Characterization of Simultaneous Uptake of Xylose and Glucose in Caldicellulosiruptor Kronotskyensis for Optimal Hydrogen Production

Abstract BackgroundCaldicellulosiruptor kronotskyensis has gained interest for its ability to grow on various lignocellulosic biomass. The aim of this study was to investigate the growth profiles of C . kronotskyensis in the presence of mixtures of glucose-xylose. Recently, we characterized a diauxic-like pattern for C. saccharolyticus on lignocellulosic sugar mixtures. In this study we aimed to investigated further whether C . kronotskyensis has adapted to uptake glucose in the disaccharide form (cellobiose) rather than the monosaccharide (glucose). ResultsInterestingly, growth of C . kronotskyensis on glucose and xylose mixtures did not display diauxic-like growth patterns. Closer investigation revealed that, in contrast to C. saccharolyticus , C . kronotskyensis does not possess a second uptake system for glucose. Both C. saccharolyticus and C . kronotskyensis share the characteristics of preferring xylose over glucose. Growth on xylose was twice as fast (μ max = 0.57 h -1 ) as on glucose (μ max = 0.28 h -1 ). It was found that C . kronotskyensis takes up glucose and xylose simultaneously with the same transporter. A study of the sugar uptake was made with different glucose-xylose ratios to find a kinetic relationship between the two sugars for transport into the cell. High concentrations of glucose inhibited xylose uptake and vice versa. The inhibition constants were estimated to be K I,glu = 0.01 cmol·L -1 and K I,xyl = 0.001 cmol·L -1 , hence glucose uptake was more severely inhibited by xylose uptake. Bioinformatic analysis indicated the lack of another sugar uptake system in C . kronotskyensis as compared to C. saccharolyticus . Therefore, it was investigated whether glucose uptake by C . kronotskyensis was in the form of cellobiose. Indeed, cellobiose is taken up faster than glucose, nevertheless, the growth rate on each sugar remained similar. ConclusionsC . kronotskyensis possesses a xylose transporter that might take up glucose at an inferior rate even in the absence of xylose. Alternatively, glucose can be taken up in the form of cellobiose, but growth performance is still inferior to growth on xylose. Therefore, we propose that the catabolism of C . kronotskyensis has adapted more strongly to pentose rather than hexose thereby having obtained a specific survival edge in thermophilic lignocellulosic degradation communities.

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Characterization of simultaneous uptake of xylose and glucose in Caldicellulosiruptor kronotskyensis for optimal hydrogen production

Biotechnology for Biofuels ◽

10.1186/s13068-021-01938-6 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Thitiwut Vongkampang ◽

Krishnan Sreenivas ◽

Jonathan Engvall ◽

Carl Grey ◽

Ed W. J. van Niel

Keyword(s):

Glucose Uptake ◽

Growth Patterns ◽

Sugar Uptake ◽

Uptake System ◽

Sugar Mixtures ◽

Xylose Uptake ◽

Growth Profiles ◽

High Concentrations ◽

Xylose Transporter

Abstract Background Caldicellulosiruptor kronotskyensis has gained interest for its ability to grow on various lignocellulosic biomass. The aim of this study was to investigate the growth profiles of C. kronotskyensis in the presence of mixtures of glucose–xylose. Recently, we characterized a diauxic-like pattern for C. saccharolyticus on lignocellulosic sugar mixtures. In this study, we aimed to investigate further whether C. kronotskyensis has adapted to uptake glucose in the disaccharide form (cellobiose) rather than the monosaccharide (glucose). Results Interestingly, growth of C. kronotskyensis on glucose and xylose mixtures did not display diauxic-like growth patterns. Closer investigation revealed that, in contrast to C. saccharolyticus, C. kronotskyensis does not possess a second uptake system for glucose. Both C. saccharolyticus and C. kronotskyensis share the characteristics of preferring xylose over glucose. Growth on xylose was twice as fast (μmax = 0.57 h−1) as on glucose (μmax = 0.28 h−1). A study of the sugar uptake was made with different glucose–xylose ratios to find a kinetic relationship between the two sugars for transport into the cell. High concentrations of glucose inhibited xylose uptake and vice versa. The inhibition constants were estimated to be KI,glu = 0.01 cmol L−1 and KI,xyl = 0.001 cmol L−1, hence glucose uptake was more severely inhibited by xylose uptake. Bioinformatics analysis could not exclude that C. kronotskyensis possesses more than one transporter for glucose. As a next step it was investigated whether glucose uptake by C. kronotskyensis improved in the form of cellobiose. Indeed, cellobiose is taken up faster than glucose; nevertheless, the growth rate on each sugar remained similar. Conclusions C. kronotskyensis possesses a xylose transporter that might take up glucose at an inferior rate even in the absence of xylose. Alternatively, glucose can be taken up in the form of cellobiose, but growth performance is still inferior to growth on xylose. Therefore, we propose that the catabolism of C. kronotskyensis has adapted more strongly to pentose rather than hexose, thereby having obtained a specific survival edge in thermophilic lignocellulosic degradation communities.

