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Tanimura K, Nakayama H, Tanaka T, Kondo A. Ectoine production from lignocellulosic biomass-derived sugars by engineered Halomonas elongata. BIORESOURCE TECHNOLOGY 2013; 142:523-529. [PMID: 23765002 DOI: 10.1016/j.biortech.2013.05.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/30/2013] [Accepted: 05/02/2013] [Indexed: 06/02/2023]
Abstract
In this study, the water-retaining cyclic amino acid ectoine was produced from a variety of sugars, including glucose, xylose, cellobiose, and glucose/xylose mixture using engineered Halomonas elongata. When grown on xylose as the sole carbon source, H. elongata produced 333 mmol/kg fresh cell weight (FW) of ectoine, which was 1.4-fold higher than that produced from glucose. To improve ectoine production, an ectD deficient H. elongata mutant was constructed. The engineered H. elongata produced 377 mmol/kg FW of ectoine from a glucose/xylose mixture. Ectoine was also produced from rice straw hydrolysate. These results show that H. elongata can produce ectoine from a variety of sugars derived from lignocellulosic biomass and thus has tremendous potential as a host for producing useful compounds from biomass resources.
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Affiliation(s)
- Kosuke Tanimura
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokkodai-Cho, Nada, Kobe 657-8501, Japan
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Utilization of heme as an iron source by marine Alphaproteobacteria in the Roseobacter clade. Appl Environ Microbiol 2013; 79:5753-62. [PMID: 23872569 DOI: 10.1128/aem.01562-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bioavailability and utilization of porphyrin-bound iron, specifically heme, by marine microorganisms have rarely been examined. This study used Ruegeria sp. strain TrichCH4B as a model organism to study heme acquisition by a member of the Roseobacter clade. Analogs of known heme transporter proteins were found within the Ruegeria sp. TrichCH4B genome. The identified heme uptake and utilization system appears to be functional, as the heme genes were upregulated under iron stress, the bacterium could grow on ferric-porphyrin complexes as the sole iron source, and internalization of (55) Fe from ferric protoporphyrin IX was observed. The potential ability to utilize heme in the Roseobacter clade appears to be common, as half of the isolates in the RoseoBase database were found to have a complete heme uptake system. A degenerate primer set was designed and successfully used to identify the putative heme oxygenase gene (hmus) in the roseobacter heme uptake system from diverse nonenriched marine environments. This study found that members of the Roseobacter clade are capable of utilizing heme as an iron source and that this capability may be present in all types of marine environments. The results of this study add a new perspective to the current picture of iron cycling in marine systems, whereby relatively refractory intracellular pools of heme-bound iron may be taken up quickly and directly reincorporated into living bacteria without previous degradation or the necessity of a siderophore intermediate.
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Distribution and functions of phosphotransferase system genes in the genome of the lactic acid bacterium Oenococcus oeni. Appl Environ Microbiol 2013; 79:3371-9. [PMID: 23524676 DOI: 10.1128/aem.00380-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Oenococcus oeni, the lactic acid bacterium primarily responsible for malolactic fermentation in wine, is able to grow on a large variety of carbohydrates, but the pathways by which substrates are transported and phosphorylated in this species have been poorly studied. We show that the genes encoding the general phosphotransferase proteins, enzyme I (EI) and histidine protein (HPr), as well as 21 permease genes (3 isolated ones and 18 clustered into 6 distinct loci), are highly conserved among the strains studied and may form part of the O. oeni core genome. Additional permease genes differentiate the strains and may have been acquired or lost by horizontal gene transfer events. The core pts genes are expressed, and permease gene expression is modulated by the nature of the bacterial growth substrate. Decryptified O. oeni cells are able to phosphorylate glucose, cellobiose, trehalose, and mannose at the expense of phosphoenolpyruvate. These substrates are present at low concentrations in wine at the end of alcoholic fermentation. The phosphotransferase system (PTS) may contribute to the perfect adaptation of O. oeni to its singular ecological niche.
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Badejo AC, Badejo AO, Shin KH, Chai YG. A gene expression study of the activities of aromatic ring-cleavage dioxygenases in Mycobacterium gilvum PYR-GCK to changes in salinity and pH during pyrene degradation. PLoS One 2013; 8:e58066. [PMID: 23469141 PMCID: PMC3585252 DOI: 10.1371/journal.pone.0058066] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 01/29/2013] [Indexed: 11/30/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants found in the environment which can be removed through the use of physical and biological agents. The rate of PAH biodegradation is affected by environmental conditions of pH, salinity and temperature. Adaptation of the pyrene degrading bacteria, Mycobacterium gilvum PYR-GCK, to fluctuating environmental conditions during pyrene biodegrading activity was studied using the quantitative real time – Polymerase Chain Reaction (qRT-PCR) technique. Four aromatic ring-cleavage dioxygenase genes: phdF, phdI, pcaG and pcaH; critical to pyrene biodegradation, were studied in pH states of 5.5, 6.5, 7.5 and NaCl concentrations 0 M, 0.17 M, 0.5 M, 0.6 M, 1 M. First, we conducted a residual pyrene study using gas chromatography and flame ionization technologies. Central to a gene expression study is the use of a valid endogenous reference gene, making its determination our next approach, using the geNorm/NormFinder algorithms. Armed with a valid control gene, rpoB, we applied it to a gene expression study, using the comparative critical threshold (2ΔΔCT) quantification method. The pyrene degrading activity of the strain was strongly functional in all the NaCl concentration states, with the least activity found at 1M (∼70% degraded after 48 hours of cultivation). The transcripts quantification of three genes backed this observation with high expression levels. The gene expression levels also revealed pH 6.5 as optimal for pyrene degradation and weak degradation activity at pH of 5.5, corroborating the residual pyrene analysis. The expression of these genes as proteins has already been studied in our laboratory using proteomics techniques and this validates our current study.
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Affiliation(s)
| | | | - Kyung Hoon Shin
- Department of Environmental and Marine Science, Hanyang University, Ansan, Korea
| | - Young Gyu Chai
- Department of Molecular and Life Sciences, Hanyang University, Ansan, Korea
- * E-mail:
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55
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An in vitro study of Lactobacillus plantarum strains for the presence of plantaricin genes and their potential control of the table olive microbiota. Antonie Van Leeuwenhoek 2012; 103:821-32. [DOI: 10.1007/s10482-012-9864-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 12/01/2012] [Indexed: 10/27/2022]
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56
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Suo Y, Huang Y, Liu Y, Shi C, Shi X. The expression of superoxide dismutase (SOD) and a putative ABC transporter permease is inversely correlated during biofilm formation in Listeria monocytogenes 4b G. PLoS One 2012; 7:e48467. [PMID: 23119031 PMCID: PMC3485238 DOI: 10.1371/journal.pone.0048467] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 09/25/2012] [Indexed: 11/19/2022] Open
Abstract
Little is known about the molecular basis of biofilm formation in Listeria monocytogenes. The superoxide dismutase (SOD) of the deletion mutant of lm.G_1771 gene, which encodes for a putative ABC transporter permease, is highly expressed in biofilm. In this study, the sod gene deletion mutant Δsod, and double deletion mutant of the sod and lm. G_1771 genes Δ1771Δsod were used to investigate the role of SOD and its relationship to the expression of the putative ABC transporter permease in biofilm formation. Our results showed that the ability to form a biofilm was significantly reduced in the Δsod mutant and the Δ1771Δsod double mutant. Both Δsod and Δ1771Δsod mutants exhibited slow growth phenotypes and produced more reactive oxygen species (ROS). The growth was inhibited in the mutants by methyl viologen (MV, internal oxygen radical generator) treatment. In addition, the expression of one oxidation resistance gene (kat), two stress regulators encoding genes (perR and sigB), and one DNA repair gene (recA) were analyzed in both the wild-type L. monocytogenes 4b G and the deletion mutants by RT-qPCR. The expression levels of the four genes were increased in the deletion mutants when biofilms were formed. Taken together, our data indicated that SOD played an important role in biofilm formation through coping with the oxidant burden in deficient antioxidant defenses.
