deletions | additions       diff --git a/Fungal_weathering_in_the_lab__.md b/Fungal_weathering_in_the_lab__.md  index 04c0a57..222267a 100644  --- a/Fungal_weathering_in_the_lab__.md  +++ b/Fungal_weathering_in_the_lab__.md 
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  It is not clear if organic acid release and acidification is a primary mechanism to release nutrients from soil minerals, or a secondary effect related to the way microorganisms are growing in the soil.  Proton are exuded in response to uptake of positively charged ions regardless of if minerals are present or not, and exudation of organic acids can occur in response to many different factors such as pathogenesis and detoxification of heavy metals \cite{Dutton_1996}.  Furthermore, concentrations of organic acids in soil solution\citep{van_Hees_2000} solution \citep{van_Hees_2000}  seldom reach levels that have significant effects on mineral dissolution \citep{chadwick_changing_1999}. On the other hand, fungal hyphae attach to surfaces to be able to grow and proliferate through the soil, which may affect the surface of the minerals both physically and chemically \citep{McMaster_2008}.   Attachment is enhanced by organic compounds produced by When attached to the surfaces, fungi form a layer of extracellular polyermic substances (EPS) around  the fungus (Denny and Wilkins 1987, Gadd and Sayer 2000 in adeke) and hyphae.  \citet{Balogh_Brunstad_2008} suggested that organic acids may accumulate under such biolayers to sufficient concentrations to affect mineral dissolution. Although these authors call for more experiments to confirm this possible effect. Using Nano-scale observations using  atomic force microscopy \citet{Gazz__2013} on fungal colonization of mineral surfaces  demonstrated a biolayer of Extracellular Polymeric Substances EPS (40-80 EPS, 40-80  nm thick) thick,  to form around hyphal tips of the EMF *Paxillus involutus*. involutus* \citet{Gazz__2013}.  This material fused to form a biofilm that covered most of the mineral surface where the fungus was growing.   \citet{Saccone_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.