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Abstract A high-throughput assay was developed to screen Phytophthora species for fungicide sensitivity using optical density measurements for unbiased, automated measurement of mycelial growth. The efficacy of the optical density assay (OD) to measure phosphite sensitivity in Phytophthora species was compared to two widely used methods, radial growth (RG) and dry weight (DW) assays. Three isolates of each of Phytophthora cinnamomi , P. multivora and P. pluvialis , with known phosphite exposure and three isolates of each species with no prior phosphite exposure, were screened for phosphite sensitivity using the three assays. Mycelial growth measurements were taken after culturing for 6, 14 and 15 days for the OD, DW and RG assays respectively. Mycelial growth inhibition at 15, 80, 200 and 500 μg/mL phosphite relative to growth on control media was used to determine effective concentration values for 50% growth reduction (EC50). The species varied in their tolerance to phosphite with P. cinnamomi being the least sensitive followed by P. multivora and P. pluvialis. No significant differences in tolerance were found between isolates within the same species using any method. The OD assay produced comparable EC50 values to the RG and DW assays. The growth of the three species was more sensitive to phosphite in the DW than the RG and OD assays, however limited sample throughput and greater variation in measuring small amounts of mycelia in the dry weight assessment increase variability and limits throughput. The OD assay offers a fast method to enable an inventory of chemical resistance and is particularly advantageous for slow growing species as it requires less time and offers greater throughput than existing RG and DW methods. Highlights • A high-throughput optical density (OD) assay was developed to screen Phytophthora species for fungicide sensitivity. • Efficacy of the OD assay to measure phosphite sensitivity in Phytophthora species was compared to two widely used methods. • Phytophthora cinnamomi was the least sensitive to phosphite followed by P. multivora and P. pluvialis. • The OD assay produced comparable EC50 values to the radial growth (RG) and dry weight (DW) assays. • The OD assay requires less time and resources and offers greater throughput than existing RG and DW methods. [ABSTRACT FROM AUTHOR]

The polyvinyl alcohol (PVA) films dyed with methylene blue were decolorised after they were irradiated in a dose range from 0.059 to 1.411 Gy by thermal neutron source at the end of the channel No. 2 of the Dalat nuclear research reactor. The thermal neutron flux at an outer position of beam line at the channel No. 2 was 1.6 × 106 neutron/cm2 s. The dyed PVA films containing boric acid could be used for improvement physical qualities of the films. Response-curves of the dyed PVA films which were irradiated by the thermal-neutron source were described by the saturated exponential function of the energy transfer model. [ABSTRACT FROM AUTHOR]

A convenient and most abundantly applied method to determine the growth state of a bacterial cell culture is to determine the optical density (OD) spectrophotometrically. Dilution of the samples, which is necessary to measure within the linear range of the spectrophotometer, is time-consuming and not compatible with high-throughput applications. Here we present a direct approach to estimate the OD at 578 nm (OD 578 ) of bacterial cultures in microplates without the need for sample dilution. This could be advantageous for high-throughput analysis of bacterial cells in microplates for example when optimizing growth conditions, screening for new substrates of a bacterial strain or monitoring enzymatic activity after enzyme evolution. Pseudomonas putida cells were grown in shake flasks. The OD 578 was determined in parallel in a microplate directly without dilution and in a spectrophotometer cuvette after dilution. The resulting data set was used to identify a conversion formula, which enables direct and reliable transformation of OD measurements of undiluted samples into the corrected OD values as would have been obtained for diluted samples measured in a standard spectrophotometer. Subsequently we could show that just a few OD calibration points are required to adjust this conversion formula and make it suitable for other suspensions or cultures of bacterial strains different than P. putida . The OD calibration points can be obtained by any combination of microplate reader and cuvette spectrophotometer. For this purpose, conversion formulas for a formazine standard suspension and a suspension of Escherichia coli BL21(DE3) cells were successfully generated. The OD values calculated by both conversion formulas turned out to be identical with the values as obtained by the control measurements in the spectrophotometer. This indicates the general applicability of the conversion formula as described. [ABSTRACT FROM AUTHOR]