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Affiliation(s)
- Yujuan Suo
- MOST-USDA Joint Research Center for Food Safety and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yanyan Huang
- MOST-USDA Joint Research Center for Food Safety and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yanhong Liu
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, Wyndmoor, Pennsylvania, United States of America
| | - Chunlei Shi
- MOST-USDA Joint Research Center for Food Safety and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Xianming Shi
- MOST-USDA Joint Research Center for Food Safety and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
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Validation of the use of multiple internal control genes, and the application of real-time quantitative PCR, to study esterase gene expression in Oenococcus oeni. Appl Microbiol Biotechnol 2012; 96:1039-47. [DOI: 10.1007/s00253-012-4409-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 08/01/2012] [Accepted: 08/31/2012] [Indexed: 12/28/2022]
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58
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Mechanisms for photoinactivation of Enterococcus faecalis in seawater. Appl Environ Microbiol 2012; 78:7776-85. [PMID: 22941072 DOI: 10.1128/aem.02375-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Field studies in fresh and marine waters consistently show diel fluctuations in concentrations of enterococci, indicators of water quality. We investigated sunlight inactivation of Enterococcus faecalis to gain insight into photoinactivation mechanisms and cellular responses to photostress. E. faecalis bacteria were exposed to natural sunlight in clear, filtered seawater under both oxic and anoxic conditions to test the relative importance of oxygen-mediated and non-oxygen-mediated photoinactivation mechanisms. Multiple methods were used to assess changes in bacterial concentration, including cultivation, quantitative PCR (qPCR), propidium monoazide (PMA)-qPCR, LIVE/DEAD staining using propidium iodide (PI), and cellular activity, including ATP concentrations and expression of the superoxide dismutase-encoding gene, sodA. Photoinactivation, based on numbers of cultivable cells, was faster in oxic than in anoxic microcosms exposed to sunlight, suggesting that oxygen-mediated photoinactivation dominated. There was little change in qPCR signal over the course of the experiment, demonstrating that the nucleic acid targets were not damaged to a significant extent. The PMA-qPCR signal was also fairly stable, consistent with the observation that the fraction of PI-permeable cells was constant. Thus, damage to the membrane was minimal. Microbial ATP concentrations decreased in all microcosms, particularly the sunlit oxic microcosms. The increase in relative expression of the sodA gene in the sunlit oxic microcosms suggests that cells were actively responding to oxidative stress. Dark repair was not observed. This research furthers our understanding of photoinactivation mechanisms and the conditions under which diel fluctuations in enterococci can be expected in natural and engineered systems.
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RT-qPCR analysis of putative beer-spoilage gene expression during growth of Lactobacillus brevis BSO 464 and Pediococcus claussenii ATCC BAA-344(T) in beer. Appl Microbiol Biotechnol 2012; 96:461-70. [PMID: 22893225 DOI: 10.1007/s00253-012-4334-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 07/19/2012] [Accepted: 07/21/2012] [Indexed: 10/28/2022]
Abstract
Lactic acid bacteria (LAB) contamination of beer presents a continual economic threat to brewers. Interestingly, only certain isolates of LAB can grow in the hostile beer environment (e.g., as studied here, Lactobacillus brevis BSO 464 (Lb464) and a non-ropy isolate of Pediococcus claussenii ATCC BAA-344(T) (Pc344NR)), indicating that significant genetic specialization is required. The genes hitA, horA, horB, horC, and bsrA, which have been proposed to confer beer-spoiling ability to an organism, are suspected of counteracting the antimicrobial effects of hops. However, these genes are not present in the same combination (if at all) across beer-spoiling organisms. As such, we sought to investigate the extent to which these genes participate during Lb464 and Pc344NR mid-logarithmic growth in beer through reverse transcription quantitative PCR analysis. We first determined the optimal reference gene set needed for data normalization and, for each bacterium, established that two genes were needed for accurate assessment of gene expression. Following this, we found that horA expression was induced for Pc344NR, but not for Lb464, during growth in beer. Instead, horC expression was dramatically increased in Lb464 when growing in beer, whereas no change was detected for the other putative beer-spoilage-related genes. This indicates that HorC may be one of the principle mediators enabling growth of Lb464 in beer, whereas in Pc344NR, this may be attributable to HorA. These findings not only reveal that Lb464 and Pc344NR are unique in their beer-specific genetic expression profile but also indicate that a range of genetic specialization exists among beer-spoilage bacteria.
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60
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Galisa PS, da Silva HAP, Macedo AVM, Reis VM, Vidal MS, Baldani JI, Simões-Araújo JL. Identification and validation of reference genes to study the gene expression in Gluconacetobacter diazotrophicus grown in different carbon sources using RT-qPCR. J Microbiol Methods 2012; 91:1-7. [PMID: 22814372 DOI: 10.1016/j.mimet.2012.07.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/03/2012] [Accepted: 07/03/2012] [Indexed: 12/30/2022]
Abstract
Gluconacetobacter diazotrophicus strain PAL5 is a nitrogen-fixing endophytic bacterium originally isolated from sugarcane and later on was found to colonize other plants such as rice, elephant grass, sweet potato, coffee, and pineapple. Currently, G. diazotrophicus has been considered a plant growth-promoting bacterium due to its characteristics of biological nitrogen fixation, phytohormone secretion, solubilization of mineral nutrients and antagonism to phytopathogens. Reverse transcription followed by quantitative real-time polymerase chain reaction (RT-qPCR) is a method applied for the quantification of nucleic acids because of its specificity and high sensitivity. However, the decision about the reference genes suitable for data validation is still a major issue, especially for nitrogen-fixing bacteria. To evaluate and identify suitable reference genes for gene expression normalization in the diazotrophic G. diazotrophicus, mRNA levels of fourteen candidate genes (rpoA, rpoC, recA, rpoD, fabD, gmk, recF, rho, ldhD, gyrB, gyrBC, dnaG, lpxC and 23SrRNA) and three target genes (matE, omp16 and sucA) were quantified by RT-qPCR after growing the bacteria in different carbon sources. The geNorm and Normfinder programs were used to calculate the expression stabilities. The analyses identified three genes, rho, 23SrRNA and rpoD, whose expressions were stable throughout the growth of strain PAL5 in the chosen carbon sources. In conclusion our results strongly suggest that these three genes are suitable to be used as reference genes for real-time RT-qPCR data normalization in G. diazotrophicus.
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Affiliation(s)
- Péricles S Galisa
- Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, Brazil
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61
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Importance of RNA stabilization: evaluation of ansB, ggt, and rpoA transcripts in microaerophilic Campylobacter jejuni 81-176. Arch Microbiol 2012; 194:803-8. [DOI: 10.1007/s00203-012-0820-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/10/2012] [Accepted: 04/27/2012] [Indexed: 11/29/2022]
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62
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Schmid S, Bevilacqua C, Crutz-Le Coq AM. Alternative sigma factor σH activates competence gene expression in Lactobacillus sakei. BMC Microbiol 2012; 12:32. [PMID: 22409597 PMCID: PMC3364868 DOI: 10.1186/1471-2180-12-32] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 03/12/2012] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Alternative sigma factors trigger various adaptive responses. Lactobacillus sakei, a non-sporulating meat-borne bacterium, carries an alternative sigma factor seemingly orthologous to σ(H) of Bacillus subtilis, best known for its contribution to the initiation of a large starvation response ultimately leading to sporulation. As the role of σ(H)-like factors has been little studied in non-sporulating bacteria, we investigated the function of σ(H) in L. sakei. RESULTS Transcription of sigH coding for σ(H) was hardly affected by entry into stationary phase in our laboratory conditions. Twenty-five genes potentially regulated by σ(H) in L. sakei 23 K were revealed by genome-wide transcriptomic profiling of sigH overexpression and/or quantitative PCR analysis. More than half of them are involved in the synthesis of a DNA uptake machinery linked to genetic competence, and in DNA metabolism; however, σ(H) overproduction did not allow detectable genetic transformation. σ(H) was found to be conserved in the L. sakei species. CONCLUSION Our results are indicative of the existence of a genetic competence state activated by σ(H) in L. sakei, and sustain the hypothesis that σ(H)-like factors in non sporulating Firmicutes share this common function with the well-known ComX of naturally transformable streptococci.
