Scanning electron microscopy of immobilized bacteria in gel beads: a comparative study of fixation methods
1990; Elsevier BV; Volume: 11; Issue: 3-4 Linguagem: Inglês
10.1016/0167-7012(90)90052-8
ISSN1872-8359
AutoresAlexander R. W. van Neerven, RenéH. Wijffels, Alexander J. B. Zehnder,
Tópico(s)Hydrogels: synthesis, properties, applications
ResumoDifferent methods were tested for the preparation of immobilizing material and bacteria entrapped in it for scanning electron microscopy (SEM). Nitrifying and denitrifying bacteria embedded in calcium alginate and K-carrageenan beads were used in this investigation. The internal and external structure of the beads and the appearance of the immobilized bacteria were compared different processing techniques for SEM. Freeze-drying, critical point-drying and freeze-substitution were used as dehydration methods. Shrinkage of the beads occurred to various extents with all methods tried. Some procedures produced artefacts in both bacteria and gel matrix. The comparison between the different methods revealed that chemical fixation, combined with dehydration in an ethanol series, preserved best a compact gel matrix and the appearance of the bacteria. Nice featured beads with sharp edges were obtained when the beads were cut in the cold vapour of liquid N2 of if the beads were pretreated with polyethylene glycol 2000.
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