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The initial transfer of fructosyl units in the utilization of sucrose led to the formation of fructose, oligomers or levan and was apparently controlled by the concentrations of sugars in the medium. In continuous fermentation, the rather low levels of monomeric sugars in the broth prevented the formation of sorbitol and oligomers, whereas the production of(More)
Eleven microbial strains were tested for their ability to produce xylonic acid from xylose. The production of xylonic acid by one of the strains,Pseudomonas fragi ATCC 4973, was further studied in laboratory fermenter scale. The yield of xylonic acid was 92 % of original sugar. Xylonic acid production seemed to be growth associated and it was found to be(More)
Cellobiohydrolase II of Trichoderma reesei was produced in laboratory and pilot scale using a transformant strain of Saccharomyces cerevisiae harbouring a multicopy expression plasmid. Different strategies were compared for concentration and partial purification of the enzyme produced in a 200 1 pilot cultivation. After efficient separation of biomass and(More)
In nature many micro-organisms tend to bind to solid surfaces. This tendency has long been utilized in a number of processes, for example in producing vinegar and acetic acid in bioreactors filled with wood shavings. Acetobacteria are attached to the surface of these shavings. In modern technical language: they are immobilized. Also yeast cells can be(More)
The hemicellulase separated from birchwood by steaming and water extraction comprised mainly of acetyl- and 4-O-methyglucurono-substituted xylo-oligomers. The liberation of the acidic side groups affected the rate and yield of the enzymatic hydrolysis of the xylo-oligomers. The hemicellulase ofTrichoderma reesei was superior to that ofAspergillus awamori(More)
A process for production of mold lactase was developed. Tests were carried out in pilot and industrial scale with an Aspergillus niger strain selected after screening a number of molds. A computer coupled autoanalyzer system was used for monitoring enzyme formation in the pilot fermentor. Lactase production was investigated using different pH- and(More)
The bioconversion of xylose into xylitol in fed-batch fermentation with a recombinantSaccharomyces cerevisiae strain, transformed with the xylose-reductase gene ofPichia stipitis, was studied. When only xylose was fed into the fermentor, the production of xylitol continued until the ethanol that had been produced during an initial growth phase on glucose,(More)