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Showing papers on "Lysis published in 2015"


Journal ArticleDOI
TL;DR: C cultivation conditions for a recombinant P. pastoris Δoch1 strain are determined allowing high productivity and product purity and the effects of the 3 process parameters temperature, pH and dissolved oxygen concentration on cell physiology, cell morphology, cell lysis and productivity are investigated in a multivariate manner.
Abstract: Pichia pastoris is a prominent host for recombinant protein production, amongst other things due to its capability of glycosylation. However, N-linked glycans on recombinant proteins get hypermannosylated, causing problems in subsequent unit operations and medical applications. Hypermannosylation is triggered by an α-1,6-mannosyltransferase called OCH1. In a recent study, we knocked out OCH1 in a recombinant P. pastoris CBS7435 MutS strain (Δoch1) expressing the biopharmaceutically relevant enzyme horseradish peroxidase. We characterized the strain in the controlled environment of a bioreactor in dynamic batch cultivations and identified the strain to be physiologically impaired. We faced cell cluster formation, cell lysis and uncontrollable foam formation. In the present study, we investigated the effects of the 3 process parameters temperature, pH and dissolved oxygen concentration on 1) cell physiology, 2) cell morphology, 3) cell lysis, 4) productivity and 5) product purity of the recombinant Δoch1 strain in a multivariate manner. Cultivation at 30°C resulted in low specific methanol uptake during adaptation and the risk of methanol accumulation during cultivation. Cell cluster formation was a function of the C-source rather than process parameters and went along with cell lysis. In terms of productivity and product purity a temperature of 20°C was highly beneficial. In summary, we determined cultivation conditions for a recombinant P. pastoris Δoch1 strain allowing high productivity and product purity.

324 citations


Journal ArticleDOI
Suxia Shen1, Tiehua Zhang1, Yuan Yuan1, Songyi Lin1, Jingyue Xu1, Haiqing Ye1 
TL;DR: The results indicate that bacterial cell morphology, membrane integrity, and permeability are damaged when the E. coli and S. aureus cells are exposed to the minimum inhibitory concentrations of cinnamaldehyde.

207 citations


Journal ArticleDOI
TL;DR: A combination of differential detergent lysis with tunable resistive pulse sensing or flow cytometry may prove useful for simple and fast differentiation between exosomes and other extracellular vesicle subpopulations as well as between vesicular and non-vesicular structures.
Abstract: Extracellular vesicles (including exosomes, microvesicles and apoptotic bodies) are currently attracting rapidly increasing attention from various fields of biology due to their ability to carry complex information and act as autocrine, paracrine and even endocrine intercellular messengers. In the present study we investigated the sensitivity of size-based subpopulations of extracellular vesicles to different concentrations of detergents including sodium dodecyl sulphate, Triton X-100, Tween 20 and deoxycholate. We determined the required detergent concentration that lysed each of the vesicle subpopulations secreted by Jurkat, THP-1, MiaPaCa and U937 human cell lines. We characterized the vesicles by tunable resistive pulse sensing, flow cytometry and transmission electron microscopy. Microvesicles and apoptotic bodies were found to be more sensitive to detergent lysis than exosomes. Furthermore, we found evidence that sodium dodecyl sulphate and Triton X-100 were more effective in vesicle lysis at low concentrations than deoxycholate or Tween 20. Taken together, our data suggest that a combination of differential detergent lysis with tunable resistive pulse sensing or flow cytometry may prove useful for simple and fast differentiation between exosomes and other extracellular vesicle subpopulations as well as between vesicular and non-vesicular structures.

