TOTAL AND VIABLE AIRBORNE BACTERIAL LOAD IN 2 DIFFERENT AGRICULTURAL ENVIRONMENTS USING GAS-CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY AND CULTURE - A PROTOTYPE STUDY

Airborne exposure to bacterial components found in agricultural enviro nments can lead to pulmonary inflammation. Total (viable and nonviable ) bacterial load was monitored in a stable and a dairy by a new approa ch, gas chromatography-tandem mass spectrometry measurement of muramic acid, a component of gram positive and gram negative bacterial peptid oglycan. Also used to assess the gram negative bacterial load were 3-h ydroxy fatty acids, markers of bacterial lipopolysaccharide. culture, an established procedure for assessing the viable bacterial portion of airborne dust, served as a basis for comparison. The muramic acid and 3-hydroxy fatty acid concentrations (total C-12:0, C-14:0, and C-16:0 ) showed a correlation with an R-2 of 0.81. Dust and muramic acid leve ls also correlated. However, although relative muramic acid levels wer e lower in the stable than the dairy, colony forming units (CFU) were considerably higher in the stable. The total bacterial load (estimated from muramic acid values) for both the stable and dairy was also high er than would have been predicted from culture. These results suggest that nonculture based approaches and culture provide complementary but independent measurements of airborne biopollution.