Biofilm effects on the peroxidase-oxidase reaction

Green synthesis of ZnO nanoparticles with Veronica multifida and their antibiofilm activity

In the present study, Veronica multifida leaf extract and zinc acetate dihydrate were utilized to synthesize zinc oxide (ZnO) nanoparticles (NPs) eco-friendly and cost-effectively under different physical conditions. Soxhlet extractor was used for the preparation of aqueous plant extract. UV-Vis (ultraviolet–visible) spectrophotometer, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscope (TEM) were used to characterize the ZnO NPs. UV-Vis spectrophotometer in the range of 200–800 nm was used to get information about the formation of ZnO NPs at different pH and temperatures. FTIR spectrum revealed the presence of functional groups in ZnO NPs. XRD, scanning electron microscope, and TEM analyses confirmed the crystal structure and average size of ZnO NPs. The antimicrobial activities of ZnO NPs were tested on microorganisms, that is, Escherichia coli ATCC 43895 , Staphylococcus aureus ATCC 29213 , Bacillus subtilis, Bacillus licheniformis, Pseudomonas aeruginosa, and Salmonella typhimurium. Moreover, antibiofilm activity of ZnO NPs was performed against P. aeruginosa and S. aureus ATCC 29213. ZnO NPs have shown effective antimicrobial and antibiofilm activities against tested microorganisms. The results elucidated that eco-friendly and cost-effectively produced ZnO NPs could be used as coating materials and in a wide range of industrial applications, such as pharmaceutical industries and cosmetics.

Biofilm inhibition and pathogenicity attenuation in bacteria by Proteus mirabilis

Biofilms play an important role in the antibiotic resistance of encased bacteria, and biofilm formation is regulated by quorum sensing (QS). Inhibiting the QS system may, therefore, degrade the integrity of a biofilm and expose the bacterial pathogens within it to the deleterious effects of molecules such as antibiotics. Moreover, the use of QS inhibitors (QSIs) may provide a novel approach for treating bacterial infections of aquacultures. In the present study, the bacterium Proteus mirabilis was identified as a potential producer of QSIs. Varying concentrations (0.1-1.1%) of filtrates prepared from the culture of P. mirabilis inhibited biofilm formation by the pathogens Pseudomonas aeruginosa, Vibrio harveyi and Staphylococcus aureus by as much as 58.9%, 41.5% and 41.9%, respectively. These filtrates as well as the crude aqueous extracts prepared from them increased the sensitivities of pathogens to the inhibitory effects of kanamycin. The filtrates also showed pathogenicity attenuation potential in P. aeruginosa by decreasing the production of virulence factors. Moreover, the filtrates did not influence the planktonic growth of these pathogens. The results indicate that P. mirabilis may act as a non-specific (or broad-spectrum) inhibitor of biofilm formation that will help control infectious diseases that adversely affect the aquaculture industry.

Novel concepts in evaluating antimicrobial therapy for bacterial lung infections in patients with cystic fibrosis

Cystic fibrosis (CF) patients suffer typically from bacterial infections of their airways. Whilst current antibiotic-based treatment of these infections has brought much benefit to patients, it has been difficult to make either direct or indirect assessments of the in vivo efficacy of any specific treatment used. Traditional culture-based assessment has for example been rarely used to determine the direct impact of therapy on the bacteria in the airways. Instead, the "success" of a treatment is most often gauged through measures of respiratory and general health. New culture-independent approaches though are emerging that offer much promise here however in allowing a more comprehensive evaluation of antimicrobial efficacy. These new methods offer an opportunity to examine bacterial outcomes rather than host outcomes alone. Application of these novel techniques in a systematic way will lead to the rationalisation and, likely greater still individualisation, of therapy for CF patients. This review discusses host and microbiological factors that may influence antibiotic efficacy. Moreover, the degree to which the inherent complexity of CF respiratory infections complicates the process of determining treatment impact and the need to identify more robust microbiological outcome measures will also be reviewed.

Sample handling and chemical kinetics in an acoustically levitated drop microreactor

Accurate measurement of enzyme kinetics is an essential part of understanding the mechanisms of biochemical reactions. The typical means of studying such systems use stirred cuvettes, stopped-flow apparatus, microfluidic systems, or other small sample containers. These methods may prove to be problematic if reactants or products adsorb to or react with the container’s surface. As an alternative approach, we have developed an acoustically-levitated drop reactor eventually intended to study enzyme-catalyzed reaction kinetics related to free radical and oxidative stress chemistry. Microliter-scale droplet generation, reactant introduction, maintenance, and fluid removal are all important aspects in conducting reactions in a levitated drop. A three capillary bundle system has been developed to address these needs. We report kinetic measurements for both luminol chemiluminescence and the reaction of pyruvate with nicotinamide adenine dinucleotide, catalyzed by lactate dehydrogenase, to demonstrate the feasibility of using a levitated drop in conjunction with the developed capillary sample handling system as a microreactor.

Design and implementation of an efficient acoustically levitated drop reactor for in stillo measurements

We present the details necessary for building an efficient acoustic drop levitator with reduced electrical power consumption and greater drop stability compared to previous designs. The system is optimized so that the levitated drop may be used as a chemical reactor. By introducing a temperature, pressure, and relative humidity sensor for feedback control of a linear actuator for adjusting resonator length, we have built a completely automated system capable of continuous levitation for extended periods of time. The result is a system capable of portable operation and interfacing with a variety of detection instrumentation for in stillo (in drop) measurements.