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Affiliation(s)
- Solveig Schmid
- UMR1319 Micalis, INRA F-78350, Jouy-en-Josas, France
- UMR Micalis, AgroParisTech, INRA F-78350, Jouy-en-Josas, France
- Conceptus SAS, 50 avenue de Saint Cloud, F-78000 Versailles, France
| | - Claudia Bevilacqua
- UMR1313 Génétique Animale et Biologie Intégrative, plateforme ICE, INRA F-78350, Jouy-en-Josas, France
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63
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The effects of pH oscillation on Lactobacillus rhamnosus batch cultivation. Appl Microbiol Biotechnol 2012; 95:1265-73. [DOI: 10.1007/s00253-012-3946-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 01/27/2012] [Accepted: 02/06/2012] [Indexed: 01/08/2023]
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64
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Kim OB, Richter H, Zaunmüller T, Graf S, Unden G. Role of secondary transporters and phosphotransferase systems in glucose transport by Oenococcus oeni. J Bacteriol 2011; 193:6902-11. [PMID: 22020640 PMCID: PMC3232829 DOI: 10.1128/jb.06038-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Accepted: 10/05/2011] [Indexed: 11/20/2022] Open
Abstract
Glucose uptake by the heterofermentative lactic acid bacterium Oenococcus oeni B1 was studied at the physiological and gene expression levels. Glucose- or fructose-grown bacteria catalyzed uptake of [(14)C]glucose over a pH range from pH 4 to 9, with maxima at pHs 5.5 and 7. Uptake occurred in two-step kinetics in a high- and low-affinity reaction. The high-affinity uptake followed Michaelis-Menten kinetics and required energization. It accumulated the radioactivity of glucose by a factor of 55 within the bacteria. A large portion (about 80%) of the uptake of glucose was inhibited by protonophores and ionophores. Uptake of the glucose at neutral pH was not sensitive to degradation of the proton potential, Δp. Expression of the genes OEOE_0819 and OEOE_1574 (here referred to as 0819 and 1574), coding for secondary transporters, was induced by glucose as identified by quantitative real-time (RT)-PCR. The genes 1574 and 0819 were able to complement growth of a Bacillus subtilis hexose transport-deficient mutant on glucose but not on fructose. The genes 1574 and 0819 therefore encode secondary transporters for glucose, and the transports are presumably Δp dependent. O. oeni codes, in addition, for a phosphotransferase transport system (PTS) (gene OEOE_0464 [0464] for the permease) with similarity to the fructose- and mannose-specific PTS of lactic acid bacteria. Quantitative RT-PCR showed induction of the gene 0464 by glucose and by fructose. The data suggest that the PTS is responsible for Δp-independent hexose transport at neutral pH and for the residual Δp-independent transport of hexoses at acidic pH.
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Affiliation(s)
- Ok Bin Kim
- Department of Life Sciences, Ewha Womans University, 120-750 Seoul, South Korea
| | - Hanno Richter
- Institute for Microbiology and Wine Research, Johannes Gutenberg University Mainz, Becherweg 15, 55099 Mainz, Germany
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York
| | - Tanja Zaunmüller
- Institute for Microbiology and Wine Research, Johannes Gutenberg University Mainz, Becherweg 15, 55099 Mainz, Germany
| | - Sabrina Graf
- Institute for Microbiology and Wine Research, Johannes Gutenberg University Mainz, Becherweg 15, 55099 Mainz, Germany
| | - Gottfried Unden
- Institute for Microbiology and Wine Research, Johannes Gutenberg University Mainz, Becherweg 15, 55099 Mainz, Germany
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Grimm A, Cho GS, Hanak A, Dorn A, Huch M, Franz CMAP. Characterization of Putative Adhesion Genes in the Potentially Probiotic Strain Lactobacillus plantarum BFE 5092. Probiotics Antimicrob Proteins 2011; 3:204-13. [DOI: 10.1007/s12602-011-9082-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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66
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Expression of Lactobacillus pentosus B96 bacteriocin genes under saline stress. Food Microbiol 2011; 28:1339-44. [DOI: 10.1016/j.fm.2011.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 05/23/2011] [Accepted: 06/01/2011] [Indexed: 11/18/2022]
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67
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Yu LJ, Wu JR, Zheng ZZ, Lin CC, Zhan XB. Changes in gene transcription and protein expression involved in the response of Agrobacterium sp. ATCC 31749 to nitrogen availability during curdlan production. APPL BIOCHEM MICRO+ 2011. [DOI: 10.1134/s0003683811050188] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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68
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Quantitative expression analysis of mleP gene and two genes involved in the ABC transport system in Oenococcus oeni during rehydration. Appl Microbiol Biotechnol 2011; 91:1601-9. [DOI: 10.1007/s00253-011-3498-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/08/2011] [Accepted: 07/18/2011] [Indexed: 11/27/2022]
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69
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The effect of temperature and pH gradients on Lactobacillus rhamnosus gene expression of stress-related genes. Bioprocess Biosyst Eng 2011; 34:1169-76. [DOI: 10.1007/s00449-011-0568-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 06/30/2011] [Indexed: 11/25/2022]
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70
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Adams PG, Mothersole DJ, Ng IW, Olsen JD, Hunter CN. Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1044-55. [PMID: 21663730 DOI: 10.1016/j.bbabio.2011.05.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/18/2011] [Accepted: 05/19/2011] [Indexed: 10/18/2022]
Abstract
In the model photosynthetic bacterium Rhodobacter sphaeroides domains of light-harvesting 2 (LH2) complexes surround and interconnect dimeric reaction centre-light-harvesting 1-PufX (RC-LH1-PufX) 'core' complexes, forming extensive networks for energy transfer and trapping. These complexes are housed in spherical intracytoplasmic membranes (ICMs), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. The kinetics of LH2 assembly were measured in PufX mutants that assemble monomeric core complexes, as a consequence of either a twelve-residue N-terminal truncation of PufX (PufXΔ12) or the complete removal of PufX (PufX(-)). Lower rates of LH2 assembly and retarded maturation of membrane invagination were observed for the larger and less curved ICM from the PufX(-) mutant, consistent with the proposition that local membrane curvature, initiated by arrays of bent RC-LH1-PufX dimers, creates a favourable environment for stable assembly of LH2 complexes. Transmission electron microscopy and high-resolution atomic force microscopy were used to examine ICM morphology and membrane protein organisation in these mutants. Some partitioning of core and LH2 complexes was observed in PufX(-) membranes, resulting in locally ordered clusters of monomeric RC-LH1 complexes. The distribution of core and LH2 complexes in the three types of membrane examined is consistent with previous models of membrane curvature and domain formation (Frese et al., 2008), which demonstrated that a combination of crowding and asymmetries in sizes and shapes of membrane protein complexes drives membrane organisation.
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Affiliation(s)
- Peter G Adams
- Department of Molecular Biology and Biochemistry, University of Sheffield, United Kingdom
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71
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Cyclopropanation of membrane unsaturated fatty acids is not essential to the acid stress response of Lactococcus lactis subsp. cremoris. Appl Environ Microbiol 2011; 77:3327-34. [PMID: 21421775 DOI: 10.1128/aem.02518-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cyclopropane fatty acids (CFAs) are synthetized in situ by the transfer of a methylene group from S-adenosyl-L-methionine to a double bond of unsaturated fatty acid chains of membrane phospholipids. This conversion, catalyzed by the Cfa synthase enzyme, occurs in many bacteria and is recognized to play a key role in the adaptation of bacteria in response to a drastic perturbation of the environment. The role of CFAs in the acid tolerance response was investigated in the lactic acid bacterium Lactococcus lactis MG1363. A mutant of the cfa gene was constructed by allelic exchange. The cfa gene encoding the Cfa synthase was cloned and introduced into the mutant to obtain the complemented strain for homologous system studies. Data obtained by gas chromatography (GC) and GC-mass spectrometry (GC-MS) validated that the mutant could not produce CFA. The CFA levels in both the wild-type and complemented strains increased upon their entry to stationary phase, especially with acid-adapted cells or, more surprisingly, with ethanol-adapted cells. The results obtained by performing quantitative reverse transcription-PCR (qRT-PCR) experiments showed that transcription of the cfa gene was highly induced by acidity (by 10-fold with cells grown at pH 5.0) and by ethanol (by 9-fold with cells grown with 6% ethanol) in comparison with that in stationary phase. Cell viability experiments were performed after an acidic shock on the mutant strain, the wild-type strain, and the complemented strain, as a control. The higher viability level of the acid-adapted cells of the three strains after 3 h of shock proved that the cyclopropanation of unsaturated fatty acids is not essential for L. lactis subsp. cremoris survival under acidic conditions. Moreover, fluorescence anisotropy data showed that CFA itself could not maintain the membrane fluidity level, particularly with ethanol-grown cells.