170 citations


Journal ArticleDOI
TL;DR: It is proposed that pulmonary inflammation during pneumococcal pneumonia arises in large part from the interaction of the bacterial cell wall with complement and noncomplement-mediated host defenses.
Abstract: Using a rabbit model of experimental pneumonitis, the components on the surface of the pneumococcus that incite pulmonary inflammation were identified. Rabbits were challenged intratracheally with live pneumococci, capsular polysaccharide, purified cell walls, or cell wall subcomponents. Leukocytosis and elevation of protein concentration was quantitated in bronchial lavage fluid during the first 24 h after challenge. Of the pneumococcal surface components tested, cell wall preparations had the highest specific activity in inducing inflammation; abnormalities in bronchial lavage fluid cytochemistry appeared rapidly and in a dose-dependent manner. Cell wall building blocks and the products of penicillin-induced hydrolysis of the cell wall were also highly inflammatory, indicating that inflammation can be generated by disruption of the cell wall during lysis of bacteria by beta-lactam antibiotics. Administration of inhibitors of arachidonic acid metabolism suggested that inhibition of the lipoxygenase pathw...

125 citations


Journal ArticleDOI
TL;DR: It is concluded that BCT tubes can prevent lysis and cellular release of genomic DNA of blood samples from cancer patients when stored at room temperature, and could therefore be of benefit for blood specimen collections in clinical trials.

94 citations


Journal ArticleDOI
TL;DR: It is shown that, after interaction of APOL1 with lipid bilayers at acidic pH, subsequent pH neutralization triggers the opening of pH-gated channels that selectively conduct cations across the bilayer, which is consistent with a model of lysis that involves endocytic recycling of APol1 and the formation of cation-selective channels, at neutral pH, in the parasite plasma membrane.
Abstract: Apolipoprotein L-1 (APOL1), the trypanolytic factor of human serum, can lyse several African trypanosome species including Trypanosoma brucei brucei, but not the human-infective pathogens T. brucei rhodesiense and T. brucei gambiense, which are resistant to lysis by human serum. Lysis follows the uptake of APOL1 into acidic endosomes and is apparently caused by colloid-osmotic swelling due to an increased ion permeability of the plasma membrane. Here we demonstrate that nanogram quantities of full-length recombinant APOL1 induce ideally cation-selective macroscopic conductances in planar lipid bilayers. The conductances were highly sensitive to pH: their induction required acidic pH (pH 5.3), but their magnitude could be increased 3,000-fold upon alkalinization of the milieu (pKa = 7.1). We show that this phenomenon can be attributed to the association of APOL1 with the bilayer at acidic pH, followed by the opening of APOL1-induced cation-selective channels upon pH neutralization. Furthermore, the conductance increase at neutral pH (but not membrane association at acidic pH) was prevented by the interaction of APOL1 with the serum resistance-associated protein, which is produced by T. brucei rhodesiense and prevents trypanosome lysis by APOL1. These data are consistent with a model of lysis that involves endocytic recycling of APOL1 and the formation of cation-selective channels, at neutral pH, in the parasite plasma membrane.

92 citations


Journal ArticleDOI
TL;DR: The REAP procedure is performed at low temperature and takes <2 min, which minimizes protein degradation, protein modification, and diffusion of soluble proteins out of the nuclear compartment while maintaining the integrity of protein complexes.
Abstract: This protocol presents a rapid, efficient, and practical (REAP) method to separate nuclei from cultured cells in vitro with as little damage and contamination as possible. The REAP procedure is performed at low temperature and takes <2 min, which minimizes protein degradation, protein modification, and diffusion of soluble proteins out of the nuclear compartment while maintaining the integrity of protein complexes. A mild detergent, NP-40, is used together with mild mechanical shearing to disrupt the plasma membrane, leaving the nuclear membrane intact. The REAP method can be used with various cell lines grown in vitro and requires minimal optimization. The isolated nuclei are suitable for numerous downstream applications (e.g., western blotting, 2D gel electrophoresis, and immunoprecipitation). If desired, aliquots of whole-cell lysate and the cytoplasmic fraction can be saved for comparison.

