Detection of biological aerosols by luminescence techniques

Abstract

Luciferin–luciferase (LL) luminescence techniques were used to successfully measure the adenosine triphosphate (ATP) content (pg/ml) in aerosol samples containing either vegetative bacterial cells or spores. Aerosols were collected with wet or dry sampling devices. Evaluation for the presence of total biomass from both bacterial and nonbacterial sources of ATP was achieved by suspending the collected aerosol samples in phosphate-buffered saline (PBS), using a pipette to draw off a 50-μl aliquot of the PBS suspension into a Filtravette™, and then adding bacterial releasing agent (BRA). The sample was then reacted with LL, and the resulting relative luminescence units (RLUs), indicative of the total ATP content, were measured. Identical techniques were used to prepare the bacterial cells for analysis with one additional step: a wash with somatic cell releasing agent (SRA) before adding BRA. This step removes interfering substances or nonbacterial sources of ATP. For spore analysis, an equivolume sample of the PBS suspension was added to an equivolume of trypticase soy broth (TSB), incubated at 37 °C for 15 min, and processed using methods identical to bacterial cell analysis. With the use of these techniques we were able to detect Bacillus subtilis variation niger, formerly known as Bacillus globigii (BG) in artificially inoculated aerosol samples at concentrations ≥ 105 colony-forming units (CFU) per milliliter. Results of field and chamber trials show that one can detect the presence of bacterial and nonbacterial sources of ATP. These techniques may be appropriate to situations where the measurement of bacterial aerosols is needed. © 1999 John Wiley & Sons, Inc.* Field Analyt Chem Technol 3: 283–290, 1999