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Coton M, Fernández M, Trip H, Ladero V, Mulder NL, Lolkema JS, Alvarez MA, Coton E. Characterization of the tyramine-producing pathway in Sporolactobacillus sp. P3J. MICROBIOLOGY-SGM 2011; 157:1841-1849. [PMID: 21415114 DOI: 10.1099/mic.0.046367-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A sporulated lactic acid bacterium (LAB) isolated from cider must was shown to harbour the tdc gene encoding tyrosine decarboxylase. The isolate belonged to the Sporolactobacillus genus and may correspond to a novel species. The ability of the tdc-positive strain, Sporolactobacillus sp. strain P3J, to produce tyramine in vitro was demonstrated by using HPLC. A 7535 bp nucleotide sequence harbouring the putative tdc gene was determined. Analysis of the obtained sequence showed that four tyramine production-associated genes [tyrosyl-tRNA synthetase (tyrS), tyrosine decarboxylase (tdc), tyrosine permease (tyrP) and Na(+)/H(+) antiporter (nhaC)] were present and were organized as already described in other tyramine-producing LAB. This operon was surrounded by genes showing the highest identities with mobile elements: a putative phage terminase and a putative transposase (downstream and upstream, respectively), suggesting that the tyramine-forming trait was acquired through horizontal gene transfer. Transcription analyses of the tdc gene cluster suggested that tyrS and nhaC are expressed as monocistronic genes while tdc would be part of a polycistronic mRNA together with tyrP. The presence of tyrosine in the culture medium induced the expression of all genes except for tyrS. A clear correlation was observed between initial tyrosine concentration and tyramine production combined with an increase in the final pH reached by the culture. Finally, cloning and expression of the tyrP gene in Lactococcus lactis demonstrated that its product catalyses the exchange of tyrosine and tyramine.
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Affiliation(s)
- Monika Coton
- ADRIA Normandie, Boulevard du 13 Juin 1944, 14310 Villers-Bocage, France
| | - María Fernández
- Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain
| | - Hein Trip
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | - Victor Ladero
- Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain
| | - Niels L Mulder
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | - Juke S Lolkema
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | - Miguel A Alvarez
- Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain
| | - Emmanuel Coton
- ADRIA Normandie, Boulevard du 13 Juin 1944, 14310 Villers-Bocage, France
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Multigenic expression analysis as an approach to understanding the behaviour of Oenococcus oeni in wine-like conditions. Int J Food Microbiol 2010; 144:88-95. [DOI: 10.1016/j.ijfoodmicro.2010.08.032] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 08/26/2010] [Accepted: 08/31/2010] [Indexed: 11/22/2022]
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74
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Calles-Enríquez M, Eriksen BH, Andersen PS, Rattray FP, Johansen AH, Fernández M, Ladero V, Alvarez MA. Sequencing and transcriptional analysis of the Streptococcus thermophilus histamine biosynthesis gene cluster: factors that affect differential hdcA expression. Appl Environ Microbiol 2010; 76:6231-8. [PMID: 20656875 PMCID: PMC2937487 DOI: 10.1128/aem.00827-10] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 07/11/2010] [Indexed: 11/20/2022] Open
Abstract
Histamine, a toxic compound that is formed by the decarboxylation of histidine through the action of microbial decarboxylases, can accumulate in fermented food products. From a total of 69 Streptococcus thermophilus strains screened, two strains, CHCC1524 and CHCC6483, showed the capacity to produce histamine. The hdc clusters of S. thermophilus CHCC1524 and CHCC6483 were sequenced, and the factors that affect histamine biosynthesis and histidine-decarboxylating gene (hdcA) expression were studied. The hdc cluster began with the hdcA gene, was followed by a transporter (hdcP), and ended with the hdcB gene, which is of unknown function. The three genes were orientated in the same direction. The genetic organization of the hdc cluster showed a unique organization among the lactic acid bacterial group and resembled those of Staphylococcus and Clostridium species, thus indicating possible acquisition through a horizontal transfer mechanism. Transcriptional analysis of the hdc cluster revealed the existence of a polycistronic mRNA covering the three genes. The histidine-decarboxylating gene (hdcA) of S. thermophilus demonstrated maximum expression during the stationary growth phase, with high expression levels correlated with high histamine levels. Limited expression was evident during the lag and exponential growth phases. Low-temperature (4 degrees C) incubation of milk inoculated with a histamine-producing strain showed lower levels of histamine than did inoculated milk kept at 42 degrees C. This reduction was attributed to a reduction in the activity of the HdcA enzyme itself rather than a reduction in gene expression or the presence of a lower cell number.
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Affiliation(s)
- Marina Calles-Enríquez
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Benjamin Hjort Eriksen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Pia Skov Andersen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Fergal P. Rattray
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Annette H. Johansen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - María Fernández
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Victor Ladero
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Miguel A. Alvarez
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
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Capozzi V, Russo P, Beneduce L, Weidmann S, Grieco F, Guzzo J, Spano G. Technological properties of Oenococcus oeni strains isolated from typical southern Italian wines. Lett Appl Microbiol 2010; 50:327-34. [PMID: 20408255 DOI: 10.1111/j.1472-765x.2010.02795.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To isolate indigenous Oenococcus oeni strains suitable as starters for malolactic fermentation (MLF), using a reliable polyphasic approach. METHODS AND RESULTS Oenococcus oeni strains were isolated from Nero di Troia wines undergoing spontaneous MLF. Samples were taken at the end of alcoholic fermentation and during MLF. Wine samples were diluted in a sterile physiological solution and plated on MRS and on modified FT80. Identification of O. oeni strains was performed by a polymerase chain reaction (PCR) experiment using strain-specific primers. Strains were further grouped using a multiplex RAPD-PCR analysis. Then, six strains were inoculated in two winelike media with two different ethanol concentrations (11 and 13% vol / vol) with a view to evaluate their capacity to grow and to perform MLF. In addition, a quantitative PCR (qRT-PCR) approach was adapted to monitor the physiological state of the strains selected. CONCLUSION A positive correlation between the malolactic activity performance and the ability to develop and tolerate stress conditions was observed for two selected O. oeni strains. SIGNIFICANCE AND IMPACT OF THE STUDY The results reported are useful for the selection of indigenous MLF starter cultures with desired oenological traits from typical regional wines. It should be the base for the improvement in organoleptic quality of typical red wine.
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Affiliation(s)
- V Capozzi
- Dipartimento di Scienze degli Alimenti, Facoltà di Agraria, Foggia, Italy
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76
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Ritt JF, Remize F, Grandvalet C, Guzzo J, Atlan D, Alexandre H. Peptidases specific for proline-containing peptides and their unusual peptide-dependent regulation in Oenococcus oeni. J Appl Microbiol 2010; 106:801-13. [PMID: 19302100 DOI: 10.1111/j.1365-2672.2008.04032.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Growth of the lactic acid bacterium (LAB) Oenococcus oeni, which is involved in malolactic fermentation during the winemaking process, is stimulated by peptides originating from yeast. In this study, we investigated the impact of peptides on O. oeni growth, peptidase activity and the expression of genes encoding the studied peptidases. METHODS AND RESULTS Low levels of PepN activity and very high levels of PepI activity were observed in O. oeni, whereas levels of PepX activity were intermediate. The level of biosynthesis of these O. oeni peptidases was shown to depend on peptides present in the culture medium. These results were confirmed by transcriptional analyses of putative pep genes. The mechanism of repression by peptides did not involve a CodY-like regulator. CONCLUSIONS Peptides from yeast decrease the levels of enzymatic activity and relative gene expression of O. oeni peptidases. Peptidases specific for proline-containing peptides are important for O. oeni nitrogen metabolism. SIGNIFICANCE AND IMPACT OF THE STUDY We report here for the first time that the enzymes involved in the assimilation of proline-containing peptides by O. oeni differ from the well-described proteolytic system of milk LAB. This may reflect a specific adaptation to the wine environment.
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Affiliation(s)
- J-F Ritt
- Laboratoire de Recherche en Vigne et Vin, Institut Universitaire de la Vigne et du Vin Jules Guyot, Université de Bourgogne, Dijon, France
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77
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Quintero Y, Poblet M, Guillamón JM, Mas A. Quantification of the expression of reference and alcohol dehydrogenase genes of some acetic acid bacteria in different growth conditions. J Appl Microbiol 2010; 106:666-74. [PMID: 19200331 DOI: 10.1111/j.1365-2672.2008.04046.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AIMS The aim of this study was to develop a reliable system to analyse the expression of the pyrroloquinoline quinone (PQQ)-alcohol dehydrogenase (ADH) and test its ability to predict the growth and oxidative activity of some acetic acid bacteria (AAB). METHODS AND RESULTS Specific primers were designed for use in RT-PCR to quantify ADH expression and several housekeeping genes in four species of AAB. 16S rRNA gene was selected as an internal control. The relative expression of adhA was measured in Acetobacter aceti, Acetobacter pasteurianus, Gluconacetobacter hansenii and Gluconobacter oxydans grown in two media that had glucose or ethanol as the carbon source. AAB adhA expression was shown to be related to the two Acetobacter species' ability to oxidise and grow on ethanol, whereas G. oxydans were unable to grow on ethanol and the growth of Ga. hansenii was not related to adhA expression. CONCLUSIONS The differential expression of ADH could be a marker to analyse both growth and oxidation ability in some AAB, especially those of the genus Acetobacter. SIGNIFICANCE AND IMPACT OF THE STUDY Several housekeeping genes were tested in AAB and after growth in different media and it was evident that only the ribosomal coding genes were adequate as reference genes for RT-PCR.
