scholarly journals Evidence that Ralstonia eutropha (Alcaligenes eutrophus) contains a functional homologue of the Ralstonia solanacearum Phc cell density sensing system

2000 ◽  
Vol 38 (2) ◽  
pp. 359-367 ◽  
Author(s):  
Ram P. Garg ◽  
Wandee Yindeeyoungyeon ◽  
Anja Gilis ◽  
Timothy P. Denny ◽  
Daniel van der Lelie ◽  
...  
Keyword(s):  
Cell Density ◽  
Ralstonia Solanacearum ◽  
Ralstonia Eutropha ◽  
Alcaligenes Eutrophus ◽  
Sensing System

The intra-genus and inter-species quorum-sensing autoinducers exert distinct control over Vibrio cholerae biofilm formation and dispersal

2019 ◽  
Author(s):  
Andrew A. Bridges ◽  
Bonnie L. Bassler
Keyword(s):  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Cell Density ◽  
Biofilm Formation ◽  
Specific Information ◽  
High Cell ◽  
Coincidence Detector ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Cell Densities

AbstractVibrio cholerae possesses multiple quorum-sensing systems that control virulence and biofilm formation among other traits. At low cell densities, when quorum-sensing autoinducers are absent, V. cholerae forms biofilms. At high cell densities, when autoinducers have accumulated, biofilm formation is repressed and dispersal occurs. Here, we focus on the roles of two well-characterized quorum-sensing autoinducers that function in parallel. One autoinducer, called CAI-1, is used to measure vibrio abundance, and the other autoinducer, called AI-2, is a broadly-made universal autoinducer that is presumed to enable V. cholerae to assess the total bacterial cell density of the vicinal community. The two V. cholerae autoinducers funnel information into a shared signal relay pathway. This feature of the quorum-sensing system architecture has made it difficult to understand how specific information can be extracted from each autoinducer, how the autoinducers might drive distinct output behaviors, and in turn, how the bacteria use quorum sensing to distinguish self from other in bacterial communities. We develop a live-cell biofilm formation and dispersal assay that allows examination of the individual and combined roles of the two autoinducers in controlling V. cholerae behavior. We show that the quorum-sensing system works as a coincidence detector in which both autoinducers must be present simultaneously for repression of biofilm formation to occur. Within that context, the CAI-1 quorum-sensing pathway is activated when only a few V. cholerae cells are present, whereas the AI-2 pathway is activated only at much higher cell density. The consequence of this asymmetry is that exogenous sources of AI-2, but not CAI-1, contribute to satisfying the coincidence detector to repress biofilm formation and promote dispersal. We propose that V. cholerae uses CAI-1 to verify that some of its kin are present before committing to the high-cell-density quorum-sensing mode, but it is, in fact, the universal autoinducer AI-2, that sets the pace of the V. cholerae quorum-sensing program. This first report of unique roles for the different V. cholerae autoinducers suggests that detection of self fosters a distinct outcome from detection of other.

Repression of Phenol Catabolism by Organic Acids in Ralstonia eutropha

1998 ◽  
Vol 64 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Frédéric Ampe ◽  
David Léonard ◽  
Nicholas D. Lindley
Keyword(s):  
Organic Acids ◽  
Organic Acid ◽  
Ralstonia Eutropha ◽  
Phenol Degradation ◽  
Alcaligenes Eutrophus ◽  
Transcriptional Level ◽  
Specific Rate ◽  
Diauxic Growth ◽  
Benzoate Degradation ◽  
Specific Activities

ABSTRACT During batch growth of Ralstonia eutropha (previously named Alcaligenes eutrophus) on phenol in the presence of acetate, acetate was found to be the preferred substrate; this organic acid was rapidly metabolized, and the specific rate of phenol consumption was considerably decreased, although phenol consumption was not abolished. This decrease corresponded to a drop in phenol hydroxylase and catechol-2,3-dioxygenase specific activities, and the synthesis of the latter was repressed at the transcriptional level. Studies with a mutant not able to consume acetate indicated that the organic acid itself triggers the repression. Other organic acids were also found to repress phenol degradation. One of these, benzoate, was found to completely block the catabolism of phenol (diauxic growth). A mutant unable to metabolize benzoate was also unable to develop on benzoate-phenol mixtures, indicating that the organic acid rather than a metabolite involved in benzoate degradation was responsible for the repression observed.

scholarly journals Cell Density-Dependent Gene Contributes to Efficient Seed Colonization by Pseudomonas putida KT2440

2004 ◽  
Vol 70 (9) ◽  
pp. 5190-5198 ◽  
Author(s):  
Manuel Espinosa-Urgel ◽  
Juan-Luis Ramos
Keyword(s):  
Pseudomonas Putida ◽  
Cell Density ◽  
Phosphate Starvation ◽  
Pseudomonas Putida Kt2440 ◽  
Potential Implication ◽  
Sensing System ◽  
Serovar Typhimurium ◽  
Seed Colonization ◽  
Signaling Process ◽  
Inducible Gene

