Metabolic synergies in the biotransformation of organic and metallic toxic compounds by a saprotrophic soil fungus

Abstract

The saprotrophic fungus Penicillium griseofulvum was chosen as model organism to study responses to a mixture of hexachlorocyclohexane (HCH) isomers (α-HCH, β-HCH, γ-HCH, δ-HCH) and potentially toxic metals (vanadium, lead) in solid and liquid media. The P. griseofulvum FBL 500 strain was isolated from polluted soil containing high concentrations of HCH isomers and potentially toxic elements (Pb, V). Experiments were performed in order to analyse the tolerance/resistance of this fungus to xenobiotics and to shed further light on fungal potential in inorganic and organic biotransformations. The aim was to examine the ecological and bioremedial potential of this fungus verifying the presence of mechanisms that allow it to transform HCH isomers and metals under different extreme test conditions. To our knowledge, this work is the first to provide evidence on the biotransformation of HCH mixtures, in combination with toxic metals, by a saprotrophic non-white-rot fungus and on the metabolic synergies involved.

Roles of saprotrophic fungi in biodegradation or transformation of organic and inorganic pollutants in co-contaminated sites

“…Such mechanisms of solubilization and immobilization influence the bioavailability of metals, metalloids, and radionuclides, and their toxicity and distribution (Gadd 2007(Gadd , 2010Gadd et al 2012). Metals and metalloids can have negative effects on fungi, affecting survival, metabolism, morphology, reproduction and spore germination and impairing their functions in the ecosystem (Gadd et al 2012;Fester et al 2014;Dighton 2016;Harms et al 2017;Ceci et al 2018).…”

“…Similarly metal sorption to cells is a fundamental step in all fungal-metal interactions (Gadd 2001(Gadd , 2009(Gadd , 2010Ceci et al 2015Ceci et al , 2018. A low bioavailability may be beneficial for reducing pollutant toxicity and mobilization via leaching, enabling fungal growth in soils with high concentrations of pollutants.…”

“…It is often reported how metals can cause a general inhibition of microbial metabolism and of some basic traceable activities like nitrogen transformations, respiration, and organic matter decomposition (Baldrian et al 2000;Wuana et al 2014). However, fewer studies have focused on fungal behaviour when metals and xenobiotics are both present at potentially toxic concentrations, and what impact different toxic metals may have on organic pollutant biodegradation (Gharieb 2002;Sharaf and Alharbi 2013;Ma et al 2014;Sharma and Malaviya 2014;Urík et al 2014;Fuentes et al 2016;Jia et al 2017;Ma et al 2017;Ceci et al 2018). This review will discuss the situation in which filamentous fungi degrade xenobiotic substances in the presence of toxic metals or in extreme chemical conditions.…”

“…The discussion will be focused on documented fungal behaviour and performance in co-contaminated environments (Chen et al 2015b;Wang et al 2017), with particular emphasis on saprotrophic soil fungi, the roles they play regarding xenobiotic persistence in soil or water, and the biotransformation processes that they can perform through enzymatic degradation, and biochemical or physical immobilization mechanisms (Sandrin et al 2000;Iqbal et al 2005;Rao et al 2010;Urík et al 2014;Zhai et al 2015;Sharma and Malaviya 2016;Wu et al 2016;Ceci et al 2018).…”

EMIn-depth profiling of calcite precipitation by environmental bacteria reveals fundamental mechanistic differences with relevance to application

“…The success of MICP in biological engineering of the environment has led to the 69 investigation of its potential for exploitation in other areas. These areas include 70 bioremediation of heavy-metal contaminated soils via immobilisation of metals in precipitates 71 (Achal et al, 2011;Ceci et al, 2018), or wastewater treatment using this technology to 72 remove excess calcium. Geotechnical engineering represents another area of interest, 73…”