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Affiliation(s)
- Y Quintero
- Grup de Recerca en Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia de Tarragona, Universitat Rovira i Virgili, Tarragona, Spain
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78
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Characterization of the CtsR stress response regulon in Lactobacillus plantarum. J Bacteriol 2009; 192:896-900. [PMID: 19933364 DOI: 10.1128/jb.01122-09] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus plantarum ctsR was characterized. ctsR was found to be cotranscribed with clpC and induced in response to various abiotic stresses. ctsR deletion conferred a heat-sensitive phenotype with peculiar cell morphological features. The transcriptional pattern of putative CtsR regulon genes was examined in the Delta ctsR mutant. Direct CtsR-dependent regulation was demonstrated by DNA-binding assays using recombinant CtsR and the promoters of the ctsR-clpC operon and hsp1.
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79
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Ells TC, Speers RA, Hansen LT. Insertional mutagenesis of Listeria monocytogenes 568 reveals genes that contribute to enhanced thermotolerance. Int J Food Microbiol 2009; 136:1-9. [PMID: 19836093 DOI: 10.1016/j.ijfoodmicro.2009.09.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 08/13/2009] [Accepted: 09/18/2009] [Indexed: 11/19/2022]
Abstract
The objectives of this study were to identify molecular mechanisms of thermotolerance using transposon mutants of Listeria monocytogenes 568, serotype 1/2a, and to compare their thermal death kinetics at 52, 56 and 60 degrees C. Sixteen Tn917 transposon mutants with enhanced heat resistance were acquired from a library of 4300 mutants following a multi-step screening process. Genetic regions with Tn917 insertions encompassed a broad range of functionalities including; transport, metabolism, replication and repair, general stress, and structural properties. Modeling of the heat inactivation data using the Geeraerd et al. and Whiting (Fermi) models showed that the mutants' enhanced thermal resistance was manifested mostly through a significant (p<or=0.05) extension of the lag period on the thermal death curve. This new knowledge impacts our understanding of molecular mechanisms affecting the kinetics of thermally induced cell death and enables the development of safer thermal processes.
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Affiliation(s)
- Timothy C Ells
- Agriculture and Agri-Food Canada, Atlantic Food and Horticulture Research Centre, Kentville, NS, Canada
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80
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Mathiesen G, Sveen A, Brurberg MB, Fredriksen L, Axelsson L, Eijsink VG. Genome-wide analysis of signal peptide functionality in Lactobacillus plantarum WCFS1. BMC Genomics 2009; 10:425. [PMID: 19744343 PMCID: PMC2748100 DOI: 10.1186/1471-2164-10-425] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 09/10/2009] [Indexed: 11/10/2022] Open
Abstract
Background Lactobacillus plantarum is a normal, potentially probiotic, inhabitant of the human gastrointestinal (GI) tract. The bacterium has great potential as food-grade cell factory and for in situ delivery of biomolecules. Since protein secretion is important both for probiotic activity and in biotechnological applications, we have carried out a genome-wide experimental study of signal peptide (SP) functionality. Results We have constructed a library of 76 Sec-type signal peptides from L. plantarum WCFS1 that were predicted to be cleaved by signal peptidase I. SP functionality was studied using staphylococcal nuclease (NucA) as a reporter protein. 82% of the SPs gave significant extracellular NucA activity. Levels of secreted NucA varied by a dramatic 1800-fold and this variation was shown not to be the result of different mRNA levels. For the best-performing SPs all produced NucA was detected in the culture supernatant, but the secretion efficiency decreased for the less well performing SPs. Sequence analyses of the SPs and their cognate proteins revealed four properties that correlated positively with SP performance for NucA: high hydrophobicity, the presence of a transmembrane helix predicted by TMHMM, the absence of an anchoring motif in the cognate protein, and the length of the H+C domain. Analysis of a subset of SPs with a lactobacillal amylase (AmyA) showed large variation in production levels and secretion efficiencies. Importantly, there was no correlation between SP performance with NucA and the performance with AmyA. Conclusion This is the first comprehensive experimental study showing that predicted SPs in the L. plantarum genome actually are capable of driving protein secretion. The results reveal considerable variation between the SPs that is at least in part dependent on the protein that is secreted. Several SPs stand out as promising candidates for efficient secretion of heterologous proteins in L. plantarum. The results for NucA provide some hints as to the sequence-based prediction of SP functionality, but the general conclusion is that such prediction is difficult. The vector library generated in this study is based on exchangeable cassettes and provides a powerful tool for rapid experimental screening of SPs.
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Affiliation(s)
- Geir Mathiesen
- Norwegian University of Life Sciences, Center for Molecular Microbiology, Department of Chemistry Biotechnology and Food Science, Chr. M. Falsensvei 1, P.O. Box 5003, N-1432 As, Norway.
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81
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Rieu A, Guzzo J, Piveteau P. Sensitivity to acetic acid, ability to colonize abiotic surfaces and virulence potential of Listeria monocytogenes EGD-e after incubation on parsley leaves. J Appl Microbiol 2009; 108:560-70. [PMID: 19778346 DOI: 10.1111/j.1365-2672.2009.04463.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To investigate how the survival of Listeria monocytogenes on parsley leaves may affect its ability to sustain process-related harsh conditions and its virulence. METHODS AND RESULTS Parsley seedlings were spot inoculated with stationary phase cells of L. monocytogenes EGD-e and incubated for 15 days. Each day, bacterial cells were harvested and enumerated, and their ability to survive acetic acid challenge (90 min, pH 4.0), to colonize abiotic surfaces and to grow as biofilms was assessed. After a 3-log decrease over the first 48 h, the population stabilized to about 10(6) CFU g(-1) until the sixth day. After the sixth day, L. monocytogenes was no longer detected, even after specific enrichment. Incubation on parsley leaves affected the ability of L. monocytogenes to survive acetic acid challenge (90 min, pH 4.0) and to adhere to stainless steel although the ability to grow as biofilm was preserved. To further investigate these physiological alterations, the mRNA levels of six target genes (bsh, clpC, groEL, inlA, opuC, prfA) was quantified using reverse transcription qPCR after 5 h of incubation on parsley leaves. A decrease was observed in all but one (bsh) target, including groEL and clpC which are involved in resistance to salt and acid. Moreover, the decrease in the levels of inlA, prfA and opuC transcripts after incubation on parsley suggested a repression of some genes involved in pathogenicity. In vitro assessment of mammalian cell adherence and invasion using Caco-2 cells confirmed the repression of the virulence factor InlA; however, the virulence potential in vivo in the chick embryo model was not affected. CONCLUSION Listeria monocytogenes did undergo rapid changes to adapt its physiology to the phyllosphere. SIGNIFICANCE AND IMPACT OF THE STUDY This study highlights the physiological changes undergone by L. monocytogenes during/after survival on parsley leaves.
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Affiliation(s)
- A Rieu
- Laboratoire de Recherche En Vigne et Vin REVV, Université de Bourgogne, IUVV, Dijon, France
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82
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Linares DM, Fernández M, Martín MC, Alvarez MA. Tyramine biosynthesis in Enterococcus durans is transcriptionally regulated by the extracellular pH and tyrosine concentration. Microb Biotechnol 2009; 2:625-33. [PMID: 21255297 PMCID: PMC3815318 DOI: 10.1111/j.1751-7915.2009.00117.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The microbial decarboxylation of some amino acids leads to the undesirable presence of biogenic amines in foods. One of the most abundant and frequent biogenic amines found in fermented foods is tyramine, which is produced by the decarboxylation of tyrosine. In the present work, transcriptional analysis of tyramine biosynthesis in Enterococcus durans IPLA655, a strain isolated from cheese, was studied. The gene coding for the tyrosine decarboxylase (tdcA) and that coding for the tyrosine-tyramine antiporter (tyrP) form an operon transcribed from the promoter P(tdcA), the expression of which is regulated by the extracellular pH and tyrosine concentration. Quantification of gene expression during the log phase of growth showed high concentrations of tyrosine and acidic pH conditions to induce tdcA-tyrP polycistronic messenger transcription.
