Microbial alteration of mineral substrates

Compilation of 5 articles published in international peer review journals The research project was motivated by two-sided observations, firstly direct field studies on the involvement of microbes, here fungi, in sediments structure, texture and digenesis, and secondly their role in mineral substrates' alteration as a natural bioweathering process, which considerably affects rocks surfaces; buildings and other human constructions, not to let apart their use as metal detoxifying agents, ore bioleaching and recovery, all of which have considerable economic and scientific impact. The research project aimed at studying those aspects of fungal interaction with natural mineral surfaces which are mainly related to geology, thus: Natural rock samples representing geological formation were used as substrates for fungal interaction: limestones, dolomites and a number of other minerals. The mineral substrates were prepared as standard petrographic thin sections, slabs and chips. This proved to be very important, as these settings for the first time made it possible to study and observe "in situ" under optical and SEM microscopy those changes produced on the petrography and mineralogy of involved minerals and the close relationship of fungal colonization to rock geometry and grain boundaries. Investigating whether fungal interaction with mineral substrates can produce "sedimentological-like" features comparable to sediment diagenesis. Within this context, detailed studies were performed on the formation of authigenic minerals, the formation of new "mycogenic fabrics", cementation, micritization, replacement, alveolar structures, pitting, bioleaching and tunneling, all of which had a significant impact on the original substrate structure. These parameters were reported for the first time, and because of their high resemblance to their "sedimentological" equivalents, they were attributed the term "diagenetic". Though this is not fully in tandem with the usage of geological terminology, their production by microbial activity necessitated it. Studying the fungal colonization strategies in relation with exposed mineral surface geometry: e.g. vertical vs. horizontal positioning of the mineral, crystal size, 2-D or 3D colonization, and importantly, whether the involved fungi display a thigmotropic behavior in relation with the mineral surface during the colonization.