79 citations


Journal ArticleDOI
TL;DR: The CER extraction method, as previously applied to bacterialBiofilms, also represents a suitable method for isolation of water soluble EPS from the archaeal biofilms of S. acidocaldarius, allowing the investigation of composition and function of EPS components in these types of biofilm.
Abstract: Extracellular polymeric substances (EPS) are the major structural and functional components of microbial biofilms. The aim of this study was to establish a method for EPS isolation from biofilms of the thermoacidophilic archaeon Sulfolobus acidocaldarius as a basis for EPS analysis. Biofilms of S. acidocaldarius were cultivated on the surface of gellan gum-solidified Brock medium at 78 °C for 4 days. Five EPS extraction methods were compared, including shaking of biofilm suspensions in phosphate buffer, cation-exchange resin (CER) extraction and stirring with addition of EDTA, crown ether or NaOH. With respect to EPS yield, impact on cell viability and compatibility with subsequent biochemical analysis, the CER extraction method was found to be the best suited isolation procedure resulting in the detection of carbohydrates and proteins as the major constituents and DNA as a minor component of the EPS. Culturability of CER-treated cells was not impaired. Analysis of the extracellular proteome using two-dimensional gel electrophoresis resulted in the detection of several hundredshundred of protein spots, mainly with molecular masses of 25 kDa to 116 kDa and pI values of 5 to 8. Identification of proteins suggested a cytoplasmic origin for many of these proteins, possibly released via membrane vesicles or biofilm-inherent cell lysis during biofilm maturation. Functional analysis of EPS proteins, using fluorogenic substrates as well as zymography, demonstrated the activity of diverse groups of enzymes such as proteases, lipases, esterases, phosphatases and glucosidases. In conclusion, the CER extraction method, as previously applied to bacterial biofilms, also represents a suitable method for isolation of water soluble EPS from the archaeal biofilms of S. acidocaldarius, allowing the investigation of composition and function of EPS components in these types of biofilms.

75 citations


Journal ArticleDOI
TL;DR: The efficiency of the solar driven TiO 2 photocatalytic process was evaluated in the treatment of natural water from a Portuguese river containing cyanobacterial blooms, in which prevails the genus Microcystis .

72 citations


Journal ArticleDOI
TL;DR: A simple, rapid method for MIL-based plasmid DNA extraction from crude bacterial cell lysate in which DNA-enriched MIL is transferred directly to a PCR tube for analysis.

71 citations


Journal ArticleDOI
TL;DR: Observations supported the proposal of two independent mechanisms contributing equally to sludge reduction: under anaerobic conditions: sludge hydrolysis of non-bacterial material, and under aerobic conditions: bacterial cell lysis and oxidation of released biodegradable compounds.

Journal ArticleDOI
TL;DR: EtNa is a quick and low-cost gDNA extraction protocol that is efficient for bacteria and yeast over a broad range of concentrations and based on a hot alkaline ethanol lysis.
Abstract: Guanidine thiocyanate breakage of microorganisms has been the standard initial step in genomic DNA (gDNA) extraction of microbial DNA for two decades, despite the requirement for pretreatments to extract DNA from microorganisms other than Gram-negative bacteria. We report a quick and low-cost gDNA extraction protocol called EtNa that is efficient for bacteria and yeast over a broad range of concentrations. EtNa is based on a hot alkaline ethanol lysis. The solution can be immediately centrifuged to yield a crude gDNA extract suitable for PCR, or it can be directly applied to a silica column for purification.

Journal ArticleDOI
26 Jan 2015-PLOS ONE
TL;DR: It is demonstrated that gramicidin A not only caused membrane permeabilization but also induced the formation of hydroxyl radicals, which are a possible end product of the transient depletion of NADH from the tricarboxylic acid cycle.
Abstract: Gramicidin A is an antimicrobial peptide that destroys gram-positive bacteria. The bactericidal mechanism of antimicrobial peptides has been linked to membrane permeation and metabolism disruption as well as interruption of DNA and protein functions. However, the exact bacterial killing mechanism of gramicidin A is not clearly understood. In the present study, we examined the antimicrobial activity of gramicidin A on Staphylococcus aureus using biochemical and biophysical methods, including hydroxyl radical and NAD+/NADH cycling assays, atomic force microscopy, and Fourier transform infrared spectroscopy. Gramicidin A induced membrane permeabilization and changed the composition of the membrane. The morphology of Staphylococcus aureus during gramicidin A destruction was divided into four stages: pore formation, water permeability, bacterial flattening, and lysis. Changes in membrane composition included the destruction of membrane lipids, proteins, and carbohydrates. Most interestingly, we demonstrated that gramicidin A not only caused membrane permeabilization but also induced the formation of hydroxyl radicals, which are a possible end product of the transient depletion of NADH from the tricarboxylic acid cycle. The latter may be the main cause of complete Staphylococcus aureus killing. This new finding may provide insight into the underlying bactericidal mechanism of gA.