Background Serum anti-single stranded DNA antibody (anti-ssDNAab) is used as a marker for systemic lupus erythematosus. We found a ‘prozone-like phenomenon,’ which was different from an original prozone phenomenon, in chemiluminescent enzyme immunoassay using magnetic particles for the measurement of serum anti-ssDNAab titers. We investigated mechanisms of the prozone-like phenomenon and countermeasures to prevent it from being overlooked. Methods This study examined 679 samples from patients tested for anti-ssDNAab titer at our hospital. In addition, the BF photometry OD value 2 (OD2), an index of optical density, was monitored simultaneously. Results The undiluted samples with a prozone-like phenomenon showed extremely lower OD2. Those samples were able to be distinguished from other samples by setting OD2 criteria based on the 95% prediction interval. Significant differences ( p  < 0.05) were found in the titer ratios (ten-fold diluted against undiluted) between groups with >1.5 and other groups with <1.5 for the ratios of OD2. Conclusions We proposed two valuable methods to find a prozone-like phenomenon: one by setting OD2 criteria based on the 95% prediction interval and the other by analyzing the ratios both in titers and OD2 between undiluted and 10-fold diluted samples. [ABSTRACT FROM AUTHOR]

Abstract The nematic (5CB) and cholesteric (the mixture of 5CB with chiral M5) liquid crystals (LC) doped with organo-modified inorganic platelets Laponite® (LO) were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD), microscopic image analysis, and optical density measurements. Cetyl-trimethylammonium-bromide (CTAB) was used as an organo-modifier and "cold" and "hot" methods were applied for obtaining of LO c and LO h samples, respectively. The data of DSC and XRD for nematic 5CB + LO compositions evidenced the presence of strong interactions between 5CB molecules and LO platelets and the better exfoliation for LO c as compared with LO h platelets. Microscopic structure, optical density and selective reflection for cholesteric compositions evidenced the strong integration of LO c platelets inside LC medium. The observed optical behavior reflects combination of initial perturbation of cholesteric matrix by LO c particles and initiation of formation of topological defects at small concentration of LO c , C < 0.1%, as well as the partial trapping of LO c by large scale oily streaks at higher concentrations, C ≥ 0.1%. Graphical abstract Image 2 Highlights • Nematic and cholesteric liquid crystal (LC) colloids doped with organo-modified Laponite® (LO) were studied. • Organo-modified platelets were obtained by "cold" (LO c) and "hot" (LO h) methods. • Data of DSC and XRD evidenced the presence of strong interactions between LC and LO platelets. • LO c platelets were better exfoliated in LC structures than LO h platelets. • Partial trapping of LO c by cholesteric oily streaks at high concentrations of LOc, C ≥ 0.1%, was observed. [ABSTRACT FROM AUTHOR]

A simple low-temperature evaporation technique for growing single crystals of methyl ammonium lead tribromide [CH3NH3PbBr3] with characterization emphasis on optical and electrical properties is described. X-ray diffraction (XRD) analysis was conducted to investigate the structural quality of resulting crystals. Optical properties were measured to determine optical band-gap, refractive index and extinction coefficient. Electrical properties were measured for understanding dominant polarization coefficient over wide range of frequencies at ambient temperatures to generate information for defect screening and device performance. [ABSTRACT FROM AUTHOR]

The optical properties of benign and malignant human brain tumors were investigated to provide a new diagnosis method. We studied various samples of adult human brain tissue (male and female) in two linear (by Optical density) and nonlinear (by Z-scan method) regimes. The obtained experimental results show that optical density for malignant is more than benign tissues and the nonlinear behavior of benign and malignant tissues are completely different because the nonlinear refractive index had a negative sign for benign tumor and a positive sign for malignant tumor. Results can be used for diagnosis between benign and malignant brain tissue. [ABSTRACT FROM AUTHOR]

