Untitled

Abstract

Seven commercial 3- to 7-ring (R) polycyclic aromatic hydrocarbons (PAH) as well as PAH derived from lignite tar were spiked into 3 soils (0.8 to 9.7% of organic carbon). The disappearance of the original PAH was determined for the freshly spiked soils, for soils incubated for up to 287 d with their indigenous microflora, and for autoclaved, unsterile and pasteurized soils inoculated with basidiomycetous and ascomycetous fungi. Three to 12 d after spiking, 22 to 38% of the PAH could no longer be recovered from the soils. At 287 d, 88.5 to 92.7%, 83.4 to 87.4%, and 22.0 to 42.1% of the 3-, 4-, and 5- to 7-R PAH, respectively, had disappeared from the unsterile, uninoculated soils. In 2 organic-rich sterile soils, the groups of wood- and straw-degrading, terricolous, and ectomycorrhizal fungi reduced the concentration of 5 PAH by 12.6, 37.9, and 9.4% in 287 d. Five- to 7-R PAH were degraded as efficiently as most of the 3- to 4-R PAH. In organic-rich unsterile soils inoculated with wood- and straw-degrading fungi, the degradation of 3- to 4-R PAH was not accelerated by the presence of fungi. The 5- to 7-R PAH, which were not attacked by bacteria, were degraded by fungi to 29 to 42% in optimum combinations of fungal species and soil type. In organic-poor unsterile soil, these same fungi delayed the net degradation of PAH possibly for 2 reasons. Mycelia of Pleurotus killed most of the indigenous soil bacteria expected to take part in the degradation of PAH, whereas those of Hypholoma and Stropharia promoted the development of opportunistic bacteria in the soil, which must not necessarily be PAH degraders. Contemporarily, the contribution of the fungi themselves to PAH degradation may be negligible in the absence of soil organic matter due to the lower production of ligninolytic enzymes. It is concluded that fungi degrade PAH irrespective of their molecular size in organic-rich and wood chip-amended soils which promote fungal oxidative enzyme production.

Humic Substances Extracted by Alkali Are Invalid Proxies for the Dynamics and Functions of Organic Matter in Terrestrial and Aquatic Ecosystems

“…An X indicates the attribute was mentioned as a defining element by the source heading the column. High molecular weight X X ‡ X X X Myneni et al, 1999;Piccolo, 2001;Sutton and Sposito, 2005;Wershaw, 1986Wershaw, , 1993 Predominantly aromatic X X Baldock et al, 1992 Refractory X X Gramss et al, 1999aGramss et al, , 1999bGramss et al, , 1999cKononova, 1966;Mathur and Paul, 1967;Tatzber et al, 2009 Formed by secondary synthesis X X X Burdon, 2001;Lehmann and Kleber, 2015 Based on solubility characteristics X X X X This attribute forms the basis of the extraction procedure: solubilization with an ionizing liquid † Implied. ‡ "a few 100 to several thousand Da. "…”

Reflection on Molecular Approaches Influencing State-of-the-Art Bioremediation Design: Culturing to Microbial Community Fingerprinting to Omics

“…For example, halophilic archaea have been shown to degrade various pollutants in saline environments that would challenge most bacterial degraders (Erdogmus et al 2013). Also, fungal nonspecific enzymes are able to transform hydrophobic contaminants unavailable to bacteria residing in soil pore-water and groundwater aquifers (Cameron et al 2000; Eggen 1999; Gramss et al 1999; Yu et al 2005). Furthermore, various wood-rotting, soil-inhabiting, and sediment fungi have been shown to break down different classes of contaminants often encountered in the field ranging from pesticides to polychlorinated biphenyls (Cameron et al 2000; Gramss et al 1999; Potin et al 2004; Rafin et al 2013; Ravelet et al 2000; Vogel et al 1987; Wang et al 2014; Ye et al 2011; Zafra et al 2015; Zhao et al 2013).…”

Characterization of pyrene biodegradation by white‐rot fungus Polyporus sp. S133

“…But most low‐molecular‐weight (LMW) (two to three rings) PAHs are easily biodegraded by a variety of bacteria from the environment. For HMW PAHs, fungal metabolism has been widely examined for the potential for detoxification .…”