Volatile organic compounds in leaves of Osmanthus fragrans and their effect on airborne microorganisms

To clarify the functions of plant volatile organic compounds(VOCs) on bacteriostasis and air decontamination,composition and content of VOCs in leaves of four cultivars of Osmanthus fragrans: 'Thunbergii', 'Odoratus','Aurantiacus' and 'Semperflorens' were analyzed under near-natural conditions using the thermal-desorption cold trap gas chromatography/mass spectrometer technique.The airborne microorganism count(bacteria,fungi,and actinomycetes) for the four cultivars and a control of open ground were determined for March,May,July,September,and November in 2011 using natural sedimentation.Results showed that the major VOCs as follows:(Z)-acetate-3-hexen-1-ol,hexanal,octanal,nonanal,decanal,6-methyl-5-hepten-2-one,and 3-hexenol in 'Thunbergii';(Z)-acetate-3-hexen-1-ol,hexanal,benzaldehyde,nonanal,decanal,6-methyl-5-hepten-2-one,and nonane in 'Semperflorens';(Z)-acetate-3-hexen-1-ol,hexanal,octanal,nonanal,decanal,nonene,6-methyl-5-hepten-2-one,and 3-hexenol in 'Odoratus' and 'Aurantiacus'.Compared to a control of open ground,the 'Thunbergii' stands for the five data collection months had significantly lower(P 0.01) bacterial counts;the 'Thunbergii' stands for March,July,and September had significantly lower(P 0.01) fungal counts;and all four cultivars for the five data collection months had significantly reduced(P 0.01) actinomycete counts.Thus,the four O.fragrans cultivars could reduce the quantity of airborne microorganisms thereby improving air quality.[Ch,3 fig.1 tab.18 ref.]