The paper presents the results of producing lubricating grease from industrial and household waste in the laboratory. Partially prepared diesel engine oil SAE 10W-40 was used as a dispersion environment, and high and low pressure polyethylene (household polyethylene bags used) was used as thickener. It has been established that by using selected base oil, thickener and anti-wear additive DF-11, recycling oils can be obtained, which will be classified according to DIN 51502 to K2PF-30 and K3PF-30. It is proposed to expand the raw material base for the production of recycling oils through the using of waste industrial, hydraulic, transmission oils, as well as high-boiling petroleum fractions extracted from oil sludge or acidic tar and selective waste distillate oils. On the basis of the analysis of the researching results, it was established that on the basis of exhausting motor oil and polyethylene with the addition of additives of different functional purpose, it is possible to obtain a number of antifriction plastic lubricants used in swing bearings, railway and protective greases that can be used in the range of operating temperatures, on average up to 100°C. [ABSTRACT FROM AUTHOR]

The paper presents results of the study on efficient production of microalgae (Chlorella sp.) biomass. Culture was conducted on the basis of synthetic medium, in a laboratory storage tank photobioreactor with an active volume of 5 dm3, under forced aeration and mixing conditions. The culture control consisted in the spectrophotometric measurement of changes in the optical density of the culture medium as well as the determination of basic nutrients (total nitrogen and phosphorus) in the culture medium. In addition, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) values were measured in biomass suspension. Within 35 days, algae absorbed about 230 g of nitrogen (over 30% by weight) and about 36 mg of phosphorus (over 90% by weight), and the OD686 exceeded 1.2. During this time, the COD value increased by over 80% and the total organic carbon content by over 20%. The high efficiency of algae biomass production has been achieved by limiting the possibility of bacterial infection and ensuring appropriate conditions, including aeration, circulation and availability of biogenic compounds. [ABSTRACT FROM AUTHOR]

The polyvinyl alcohol (PVA) films dyed methylene blue containing different masses of boric acid and PVA powder were investigated. The dyed PVA films were irradiated by 60Co γ-source in a dose range from 10 to 150 kGy. The optical density changes at pre and post-irradiation of these films were studied by UV-VIS 2450 spectrophotometer at 668 nm wavelength. The gamma dose-response curves of the dyed PVA films were described by saturated exponential function of the energy transfer model with a high correlative coefficient. Fading effect of the dyed films after irradiation was investigated carefully. [ABSTRACT FROM AUTHOR]

The possibilities of increasing the interaction between the components of previously developed thermoplastic vulcanisates based on polypropylene and a combination of isoprene and nitrile butadiene rubbers were studied. The morphology of the composites was recorded by means of optical microscopy using an analytical complex based on a Leica DM-2500 optical microscope, a Leica DFC-420C digital high-resolution colour camera with a Peltier cooling system, and a specialised computer desk. The parameters of crystallisation of polypropylene were measured by differential scanning calorimetry using a DSC 204F1 Phoenix instrument (Netzsch). The physicomechanical properties of the vulcanisates were also determined. Maleinised polypropylene, a copolymer of ethylene with vinyl acetate, and their mixtures were used as compatibilising additives. Maleinised polypropylene was introduced together with polypropylene in a quantity of 1-10 parts; no changes in properties were observed with increase in the dosage above 4 parts, so this dosage was used. The copolymer of ethylene with vinyl acetate (1-10 parts) was introduced into the rubber phase at the stage of rubber mix preparation specially to improve the compatibility of polypropylene and nitrile butadiene rubber. The introduction of maleinised polypropylene leads to an increase in the workability and in the level of elastic strength properties, in particular the tensile elastic modulus and hardness. A considerable increase in the uniformity of distribution of components throughout the volume, a finer dispersion of the rubbers in the polypropylene matrix, and a reduction in the number of pores in the material were shown, and also an increase in the degree of polypropylene crystallinity measured under experimental conditions. The most positive effect is observed with the combined introduction of the copolymer of ethylene with vinyl acetate and the maleinised polypropylene: the nominal stress under elongation increases by 34%, and the elongation at break by 15%. The combined introduction of the compatibilising additives improves the compatibility of the components of the system, the phase boundaries become more diffuse, there is a reduction in the optical density of rubber-rich zones, and these zones are penetrated by polypropylene fibrils. [ABSTRACT FROM AUTHOR]