Journal ArticleDOI
TL;DR: It is shown that the spanins of the paradigm coliphage lambda mediate efficient membrane fusion, supporting the notion that the last step of lysis is the fusion of the IM and OM, and data are provided indicating that spanin-mediated fusion is regulated by the meshwork of the PG, thus coupling fusion to murein degradation by the phage endolysin.
Abstract: In general, phages cause lysis of the bacterial host to effect release of the progeny virions. Until recently, it was thought that degradation of the peptidoglycan (PG) was necessary and sufficient for osmotic bursting of the cell. Recently, we have shown that in Gram-negative hosts, phage lysis also requires the disruption of the outer membrane (OM). This is accomplished by spanins, which are phage-encoded proteins that connect the cytoplasmic membrane (inner membrane, IM) and the OM. The mechanism by which the spanins destroy the OM is unknown. Here we show that the spanins of the paradigm coliphage lambda mediate efficient membrane fusion. This supports the notion that the last step of lysis is the fusion of the IM and OM. Moreover, data are provided indicating that spanin-mediated fusion is regulated by the meshwork of the PG, thus coupling fusion to murein degradation by the phage endolysin. Because endolysin function requires the formation of μm-scale holes by the phage holin, the lysis pathway is seen to require dramatic dynamics on the part of the OM and IM, as well as destruction of the PG.

Journal ArticleDOI
TL;DR: D detergent sclerosants including sodium tetradecyl sulphate (STS) and polidocanol are clinically used to induce endovascular fibrosis and vessel occlusion and exhibit remarkable differences in their interaction with lipid membranes, target cells and circulating proteins with potential implications in a range of clinical applications.
Abstract: Commonly used detergent sclerosants including sodium tetradecyl sulphate (STS) and polidocanol (POL) are clinically used to induce endovascular fibrosis and vessel occlusion. They achieve this by lysing the endothelial lining of target vessels. These agents are surface active (surfactant) molecules that interfere with cell membranes. Surfactants have a striking similarity to the phospholipid molecules of the membrane lipid bilayer. By adsorbing at the cell membrane, surfactants disrupt the normal architecture of the lipid bilayer and reduce the surface tension. The outcome of this interaction is concentration dependent. At high enough concentrations, surfactants solubilise cell membranes resulting in cell lysis. At lower concentrations, these agents can induce a procoagulant negatively charged surface on the external aspect of the cell membrane. The interaction is also influenced by the ionic charge, molecular structure, pH and the chemical nature of the diluent (e.g. saline vs. water). The ionic charge of the surfactant molecule can influence the effect on plasma proteins and the protein contents of cell membranes. STS, an anionic detergent, denatures the tertiary complex of most proteins and in particular the clinically relevant clotting factors. By contrast, POL has no effect on proteins due to its non-ionic structure. These agents therefore exhibit remarkable differences in their interaction with lipid membranes, target cells and circulating proteins with potential implications in a range of clinical applications.

