Characterization of native crystalline cellulose in the cell walls of Oomycota

Abstract

Cellulose samples from 4 Oomycetes species ( Saprolegnia parasitica, Pythium aphanidermatum, Pythium butleri and Phytophtora cactorum) have been investigated. They were purified by mild hydrolysis of the cell walls, followed by extraction in diluted NaOH. The β-(1–3) glucan, the main component of the hyphal cell wall, was then easily extracted. The purified cellulose was characterized by X-ray diffractometry, FT-IR, and electron microscopy. Both X-ray and electron diffratograms were poorly resolved and were similar to those of cellulose IV I. In addition, the observation of their cell walls revealed a microfibrillar network, the individual microfibril was, however, extremely narrow in width. Although the interpretation of their structure still remains uncertain because of the low crystalline nature, the detailed d-spacing analysis and the FT-IR inspection suggested that Oomycota cellulose could be either interpreted as cellulose IV 1 or low crystalline cellulose I β. The latter is favored from the taxonomic point of view.