deletions | additions       diff --git a/Fungal_weathering_in_the_lab__.md b/Fungal_weathering_in_the_lab__.md  index 48e80fc..0acf1af 100644  --- a/Fungal_weathering_in_the_lab__.md  +++ b/Fungal_weathering_in_the_lab__.md 
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Using atomic force microscopy Gazze et al (2013) demonstrated a biolayer of Extracellular Polymeric Substances EPS (40-80 nm thick) to form around hyphal tips of the EMF _Paxillus involutu_s. This material fused to form a biofilm that covered most of the mineral surface where the fungus was growing. Saccone et al (2011) found similar biolayes formed by P. involutus growing on hornblende, chlorit and biotite surfaces. Furthermore, the hornblende surface was less resistant to mechanical forcing under the biolayer compared to freshly cleaved surfaces suggesting that enhanced weathering had occurred. In addition, several studies have demonstrated dissolution channels on minerals where EMF hyphae have been growing. Sometimed these tracks can be 50 nm deep (Gazze et al 2012).  In some laboratory experiments with axenic cultures of microorganism it has been found that attachment to biotite surfaces yielded stronger dissolution compared to when they were  separated by a membrane. This demonstrate that not only the chemicals produced but also the physical attachment is important for mineral dissolution (Ahmed and Holmström). However, in other experiments, no additional effect on weathering was found when EMF hyphae were attached to minerals in axenic growth in solution cultures (Balogh-Brunstrad 2008b). One problem with axenic solution experiments is that no sink (the plant) is available for the released elements. In one study with axenic pine seedlings ectomycorrhizal with P. involutus, Bonneville (2011) found large removal of K, Mg and Fe under hyphae attached to biotite, which suggests that hyphal attachment and a sink for element removal (the plant) is important for mineral dissolution. Furthermore, it could be demonstrated that the biotite surface was strongly acidified under the hyphae, which suggests that specific chemical conditions occur under biolayers formed by the fungal mycelium. Schmalenberger et al (2015) demonstrated mineral specific exudation of oxalate by P. involutus using labelled 14CO2 given to the host plant. Oxalate was exuded in response to minerals in the following sequence Gabbro> limestone, olivine and basalt > granite and quartz.