Journal ArticleDOI
TL;DR: This system has been validated for logarithmic dilutions of aforementioned bacteria and viruses from various sample matrices including blood plasma and culture media and extraction of human DNA from whole blood and is amenable to concatenation with downstream modules for multiplex nucleic acid amplification as recently demonstrated for panel testing of various pathogens at the point of care.
Abstract: We present total nucleic acid extraction from whole blood, Gram-positive Bacillus subtilis, Gram-negative Escherichia coli, and Rift Valley fever RNA virus on a low-cost, centrifugal microfluidic LabDisk cartridge processed in a light-weight (<2 kg) and portable processing device. Compared to earlier work on disk based centrifugal microfluidics, this includes the following advances: combined lysis and nucleic acid purification on one cartridge and handling of sample volumes as large as 200 μL. The presented system has been validated for logarithmic dilutions of aforementioned bacteria and viruses from various sample matrices including blood plasma and culture media and extraction of human DNA from whole blood. Recovered DNA and RNA concentrations in the eluate were characterized by quantitative PCR to: 58.2–98.5%, 45.3–102.1% and 29.5–34.2% versus a manual reference for Bacillus subtilis, Escherichia coli and Rift Valley fever virus, respectively. For extraction of human DNA from whole blood, similar results for on-disk ((10.1 ± 7.6) × 104 DNA copies) and manual reference extraction ((10.2 ± 6.3) × 104 DNA copies) could be achieved. Eluates from on-disk extraction show slightly increased ethanol concentrations of 4.1 ± 0.3% to 5.5 ± 0.2% compared to a manual reference (2.0 ± 0.5% to 3.6 ± 0.6%). The complete process chain for sample preparation is automatically performed within ∼30 minutes, including ∼15 minutes lysis time. It is amenable to concatenation with downstream modules for multiplex nucleic acid amplification as recently demonstrated for panel testing of various pathogens at the point of care.

Journal ArticleDOI
TL;DR: It is reported that Vibrio cholerae, the cholera pathogen, is tolerant to antibiotics targeting cell wall synthesis, and these findings suggest the enzymes that mediate cell wall degradation are critical for determining bacterial cell fate - sphere formation vs. lysis – after treatment with antibiotics that targetcell wall synthesis.
Abstract: In many bacteria, inhibition of cell wall synthesis leads to cell death and lysis. The pathways and enzymes that mediate cell lysis after exposure to cell wall-acting antibiotics (e.g. beta lactams) are incompletely understood, but the activities of enzymes that degrade the cell wall (‘autolysins’) are thought to be critical. Here, we report that Vibrio cholerae, the cholera pathogen, is tolerant to antibiotics targeting cell wall synthesis. In response to a wide variety of cell wall- acting antibiotics, this pathogen loses its rod shape, indicative of cell wall degradation, and becomes spherical. Genetic analyses revealed that paradoxically, V. cholerae survival via sphere formation required the activity of D,D endopeptidases, enzymes that cleave the cell wall. Other autolysins proved dispensable for this process. Our findings suggest the enzymes that mediate cell wall degradation are critical for determining bacterial cell fate - sphere formation vs. lysis – after treatment with antibiotics that target cell wall synthesis.

Journal ArticleDOI
TL;DR: The characterization, antimicrobial spectrum and molecular mass of bifidocin A suggested that it was a novel bacteriocin with potential research and application value in food industry.

Journal ArticleDOI
TL;DR: The results indicate that the CHAP domain alone is necessary and sufficient for lysis of live S. aureus, while the amidase-2 domain is insufficient for cell lysis when provided alone.
Abstract: Increases in the prevalence of antibiotic-resistant strains of Staphylococcus aureus have elicited efforts to develop novel antimicrobials to treat these drug-resistant pathogens. One potential treatment repurposes the lytic enzymes produced by bacteriophages as antimicrobials. The phage Twort endolysin (PlyTW) harbors three domains, a cysteine, histidine-dependent amidohydrolases/peptidase domain (CHAP), an amidase-2 domain and a SH3b-5 cell wall binding domain (CBD). Our results indicate that the CHAP domain alone is necessary and sufficient for lysis of live S. aureus, while the amidase-2 domain is insufficient for cell lysis when provided alone. Loss of the CBD results in ∼10X reduction of enzymatic activity in both turbidity reduction and plate lysis assays compared to the full length protein. Deletion of the amidase-2 domain resulted in a protein (PlyTW Δ172-373) with lytic activity that exceeded the activity of the full length construct in both the turbidity reduction and plate lysis assays. Addition of Ca(2+) enhanced the turbidity reduction activity of both the full length protein and truncation constructs harboring the CHAP domain. Chelation by addition of EDTA or the addition of zinc inhibited the activity of all PlyTW constructs.

