Microbial degradation of pyrene in holm oak (Quercus ilex) phyllosphere: Role of particulate matter in regulating bioaccessibility

8 páginas.- 3 ilustraciones.- 4 tablas.- 72 referencias.- Supplementary data to this article can be found online a https://doi.org/10.1016/j.scitotenv.2021.14743

In this study we first measured the mineralization of pyrene on leaves of urban holm oak (Quercus ilex) by autochthonous microorganisms and an inoculated PAH degrading bacterium (i.e., Mycobacterium gilvum), selected as a model phyllosphere species, as well as the leaf-water (KLW) and leaf-air (KLA) partition coefficients for this chemical. Mineralization was investigated in two different experimental systems in terms of leaf and microorganism environment. Additionally, the influence on pyrene partitioning and mineralization when particulate matter (PM) was present on the leaf surface or removed was studied. Mineralization of 14C-labeled pyrene by autochthonous microorganisms was lower than 1% after approximately two weeks, while M. gilvum mineralized 5% to 17% of pyrene. These extents corresponded to mineralization half-lives that ranged between ~30 to ~200 days. We proposed that PM present at the leaf surface reduced the accumulation of pyrene by inner compartments (cuticle) distantly located from microbial cells and enhanced the bioaccessibility of pyrene, speeding up microbial activity and therefore mineralization. These results highlight that plant-phyllosphere microorganism interaction is more complex than currently established and deserves additional studies to further comprehend the air purification ecosystem service of phyllosphere microorganisms. © 2021 Elsevier B.V.

We would like to acknowledge the Italian Society of Ecology (SItE) and the “Luigi and Francesca Brusarosco” Prize for supporting ET as visiting scientist at IRNAS, the University of Insubria for supporting the Post Doc salary of ET, and the Spanish Ministry of Science, Innovation and Universities (CGL2016-77497-R and PID2019-109700RBC21), for supporting the work of R. Posada-Baquero and J.J Ortega-Calvo.

Peer reviewed