To gain further understanding of the nature of the cellulose depolymerizing agent or agents of brown-rot fungi, brown-rotted cellulose was chemically and physically characterized. Various culture conditions, such as low nitrogen and elevated oxygen levels, did not induce degradation of cellulose by Postia placenta in liquid cultures. Therefore, brown-rotted cellulose for analysis was prepared by a nonliquid method using a soil-block technique. Analysis of the molecular weight distribution of the degraded cellulose indicated a fairly tight distribution centered around DP 232. From X-ray diffraction analysis it appears that there was a preferential attack on the smaller crystallites and amorphous regions of the cellulose by the fungus, confirming earlier work. Infrared spectroscopy and carboxyl determinations with methylene blue showed that carboxyl groups were present in the degraded cellulose. Uronic acids were not detected in acid hydrolysates of the brown-rotted cellulose, indicating that oxidation was not at C-6. However, several acids were separated and are currently being studied.

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