Air-borne xylene degradation by Bougainvillea buttiana and the role of epiphytic bacteria in the degradation

The efficiency of xylene removal from contaminated air by thirteen perennial plants was studied. The results showed that Bougainvillea buttiana had the highest xylene removal efficiency. Different parts of B. buttiana such as stems, epicuticular waxes, and plant stomata (including microorganism-associated plant leaves) can uptake xylene 53.1±1.9%, 32.3±0.9, and 14.6±0.0%, respectively. Metabolite products found in treated plants may result from stress or defense compounds triggered by exposure to xylene. Moreover, possible degradation products in B. buttiana stems were analyzed after treatment with xylene at 100 ppm. Various metabolites in B. buttiana stems such as 2,6-dimethoxyphenol, 4-hydroxy-3,5-dimethoxy benzoic acid, 1-isopropyl-4-methylbenzene, p-tolualdehyde, 2,5-dimethoxy-4-methylbenzaldehyde, 2,4-dihydroxy-2,5-dimethyl-3(2H)-furanone, 3-methyl-2-butenal, dihydroxy acetone, propanedial, and many organic acids are related to the xylene degradation pathway. In addition, microorganism-associated B. buttiana leaves especially Enterobacter cloacae LSRC11, Staphylococcus sp. A1 and Pseudomonas aeruginosa enhanced the plant resulting in quicker xylene removal.