Muramic and dipicolinic acids in atmospheric particulate matter as biomarkers of bacteria and bacterial spores.
Airborne bacteria are components of the atmospheric aerosol particles and can be responsible of allergic disease, regardless of their viability. In this paper, we report a method for the determination of total (viable and nonviable) bacterial content in airborne particles, using muramic and dipicolinic acids as biomarkers of bacteria and bacterial spores, respectively. The analytical procedure was optimized with bacteria and spores of Bacillus subtilis. After extraction and purification, the two biomarkers were analyzed by HPLC-ESI-MS/MS and their percentage was evaluated to be used as conversion factor. The present method for the determination of the total bacterial content was then applied to environmental samples, after a proper collection in an urban site. Thanks to the use of a low pressure impactor, capable of fractionating particles into the range of 0.03-10 μm, it was also possible to study the bacterial content in ultrafine, fine, and coarse particulate matter. The results from this study showed that muramic and dipicolinic acids can be determined together in one chromatographic run in reversed phase ion pair chromatography. Bacteria were more abundant than bacterial spores in the urban atmosphere, both showing a higher concentration in the coarse fraction of particles, although bacteria and bacterial spore amounts per unit mass of ultrafine particles were higher than in fine and coarse particles.
['Di Filippo|Patrizia|P|', 'Pomata|Donatella|D|', 'Riccardi|Carmela|C|', 'Buiarelli|Francesca|F|', 'Uccelletti|Daniela|D|', 'Zanni|Elena|E|']
D000336:Aerosols D000391:Air Microbiology D001272:Atmosphere D001412:Bacillus subtilis D002851:Chromatography, High Pressure Liquid D057230:Limit of Detection D009112:Muramic Acids D052638:Particulate Matter D010848:Picolinic Acids D021241:Spectrometry, Mass, Electrospray Ionization D013171:Spores, Bacterial D053719:Tandem Mass Spectrometry
Dipicolinic acid Bacteria Bacterial spores Conversion factors Bioaerosol Muramic acid