Rapid assessment of fungal growth and screening antifungal compounds, such as nanoparticles (NPs), for effectiveness is a challenging procedure because no primary standards exist as they do for yeasts and bacteria. Because fungi do not grow as single cells, but as hyphal filaments, they cannot be quantified by the usual enumeration techniques used in bacteriology. The growth of three postharvest fungal isolates (Alternaria alternata, Rhizopus stolonifer, and Botrytis cinerea) was investigated at different inoculum concentrations and in three nutrient media (Sabouraud dextrose agar, potato dextrose agar, and yeast extract dextrose agar [YED]) with a turbidimetric assay. Sequential measurements were performed to generate optical density versus time plots, whereas the growth responses were expressed quantitatively as the generated trapezoidal area. YED medium showed the lowest variation among replicated experiments; potato dextrose agar showed the next lowest, but there was no significant difference. The inoculum size had a minimal effect on the variation of the fungal dynamics. Microscopic assessment of the fungal growth confirmed that YED medium allowed the most homogeneous development of the studied fungi. Therefore, we developed a rapid and reliable technique to evaluate the efficacy of novel antifungal compounds such as zinc oxide NPs. Turbidimetric assessment showed that these NPs were able to inhibit the growth of all three isolates. A. alternata and B. cinerea did not show a significant difference in the level of inhibition at 15 mM, whereas R. stolonifer showed the highest inhibition at the same concentration. [ABSTRACT FROM AUTHOR]

Ultrafine titanium dioxide (TiO2) nanowires were synthesised using a hydrothermal method with different volumes of ethylene glycol (EG) and annealing temperatures. It shows that sodium titanate nanowires synthesised using 5 and 10 ml EG, which annealed at 400°C produced TiO2 nanowires that correspond to a photochemically active phase, which is anatase. The influences of annealing temperatures (400–600°C) on the morphological arrangement of TiO2 nanowires were evident in the field emission scanning electron microscopy. The annealing temperature of 500°C led to agglomeration, which formed a mixture of TiO2 nanoparticles and nanowires. High thermal stability of TiO2 nanowires revealed by thermogravimetric analysis and Fourier transform infrared spectroscopy spectrum showed the presence of the Ti–O–Ti vibrations as evidenced due to TiO2 lattices. An antibacterial study using TiO2 nanowires toward Escherichia coli and Klebsiella pneumoniae showed large zones of inhibition that indicated susceptibility of the microbe toward TiO2. Growth kinetic analysis shows that addition of TiO2 has reduced optical density (OD) suggesting an inhibition of the growth of bacteria. These results indicate TiO2 nanowires can be effectively used as an antimicrobial agent against gram‐bacteria. The TiO2 nanowires could be exploited in the medical, packaging and detergent formulation industries and wastewater treatment. [ABSTRACT FROM AUTHOR]

This paper reports about excitons in strongly correlated oxide nanocrystals Ni c Mg 1-c O (c = 0.008 and c = 1). At 8 K two weak peaks were firstly observed in the optical density spectrum of NiO nanocrystals at the energies of 3.510 eV and 3.543 eV. The intensity of the peaks subsides with an increase of temperature and a decrease of nanoparticle sizes from 25 nm to 10 nm. The peaks were attributed to the formation of p-d charge transfer excitons {d 9 h}. A tunneling annihilation for {d 9 h} excitons diminishes their lifetime drastically, even at low temperatures. This fact is considered as an inherent feature in the p-d charge transfer excitons {d 9 h}, which makes them significantly different from the Wannier-Mott excitons for semiconductors with direct allowed transitions. We believe that energy shift between two peaks originates due to the spin-orbit splitting of the top of the valence band, equals 33 meV. In p-d charge transfer photoluminescence excitation spectrum of Ni c Mg 1-c O (c = 0.008), we have revealed two [d 9 h] exciton lines near the charge transfer band edge. Energy shift of these lines (equals 25 meV) is due to the spin-orbit splitting of MgO valence band top. [ABSTRACT FROM AUTHOR]

