Incomplete Degradation of Polycyclic Aromatic Hydrocarbons in Soil Inoculated With Wood-Rotting Fungi and Their Effect on the Indigenous Soil Bacteria

Abstract

Soil artificially contaminated with fluorene, phenanthrene, pyrene, and benz[a]anthracene was inoculated with the wood-rotting fungi Plrurotus ostreatus and Antrodia vaillantii. During 12 weeks of incubation, polycyclic aromatic hydrocarbon (PAH) degradation and the formation of persistent degradation products were monitored by chemical analysis. In addition, the effect on the indigenous soil bacteria was studied by plate count techniques and by measuring the concentration of bacteria-specific phospholipid fatty acids (PLFAs). In both soils inoculated with fungi, the PAH degradation was enhanced compared to the control soil without fungi. The white-rot fungus P. ostreatus accelerated the degradation rate radically the first weeks, while the effect of the brown-rot fungus was more pronounced at later stages during the 12-week study. In a soil with no amendments, the final degradation result was similar to that in the soil with added fungi, although the degradation pattern for the individual PAHs was different. Furthermore, the degradation by P. ostreatus was accompanied by an accumulation of PAH metabolites, that is, 9-fluorenone, benz[a]anthracene-7,12-dione, and two compounds identified as 4-hydroxy-9-fluorenone and 4-oxapyrene-5-one, that was not seen in the other soils. The inoculation with the white-rot fungus also had a large negative effect on the indigenous soil bacteria. This could be an important drawback of using the white-rot fungus P. ostreatus in soil bioremediation since a sequential fungal-bacterial degradation probably is needed for a complete degradation of PAHs in soil. In the soil inoculated with A. vaillantii, on the other hand, no metabolites accumulated, and no negative effects were observed on the indigenous microorganisms.

Mobilizing agents enhance fungal degradation of polycyclic aromatic hydrocarbons and affect diversity of indigenous bacteria in soil

“…To our knowledge, no information is currently available concerning possible relationships between I. lacteus and the indigenous bacteria in PAH-contaminated sites. Some studies, on the other hand, have reported a negative impact of P. ostreatus on bacterial communities in similar scenarios (Andersson et al, 2003;Gramms et al, 1999). In particular, the accumulation of dead-end products arising from PAH degradation by P. ostreatus had clear negative effect on the indigenous microbiota (Andersson et al 2003).…”

“…Some studies, on the other hand, have reported a negative impact of P. ostreatus on bacterial communities in similar scenarios (Andersson et al, 2003;Gramms et al, 1999). In particular, the accumulation of dead-end products arising from PAH degradation by P. ostreatus had clear negative effect on the indigenous microbiota (Andersson et al 2003). In the present study, however, RP-HPLC analyses did not show any accumulation of PAH degradation intermediates.…”

Living in a fungal world: impact of fungi on soil bacterial niche development

“…This was ascribed to the production of bacterial inhibiting compounds by the fungus, which is in agreement with the results of other studies reporting bactericidal effects of Pleurotus sp. in soils [73,74]. Indeed, in situ bactericidal effects are likely to have evolved widely in the fungal kingdom as discussed earlier (Section 2.1).…”

Micro-community associated with ectomycorrhizalRussulasymbiosis and sporocarp-producingRussulain Fagaceae dominant nature areas in southern China

“…The mycosphere effect might exert strong influences on the bacterial community of soil(36), in which bacterial activity is stimulated by trehalose, which is degraded by hyphosphere and derived from fungi (37, 38). Andersson(39)(2003)., who used phospholipid fatty acid profiles to characterize bacterial communities, has demonstrated that basidiomycete wood-decomposing fungi are able to influence bacterial community structure. Bacteria adapted to the mycospheres of three or more or just one fungal species was defined as specific selective bacterial(40).…”