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Microtitre Plates (microtitre + plate)
Selected AbstractsFactors affecting the attachment of micro-organisms isolated from ultrafiltration and reverse osmosis membranes in dairy processing plantsJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009X. Tang Abstract Aims:, To identify the types of micro-organisms involved in the formation of biofilms on dairy ultrafiltration and reverse osmosis membranes and investigate factors affecting the attachment of those isolates. Methods and Results:, Micro-organisms isolated from industrial membranes following standard cleaning were identified using the API culture identification system. Thirteen different isolates representing eight genera were isolated and their ability to attach to surfaces was compared using a microtitre plate assay. Three Klebsiella strains attached best, while mixed strains of Pseudomonas and Klebsiella attached better than individual strains. Whey enhanced the attachment of the isolates. The micro-organisms were characterized according to cell surface hydrophobicity using the microbial adhesion to hydrocarbon (MATH) test, and cell surface charge by measuring the zeta potential. These cell surface characteristics did not show a clear relationship with the attachment of our strains. Conclusions:, A variety of different micro-organisms is associated with dairy ultrafiltration and reverse osmosis membranes after cleaning, suggesting several possible sources of contamination. The cleaning of these membranes may be inadequate. The attachment of the different isolates is highly variable and enhanced in the presence of whey. Significance and Impact of the Study:, Knowledge of persistent microflora colonizing dairy membrane systems will help develop strategies to mitigate biofilm development in this environment, improving hygiene in membrane processing plants. [source] Direct analysis of single leaf disks for chemopreventive glucosinolatesPHYTOCHEMICAL ANALYSIS, Issue 3 2002Qiaomei Wang Abstract Natural isothiocyanates, produced during plant tissue damage from methionine-derived glucosinolates, are potent inducers of mammalian phase 2 detoxification enzymes such as quinone reductase (QR). A greatly simplified bioassay for glucosinolates based on induction and colorimetric detection of QR activity in murine hepatoma cells is described. It is demonstrated that excised leaf disks of Arabidopsis thaliana (ecotype Columbia) can directly and reproducibly substitute for cell-free leaf extracts as inducers of murine QR, which reduces sample preparation to a minimum and maximizes throughput. A comparison of 1 and 3,mm diameter leaf disks indicated that QR inducer potency was proportional to disk circumference (extent of tissue damage) rather than to area. When compared to the QR inducer potency of the corresponding amount of extract, 1,mm leaf disks were equally effective, whereas 3,mm disks were 70% as potent. The QR inducer potency of leaf disks correlated positively with the content of methionine-derived glucosinolates, as shown by the analysis of wild-type plants and mutant lines with lower or higher glucosinolate content. Thus, the microtitre plate-based assay of single leaf disks provides a robust and inexpensive visual method for rapidly screening large numbers of plants in mapping populations or mutant collections and may be applicable to other glucosinolate-producing species. Copyright © 2002 John Wiley & Sons, Ltd. [source] In vitro inhibition of oral streptococci binding to the acquired pellicle by algal lectinsJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2007E.H. Teixeira Abstract Aims:, The initial colonization of the tooth by streptococci involves their attachment to adsorbed components of the acquired pellicle. Avoiding this adhesion may be successful in preventing caries at early stages. Salivary mucins are glycoproteins that when absorbed onto hydroxyapatite may provide binding sites for certain bacteria. Algal lectins may be especially interesting for oral antiadhesion trials because of their great stability and high specificity for mucins. This work aimed to evaluate the potential of two algal lectins to inhibit the adherence of five streptococci species to the acquired pellicle in vitro. Methods and Results:, The lectins used were extracted from Bryothamnion triquetrum (BTL) and Bryothamnion seaforthii (BSL). Fluorescence microscopy was applied to visualize the ability of fluorescein isothiocyanate-labelled lectins to attach to the pellicle and revealed a similar capability for both lectins. Streptococcal adherence assays were performed using saliva-coated microtitre plates. BSL inhibited more than 75% of Streptococcus sanguis, Streptococcus mitis, Streptococcus sobrinus and Streptococcus mutans adherence, achieving 92% to the latter. BTL only obtained statistically significant results on S. mitis and S. sobrinus, whose adherence was decreased by 32·5% and 54·4%, respectively. Conclusion:, Algal lectins are able to inhibit streptococcal adherence. Significance and Impact of the Study:, Our results support the proposed application of lectins in antiadhesion therapeutics. [source] Toward a Microfluidic-Based Rapid Amylase Assay SystemJOURNAL OF FOOD SCIENCE, Issue 6 2009Richard J. Holmes ABSTRACT:, This article describes work into a prototype system for the assay of amylase, using microfludic technologies. The new system has a significantly shorter cycle time than the current laboratory methods, which generally use microtitre plates, yet is capable of generating significantly superior results. As such, we have shown that sensitivity is enhanced by a factor of 10 in the standard assay trials, and by a factor of 2 in the real-sample lab trials. In both assays, the use of a microreactor system reduced the reaction time by a factor of 6.2, from 20 min incubation to 3.2 min. Basing the conclusion on the Megazyme Cerealpha Standard Method, and using the Cerealpha units as a measure of assay efficiency, the typical response for the microfluidic assay was shown to be 1.0 × 10,3 CU/mL (standard deviation [SD] 2.5 × 10,4 CU/mL), compared to 2.56 × 10,4 CU/mL (SD 5.94 × 10,5 CU/mL) for the standard macroassay. It is believed that this improvement in the reaction schematics is due to the inherent advantages of microfluidic devices such as superior mixing, higher thermal