The wide application of titanium dioxide nanoparticles and phosphorus in the manufacturing of many industrial products mainly used in agricultural sector has resulted in the release of considerable amounts of these compounds into freshwater aquatic ecosystem. These compounds may cause some unexpected effects to aquatic organisms. This study assessed the binary effects of Titanium nanoparticles (nTiO 2 ) and Phosphorus on Chlorella ellipsoides . Toxicological assay test of the compounds nTiO 2 (1.25 μM) alone and the combination of Titanium dioxide (1.25 μM) and Phosphorus (16, 32, 80, 160, 240 μM) was assessed, after 96 h exposures, for optical density (OD 680 ), specific growth rate, chlorophyll levels and lipid peroxidation via Malondialdehyde (MDA) activity. Superoxide dismutase (SOD), peroxidase (POD) and glutathione-s-transferase (GST) activities were also measured. Two-way ANOVA showed a significant interaction (P < 0.05) between binary mixture. Co-exposure showed a decreased phosphorus bioconcentration in the microalgae with significant increase (P < 0.05) in chlorophyll a/b and total chlorophyll contents. A significant decrease (P < 0.05) in specific growth rate and optical density were recorded whereas, antioxidant enzymes (MDA, SOD, POD, GST) activities were significantly (P < 0.05) increased. These results showed that the addition of nTiO 2 to Phosphorus affected the physiology of microalgae and should be of great concern for freshwater biodiversity. [ABSTRACT FROM AUTHOR]

The article presents the results of the research into influence of a long-term (50 years) application of different fertilizer rates and fertilizer systems in the field crop rotation on the humus composition and optical parameters of humic acids of a heavy-loamy podzolized chernozem of the Right Bank Forest-Steppe of Ukraine. It was found that application of fertilizers significantly affects the dominance of humic acids over fulvic acids in the composition of soil, which indicates humate type of soil. Chroma index of humic acids is within 3.56-3.75 depending on a fertilizer. Indicators of the optical properties of humic acids of a podzolized chernozem have a high degree of humification. [ABSTRACT FROM AUTHOR]

Background Traumatic Brain Injury (TBI) is one of the most common surgical emergencies in service hospitals of India. Computed tomography (CT) has been a consistent and reliable technique for detecting intracranial hemorrhages but is limited by its non-availability in most service hospitals. Therefore the need for a cheaper, portable and easily available option required to be explored. The aim of this study was to determine the sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of Near Infra Red Spectroscopy (NIRS) against the gold standard of NCCT head. Methods An observational, prospective study was conducted in 100 patients of closed head injury, attending the emergency department or surgical OPD of a service zonal hospital with NIRS. All these patients were subsequently subjected to NCCT head. Sensitivity, specificity, and positive and negative predictive values of NIRS were calculated. The study was conducted from Oct 2010 to Jul 2012. Results All the 100 patients were evaluated with NIRS and subsequently subjected to NCCT head. The results were compiled and statistical analysis of the same was conducted. The data revealed a sensitivity of 58.46%, a specificity of 42.86%, a positive predictive value of 65.52% and a negative predictive value of 35.71%. Conclusion Near Infra Red Spectroscopy (NIRS) is a good screening tool for prediction of intra cerebral haemorrhage in the field and even intensive care units. This was the first study of its kind in the Indian subcontinent and the results suggest that NIRS is a good device to predict intracranial subdural and epidural haematomas. It is however not superior to computer tomography and magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

