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Effects of long-term mineral fertilization and manuring on the biomass of arbuscular mycorrhizal fungi (AMF) were studied in a field experiment. Mineral fertilization reduced the growth of AMF, as estimated using both measurements of hyphal length and the signature fatty acid 16:1omega5, whereas manuring alone increased the growth of AMF. The results of AMF root colonization followed the same pattern as AMF hyphal length in soil samples, but not AMF spore densities, which increased with increasing mineral and organic fertilization. AMF spore counts and concentration of 16:1omega5 in soil did not correlate positively, suggesting that a significant portion of spores found in soil samples was dead. AMF hyphal length was not correlated with whole cell fatty acid (WCFA) 18:2omega6,9 levels, a biomarker of saprotrophic fungi, indicating that visual measurements of the AMF mycelium were not distorted by erroneous involvement of hyphae of saprotrophs. Our observations indicate that the measurement of WCFAs in soil is a useful research tool for providing information in the characterization of soil microflora.

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Filip Z., Hermann S., Demnerová K. (2008): FT-IR spectroscopic characteristics of differently cultivated Escherichia coli. Czech J. Food Sci., 26: 458-463. FT-IR spectra were recorded of Escherichia coli cell mass with the aim of obtaining spectral traits possibly useful in a rapid detection and characterisation of this indicator bacterium. A well differentiated spectrum was obtained from the cell mass harvested in a stationary phase of growth, e.g., after 24 h, from a minimum nutrient broth. The cell mass, harvested either earlier or grown in nutrient solutions which contained an enhanced carbon or nitrogen concentrations delivered somewhat different IR spectra, apparently due to a higher content of nucleic acid components as related to other structural constituents of bacterial cells. Consequently, the FT-IR spectra of E. coli, although rather rapidly to collect, seem only capable of delivering useful and reproducible information if the cell mass is obtained under standardised cultural conditions.

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