| Popis: |
A program concerning the conversion of hemicellulosic residues to extracellular polysaccharides (EPS) with favorable application properties has been initiated. A number of microorganisms including Cryptococcus laurentii, Klebsiella pneumoniae, Arthrobacter viscosus, a Pseudomonas sp., and an as-yet-unidentified phylloplane isolate (DS-1) appear to be suitable for such purpose. We have demonstrated that these isolates can convert either xylose, an enzymatic oligomeric digest (Trichoderma longibrachiatum) of xylan, a mineral acid hemicellulose hydrolysate, or a five monosaccharide mixture simulating sulfite process liquors, to EPS. Several physiological parameters relating to maximizing acidic (hexadecyltrimethylammonium-precipitable) EPS are detailed. Under optimum conditions, up to ca. 14 gm/1 of EPS has been obtained. Following additional purification steps, the molecular weight distributions (600–4500 Kd) of the EPS so formed were estimated by size exclusion chromatography. The compositions of these several pentosan-derived EPS were determined on their hydrolysates; and some preliminary data on their intrinsic viscosities was assembled. The relationships among EPS composition, substrate utilized, microbial growth phase, and molecular properties are exemplified. |