In extracorporeal blood purification, such as hemoperfusion, activated carbon (activated charcoal) beads are commonly used as an adsorbent, but their judgment in terms of extent of microparticle release is of great importance since the microparticles may represent the risk of entering the bloodstream. To quantitatively assess the release of carbon microparticles (CMPs) in the samples of the aqueous perfusion medium, in which the beads have been perfused, the calibration procedure with different concentrations of CMPs is likely to be needed. For this purpose, carbon beads were mechanically crushed to a fine powder, whose microparticles (<10 μm) were then serially diluted in the aqueous medium within the wide range of concentrations (0.2–100 μg/ml). To test these concentrations of CMPs, the micro-aliquots of each dilution of suspended CMPs were dried on a surface of hydrophobic membrane and at the optical magnification of 20× the dry residues were than analyzed by measuring the sum of densities. This simple and affordable technique was shown to be considerably more sensitive than spectrophotometry of the aqueous suspensions of CMPs. [ABSTRACT FROM AUTHOR]

Most amphibians produce their own defensive chemicals; however, poison frogs sequester their alkaloid-based defenses from dietary arthropods. Alkaloids function as a defense against predators, and certain types appear to inhibit microbial growth. Alkaloid defenses vary considerably among populations of poison frogs, reflecting geographic differences in availability of dietary arthropods. Consequently, environmentally driven differences in frog defenses may have significant implications regarding their protection against pathogens. While natural alkaloid mixtures in dendrobatid poison frogs have recently been shown to inhibit growth of non-pathogenic microbes, no studies have examined the effectiveness of alkaloids against microbes that infect these frogs. Herein, we examined how alkaloid defenses in the dendrobatid poison frog, Oophaga pumilio, affect growth of the known anuran pathogens Aeromonas hydrophila and Klebsiella pneumoniae. Frogs were collected from five locations throughout Costa Rica that are known to vary in their alkaloid profiles. Alkaloids were isolated from individual skins, and extracts were assayed against both pathogens. Microbe subcultures were inoculated with extracted alkaloids to create dose-response curves. Subsequent spectrophotometry and cell counting assays were used to assess growth inhibition. GC-MS was used to characterize and quantify alkaloids in frog extracts, and our results suggest that variation in alkaloid defenses lead to differences in inhibition of these pathogens. The present study provides the first evidence that alkaloid variation in a dendrobatid poison frog is associated with differences in inhibition of anuran pathogens, and offers further support that alkaloid defenses in poison frogs confer protection against both pathogens and predators. [ABSTRACT FROM AUTHOR]

Fifty six strains of Micrococcus sp. were isolated from the water samples from Barada River in Damascus. Ten isolates of Micrococcus sp. species were taken for the present study for investigate biodegradation ability of vegetable oil wastes under the influence of this genus. The vegetable oil wastes dependent growths of these isolates were assessed for 15 days by monitoring the gradient fluxes in pH, optical density OD and total viable count TVC in the medium. Results showed an increase in OD and TVC as well as fluctuations in pH values. The relationship between these values was studied and determined if the relationships were statistically significant, and values were compared with the results in the positive control to the same strain. Biodegradation activity of different Micrococcus sp. species was tested in vegetable oil wastes which showed a good activity with 1% concentration of vegetable oil wastes, but decreased in 2% and 3% concentration. The genus Micrococcus sp. showed a good ability to grow in different concentrations of vegetable oil wastes, that refers to the ability of the genus to use vegetable oil wastes as the only carbon source. [ABSTRACT FROM AUTHOR]

The effects of a dipolar static magnetic field of strength 400, 800, 1200 and 1600 Gauss were prepared locally, on the ultra-structure of E. coli type 1 bacterium cells have been studied. Equal volumes of liquid culture media were exposed to the magnetic field for different periods, the three most effective periods, namely: 24 hrs, 48 hrs and 72 hrs were chosen for all our experimental studies. After API kit test of treated E. coli culture media as control group. Results indicated that exposure of the microorganisms to the demonstrated magnetic field caused pronounced changes in the Arginine dihydrolase (ADH), Citrate utilization (CIT) and Gelatinase (GEL) were observed on the cell growth. Besides, changes in the morphology of the E. coli colonies were observed after exposure period and subculture on MacConkey agar. Furthermore, the bacterial growth subculture tested for morphological and biological activity, the results suggested that a mutation occurred in bacterial cells. [ABSTRACT FROM AUTHOR]