Journal ArticleDOI
26 May 2015-Langmuir
TL;DR: Using atomic force microscopy to probe the mechanobiology of a model AMP on living Klebsiella pneumoniae bacterial cells shows that AFM measurements may provide valuable insights into the physical events that precede bacterial lysis by AMPs.
Abstract: Increasing rates of antimicrobial-resistant medically important bacteria require the development of new, effective therapeutics, of which antimicrobial peptides (AMPs) are among the promising candidates. Many AMPs are membrane-active, but their mode of action in killing bacteria or in inhibiting their growth remains elusive. This study used atomic force microscopy (AFM) to probe the mechanobiology of a model AMP (a derivative of melittin) on living Klebsiella pneumoniae bacterial cells. We performed in situ biophysical measurements to understand how the melittin peptide modulates various biophysical behaviors of individual bacteria, including the turgor pressure, cell wall elasticity, and bacterial capsule thickness and organization. Exposure of K. pneumoniae to the peptide had a significant effect on the turgor pressure and Young’s modulus of the cell wall. The turgor pressure increased upon peptide addition followed by a later decrease, suggesting that cell lysis occurred and pressure was lost through d...

Journal ArticleDOI
13 Jul 2015-PLOS ONE
TL;DR: The present work describes an improved method of DNA extraction namely “powdered glass method” from diverse soils, which involves the use of sterile glass powder for cell lysis followed by addition of 1% powdered activated charcoal as purifying agent to remove humic substances.
Abstract: A rapid, cost effective method of metagenomic DNA extraction from soil is a useful tool for environmental microbiology The present work describes an improved method of DNA extraction namely “powdered glass method” from diverse soils The method involves the use of sterile glass powder for cell lysis followed by addition of 1% powdered activated charcoal (PAC) as purifying agent to remove humic substances The method yielded substantial DNA (587 ± 004 μg/g of soil) with high purity (A260/280: 176 ± 005) and reduced humic substances (A340: 0047 ± 003) The quality of the extracted DNA was compared against five different methods based on 16S rDNA PCR amplification, BamHI digestion and validated using quantitative PCR The digested DNA was used for a metagenomic library construction with the transformation efficiency of 4 X 106 CFU mL-1 Besides providing rapid, efficient and economical extraction of metgenomic DNA from diverse soils, this method’s applicability is also demonstrated for cultivated organisms (Gram positive B subtilis NRRL-B-201, Gram negative E coli MTCC40, and a microalgae C sorokiniana UTEX#1666)

Journal ArticleDOI
TL;DR: It is suggested that P7 could be applied as a candidate for the development of new food preservatives as it exerts its antibacterial activities by penetrating cell membranes and targets intracellular DNA.

