Konings W N, Lolkema J S, Bolhuis H, van Veen H W, Poolman B, Driessen A J
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands.
Antonie Van Leeuwenhoek. 1997 Feb;71(1-2):117-28. doi: 10.1023/a:1000143525601.
Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural and functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist.
乳酸菌在许多食品发酵过程中起着至关重要的作用。它们是厌氧生物，通过底物磷酸化获取代谢能量。此外，三种次级能量转导过程有助于产生质子动力：如乳酸排泄中的质子/底物同向转运、如苹果酸-乳酸发酵和柠檬酸-乳酸发酵以及组氨酸/组胺交换中的产电前体/产物交换，以及如酒类酒球菌中苹果酸和柠檬酸摄取中的产电单向转运。在其中一些过程中，代谢过程中会额外消耗H⁺，导致产生内部呈碱性的pH梯度。乳酸菌还发展出了多药耐药系统。在乳酸乳球菌中，已鉴定出三种毒素排泄系统：阳离子毒素可通过毒素/质子反向转运系统和ABC转运蛋白排泄。这种阳离子ABC转运蛋白与人类MDR1（P-糖蛋白）具有惊人的高度结构和功能相似性。对于阴离子，存在一种ATP驱动的类似ABC的排泄系统。