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Characterization of an ATP Translocase Identified in the Destructive Plant Pathogen “Candidatus Liberibacter asiaticus”

Journal of Bacteriology ◽

10.1128/jb.01279-09 ◽

2009 ◽

Vol 192 (3) ◽

pp. 834-840 ◽

Cited By ~ 32

Author(s):

Cheryl M. Vahling ◽

Yongping Duan ◽

Hong Lin

Keyword(s):

Plant Pathogen ◽

Bioinformatic Analysis ◽

Intracellular Bacteria ◽

Cell Competition ◽

Candidatus Liberibacter ◽

Citrus Huanglongbing ◽

Liberibacter Asiaticus ◽

High Concentrations ◽

Obligate Intracellular Bacteria

ABSTRACT ATP/ADP translocases transport ATP across a lipid bilayer, which is normally impermeable to this molecule due to its size and charge. These transport proteins appear to be unique to mitochondria, plant plastids, and obligate intracellular bacteria. All bacterial ATP/ADP translocases characterized thus far have been found in endosymbionts of protozoa or pathogens of higher-order animals, including humans. A putative ATP/ADP translocase was uncovered during the genomic sequencing of the intracellular plant pathogen “Candidatus Liberibacter asiaticus,” the causal agent of citrus huanglongbing. Bioinformatic analysis of the protein revealed 12 transmembrane helices and predicted an isoelectric point of 9.4, both of which are characteristic of this family of proteins. The “Ca. Liberibacter asiaticus” gene (nttA) encoding the translocase was subsequently expressed in Escherichia coli and shown to enable E. coli to import ATP directly into the cell. Competition assays with the heterologous E. coli system demonstrated that the translocase was highly specific for ATP and ADP but that other nucleotides, if present in high concentrations, could also be taken up and/or block the ability of the translocase to import ATP. In addition, a protein homologous to NttA was identified in “Ca. Liberibacter solanacearum,” the bacterium associated with potato zebra chip disease. This is the first reported characterization of an ATP translocase from “Ca. Liberibacter asiaticus,” indicating that some intracellular bacteria of plants also have the potential to import ATP directly from their environment.

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Characterization of sugar uptake in wild-type Streptomyces clavuligerus, which is impaired in glucose uptake, and in a glucose-utilizing mutant.

Journal of Bacteriology ◽

10.1128/jb.171.12.6808-6814.1989 ◽

1989 ◽

Vol 171 (12) ◽

pp. 6808-6814 ◽

Cited By ~ 21

Author(s):

M Garcia-Dominguez ◽

J F Martin ◽

P Liras

Keyword(s):

Glucose Uptake ◽

Streptomyces Clavuligerus ◽

Sugar Uptake ◽

Wild Type

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Zinc Import Mediated by AdcABC is Critical for Colonization of the Dental Biofilm by Streptococcus mutans in an Animal Model

10.1101/2021.01.22.427828 ◽

2021 ◽

Author(s):

Tridib Ganguly ◽

Alexandra M. Peterson ◽

Jessica K. Kajfasz ◽

Jacqueline Abranches ◽

José A. Lemos

Keyword(s):

