Isolation of pathogen microorganisms using immobilized antibodies onto magnetic silicate beads

TUTTOLOMONDO, V; TEVES, S; COPELLO, G; M.E. VILLANUEVA; F.P. PEREYRA GERBER; DIAZ, L

San Miguel de Tucumán

Congreso; XLV Reunión anual - Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

In medical and food microbiology, specific microorganisms must be detectable in the presence of dominant background microflora. Our aim was to develop a versatile system for pathogen bacterial isolation from contaminated media. For this purpose Salmonella anti-OS A polyclonal antibodies (Ab) were immobilized onto home-made magnetic silicate beads by the sol-gel aqueous route. A FeCl3 and FeCl2 aqueous mixture was coprecipitated with NaOH. The ferrofluid thus generated was mixed with a sodium silicate solution and used as the aqueous phase of an inverse microemulsion system. Thus magnetic beads were generated by an aqueous route sol-gel process. The obtained beads were functionalized with APTES to provide NH2 groups and treated with glutaraldehyde, a bifunctional reagent that attaches to both APTES and Ab free NH2 groups. These beads are recoverable by means of a magnet after an assay. Different mixtures of generic Salmonella spp and generic Escherichia coli were used to evaluate the specificity and sensibility of the system. Specificity was demonstrated with a minimum background. Sensibility was demonstrated with a high recovery of Salmonella OS A even from a 90:10 mixture of generic E. coli:Salmonella OSA. The system appears as a promising technology for early detection of pathogenic bacteria in a muc shorter time compared to the classical methodology (approximately 48 hours).