Journal ArticleDOI
TL;DR: The present data shows that the novel pSWCNTs-Ag are non-toxic to human cells at their bactericidal concentration, as compared to plain SWCNTS-Ag, and may be safe alternative antimicrobials to treat foodborne pathogens.
Abstract: Resistance of food borne pathogens such as Salmonella to existing antibiotics is of grave concern. Silver coated single walled carbon nanotubes (SWCNTs-Ag) have broad-spectrum antibacterial activity and may be a good treatment alternative. However, toxicity to human cells due to their physico-chemical properties is a serious public health concern. Although pegylation is commonly used to reduce metal nanoparticle toxicity, SWCNTs-Ag have not been pegylated as yet, and the effect of pegylation of SWCNTs-Ag on their anti-bacterial activity and cell cytotoxicity remains to be studied. Further, there are no molecular studies on the anti-bacterial mechanism of SWCNTs-Ag or their functionalized nanocomposites. In this study we created novel pegylated SWCNTS-Ag (pSWCNTs-Ag), and employed 3 eukaryotic cell lines to evaluate their cytotoxicity as compared to plain SWCNTS-Ag. Simultaneously, we evaluated their antibacterial activity on Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) by the MIC and growth curve assays. In order to understand the possible mechanisms of action of both SWCNTs-Ag and pSWCNTs-Ag, we used electron microscopy (EM) and molecular studies (qRT-PCR). pSWCNTs-Ag inhibited Salmonella Typhimurium at 62.5 μg/mL, while remaining non-toxic to human cells. By comparison, plain SWCNTs-Ag were toxic to human cells at 62.5 μg/mL. EM analysis revealed that bacteria internalized either of these nanocomposites after the outer cell membranes were damaged, resulting in cell lysis or expulsion of cytoplasmic contents, leaving empty ghosts. The expression of genes regulating the membrane associated metabolic transporter system (artP, dppA, and livJ), amino acid biosynthesis (trp and argC) and outer membrane integrity (ompF) protiens, was significantly down regulated in Salmonella treated with both pSWCNTs-Ag and SWCNTs-Ag. Although EM analysis of bacteria treated with either SWCNTs-Ag or pSWCNTs-Ag revealed relatively similar morphological changes, the expression of genes regulating the normal physiological processes of bacteria (ybeF), quorum sensing (sdiA), outer membrane structure (safC), invasion (ychP) and virulence (safC, ychP, sseA and sseG) were exclusively down regulated several fold in pSWCNTs-Ag treated bacteria. Altogether, the present data shows that our novel pSWCNTs-Ag are non-toxic to human cells at their bactericidal concentration, as compared to plain SWCNTS-Ag. Therefore, pSWCNTs-Ag may be safe alternative antimicrobials to treat foodborne pathogens.

Journal ArticleDOI
15 Jan 2015-Talanta
TL;DR: The nanocomposites have been further used for the isolation of DNA from a series of real sample matrices, including synthetic λ-DNA sample, human whole blood and Escherichia coli cell lysate, and are at least comparable to those achieved by using the reported sorbent materials or commercial kits.

Journal ArticleDOI
TL;DR: The methods described here are amenable to an integrated point-of-care device for the assessment of tumor protein expression in fine needle aspirate biopsies and are capable of sensitive quantification of proteins with a dynamic range >4 orders of magnitude.
Abstract: We exploit the mechanical action of surface acoustic waves (SAW) to differentially lyse human cancer cells in a chemical-free manner. The extent to which cells were disrupted is reported for a range of SAW parameters, and we show that the presence of 10 μm polystyrene beads is required to fully rupture cells and their nuclei. We show that SAW is capable of subcellular fractionation through the chemical-free isolation of nuclei from whole cells. The concentration of protein was assessed in lysates with a sensitive microfluidic antibody capture (MAC) chip. An antibody-based sandwich assay in a microfluidic microarray format was used to detect unlabeled human tumor suppressor protein p53 in crude lysates, without any purification step, with single-molecule resolution. The results are digital, enabling sensitive quantification of proteins with a dynamic range >4 orders of magnitude. For the conditions used, the efficiency of SAW-induced mechanical lysis was determined to be 12.9% ± 0.7% of that for conventional detergent-based lysis in yielding detectable protein. A range of possible loss mechanisms that could lead to the drop in protein yield are discussed. Our results show that the methods described here are amenable to an integrated point-of-care device for the assessment of tumor protein expression in fine needle aspirate biopsies.

Journal ArticleDOI
TL;DR: Evaluating membrane protein localization using this approach requires only standard biochemistry laboratory equipment for cell lysis, gel electrophoresis and western blotting and can be completed in 4 h.
Abstract: Membrane proteins have crucial roles in signaling and as anchors for cell surface display. Proper secretion of a membrane protein can be evaluated by its susceptibility to digestion by an extracellular protease, but this requires a crucial control to confirm membrane integrity during digestion. This protocol describes how to use this approach to determine how efficiently a protein is secreted to the outer surface of Gram-negative bacteria. Its success relies upon careful selection of an appropriate intracellular reporter protein that will remain undigested if the membrane barrier remains intact, but that is rapidly digested when cells are lysed before evaluation. Reporter proteins that are resistant to proteases (e.g., maltose-binding protein) do not return accurate results; in contrast, proteins that are more readily digested (e.g., SurA) serve as more sensitive reporters of membrane integrity, yielding more accurate measurements of membrane protein localization. Similar considerations apply when evaluating membrane protein localization in other contexts, including eukaryotic cells and organelle membranes. Evaluating membrane protein localization using this approach requires only standard biochemistry laboratory equipment for cell lysis, gel electrophoresis and western blotting. After expression of the protein of interest, this procedure can be completed in 4 h.