ABSTRACT We have characterized the expression pattern of a gene, ddcA, involved in initial colonization of corn seeds by Pseudomonas putida KT2440. The ddcA gene codes for a putative membrane polypeptide belonging to a family of conserved proteins of unknown function. Members of this family are widespread among prokaryotes and include the products of a Salmonella enterica serovar Typhimurium gene expressed during invasion of macrophages and psiE, an Escherichia coli phosphate starvation-inducible gene. Although its specific role is undetermined, the presence of ddcA in multicopy restored the seed adhesion capacity of a KT2440 ddcA mutant. Expression of ddcA is growth phase regulated, being maximal at the beginning of stationary phase. It is independent of RpoS, nutrient depletion, or phosphate starvation, and it is not the result of changes in the medium pH during growth. Expression of ddcA is directly dependent on cell density, being also stimulated by the addition of conditioned medium and of seed exudates. This is the first evidence suggesting the existence of a quorum-sensing system in P. putida KT2440. The potential implication of such a signaling process in seed adhesion and colonization by the bacterium is discussed.

scholarly journals Biocontrol of Ralstonia solanacearum by Treatment with Lytic Bacteriophages

2011 ◽  
Vol 77 (12) ◽  
pp. 4155-4162 ◽  
Author(s):  
Akiko Fujiwara ◽  
Mariko Fujisawa ◽  
Ryosuke Hamasaki ◽  
Takeru Kawasaki ◽  
Makoto Fujie ◽  
...  
Keyword(s):  
Cell Density ◽  
Ralstonia Solanacearum ◽  
Experimental Period ◽  
The Other ◽  
Bacterial Cells ◽  
Effective Prevention ◽  
Tomato Plants ◽  
Content Type ◽  
Tomato Seedlings ◽  
Lower Cell Density

ABSTRACTRalstonia solanacearumis a Gram-negative bacterium and the causative agent of bacterial wilt in many important crops. We treatedR. solanacearumwith three lytic phages: φRSA1, φRSB1, and φRSL1. Infection with φRSA1 and φRSB1, either alone or in combination with the other phages, resulted in a rapid decrease in the host bacterial cell density. Cells that were resistant to infection by these phages became evident approximately 30 h after phage addition to the culture. On the other hand, cells infected solely with φRSL1 in a batch culture were maintained at a lower cell density (1/3 of control) over a long period. Pretreatment of tomato seedlings with φRSL1 drastically limited penetration, growth, and movement of root-inoculated bacterial cells. All φRSL1-treated tomato plants showed no symptoms of wilting during the experimental period, whereas all untreated plants had wilted by 18 days postinfection. φRSL1 was shown to be relatively stable in soil, especially at higher temperatures (37 to 50°C). Active φRSL1 particles were recovered from the roots of treated plants and from soil 4 months postinfection. Based on these observations, we propose an alternative biocontrol method using a unique phage, such as φRSL1, instead of a phage cocktail with highly virulent phages. Using this method, φRSL1 killed some but not all bacterial cells. The coexistence of bacterial cells and the phage resulted in effective prevention of wilting.

scholarly journals Production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by Ralstonia eutropha in high cell density palm oil fermentations

2011 ◽  
Vol 109 (1) ◽  
pp. 74-83 ◽  
Author(s):  
Sebastian L. Riedel ◽  
Johannes Bader ◽  
Christopher J. Brigham ◽  
Charles F. Budde ◽  
Zainal Abidin Mohd Yusof ◽  
...  
Keyword(s):  
Cell Density ◽  
Palm Oil ◽  
Ralstonia Eutropha ◽  
High Cell Density ◽  
High Cell

scholarly journals The BpsIR Quorum-Sensing System of Burkholderia pseudomallei

2005 ◽  
Vol 187 (2) ◽  
pp. 785-790 ◽  
Author(s):  
Yan Song ◽  
Chao Xie ◽  
Yong-Mei Ong ◽  
Yunn-Hwen Gan ◽  
Kim-Lee Chua
Keyword(s):  
Quorum Sensing ◽  
Cell Density ◽  
Burkholderia Pseudomallei ◽  
Homoserine Lactone ◽  
Positive Regulation ◽  
Density Dependent ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT BpsIR, a LuxIR quorum-sensing homolog, is required for optimal expression of virulence and secretion of exoproducts in Burkholderia pseudomallei. Cell density-dependent expression of bpsI and bpsR, the positive regulation of bpsIR expression by BpsR, and the synthesis of N-octanoyl-homoserine lactone (C8HSL) by BpsI are described in this report.

Cell separation from high cell density broths of Alcaligenes eutrophus by using a coagulant

1996 ◽  
Vol 10 (12) ◽  
Author(s):  
HeeWook Ryu ◽  
KyungSuk Cho ◽  
YoungKeun Chang ◽  
HoNam Chang
Keyword(s):  
Cell Density ◽  
Cell Separation ◽  
High Cell Density ◽  
Alcaligenes Eutrophus ◽  
High Cell

Staphyloferrin B, a Citrate Siderophore of Ralstonia eutropha

1999 ◽  
Vol 54 (11) ◽  
pp. 867-875 ◽  
Author(s):  
Maik Münzinger ◽  
Kambiz Taraz ◽  
Herbert Budzikiewicz
Keyword(s):  
Culture Medium ◽  
New Genus ◽  
Ralstonia Eutropha ◽  
Alcaligenes Eutrophus ◽  
Chemical Degradation ◽  
Spectroscopic Methods ◽  
Relationship Of ◽  
The Relationship

Abstract The structure and stereochemistry of the siderophore isolated from the culture medium of Ralstonia eutropha (formerly Alcaligenes eutrophus) could be elucidated as staphyloferrin B by spectroscopic methods and chemical degradation. The relationship of the three species of the new genus Ralstonia is reflected in the observation that all three form citrate sidero-phores.

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