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Affiliation(s)
- Daniel M Linares
- Instituto de Productos Lácteos de Asturias (IPLA), Consejo Superior de Investigaciones Científicas (CSIC), Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain
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83
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Bon E, Delaherche A, Bilhère E, De Daruvar A, Lonvaud-Funel A, Le Marrec C. Oenococcus oeni genome plasticity is associated with fitness. Appl Environ Microbiol 2009; 75:2079-90. [PMID: 19218413 PMCID: PMC2663225 DOI: 10.1128/aem.02194-08] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 02/02/2009] [Indexed: 12/19/2022] Open
Abstract
Oenococcus oeni strains are well-known for their considerable phenotypic variations in terms of tolerance to harsh wine conditions and malolactic activity. Genomic subtractive hybridization (SH) between two isolates with differing enological potentials was used to elucidate the genetic bases of this intraspecies diversity and identify novel genes involved in adaptation to wine. SH revealed 182 tester-specific fragments corresponding to 126 open reading frames (ORFs). A large proportion of the chromosome-related ORFs resembled genes involved in carbohydrate transport and metabolism, cell wall/membrane/envelope biogenesis, and replication, recombination, and repair. Six regions of genomic plasticity were identified, and their analysis suggested that both limited recombination and insertion/deletion events contributed to the vast genomic diversity observed in O. oeni. The association of selected sequences with adaptation to wine was further assessed by screening a large collection of strains using PCR. No sequences were found to be specific to highly performing (HP) strains alone. However, there was a statistically significant positive association between HP strains and the presence of eight gene sequences located on regions 2, 4, and 5. Gene expression patterns were significantly modified in HP strains, following exposure to one or more of the common stresses in wines. Regions 2 and 5 showed no traces of mobile elements and had normal GC content. In contrast, region 4 had the typical hallmarks of horizontal transfer, suggesting that the strategy of acquiring genes from other bacteria enhances the fitness of O. oeni strains.
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84
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The Lactobacillus plantarum ftsH gene is a novel member of the CtsR stress response regulon. J Bacteriol 2008; 191:1688-94. [PMID: 19074391 DOI: 10.1128/jb.01551-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FtsH proteins have dual chaperone-protease activities and are involved in protein quality control under stress conditions. Although the functional role of FtsH proteins has been clearly established, the regulatory mechanisms controlling ftsH expression in gram-positive bacteria remain largely unknown. Here we show that ftsH of Lactobacillus plantarum WCFS1 is transiently induced at the transcriptional level upon a temperature upshift. In addition, disruption of ftsH negatively affected the growth of L. plantarum at high temperatures. Sequence analysis and mapping of the ftsH transcriptional start site revealed a potential operator sequence for the CtsR repressor, partially overlapping the -35 sequence of the ftsH promoter. In order to verify whether CtsR is able to recognize and bind the ftsH promoter, CtsR proteins of Bacillus subtilis and L. plantarum were overproduced, purified, and used in DNA binding assays. CtsR from both species bound specifically to the ftsH promoter, generating a single protein-DNA complex, suggesting that CtsR may control the expression of L. plantarum ftsH. In order to confirm this hypothesis, a DeltactsR mutant strain of L. plantarum was generated. Expression of ftsH in the DeltactsR mutant strain was strongly upregulated, indicating that ftsH of L. plantarum is negatively controlled by CtsR. This is the first example of an ftsH gene controlled by the CtsR repressor, and the first of the low-G+C gram-positive bacteria where the regulatory mechanism has been identified.
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85
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Ritz M, Garenaux A, Berge M, Federighi M. Determination of rpoA as the most suitable internal control to study stress response in C. jejuni by RT-qPCR and application to oxidative stress. J Microbiol Methods 2008; 76:196-200. [PMID: 19041906 DOI: 10.1016/j.mimet.2008.10.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 10/15/2008] [Accepted: 10/22/2008] [Indexed: 10/21/2022]
Abstract
Campylobacter jejuni represents one of the major causes of bacterial enteritis caused by food in humans. There are still mechanisms to be deciphered to better understand better its physiology and pathogenesis. Study of gene expression levels by RT-qPCR could be used, but to be accurate and reproducible, a good internal control has to be chosen. The aim of this study was to identify a highly stable housekeeping gene in Campylobacter jejuni that could constitute a good internal control to study gene expression variations between different growth phases or stress conditions. Expression levels of six different housekeeping genes (gyrA, ilvC, rpoA, slyD, thiC and rrs) were measured by RT-qPCR under different conditions (exponential phase, stationary phase, cold shock, cold shock+oxidative stress, oxidative stress). The rpoA gene was chosen as the best internal control. In a previous study, 9 proteins were identified as involved in oxidative stress response, among which 3 virulence factors. Expression levels of genes coding for these proteins was evaluated by RT-qPCR using rpoA as an internal control. The results obtained were concordant with what had been observed at the proteomic level, validating the methods used and confirming the hypothesis of a potential link between oxidative stress and virulence factors expression.
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Affiliation(s)
- M Ritz
- UMR-INRA 1014, Sécurité des Aliments, Ecole Nationale Vétérinaire de Nantes, Nantes cedex 03, France
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86
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Influence of ethanol and pH on the gene expression of the citrate pathway in Oenococcus oeni. Food Microbiol 2008; 26:197-203. [PMID: 19171263 DOI: 10.1016/j.fm.2008.09.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 09/02/2008] [Accepted: 09/03/2008] [Indexed: 11/21/2022]
Abstract
The consumption of citrate by the malolactic bacterium Oenococcus oeni changes the aromatic profile of wines due to the production of volatile compounds such as diacetyl and acetic acid. In this study, the expression of genes related to citrate utilization in the O. oeni strain PSU-1 was investigated to further understand the role of this metabolic pathway in the adaptation to wine environment and its impact on organoleptic qualities. Different conditions of ethanol content (0% and 10%) and pH (3.5 and 4.0) were assayed to evaluate the transcriptional response to both these stress factors. In the presence of ethanol, metabolic and transcriptional behavior was different than the observed when ethanol was absent. The expression of citrate pathway genes was mainly affected by ethanol, while pH showed a lower effect. Among the studied genes, citE, ackA and alsD were the genes revealing a distinctive transcriptional response. The differences observed in gene expression were in correlation with the different content of end products such as acetic acid and diacetyl. The increment of gene expression observed in the presence of ethanol at low pH suggests the participation of citrate metabolism in the response to stress conditions.
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87
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Grandvalet C, Assad-García JS, Chu-Ky S, Tollot M, Guzzo J, Gresti J, Tourdot-Maréchal R. Changes in membrane lipid composition in ethanol- and acid-adapted Oenococcus oeni cells: characterization of the cfa gene by heterologous complementation. Microbiology (Reading) 2008; 154:2611-2619. [DOI: 10.1099/mic.0.2007/016238-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Cosette Grandvalet
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
| | - Juan Simón Assad-García
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
| | - Son Chu-Ky
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
| | - Marie Tollot
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
| | - Jean Guzzo
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
| | - Joseph Gresti
- UMR 866 Equipe Physiopathologie des Dyslipidémies, Faculté des Sciences Gabriel, 6, Bd Gabriel, F-21000 Dijon, France
| | - Raphaëlle Tourdot-Maréchal
- Laboratoire Recherche en Vigne et Vin, Université de Bourgogne, Institut Universitaire de la Vigne et du Vin Jules Guyot, 1, Rue Claude Ladrey – Campus Montmuzard, BP27877, F-21078 Dijon, France
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88
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Heme uptake by Microscilla marina and evidence for heme uptake systems in the genomes of diverse marine bacteria. Appl Environ Microbiol 2008; 74:6263-70. [PMID: 18757577 DOI: 10.1128/aem.00964-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability to acquire diverse and abundant forms of iron would be expected to confer a survival advantage in the marine environment, where iron is scarce. Marine bacteria are known to use siderophores and inorganic iron, but their ability to use heme, an abundant intracellular iron form, has only been examined preliminarily. Microscilla marina, a cultured relative of a bacterial group frequently found on marine particulates, was used as a model organism to examine heme uptake. Searches of the genome revealed analogs to known heme transport proteins, and reverse transcription-quantitative PCR analysis of these genes showed that they were expressed and upregulated under iron stress and during growth on heme. M. marina was found to take up heme-bound iron and could grow on heme as a sole iron source, supporting the genetic evidence for heme transport. Similar putative heme transport components were identified in the genomes of diverse marine bacteria. These systems were found in the genomes of many bacteria thought to be particle associated but were lacking in known free-living organisms (e.g., Pelagibacter ubique and marine cyanobacteria). This distribution of transporters is consistent with the hydrophobic, light-sensitive nature of heme, suggesting that it is primarily available on phytoplankton or detritus or in nutrient-rich environments.
