Since the lignin preparations from waste liquor of oxygen-alkali pulping (OL) have been appreciably oxidized and have an increased hydrophilic property by cooking, they were more easily affected by Pseudomonas ovalis than kraft lignin and ligninsulfonate.
After incubation for 30 days, a portion of higher molecular weight of pine and beech OL were appreciably decomposed, and the nitrogen content of residual lignin increased with progress of bacterial incubation. Amino acid composition of the biodegraded lignin hydrolysate differ markedly from that of bacterial cells. It seemed that about 1020 percents of nitrogen content of biodegraded samples arised from amino acids of bacterial cells protein. Nitrogen content of the samples were almost not affected by Pronase treatment.
Slight amounts of guanine and adenine arising from bacterial nucleic acids were detected by thin layer chromatography, however, there were no detectable amounts of the nucleic acids.
Vanillin and syringaldehyde yielding groups of biodegraded OL decreased extremely. Therefore, 5-position condensed guaiacyl type and biphenyl type have consequently increased.
Methoxyl group and phenolic hydroxyl group decreased with progress of bacterial decomposition, but, p-hydroxyphenyl group and 4-methoxy isophthalic acid type structures increased such as the case of kraft lignin. Therefore, demethoxylation of OL was caused by this bacterium.
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