Effects of Heavy Metals on the Metabolome of Pinus sylvestris (Pinaceae).

The effects of Cu, Ni, and Cd on the Pinus sylvestris metabolome was studied in experimental conditions by gas chromatography-mass spectrometry (GC-MS). Structural changes in plant metabolite network became detectable on day 6 of exposure to the metals, 3-6 days earlier than visual signs of toxicity developed. Differences at the metabolome level arose earlier in a control group of plants, and specific effects of particular metals on the plant metabolome became distinct on day 9. Both nature and concentration of a metal equally contributed to the plant metabolome clustering. Plant responses (changes in concentrations of individual metabolites) to metal exposure substantially differed depending on the metal concentration (1 or 5 mM) and nature. The effects of Cd and Cu were generally similar, while the effect of Ni was often different. Dynamic changes visualized in plant metabolite matrix reflected the changes in its correlation structure, rather than depending on the set of particular compounds.

Metabolite Profile of the Micromycete Lecanicillium gracile Isolated from Plaster and Limestone.

Lecanicillium gracile is a recently described micromycete species isolated from mineral-based building materials (plaster and limestone) in interiors of cultural heritage sites in Russia. In this work, the composition of L. gracile metabolites, as well as of the culture liquid, have been characterized. The results suggest that L. gracile is a promising candidate for the search for novel biologically active compounds. During the exponential growth phase, the diversity of metabolites in the mycelium was low; the metabolome profile demonstrated predominant accumulation of monosaccharides and polyols. In the stationary phase, the metabolite diversity in the L. gracile mycelium was high; apparently, at this stage biosynthesis dominated over energy-producing processes. L. gracile synthesized extracellular polymer compounds and shifted medium рН to the alkaline range. When fungi are developing on rock substrates, their extracellular polymer matrix not only serves to facilitate the formation of biofilms with other microorganisms of lithobiont communities, but also, at alkaline pH values, it promotes the formation of secondary calcite on calcium-containing substrates, such as limestone and marble. That is, L. gracile possesses certain biochemical traits that facilitate its long-term growth on rock substrates and reflect the specific character of interactions between the fungus and the substrate materials.

[Formation of organic acids by fungi isolated from the surface of stone monuments].

Capacity of the fungi isolated from the surface of stone monuments for acid formation was studied in cultures under various carbon sources and cultivation conditions. The composition of organic nutrients was adjusted according to the results of investigation of the surface layers from the monuments in urban environment. The primary soil formed at the surface of the stone monuments under urban conditions was shown to contain a variety of carbon and nitrogen sources and is a rich substrate for fungal growth. Oxalic acid was produced by fungi grown on media with various concentrations of sugars, sugar alcohols, and organic acids. Malic, citric, fumaric, and succinic acids were identified only at elevated carbohydrate concentrations, mostly in liquid cultures. Oxalic acid was the dominant among the acids produced by Aspergillus niger at all experimental setups. Unlike A. niger, the relative content of oxalic acid produced by Penicillium citrinum decreased at high carbohydrate concentrations.