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89
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Dols-Lafargue M, Lee HY, Le Marrec C, Heyraud A, Chambat G, Lonvaud-Funel A. Characterization of gtf, a glucosyltransferase gene in the genomes of Pediococcus parvulus and Oenococcus oeni, two bacterial species commonly found in wine. Appl Environ Microbiol 2008; 74:4079-90. [PMID: 18469121 PMCID: PMC2446535 DOI: 10.1128/aem.00673-08] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Accepted: 05/01/2008] [Indexed: 11/20/2022] Open
Abstract
"Ropiness" is a bacterial alteration in wines, beers, and ciders, caused by beta-glucan-synthesizing pediococci. A single glucosyltransferase, Gtf, controls ropy polysaccharide synthesis. In this study, we show that the corresponding gtf gene is also present on the chromosomes of several strains of Oenococcus oeni isolated from nonropy wines. gtf is surrounded by mobile elements that may be implicated in its integration into the chromosome of O. oeni. gtf is expressed in all the gtf(+) strains, and beta-glucan is detected in the majority of these strains. Part of this beta-glucan accumulates around the cells forming a capsule, while the other part is liberated into the medium together with heteropolysaccharides. Most of the time, this polymer excretion does not lead to ropiness in a model medium. In addition, we show that wild or recombinant bacterial strains harboring a functional gtf gene (gtf(+)) are more resistant to several stresses occurring in wine (alcohol, pH, and SO(2)) and exhibit increased adhesion capacities compared to their gtf mutant variants.
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Affiliation(s)
- Marguerite Dols-Lafargue
- UMR 1219 Oenologie, LBMA, Université Victor Segalen Bordeaux 2, INRA, ISVV, 351 cours de la Libération, 33405 Talence, France.
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90
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Calvez S, Prevost H, Drider D. Relative expression of genes involved in the resistance/sensitivity of Enterococcus faecalis JH2-2 to recombinant divercin RV41. Biotechnol Lett 2008; 30:1795-800. [PMID: 18563584 DOI: 10.1007/s10529-008-9752-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 05/06/2008] [Accepted: 05/08/2008] [Indexed: 11/30/2022]
Abstract
The relative expression of mptABCD operon, glpQ, pde, rpoN, mptR and gap-1 was studied by reverse transcription combined with the real time polymerase chain reaction to understand the role of each gene in resistance/sensitivity of Enterococcus faecalis to class IIa bacteriocins such as recombinant divercin V41 (DvnRV41). Comparative critical threshold methods in presence or absence of DvnRV41 were then used to determine the level of expression of each gene cited above. In the presence of DvnRV41, the rpoN and glpQ genes were down-regulated, mptR, mptC, gap-1 and pde genes were up-regulated, whilst expression of mptB and mptD genes remained unmodified.
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Affiliation(s)
- Ségolène Calvez
- Laboratoire de Microbiologie, ENITIAA, Rue de la Géraudière, BP 82225, 44322 Nantes Cedex 3, France
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91
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Granger M, van Reenen CA, Dicks LMT. Effect of gastro-intestinal conditions on the growth of Enterococcus mundtii ST4SA, and production of bacteriocin ST4SA recorded by real-time PCR. Int J Food Microbiol 2008; 123:277-80. [PMID: 18234384 DOI: 10.1016/j.ijfoodmicro.2007.12.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 11/22/2007] [Accepted: 12/18/2007] [Indexed: 11/30/2022]
Abstract
Enterococcus mundtii ST4SA, isolated from soybeans, produces a 3950 Da bacteriocin (bacST4SA) active against a variety of Gram-positive and Gram-negative bacteria, including human pathogens. In this study, the effect of gastro-intestinal conditions on the survival of strain ST4SA and production of bacST4SA was studied. Strain ST4SA was cultured in MRS broth at different pH and in MRS broth supplemented with bile, pancreatic enzymes, and contents of the stomach and small intestine of pigs, respectively. After 12 and 24 h at 37 degrees C, cells were harvested, RNA isolated and cDNA prepared. Expression of the genes encoding bacST4SA, RecA, GroES and 23 S rRNA was studied by real-time PCR (RT-PCR). No significant up- or down-regulation of the genes were recorded, except when cells were grown in MRS at pH 3.5. In this case only RecA and GroES were up-regulated. Growth of strain ST4SA and production of bacST4SA are not affected by conditions in the lower intestine and the strain could be used as a probiotic.
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Affiliation(s)
- M Granger
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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92
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Leukotoxin operon and differential expressions of the leukotoxin gene in bovine Fusobacterium necrophorum subspecies. Anaerobe 2008; 14:13-8. [DOI: 10.1016/j.anaerobe.2007.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 09/14/2007] [Indexed: 11/19/2022]
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93
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Validation of an internal control gene to apply reverse transcription quantitative PCR to study heat, cold and ethanol stresses in Lactobacillus plantarum. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9556-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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94
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Rieu A, Weidmann S, Garmyn D, Piveteau P, Guzzo J. Agr system of Listeria monocytogenes EGD-e: role in adherence and differential expression pattern. Appl Environ Microbiol 2007; 73:6125-33. [PMID: 17675424 PMCID: PMC2075002 DOI: 10.1128/aem.00608-07] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In this study, we investigated the agrBDCA operon in the pathogenic bacterium Listeria monocytogenes EGD-e. In-frame deletion of agrA and agrD resulted in an altered adherence and biofilm formation on abiotic surfaces, suggesting the involvement of the agr system of L. monocytogenes during the early stages of biofilm formation. Real-time PCR experiments indicated that the transcript levels of agrBDCA depended on the stage of biofilm development, since the levels were lower after the initial attachment period than during biofilm growth, whereas transcription during planktonic growth was not growth phase dependent. The mRNA quantification data also suggested that the agr system was autoregulated and pointed to a differential expression of the agr genes during sessile and planktonic growth. Although the reverse transcription-PCR experiments revealed that the four genes were transcribed as a single messenger, chemical half-life and 5' RACE (rapid amplification of cDNA ends) experiments indicated that the full size transcript underwent cleavage followed by degradation of the agrC and agrA transcripts, which suggests a complex regulation of agr transcription.
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Affiliation(s)
- Aurélie Rieu
- UMR 1229 Microbiologie du Sol et de l'Environnement, Université de Bourgogne, INRA, F-21000 Dijon, France
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95
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Theis T, Skurray RA, Brown MH. Identification of suitable internal controls to study expression of a Staphylococcus aureus multidrug resistance system by quantitative real-time PCR. J Microbiol Methods 2007; 70:355-62. [PMID: 17590462 DOI: 10.1016/j.mimet.2007.05.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 05/02/2007] [Accepted: 05/22/2007] [Indexed: 11/26/2022]
Abstract
Quantitative real-time PCR (qRT-PCR) has become a routine technique for gene expression analysis. Housekeeping genes are customarily used as endogenous references for the relative quantification of genes of interest. The aim of this study was to develop a quantitative real-time PCR assay to analyze gene expression in multidrug resistant Staphylococcus aureus in the presence of cationic lipophilic substrates of multidrug transport proteins. Eleven different housekeeping genes were analyzed for their expression stability in the presence of a range of concentrations of four structurally different antimicrobial compounds. This analysis demonstrated that the genes rho, pyk and proC were least affected by rhodamine 6G and crystal violet, whereas fabD, tpiA and gyrA or fabD, proC and pyk were stably expressed in cultures grown in the presence of ethidium or berberine, respectively. Subsequently, these housekeeping genes were used as internal controls to analyze expression of the multidrug transport protein QacA and its transcriptional regulator QacR in the presence of the aforementioned compounds. Expression of qacA was induced by all four compounds, whereas qacR expression was found to be unaffected, reduced or enhanced. This study demonstrates that staphylococcal gene expression, including housekeeping genes previously used to normalize qRT-PCR data, is affected by growth in the presence of different antimicrobial compounds. Thus, identification of suitable genes usable as a control set requires rigorous testing. Identification of a such a set enabled them to be utilized as internal standards for accurate quantification of transcripts of the qac multidrug resistance system from S. aureus grown under different inducing conditions. Moreover, the qRT-PCR assay presented in this study may also be applied to gene expression studies of other multidrug transporters from S. aureus.