Photochromic quartz-like glasses were synthesized by an impregnation of the high-silica porous glasses with mixture of the Ag/Cu-Hal compounds (where Hal = Cl, Br, I; Cu 2+ is sensitizer) from water-salt solutions. UV/VIS/NIR optical density and visible luminescence spectra of synthesized glassy composites have been obtained. It was shown that UV radiation of these materials causes luminescence of the silver centers in a visible spectral region (450–620 nm). The assumption that the photochromic quartz-like glasses based on the matrixes from silicate nanoporous glasses are promising materials for solar engineering has been stated on the grounds of obtained results. [ABSTRACT FROM AUTHOR]

ADP-ribosyltransferase activities have been observed in many prokaryotic and eukaryotic species and viruses and are involved in many cellular processes, including cell signalling, DNA repair, gene regulation and apoptosis. In a number of bacterial toxins, mono ADP-ribosyltransferase is the main cause of host cell cytotoxicity. Several approaches have been used to analyse this biological system from measuring its enzyme products to its functions. By using a mono ADP-ribose binding protein we have now developed an ELISA method to estimate native pertussis toxin mono ADP-ribosyltransferase activity and its residual activities in pertussis vaccines as an example. This new approach is easy to perform and adaptable in most laboratories. In theory, this assay system is also very versatile and could measure the enzyme activity in other bacteria such as Cholera, Clostridium, E. coli , Diphtheria, Pertussis, Pseudomonas, Salmonella and Staphylococcus by just switching to their respective peptide substrates. Furthermore, this mono ADP-ribose binding protein could also be used for staining mono ADP-ribosyl products resolved on gels or membranes. [ABSTRACT FROM AUTHOR]

• Endotoxin content in Escherichia coli / Pseudomonas bioreactor samples. • High accuracy endotoxin quantification with novel chemical Kdo-DMB-LC assay. • Endotoxin content correlates to optical density, dry cell weight, LAL. • Linear correlation between Kdo-DMB-LC assay and LAL assay results. • Kdo-DMB-LC assay transfers endotoxin testing to the 21st century. A novel chemical assay, the so-called Kdo-DMB-liquid chromatography (LC) assay, was used for the accurate and cost-effective determination of the endotoxin content in supernatants of Gram-negative bacteria bioreactor samples. During mild acid hydrolysis, the endotoxin-specific sugar acid 3-deoxy-D- manno -oct-2-ulsonic acid (Kdo) is quantitatively released. Kdo is reacted with 1,2-diamino-4,5-methylenedioxybenzene (DMB) to obtain the highly fluorescent derivate Kdo-DMB. It is separated from the reaction mixture by reversed phase-(U)HPLC and detected by fluorescence. From the Kdo content the endotoxin content of the sample is calculated. For three batch cultivations of Escherichia coli K12 and a fed-batch cultivation of Pseudomonas putida KT2440, the evolution of the endotoxin content in dependence on the cultivation time was monitored. Under optimal, constant cultivation conditions a linear correlation between the endotoxin content and the easy-to-access bioreactor parameters optical density at 600 nm and dry cell weight was found for both endotoxin kinds. Under stress cultivation conditions the E. coli K12 cultivation showed a stronger increase of the endotoxin content at harvest in comparison to optimal conditions. Optical density and dry cell weight may be used for production reactors as an economic real-time estimation tool to determine the endotoxin content at different cultivation time points and conditions. The optical density can further be used to establish straightforward sample dilution schemes for endotoxin quantification in samples of unknown endotoxin content. The endotoxin content [ng mL−1] measured by the Kdo-DMB-LC assay and the endotoxin activity [EU mL−1] obtained by the compendial Limulus Amoebocyte Lysate assay show a high correlation for the bacterial bioreactor samples tested. [ABSTRACT FROM AUTHOR]

