Time of Flight-Secondary Ion Mass Spectrometry on isolated extracellular fractions and intact biofilms of three species of benthic diatoms

The Scottish Association for Marine Science, Oban, Argyll, Scotland, UK.
Journal of Microbiological Methods (Impact Factor: 2.03). 07/2006; 65(3):562-72. DOI: 10.1016/j.mimet.2005.10.001
Source: PubMed


Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) was used to study compositional characteristics of Extracellular Polymeric Substances (EPS) and compared these to characteristics of the EPS-matrix of intact diatom biofilms. Three benthic diatoms species were investigated, Cylindrotheca closterium, Navicula mutica and Nitzschia cf. brevissima. Comparison of the ToF-SIMS spectra of sequentially extracted EPS-fractions by cluster analysis and multidimensional scaling analysis (MDS) indicated that soluble and bound EPS were not distinguishable based on their ion spectra. On the contrary the water insoluble bicarbonate soluble (WIBS)-EPS-fraction formed a distinct cluster showing that this material was compositionally different from the other EPS-fractions. Ion spectra of the EPS-fractions were dissimilar to results obtained from intact biofilms. This suggested that during the extraction procedure, the structure of the EPS irreversibly changed, which alters the fragmentation patterns of the extracellular surface layer. Furthermore, from the examination of the positive ion spectra it was shown that the overall composition of EPS in the intact biofilms was different between diatom species. In spite of these differences, several common peak patterns were shared between different species. This suggests the presence of common structural components in the EPS of these diatoms that may play a role in building the surface EPS-layer.

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Available from: Keith E Cooksey, Jul 10, 2014
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    • "The peaks all fit with the calculated masses of MAGs and DAGs (Table 1) and the respective natural isotope distribution of the assigned ions. Moreover previous ToF-SIMS analyses aimed at comparing the extracellular polymeric substances of cultured diatoms reported abundant, yet unassigned, peaks in similar ranges (m/z 309–313 and m/z 547–551) for two out of three species studied (de Brouwer et al., 2006). Further intense peaks in the m/z 790–880 range are consistent with [M+Na] + ions of triacylglycerols (TAGs; Debois et al., 2009; Fig. 1; Table 1). "
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