Browsing by Author "SEELENFREUND, D"

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    BIOCHEMICAL AND GENETIC-STUDIES OF BACTERIA METABOLIZING LIGNIN-RELATED COMPOUNDS
    (1988) VICUNA, R; GONZALEZ, B; RUTTIMANN, C; SAPAG, A; SEELENFREUND, D
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    EFFECT OF STREPTOMYCES-VIRIDOSPORUS T7A ON KRAFT LIGNIN
    (1990) SEELENFREUND, D; VICUNA, R
    The ability of the lignino-cellulolytic actinomycete Streptomyces virdosprous T7A to attack purified fractions of kraft lignin was examined. In the presence of 0.3% yeast extract, high-molecular weight kraft lignin (MW > 3000, ether-insoluble fraction) does not affect growth of this microorganism significantly, whereas low-molecular weight kraft lignin (MW < 3000, ether-soluble fraction) inhibits its development. Accordingly, average molecular weight of the ether-insoluble fraction after bacterial growth remained unaltered, as measured by Sephadex G-50 gel permeation chromatography. Slight modifications were detected by high performance liquid chromatography in the ether-soluble fraction after incubation with the microorganism. S. viridosporus T7A partially decolorized Remazol Brilliant Blu R during growth on wheat lignocellulose. However, decolorization of either fraction of kraft lignin was not observed. These results suggest that the filamentous bacterium S. viridosporous T7A is not suitable for pulp mill effluent treatment.
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    METABOLISM OF LOW-MOLECULAR-WEIGHT LIGNIN-RELATED COMPOUNDS BY STREPTOMYCES-VIRIDOSPORUS T7A
    (1987) RUTTIMANN, C; SEELENFREUND, D; VICUNA, R
    The ability of the ligninolytic actinomycete Streptomyces viridosporus T7A to degrade selected lignin model compounds, both in the presence and in the absence of lignocellulose, was examined. Compounds studied included benzyl alcohols and aldehydes, plus dimers possessing intermonomeric linkages, which are characteristic of the lignin macromolecule. Oxidation of veratryl alcohol to the corresponding acid was significant only under ligninolytic growth conditions, i.e., in medium containing lignocellulose, while other benzyl alcohols and aldehydes were readily oxidized in its absence. S. viridosporus T7A reduces carbonylic groups of 1,2-diarylethane, but not of 1,2-diarylpropane structures, under both ligninolytic and non-ligninolytic culture conditions. Cleavage of 1,2-diarylpropane (.beta.-1), arylglycerol-.beta.-arylether (.beta.-0-4) and biphenyl structures by this strain could not be detected under either metabolic conditions.
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    MONITORING BACTERIAL CONSUMPTION OF LOW-MOLECULAR-WEIGHT LIGNIN DERIVATIVES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY
    (1986) GOYCOOLEA, M; SEELENFREUND, D; RUTTIMANN, C; GONZALEZ, B; VICUNA, R
    The lignolytic capacity of some natural bacterial isolates was examined. Strains were selected from samples of decaying wood by growth in a minimal medium containing aromatic compounds with a structural relationship to lignin as the sole carbon sources. These included derivatives of benzoic and phenylpropanoic acids, as well as a mixture of low molecular weight compounds obtained by fractionation of kraft lignin. Reversed-phase high-performance liquid chromatography analyses before and after cell growth in the latter revealed a degradation pattern of the different compounds present in the culture which was characteristic for each of the strains studied.
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    PRODUCTION OF SOLUBLE LIGNIN-RICH FRAGMENTS (APPL) FROM WHEAT LIGNOCELLULOSE BY STREPTOMYCES-VIRIDOSPORUS AND THEIR PARTIAL METABOLISM BY NATURAL BACTERIAL ISOLATES
    (1990) SEELENFREUND, D; LAPIERRE, C; VICUNA, R
    The actinomycete Streptomyces viridsporous attacks wheat lignocellulose releasing soluble lignin-rich fragments (APPL). Chemical analyses indicated that these APPI contain 20% less guaiacyl and 70% less glucose residues than the original substrate. In order to determine the effect on non-filamentous bacteria on APPL, natural isolates were selected in synthetic media containing APPL as sole carbon source. From a total of eighty cultures, two strains (Pseudomonas spp. B23 and E21) and a consortium of two strains (Enterobacter sp. V1 and Pseudomonas sp. V2) were selected for further studies. Strains Pseudomonas fluorescens biovar I and Pseudomonas acidovorans D3, previously isolated on .beta.-1 and .beta.-O-4 lignin model compounds, respectively, were included for comparative purposes. Analysis of APPL recovered after bacterial growth indicated that Pseudomonas B23 attacked preferentially both guaiacyl and syringyl lignin units while barely affected their carbohydrate content. On the other hand, Pseudomonas E21 and the consortium metabolized sugar moieties without modifying the aromatic residues of APPL. P. fluorescens biovar I and P. acidovorans D3, in spite of being able to cleave lignin linkages on dimeric model compounds, exhibited very limited growth on APPL. The former only partially degraded guaiacyl residues, while the latter did not produce detectable changes on APPL changes on APPL structure.