Journal ArticleDOI
The Citrate Transport System of Lactococcus lactis subsp. lactis biovar diacetylactis Is Induced by Acid Stress
Reads0
Chats0
TLDR
This acid stress response seems to provide L. lactis biovar diacetylactis with a selective advantage resulting from cometabolism of glucose and citrate at low pHs.Abstract:
Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrate permease P (CitP), which is encoded by the plasmidic citP gene. We have shown previously that citP is included in the citQRP operon, which is mainly transcribed from the P1 promoter in L. lactis subsp. lactis biovar diacetylactis. Furthermore, transcription of citQRP and citrate transport are not induced by the presence of citrate in the growth medium. In this work, we analyzed the influence of the extracellular pH on the expression of citP. The citrate transport system is induced by natural acidification of the medium during cell growth and by a shift to media buffered at acidic pHs. This inducible response to acid stress takes place at the transcriptional level and seems to be due to increased utilization of the P1 promoter. Increased transcription correlates with increased synthesis of CitP and results in higher citrate transport activity catalyzed by the cells. Finally, this acid stress response seems to provide L. lactis subsp. lactis biovar diacetylactis with a selective advantage resulting from cometabolism of glucose and citrate at low pHs.read more
Citations
More filters
Journal ArticleDOI
Surviving the Acid Test: Responses of Gram-Positive Bacteria to Low pH
Paul D. Cotter,Colin Hill +1 more
TL;DR: The most common mechanisms that help Gram-positive bacteria overcome the challenge posed by different acidic environments are described, i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling.
Journal ArticleDOI
Stress responses in lactic acid bacteria
Maarten van de Guchte,Pascale Serror,Christian Chervaux,Tamara Smokvina,Stanislav Dusko Ehrlich,Emmanuelle Maguin +5 more
TL;DR: The overview of LAB stress responses reveals common aspects of stress responses and suggests that the molecular bases of adaptive responses are, at least in part, species (or even subspecies) specific.
Journal ArticleDOI
Acid tolerance mechanisms utilized by Streptococcus mutans
TL;DR: Streptococcus mutans has been the focus of rigorous research efforts due to its involvement in caries initiation and progression and its remarkable ability to withstand the acid onslaught by utilizing a wide variety of highly evolved acid-tolerance mechanisms.
Book ChapterDOI
Starter cultures: General aspects
TL;DR: This article addresses general concepts surrounding the use of starter cultures in cheesemaking and the preparation and use of bulk starter cultures and culture concentrates.
Journal ArticleDOI
Environmental stress responses in Lactococcus lactis
TL;DR: An overview of the growth limits of L. lactis and the molecular characterization of its stress resistance mechanisms is presented, which may provide attractive tools for the development of food grade inducible gene expression systems.
References
More filters
Journal ArticleDOI
Plasmid complements of Streptococcus lactis NCDO 712 and other lactic streptococci after protoplast-induced curing.
TL;DR: Curing of cryptic molecules from multiple plasmid complements by protoplast regeneration may prove to be generally valuable in lactic streptococci and other gram-positive species.
Book ChapterDOI
Chloramphenicol acetyltransferase from chloramphenicol-resistant bacteria.
TL;DR: The procedure described in the chapter gives a homogeneous CAT product from R factor-containing strains of E. coli and isolates of S. aureus harboring a CM plasmid, which is equivalent to 0.5–1% of the soluble cell protein in stationary phase.
Journal ArticleDOI
Acid and base resistance in Escherichia coli and Shigella flexneri: role of rpoS and growth pH.
TL;DR: Both acid resistance and base resistance show dependence on growth pH and are regulated by rpoS under certain conditions, and in part for base resistance, the rPOS requirement can be overcome by anaerobic growth in moderate acid.
Journal ArticleDOI
Citrate metabolism in lactic acid bacteria
TL;DR: In this review the metabolic pathways involved in product formation from citrate are described, the bioenergetic consequences of this metabolism for the lactic acid bacteria are discussed and detailed information on some key enzymes in the citrate metabolism is presented.
Journal ArticleDOI
The stationary-phase sigma factor sigma S (RpoS) is required for a sustained acid tolerance response in virulent Salmonella typhimurium.
TL;DR: The results suggest AtrB serves as a link between the sustained and transient ATR systems, and suggests different acid‐sensitive targets occur in log‐phase versus stationary‐phase cells.