Open AccessPhysiological Function of Alcohol Dehydrogenases and Long-Chain (C 30 ) Fatty Acids in Alcohol Tolerance of Thermoanaerobacter ethanolicus
Author(s) -
Douglas Burdette,
Seunho Jung,
GwoJenn Shen,
Rawle I. Hollingsworth,
J. G. Zeikus
Publication year - 2002
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.68.4.1914-1918.2002
Subject(s) - alcohol dehydrogenase , biochemistry , ethanol , alcohol , lactate dehydrogenase , biology , dehydrogenase , chemistry , enzyme
A mutant strain (39E H8) of Thermoanaerobacter ethanolicus that displayed high (8% [vol/vol]) ethanol tolerance for growth was developed and characterized in comparison to the wild-type strain (39E), which lacks alcohol tolerance (<1.5% [vol/vol]). The mutant strain, unlike the wild type, lacked primary alcohol dehydrogenase and was able to increase the percentage of transmembrane fatty acids (i.e., long-chain C(30) fatty acids) in response to increasing levels of ethanol. The data support the hypothesis that primary alcohol dehydrogenase functions primarily in ethanol consumption, whereas secondary alcohol dehydrogenase functions in ethanol production. These results suggest that improved thermophilic ethanol fermentations at high alcohol levels can be developed by altering both cell membrane composition (e.g., increasing transmembrane fatty acids) and the metabolic machinery (e.g., altering primary alcohol dehydrogenase and lactate dehydrogenase activities).