Strains degrading polysaccharides produced by bacteria from paper machines.

Biofilm-degrading enzymes are potential agents for slime control in paper machines. In this work, extracellular polysaccharides were produced by bacteria isolated from paper machines and the isolated polysaccharides were used as substrates for the screening of polysaccharide-degrading microbes. Polysaccharide yields of 1.5-3.5 g/l were obtained by ethanol precipitation from cultures of strains of Klebsiella pneumoniae, Bacillus licheniformis and Pseudomonas fluorescens on sucrose medium. Two K. pneumoniae strains apparently produced an identical heteropolysaccharide containing galacturonic acid. Fructose-containing polysaccharides were the main products of B. licheniformis and P. fluorescens. Bacteria capable of hydrolyzing the fructose-containing polymers (levans) appeared to be relatively common among the strains selected for screening. None of the bacteria or mixed cultures screened were able to utilize the Klebsiella heteropolysaccharides.

Reactivity of Trametes laccases with fatty and resin acids.

Lipophilic extractives commonly referred to as wood pitch or wood resin can have a negative impact on paper machine runnability and product quality. The lipophilic extractives are composed mainly of fatty acids, resin acids, sterols, steryl esters and triglycerides. In this work, the suitability of laccases for the modification of fatty and resin acids was studied, using two model fractions. In the treatments, resin and fatty acid dispersions were treated with two different laccases, i.e. laccases from Trametes hirsuta and T. villosa. Different chromatographic methods were used to elucidate the effects of laccase treatments on the chemistry of the fatty and resin acids. Both laccases were able to modify the fatty and resin acids to some extent. In the case of fatty acids, a decrease in the amount of linoleic, oleic and pinolenic acids was observed, whereas the modification of resin acids resulted in a reduced amount of conjugated resin acids.

Applications of immobilized lipases to transesterification and esterification reactions in nonaqueous systems.

Lipases from Candida cylindracea, Aspergillus niger, and Pseudomonas fluorescens were immobilized by adsorption on anion-exchange resin and diatomaceous earth using buffer or hexane as a reaction medium. The enzyme preparations were tested in the transesterification of triolein with lauric acid and the esterification of lauric acid with different alcohols. Immobilized C. cylindracea preparations were more active when hexane was used as the reaction medium, and anion-exchange resin was a better support than diatomaceous earth. Hexane was also a better immobilization medium for A. niger lipase. No difference was observed in the lipase activity of P. fluorescens lipase immobilized in different ways. The synthetic activities of the immobilized enzymes could be predicted from their hydrolytic activities: the higher the hydrolytic activity, the higher the synthetic activity. There was no direct correlation, however, between the lipolytic and the transesterification activities.

Use of lipases in the resolution of racemic ibuprofen.

Resolution of (R,S)-ibuprofen enantiomers by esterification in different organic solvents was studied using Candida cylindracea lipase. This enzyme preparation had high enantiospecificity for S(+)-ibuprofen in the esterification reaction of a racemic ibuprofen with primary alcohols. The esterification yields of secondary alcohols were much lower than those of primary alcohols. Esterification with tertiary alcohols was not observed. The synthesis of esters was profoundly affected by the amount of water in the reaction mixture. C. cylindracea lipase was active only in very hydrophobic solvents. The esterification activity of the lipase was reduced significantly by addition of water. The R- and S-enantiomers of ibuprofen were determined without derivatization by HPLC using a chiral column.