Micholas Dean Smith,Sai Venkatesh Pingali,Xiaolin Cheng,Hugh M. O’Neill,John Katsaras,Jeremy C. Smith,James G. Elkins,Brian H. Davison,and Jonathan D. Nickels
Langmuir  Published: January 8, 2025
DOI:https://doi.org/10.1021/acs.langmuir.4c03677

Abstract

より良いバイオ製品のための分子の謎を解く(Solving a molecular mystery for better bioproducts)

Solvent toxicity limits n-butanol fermentation titer, increasing the cost and energy consumption for subsequent separation processes and making biobased production more expensive and energy-intensive than petrochemical approaches. Amphiphilic solvents such as n-butanol partition into the cell membrane of fermenting microorganisms, thinning the transverse structure, and eventually causing a loss of membrane potential and cell death. In this work, we demonstrate the deleterious effects of n-butanol partitioning upon the lateral dimension of the membrane structure, called membrane domains or lipid rafts. Lipid rafts are regions of the cell membrane enriched with certain lipids, providing a reservoir of high melting temperature lipids and a platform for membrane protein partitioning and oligomerization. Neutron scattering experiments and molecular dynamics simulations revealed that n-butanol increased the size of the lipid domains in a model membrane system. The data showed that n-butanol partitions more into the disordered lipid regions than into the raft-like phase, leading to a differential thinning of these coexisting phases in the plane of the membrane and increasing the hydrophobic mismatch. The resulting increase in line tension at the interface favors domain coalescence to minimize the ratio of the interfacial length to domain area. A detailed computational investigation of the lipid domain interface identifies the boundary as a site of membrane disorder and thinning due to an accumulation of n-butanol. Solvent-induced changes to domain morphology and membrane instability at the domain interface are unrecognized modes of solvent-induced stress to fermenting microbes, representing targets for new solvent tolerance strategies to increase the n-butanol titer.

生物化学工学
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