ABSTRACT
Bacterial surface layer proteins (S-layer) possess unique binding properties for metal ions. By combining the binding capability of S-layer proteins with the optical properties of gold nanoparticles (AuNP), namely plasmonic resonance, a colorimetric detection system for metal and metalloid ions in water was developed. Eight S-layer proteins from different bacteria species were used for the functionalization of AuNP. The thus developed biohybrid systems, AuNP functionalized with S-layer proteins, were tested with different metal salt solutions, e.g. Indium(III)-chloride, Yttrium(III)-chloride or Nickel(II)-chloride, to determine their selective and sensitive binding to ionic analytes. All tested S-layer proteins displayed unique binding affinities for the different metal ions. For each S-layer and metal ion combination markedly different reaction patterns and differences in concentration range and absorption spectra were detected by UV/vis spectroscopy. In this way, the selective detection of tested metal ions was achieved by differentiated analysis of a colorimetric screening assay of these biohybrid systems. A highly selective and sensitive detection of yttrium ions down to a concentration of 1.67â¯×â¯10-5â¯mol/l was achieved with S-layer protein SslA functionalized AuNP. The presented biohybrid systems can thus be used as a sensitive and fast sensor system for metal and metalloid ions in aqueous systems.
Subject(s)
Colorimetry/methods , Indium/isolation & purification , Nickel/isolation & purification , Water Pollutants, Chemical/isolation & purification , Yttrium/isolation & purification , Bacillaceae/chemistry , Gold/chemistry , Humans , Membrane Glycoproteins/chemistry , Metal Nanoparticles/chemistry , Protein Binding , Sporosarcina/chemistry , Surface Plasmon Resonance/methods , Water/chemistryABSTRACT
The original Bethesda classification system for reporting cervical/vaginal cytologic diagnoses has claimed besides oncologic evaluation also a statement on the presence of infectious agents. Their diagnosis should be followed by appropriate treatment. Based upon the comparison of careful bacterioscopic study in a series of 175 routine cervical smears with the results of microbiological, virological and mycological examinations the following pathogens might be-according to the authors' opinion-diagnosed as highly possible and recommended for laboratory verification: cocci, Gardnerella vaginalis, Klebsiella, Acinetobacter, Morganella Morgani, Candida, Trichomonas vaginalis, Chlamydia trachomatis and human papilloma virus.
Subject(s)
Cervix Uteri/microbiology , Vagina/microbiology , Bacteria/isolation & purification , Female , Fungi/isolation & purification , Humans , Microbiological Techniques , Vaginal Smears , Viruses/isolation & purificationABSTRACT
It was found that methyl phosphonic acid (Pn) was degraded by different Escherichia coli strains, which utilized it as the sole phosphorus source with resulting methane formation. This ability was influenced by mutations in the regulatory genes of the pho regulon. Thus, Pn was not degraded by an E. coli mutant defective in the regulatory phoB gene, responsible for the induction of pho-regulon proteins during phosphorus starvation. The intensity of Pn degradation depended on the age and concentration of the inoculum. Preincubation of bacteria in the presence of Pn accelerated subsequent degradation of both methyl phosphonic acid and its esters. Cultures developing from a small amount of inoculum degraded Pn more efficiently than heavily inoculated cultures that underwent only one cell division. However, cultures heavily inoculated with adapted cells degraded Pn as efficiently as cultures developing from a small amount of inoculum. Aeration was an important factor regulating Pn degradation: Pn was degraded more efficiently under anaerobic conditions regardless of the amount of inoculum.