Trace Metals ◽

Metal Binding ◽

Pathogenic Bacteria ◽

Bioinformatic Analysis ◽

Preliminary Evidence ◽

Infection Model ◽

Limiting Factor ◽

Uptake System ◽

Dental Biofilm ◽

High Concentrations

SummaryTrace metals are essential to all domains of life but toxic when found at high concentrations. While the importance of iron in host-pathogen interactions is firmly established, contemporary studies indicate that other trace metals, including manganese and zinc, are also critical to the infectious process. In this study, we sought to identify and characterize the zinc uptake system(s) of S. mutans, a keystone pathogen in dental caries and a causative agent of bacterial endocarditis. Different than other pathogenic bacteria, including several streptococci, that encode multiple zinc import systems, bioinformatic analysis indicated that the S. mutans core genome encodes a single, highly conserved, zinc importer commonly known as AdcABC. Inactivation of the genes coding for the metal-binding AdcA (ΔadcA) or both AdcC ATPase and AdcB permease (ΔadcCB) severely impaired the ability of S. mutans to grow under zinc-depleted conditions. Intracellular metal quantifications revealed that both mutants accumulated less zinc when grown in the presence of a sub-inhibitory concentration of a zinc-specific chelator. Notably, the ΔadcCB strain displayed a severe colonization defect in a rat oral infection model. Both Δadc strains were hypersensitive to high concentrations of manganese, showed reduced peroxide tolerance, and formed less biofilm in sucrose-containing media when cultivated in the presence of the lowest amount of zinc that support their growth, but not when zinc was supplied in excess. Collectively, this study identifies AdcABC as the lone high affinity zinc importer of S. mutans and provides preliminary evidence that zinc is a growth-limiting factor within the dental biofilm.

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A label-free real-time method for measuring glucose uptake kinetics in yeast

FEMS Yeast Research ◽

10.1093/femsyr/foaa069 ◽

2020 ◽

Author(s):

Sina Schmidl ◽

Cristina V Iancu ◽

Mara Reifenrath ◽

Jun-yong Choe ◽

Mislav Oreb

Keyword(s):

Glucose Uptake ◽

Real Time ◽

Expression System ◽

Sugar Uptake ◽

Label Free ◽

Cytosolic Ph ◽

Yeast Expression System ◽

Sugar Transporters ◽

Hexose Transporters

Abstract Glucose uptake assays commonly rely on the isotope-labeled sugar, which is associated with radioactive waste and exposure of the experimenter to radiation. Here, we show that the rapid decrease of the cytosolic pH after a glucose pulse to starved Saccharomyces cerevisiae cells is dependent on the rate of sugar uptake and can be used to determine the kinetic parameters of sugar transporters. The pH-sensitive GFP variant pHluorin is employed as a genetically encoded biosensor to measure the rate of acidification as a proxy of transport velocity in real time. The measurements are performed in the hexose transporter-deficient (hxt0) strain EBY.VW4000 that has been previously used to characterize a plethora of sugar transporters from various organisms. Therefore, this method provides an isotope-free, fluorometric approach for kinetic characterization of hexose transporters in a well-established yeast expression system.

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Molecular Characterization of the Hemin Uptake Locus (hmu) from Yersinia pestis and Analysis ofhmu Mutants for Hemin and Hemoprotein Utilization

Infection and Immunity ◽

10.1128/iai.67.8.3879-3892.1999 ◽

1999 ◽

Vol 67 (8) ◽

pp. 3879-3892 ◽

Cited By ~ 105

Author(s):

Jan M. Thompson ◽

Heather A. Jones ◽

Robert D. Perry

Keyword(s):

Yersinia Pestis ◽

Parent Strain ◽

Gram Negative Bacteria ◽

Uptake System ◽

Constitutive Activity ◽

Gene Products ◽

Lower Affinity ◽

High Concentrations ◽

Lethal Doses

ABSTRACT Sequence analysis of the hemin uptake locus (hmu) ofYersinia pestis revealed five genes, hmuRSTUV, required for use of hemin and hemoproteins as iron sources. The translated gene products have homologies with proteins of the hemin transport genes of several gram-negative bacteria. Promoters were identified upstream of hmuP′R (p1) and upstream ofhmuS (p2); p1, which contains a Fur box, is regulated by iron and Fur, while p2 exhibits weak, but constitutive, activity. HmuR, which has homology with TonB-dependent outer membrane (OM) receptors, is localized to the OM of Y. pestis and is required for utilizing hemin and all hemoproteins under iron-depleted conditions. The proposed ABC transporter, HmuTUV, is necessary for use of hemin, hemin-albumin, and myoglobin, but not hemoglobin, hemoglobin-haptoglobin, or heme-hemopexin, as iron sources. In the absence of HmuTUV, HmuS, a cytoplasmic protein, is involved in use of hemoglobin and heme-hemopexin. In mice, the 50% lethal doses ofY. pestis ΔhmuP′RSTUV mutants injected subcutaneously or retro-orbitally did not differ from that of the Hmu+ parent strain. Thus, the hmu system is not essential for infection in mice via these routes. Growth studies showed that a ΔhmuP′RSTUV mutant could grow in iron-depleted medium containing high concentrations of hemoglobin, suggesting that an Hmu-independent, lower-affinity hemoglobin uptake system may exist.

