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Potential sources of polyunsaturated fatty acids for saprophagous soil invertebrates
Elhottová, Dana ; Frouz, Jan ; Krištůfek, Václav ; Lukešová, Alena ; Nováková, Alena ; Tříska, Jan
Main sources of important nutritionally compounds - polyunsaturated fatty acids (PUFA) essential in soils animal diet were compared. The highest concentration of PUFA was found in cyanobacteria (namely Antarctic strain Pseudophormidium sp.), followed by fresh litter, algae, fungi and decomposed litter. The PUFA occurrence in bacteria including actinomycetes was rare. Leaf litter is the most important source of PUFA for soil invertebrates in regards to both PUFA concentration and occurrence in soil. The stage of litter decomposition significantly affected the content of all 13 detected PUFA. The total PUFA content decreased significantly during litter decomposition. Enrichment in certain PUFA was observed in the latest stages of litter decomposition, indicating that the soil microflora improves the nutritional value of the decaying ĺitter.
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Quantitative and qualitative changes of phenolic compounds in alder leaf litter
Elhottová, Dana ; Vrchotová, Naděžda ; Tříska, Jan ; Krištůfek, Václav
Quantitative as well as qualitative changes of phenolic compounds were investigated in different decomposition stages (I-IV) of native alder leaf litter. The Folin-Ciocalteau method was applied for the determination of total phenolic compounds and the reserved phase HPLC for the determination of the phenolic acids. Both values decreased in dependence on stage of litter decomposition. The reduction of the total phenolic compounds and the phenolic acids was 20% and 50%, respectively, in the most decomposed litter (stage IV) in comparison with fresh litter (stage I, 100%). The ratio of free (simple extracted) and bound phenolic compounds (extracted after acid hydrolysis) in the group of total phenolic compounds and phenolic acids was determined. The characteristic feature of the fresh litter (stage I) was higher amount of the free phenolic acids as well as higher ratio of the free phenolic compounds to the bound ones. The following stage II was characterised by two times higher portion of free to bound total phenolic compounds in contrary to phenolic acids where the bound acids dominat ed over the free ones. Higher level of bound to free compounds in both observed phenolic groups was typical for the most decomposed litter samples (stage III and IV).In addition, the stage III and IV were characterised by new compounds, which were formed in the litter during its decomposition and were not detectable in the previous stages (I,II).
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