efficiency, and enhanced reaction kinetics. [source] Disruption of fungal and bacterial biofilms by lauroyl glucoseLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2008D.H. Dusane Abstract Aim:, The ability of enzymatically synthesized lauroyl glucose to disrupt fungal (Candida albicans, Candida lipolytica) and bacterial (Pseudomonas aeruginosa PAO1, Pseudomonas aureofaciens) biofilms was investigated. Methods and Results:, Preformed biofilms of C. albicans and C. lipolytica in polystyrene microtitre plates were disrupted upto 45% and 65%, respectively, while P. aeruginosa and P. aureofaciens biofilms were disrupted by 51% and 57%. Precoating of the microtitre wells with lauroyl glucose affected cell attachment and biofilm growth of all the cultures to a lesser extent. With C. albicans and C. lipolytica, there was 11% and 32% decrease in the development of biofilms, respectively. With P. aeruginosa and P. aureofaciens, the reduction was 21% and 12% after 48 h. Lauroyl glucose effectively inhibited the formation of biofilms on glass slide surfaces when added along with the inoculum. Analysis by confocal laser scanning microscopy showed that the growth of the biofilms was lesser as compared with the control experiments. Lauroyl glucose displayed minimum inhibitory concentration values >500 ,g ml,1 for the test cultures and was comparable to that obtained with acetyl salicylate. Conclusion:, Lauroyl glucose reduces biofilm growth of all the four test cultures on polystyrene and glass surfaces. Significance and Impact of the Study:, This report is a novel application of the enzymatically synthesized, environmental-friendly nonionic surfactant. [source] Binding of extracellular matrix molecules by probiotic bacteriaLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2003tyriak Abstract Aims: The aim of this study was to investigate extracellular matrix (ECM) and mucin binding of selected bacterial isolates with probiotic features in comparison with commercially used probiotic bacteria. Methods and Results: ECM molecules were immobilized in microtitre plates (mucin and fetuin) or on the surface of latex beads. Porcine mucin was bound by all 13 probiotic strains tested with important inter-strain differences; however, fetuin binding was similar (weak) for all 14 strains tested. Strongly positive (three) binding of bovine fibrinogen was expressed by strains from fermented food (Lactobacillus rhamnosus GG, L. casei Shirota and L. johnsonii La1) as well as by L. casei L.c., Lactobacillus sp. 2I3 and by L. plantarum LP. The other strains expressed moderate (2) or weakly positive (1) binding of bovine fibrinogen. Strongly positive (3) binding of porcine fibronectin was observed only with two strains; however, all other strains also bound this molecule. Bovine lactoferrin was bound to a higher extent than transferrins. Significance and Impact of the Study: Some animal strains (at least L. casei L.c. and Lactobacillus sp. 2I3) are comparable with the commercially used strains with respect to their ECM binding ability. As this feature is important for probiotic bacteria to be able to colonize intestine, these strains should be considered for their wider use in fermented feed (or probiotic preparations) for animals. [source] A fast and inexpensive DNA extraction/purification protocol for brown macroalgaeMOLECULAR ECOLOGY RESOURCES, Issue 2 2007GALICE HOARAU Abstract Here we describe a rapid method for extracting DNA from dried brown algae material using a microtitre plate system in conjunction with a milling instrument. The method allows the preparation of nuclear and organelle DNA of quality suitable for polymerase chain reaction amplification. It combines high throughput with low cost per sample: DNA from 192 samples can be extracted in c. 3 h for < ,0.40 per sample, nearly tenfold cheaper than commercially available kits. Furthermore, by using microtitre plates, efficient storage and downstream processing is facilitated. [source] Biofilm formation by Streptococcus pneumoniae isolates from paediatric patientsAPMIS, Issue 4 2010TERHI TAPIAINEN Tapiainen T, Kujala T, Kaijalainen T, Ikäheimo I, Saukkoriipi A, Renko M, Salo J, Leinonen M, Uhari M. Biofilm formation by Streptococcus pneumoniae isolates from paediatric patients. APMIS 2010; 118: 255,60. The clinical significance of pneumococcal biofilm formation is largely unknown. To clarify this, we tested whether the ability of pneumococcal clinical isolates to form biofilm in vitro accounts for the diverse clinical outcomes. Clinical pneumococcal isolates were cultured from the nasopharynx (n = 106), middle ear effusion (n = 43) and blood (n = 55) of 204 children altogether. Biofilm formation, assessed by measuring optical density (OD) values in microtitre plates after crystal violet staining, did not differ between the bacteria from different sources (p = 0.18), the mean OD values of the isolates being 0.119 [95% confidence interval (CI) 0.100,0.138] in the nasopharynx samples, 0.094 (95% CI 0.069,0.119) in the acute otitis media cases, 0.109 (95% CI 0.077,0.141) in the secretory otitis media cases, 0.122 (95% CI 0.084,0.160) in those with sepsis and 0.175 (95% CI 0.071,0.280) in those with other invasive infections. Serotypes 33 and 14 were the most efficient in forming biofilms, whereas serotypes 3 and 38 were poor biofilm producers. We conclude that the clinical presentation of pneumococcal disease did not differ in relation to biofilm formation in vitro, even though there was marked variation between the clinical isolates and serotypes. [source] Statistical aspects of design and validation of microtitre-plate-based linear and non-linear parallel in vitro bioassaysBIOTECHNOLOGY JOURNAL, Issue 1 2010Hanne Zimmermann Abstract Assay validation was performed using four consecutive experiments with the related statistical evaluation. A cell-based assay on microtitre plates measured repeatedly within 1 day and on consecutive days was chosen as the model. The following problems were addressed: (i) choosing an appropriate design on a plate to avoid heterogeneities, (ii) quantification of all sources of variability and (iii) selecting between linear and non-linear parallel line assays. A mixed model was used with the random factors: rows, columns and plates and fixed effect factors with either linear or non-linear parallel line models. [source] | |||||||||||||