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Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

Water ◽

10.3390/w13131757 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1757

Author(s):

Yesica Vicente-Martínez ◽

Manuel Caravaca ◽

Antonio Soto-Meca ◽

Miguel Ángel Martín-Pereira ◽

María del Carmen García-Onsurbe

Keyword(s):

Magnetic Nanoparticles ◽

Nitrate Content ◽

Adsorption Efficiency ◽

Experimental Conditions ◽

Dependent Behavior ◽

Before And After ◽

Naoh Solution ◽

High Concentrations ◽

Interference Studies

This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increases. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters.

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Halogenated Volatile Organic Compounds in Water Samples and Inorganic Elements Levels in Ores for Characterizing a High Anthropogenic Polluted Area in the Northern Latium Region (Italy)

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18041628 ◽

2021 ◽

Vol 18 (4) ◽

pp. 1628

Author(s):

Mario Vincenzo Russo ◽

Ivan Notardonato ◽

Alberto Rosada ◽

Giuseppe Ianiri ◽

Pasquale Avino

Keyword(s):

Organic Compounds ◽

Mean Value ◽

Greenhouse Crops ◽

River Waters ◽

Liquid Liquid Extraction ◽

Volatile Organic ◽

High Concentrations ◽

Very High ◽

Inorganic Fraction

This paper shows a characterization of the organic and inorganic fraction of river waters (Tiber and Marta) and ores/soil samples collected in the Northern Latium region of Italy for evaluating the anthropogenic/natural source contribution to the environmental pollution of this area. For organic compounds, organochloride volatile compounds in Tiber and Marta rivers were analyzed by two different clean-up methods (i.e., liquid–liquid extraction and static headspace) followed by gas chromatography–electron capture detector (GC-ECD) analysis. The results show very high concentrations of bromoform (up to 1.82 and 3.2 µg L−1 in Tiber and Marta rivers, respectively), due to the presence of greenhouse crops, and of chloroform and tetrachloroethene, due to the presence of handicrafts installations. For the qualitative and quantitative assessment of the inorganic fraction, it is highlighted the use of a nuclear analytical method, instrumental neutron activation analysis, which allows having more information as possible from the sample without performing any chemical-physical pretreatment. The results have evidenced high levels of mercury (mean value 88.6 µg g−1), antimony (77.7 µg g−1), strontium (12,039 µg g−1) and zinc (103 µg g−1), whereas rare earth elements show levels similar to the literature data. Particular consideration is drawn for arsenic (414 µg g−1): the levels found in this paper (ranging between 1 and 5100 µg g−1) explain the high content of such element (as arsenates) in the aquifer, a big issue in this area.

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Characterization of the Adaptive Response to Trichloroethylene-Mediated Stresses in Ralstonia pickettii PKO1

Applied and Environmental Microbiology ◽

10.1128/aem.68.11.5231-5240.2002 ◽

2002 ◽

Vol 68 (11) ◽

pp. 5231-5240 ◽

Cited By ~ 17

Author(s):

Joonhong Park ◽

Jerome J. Kukor ◽

Linda M. Abriola

Keyword(s):

Adaptive Response ◽

Combined Effects ◽

Similar Extent ◽

Protective Response ◽

Ralstonia Pickettii ◽

Pathway Expression ◽

High Concentrations ◽

Tce Degradation ◽

Solvent Stress

ABSTRACT In Ralstonia pickettii PKO1, a denitrifying toluene oxidizer that carries a toluene-3-monooxygenase (T3MO) pathway, the biodegradation of toluene and trichloroethylene (TCE) by the organism is induced by TCE at high concentrations. In this study, the effect of TCE preexposure was studied in the context of bacterial protective response to TCE-mediated toxicity in this organism. The results of TCE degradation experiments showed that cells induced by TCE at 110 mg/liter were more tolerant to TCE-mediated stress than were those induced by TCE at lower concentrations, indicating an ability of PKO1 to adapt to TCE-mediated stress. To characterize the bacterial protective response to TCE-mediated stress, the effect of TCE itself (solvent stress) was isolated from TCE degradation-dependent stress (toxic intermediate stress) in the subsequent chlorinated ethylene toxicity assays with both nondegradable tetrachloroethylene and degradable TCE. The results of the toxicity assays showed that TCE preexposure led to an increase in tolerance to TCE degradation-dependent stress rather than to solvent stress. The possibility that such tolerance was selected by TCE degradation-dependent stress during TCE preexposure was ruled out because a similar extent of tolerance was observed in cells that were induced by toluene, whose metabolism does not produce any toxic products. These findings suggest that the adaptation of TCE-induced cells to TCE degradation-dependent stress was caused by the combined effects of solvent stress response and T3MO pathway expression.

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