Characterisation of promoters, repressors, enhancers and so on, is not only essential for unravelling the inner workings of gene regulation, but also to enable the rational engineering of novel synthetic elements. Each putative regulatory region requires experimental assessment across a range of chassis and growth conditions, in order to be categorised as a fully defined functional element. In most studies, promoter activity is represented as the magnitude of a reporter signal, usually fluorescence, normalised to the biomass, as given by the optical density (OD). Such experimental values are often obtained from a coupled time-series experiment. Applying simple mathematical reasoning, a tool that describes promoter activity at each time point has been implemented. Protein expression and maturation, are modelled as first-order differential equations, taking into account the degradation and maturation rates which need to be known in advance. The promoter activity is then expressed based on the measured values of fluorescence and OD with a formula derived by mathematical manipulations of the defined quantities and the differential equations that comprise the model. Continuous expressions for fluorescence and OD are obtained from Gaussian process regression. Validation of the tool with experimental data from several constructs showed the expected behaviour of promoter activities.

The bacterial diversity in a diesel contaminated tropical soil was investigated using diesel oxidation in gradient cultures dynamics (pH and OD) of the pure cultures. The diesel dependent growths of these isolates were assessed for 15 days by monitoring the gradient fluxes in the pH and Optical density OD of the media. Results showed an increase in OD as well as fluctuations in pH values. The mean OD data obtained was 0.515- 1.187 with pH of 6.95-7.2. From the morphological and biochemical characterization and comparison with respect to the standard references, the isolates S1P1, S3P3, S2P2, S2P1,and S3P2 were presumably the members of the genera Bacillus, Pseudomonas and Mycobacterium species. From the study, it was apparent that the tropical ecosystems contained unique organisms with the ability to deal with diesel contamination.

In the context of this work we evaluated a multisensory, noninvasive prototype platform for shake flask cultivations by monitoring three basic parameters (pH, pO2 and biomass). The focus lies on the evaluation of the biomass sensor based on backward light scattering. The application spectrum was expanded to four new organisms in addition to E. coli K12 and S. cerevisiae [1]. It could be shown that the sensor is appropriate for a wide range of standard microorganisms, e.g., L. zeae, K. pastoris, A. niger and CHO-K1. The biomass sensor signal could successfully be correlated and calibrated with well-known measurement methods like OD600, cell dry weight (CDW) and cell concentration. Logarithmic and Bleasdale-Nelder derived functions were adequate for data fitting. Measurements at low cell concentrations proved to be critical in terms of a high signal to noise ratio, but the integration of a custom made light shade in the shake flask improved these measurements significantly. This sensor based measurement method has a high potential to initiate a new generation of online bioprocess monitoring. Metabolic studies will particularly benefit from the multisensory data acquisition. The sensor is already used in labscale experiments for shake flask cultivations.

Six γ-oxa-ε-lactones, 4-phenyl-3,4-dihydro-2H-1,5-benzodioxepin-2-one (5a) and its five derivatives with methoxy groups in different positions of A and B rings (5b−f), were synthesized from corresponding flavanones. Three of the obtained lactones (5b,c,f) have not been previously described in the literature. Structures of all synthesized compounds were confirmed by complete spectroscopic analysis with the assignments of signals on 1H and 13C-NMR spectra to the corresponding atoms. In most cases, lactones 5a−f exerted an inhibitory effect on the growth of selected pathogenic bacteria (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus), filamentous fungi (Fusarium graminearum, Aspergillus niger, and Alternaria sp.), and yeast (Candida albicans). The broadest spectrum of activity was observed for unsubstituted lactone 5a, which was particularly active against filamentous fungi and yeast. Lactones with methoxy groups in the 3′ (5c) and 4′ (5d) position of B ring were more active towards bacteria whereas lactone substituted in the 7 position of the A ring (5e) exhibited higher antifungal activity. In most cases, the introduction of lactone function increased the activity of the compound compared to its flavonoid precursors, chalcones 3a−e, and flavanones 4a−f.