4 research outputs found
Comparing recovering efficiency of immunomagnetic separation and centrifugation of mycobacteria in metalworking fluids
The accurate detection and enumeration of Mycobacterium immunogenum in metalworking fluids (MWFs) is imperative from an occupational health and industrial fluids management perspective. We report here a comparison of immunomagnetic separation (IMS) coupled to flow-cytometric enumeration, with traditional centrifugation techniques for mycobacteria in a semisynthetic MWF. This immunolabeling involves the coating of laboratory-synthesized nanometer-scale magnetic particles with protein A, to conjugate a primary antibody (Ab), specific to Mycobacterium spp. By using magnetic separation and flow-cytometric quantification, this approach enabled much higher recovery efficiency and fluorescent light intensities in comparison to the widely applied centrifugation technique. This IMS technique increased the cell recovery efficiency by one order of magnitude, and improved the fluorescence intensity of the secondary Ab conjugate by 2-fold, as compared with traditional techniques. By employing nanometer-scale magnetic particles, IMS was found to be compatible with flow cytometry (FCM), thereby increasing cell detection and enumeration speed by up to two orders of magnitude over microscopic techniques. Moreover, the use of primary Ab conjugated magnetic nanoparticles showed better correlation between epifluorescent microscopy counts and FCM analysis than that achieved using traditional centrifugation techniques. The results strongly support the applicability of the flow-cytometric IMS for microbial detection in complex matrices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47949/1/10295_2005_Article_238.pd
Multiple Roles of Extracellular Polymeric Substances on Resistance of Biofilm and Detached Clusters
In this study, multiple roles of biofilm EPS were assessed
with
respect to the resistance of biofilm and detached biofilm clusters
to chlorine disinfection. Strains from an opportunistic pathogen, <i>Pseudomonas aeruginosa</i> (wild type, EPS- and EPS+) with altered
extracellular polymeric substances (EPS) secretion capabilities were
tested. The impact of biofilm EPS quantity on disinfection was evaluated
by monitoring biofilm viability, biofilm structure, removal of dissolved
organic matter (DOM), and viability of detached biofilm simultaneously
during chlorine disinfection. The obtained results suggested that
the presence of EPS increased biofilm and detached biofilm resistance
to chlorine in both presence and absence of DOM. The quantity of EPS
had an effect on biofilm structure and the structural characteristics
were closely related to both overall biofilm viability and the spatial
distribution of viable cells within the biofilm. Additionally, the
increased amount of EPS influenced selective removal of DOM with polar
functional groups. However the DOM removal did not have a significant
impact on the viability of biofilm cells during chlorine disinfection.
Meanwhile, the viability of detached biofilm clusters, particularly
the EPS overproducing strain, was significantly increased in the presence
of DOM. The combined results suggested that biofilm EPS played multiple
roles toward influencing the resistance of both biofilm and detached
biofilm to disinfectant