Journal ArticleDOI
TL;DR: In this paper, experiments with Chlorella vulgais extraction by ionic liquids (ILs) combined with CO 2 capture were conducted considering that captured CO 2 by ILs can compensate the energy consumption of extraction.

Journal ArticleDOI
TL;DR: Using fluorescence spectroscopy, biochemical assays, and mass spectrometry proteomics, the combination of adaptive focused acoustic (AFA) sonication in the presence of a binary poloxamer-based mixture of octyl-β-glucoside and Pluronic F-127 is identified to maximize the depth and yield of the proteome extraction while maintaining native protein activity.
Abstract: Recent developments in quantitative high-resolution mass spectrometry have led to significant improvements in the sensitivity and specificity of the biochemical analyses of cellular reactions, protein-protein interactions, and small-molecule-drug discovery. These approaches depend on cellular proteome extraction that preserves native protein activities. Here, we systematically analyzed mechanical methods of cell lysis and physical protein extraction to identify those that maximize the extraction of cellular proteins while minimizing their denaturation. Cells were mechanically disrupted using Potter-Elvehjem homogenization, probe- or adaptive-focused acoustic sonication, and were in the presence of various detergents, including polyoxyethylene ethers and esters, glycosides, and zwitterions. Using fluorescence spectroscopy, biochemical assays, and mass spectrometry proteomics, we identified the combination of adaptive focused acoustic (AFA) sonication in the presence of a binary poloxamer-based mixture of octyl-β-glucoside and Pluronic F-127 to maximize the depth and yield of the proteome extraction while maintaining native protein activity. This binary poloxamer extraction system allowed for native proteome extraction comparable in coverage to the proteomes extracted using denaturing SDS or guanidine-containing buffers, including the efficient extraction of all major cellular organelles. This high-efficiency cellular extraction system should prove useful for a variety of cell biochemical studies, including structural and functional proteomics.

Patent
25 Jun 2015
TL;DR: In this paper, a library of tagged nucleic acid fragments is prepared by contacting a population of cells directly with a lysis reagent having one or more protease to generate a cell lysate.
Abstract: A method of preparing a library of tagged nucleic acid fragments including contacting a population of cells directly with a lysis reagent having one or more protease to generate a cell lysate; inactivating the protease to generate an inactivated cell lysate, and applying a transposase and a transposon end composition containing a transferred strand to the inactivated cell lysate under conditions wherein the target nucleic acid and the transposon end composition undergo a transposition reaction.

Journal ArticleDOI
02 Apr 2015
TL;DR: In this article, a review of the recent studies on the lipid extraction of microalgae that mainly highlighted on the cell disruption method using variety of micro algae species was presented, in which the selection of cell disruption methods and devices are crucial in order to achieve the highest extraction percentage of lipid and other valuable intracellular (proteins, carotenoids and chlorophylls) from micro algae cell.
Abstract: The paper reviews the recent studies on the lipid extraction of microalgae that mainly highlighted on the cell disruption method using variety of microalgae species. Selection of cell disruption method and devices are crucial in order to achieve the highest extraction percentage of lipid and other valuable intracellular (proteins, carotenoids and chlorophylls) from microalgae cell. Pulsed electric field (PEF) and electrochemical lysis methods were found to be potential for enhancing the extraction efficiencies either conducted in single step extraction or used as pre-treatment followed by conventional extraction method. The PEF technology capable to extract lipid as high as 75%. While, electrochemical lysis treatment capable to extract lipid approximately 93% using Stainless Steel (SS) and Ti/IrO2 as the cathode and anode electrode respectively. PEF technology and electrochemical lysis are still considered to be a new method for microalgae lipid extraction and further investigation can still be done for better improvement of the system.