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Affiliation(s)
- Torsten Theis
- School of Biological Sciences A12, University of Sydney, Sydney, NSW, Australia
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96
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Augagneur Y, Ritt JF, Linares DM, Remize F, Tourdot-Maréchal R, Garmyn D, Guzzo J. Dual effect of organic acids as a function of external pH in Oenococcus oeni. Arch Microbiol 2007; 188:147-57. [PMID: 17406856 DOI: 10.1007/s00203-007-0230-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 02/28/2007] [Accepted: 03/01/2007] [Indexed: 10/23/2022]
Abstract
In this study we analyzed under various pH conditions including low pH, the effects of L-malic acid and citric acid, combined or not, on the growth, the proton motive force components and the transcription level of selected genes of the heterolactic bacterium Oenococcus oeni. It is shown here that L-malate enhanced the growth yield at pH equal or below 4.5 while the presence of citrate in media led to a complete and unexpected inhibition of the growth at pH 3.2. Nevertheless, whatever the growth conditions, both L-malate and citrate participated in the enhancement of the transmembrane pH gradient, whereas the membrane potential decreased with the pH. These results suggested that it was not citrate that was directly responsible for the inhibition observed in cultures done at low pH, but probably its end products. This was confirmed since, in media containing L-malate, the addition of acetate substantially impaired the growth rate of the bacterium and slightly the membrane potential and pH gradient. Finally, study of the expression of genes involved in the metabolism of organic acids showed that at pH 4.5 and 3.2 the presence of L-malate led to an increased amount of mRNA of mleP encoding a malate transporter.
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Affiliation(s)
- Yoann Augagneur
- Laboratoire de Microbiologie, UMR UB/INRA 1232, ENSBANA, Université de Bourgogne, 1 Esplanade Erasme, 21000, Dijon, France
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97
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Ramiah K, van Reenen CA, Dicks LMT. Expression of the mucus adhesion genes Mub and MapA, adhesion-like factor EF-Tu and bacteriocin gene plaA of Lactobacillus plantarum 423, monitored with real-time PCR. Int J Food Microbiol 2007; 116:405-9. [PMID: 17399831 DOI: 10.1016/j.ijfoodmicro.2007.02.011] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 11/27/2006] [Accepted: 02/27/2007] [Indexed: 11/29/2022]
Abstract
Expression of the mucus adhesion genes Mub and MapA, adhesion-like factor EF-Tu and bacteriocin gene plaA by Lactobacillus plantarum 423, grown in the presence of bile, pancreatin and at low pH, was studied by real-time PCR. Mub, MapA and EF-Tu were up-regulated in the presence of mucus, proportional to increasing concentrations. Expression of MapA was up-regulated in the presence of 3.0 g/l bile and 3.0 g/l pancreatin at pH 6.5. Similar results were recorded in the presence of 10.0 g/l bile and 10.0 g/l pancreatin at pH 6.5. Expression of Mub was down-regulated in the presence of bile and pancreatin, whilst the expression of EF-Tu and plaA remained unchanged. Expression of Mub and MapA remained unchanged at pH 4.0, whilst expression of EF-Tu and plaA were up-regulated. Expression of MapA was down-regulated in the presence of 1.0 g/l l-cysteine HCl, suggesting that the gene is regulated by transcription attenuation that involves cysteine.
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Affiliation(s)
- K Ramiah
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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98
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Beltramo C, Desroche N, Tourdot-Maréchal R, Grandvalet C, Guzzo J. Real-time PCR for characterizing the stress response of Oenococcus oeni in a wine-like medium. Res Microbiol 2006; 157:267-74. [PMID: 16171980 DOI: 10.1016/j.resmic.2005.07.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 07/01/2005] [Accepted: 07/11/2005] [Indexed: 10/25/2022]
Abstract
The tolerance of the lactic acid bacterium Oenococcus oeni to hostile wine conditions is essential for the success of malolactic fermentation (MLF). In this study, reverse transcription quantitative PCR (RT-qPCR) was used to quantify the transcript level of 13 genes that could play a role in adaptation of O. oeni in wine. To optimize survival and growth in wine, cells were adapted during growth at low pH (3.5) prior to inoculation into wine. The level of gene expression was analyzed after growth at pH 3.5 in a rich medium and during MLF in a wine-like medium. RT-qPCR analyses exhibited different expression ratios of stress genes. The data obtained showed that determination of mRNA levels could constitute a new approach to studying the stress response of O. oeni after adaptation at low pH and during growth in a wine-like medium.
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99
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Schwab C, Gänzle MG. Effect of membrane lateral pressure on the expression of fructosyltransferases in Lactobacillus reuteri. Syst Appl Microbiol 2006; 29:89-99. [PMID: 16464690 DOI: 10.1016/j.syapm.2005.09.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Indexed: 11/28/2022]
Abstract
The effect of environmental conditions on the production of homo-polysaccharides and oligosaccharides from sucrose and the regulation of glycosyltransferase genes responsible for biosynthesis of homo-polysaccharides was determined in Lactobacillus reuteri TMW1.106 (reutericyclin-producer) and LTH5448 (reutericyclin-negative). Strain L. reuteri TMW 1.106 harbours the glycosyltransferase genes gtfA and inu, strain LTH5448 harbours a fructosyltransferase, ftfA. Fructan and fructose-oligosaccharide (FOS) production in both strains was inducible by reutericyclin, trans-isohumulone, and nigericin at the levels of their minimum inhibitory concentrations (MIC) as well as phenylethanol (6mM) and elevated growth temperatures (45 degrees C), but not by nisin, CCCP or gramicidin. Elevated temperature (45 degrees C), reutericyclin or trans-isohumulone but not CCCP furthermore increased enhanced inu and ftfA transcription in L. reuteri TMW1.106 and LTH5448, respectively. Generally, effects of the various agents on fructosyltransferase transcription corresponded to their effect on formation of poly and oligosaccharides from sucrose. The effect of membrane-active agents on fructosyltransferase expression was compared to their effect on membrane biophysical parameters. The ability of chemical and physical agents to induce expression of fructosyltransferases correlated to their effect on the membrane lateral pressure as measured by pyrene-labelled phospholipids in membrane vesicles. Dextran, levan and fructose-oligosaccharides added at 50gL(-1) protected L. reuteri towards the membrane-active inhibitors nisin, reutericyclin, and CCCP. The induction of glycosyltransferases by membrane stress indicates a protective role of fructans and FOS to lactobacilli exposed to physical and chemical environmental stressors.
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Affiliation(s)
- Clarissa Schwab
- TU München, Lehrstuhl Technische Mikrobiologie, D-85350 Freising, Germany
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100
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Vermeulen N, Pavlovic M, Ehrmann MA, Gänzle MG, Vogel RF. Functional characterization of the proteolytic system of Lactobacillus sanfranciscensis DSM 20451T during growth in sourdough. Appl Environ Microbiol 2005; 71:6260-6. [PMID: 16204547 PMCID: PMC1266010 DOI: 10.1128/aem.71.10.6260-6266.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein hydrolysis and amino acid metabolism contribute to the beneficial effects of sourdough fermentation on bread quality. In this work, genes of Lactobacillus sanfranciscensis strain DSM 20451 involved in peptide uptake and hydrolysis were identified and their expression during growth in sourdough was determined. Screening of the L. sanfranciscensis genome with degenerate primers targeting prt and analysis of proteolytic activity in vitro provided no indication for proteolytic activity. Proteolysis in aseptic doughs and sourdoughs fermented with L. sanfranciscensis was inhibited upon the addition of an aspartic protease inhibitor. These results indicate that proteolysis was not linked to the presence of L. sanfranciscensis DSM 20451 and that this strain does not harbor a proteinase. Genes encoding the peptide transport systems Opp and DtpT and the intracellular peptidases PepT, PepR, PepC, PepN, and PepX were identified. Both peptide uptake systems and the genes pepN, pepX, pepC, and pepT were expressed by L. sanfranciscensis growing exponentially in sourdough, whereas pepX was not transcribed. The regulation of the expression of Opp, DtpT, and PepT during growth of L. sanfranciscensis in sourdough was investigated. Expression of Opp and DtpT was reduced approximately 17-fold when the peptide supply in dough was increased. The expression of PepT was dependent on the peptide supply to a lesser extent. Thus, the accumulation of amino nitrogen by L. sanfranciscensis in dough is attributable to peptide hydrolysis rather than proteolysis and amino acid metabolism by L. sanfranciscensis during growth in sourdough is limited by the peptide availability.
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Affiliation(s)
- Nicoline Vermeulen
- Food Microbiology and Probiotics, Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
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