Integrated systems for biosurfactant synthesis

Abstract: Biosurfactants are difficult to produce in an economic manner for several reasons

Amplification and expression of recombinant genes in serum-independent Chinese hamster ovary cells

AbstractCHO SSF3 cells grow as a suspension culture in unmodified commercial medium with only low-molecular weight ingredients. Continuous serum-free culture unexpectedly induced expression of a low dihydrofolate reductase activity in the originally dhfr− CHO cells. Nevertheless, it was possible with methotrexate to induce amplification of a gene coding for the hybrid plasminogen activator K2tu-PA cotransfected with a dhfr gene. Expression of K2tu-PA expression was proportionally increased to that of dhfr, which was measured with fluorescent methotrexate. Because no serum proteases were present, secreted K2tu-PA was not converted to the enzymatically active form, but was exclusively recovered in proenzyme form

Pectinolytic Enzymes from Actinomycetes for the Degumming of Ramie Bast Fibers

Actinomycetes isolated from 10 different soil and compost samples were screened for production of pectinolytic enzyme activities when grown on pectin-containing solid and liquid media. Pectinolytic enzymes, detected by using plate diffusion tests with a medium containing ramie (Boehmeria nivea) plant material as the sole carbon source, were mainly pectate lyases, but low activities of pectinesterases were also observed. Polygalacturonases and polymethylgalacturonases were not produced. Multiple forms of pectate lyases were detected in the culture supernatants of some of the strains by using the zymogram technique of isoelectric focusing gels. Xylanolytic and cellulolytic activities were always found to be associated with pectinolytic activities. None of the pectinolytic enzymes were produced in a medium with glucose as the sole carbon source. Treatment of ramie bast fibers with crude enzyme preparations from a selection of strains showed a good correlation between the pectate lyase activity applied and the degumming effect, resulting in good separation of the bast fibers

On the Mechanism of Oxidation of Non-Phenolic Lignin Model Compounds by the Laccase-ABTS Couple

ISSN:0018-3830ISSN:1437-434

Aromatic ring cleavage of veratryl alcohol by Phanerochaete chrysosporium

AbstractTwo oxidation products of veratryl alcohol were isolated from ligninolytic cultures of Phanerochaete chrysosporium. After purification the compounds were characterized by 1H-NMR, mass spectrometry and infrared spectrometry. The structural information suggests that the compounds are two isomers of a ring cleavage product from veratryl alcohol. Both compounds were also found as by-products when veratryl alcohol was oxidized to veratraldehyde with the crude extracellular ligninase preparation

Heterogeneity within the alkane-inducible cytochrome P450 gene family of the yeast Candida tropicalis

The reexamination of a genomic lambda gt11 Candida tropicalis expression library for the presence of genes related to the previously reported alkane-inducible cytochrome P450alk gene (P450alk), which is the first member of the P450LII gene family, was undertaken. A positive clone with a DNA fragment having 69% similarity with a portion of P450alk was isolated. As in the case of P450alk, this new putative P450 gene was also induced by tetradecane when C. tropicalis was grown on this carbon source and was therefore named P450alk2, P450alk1 corresponding to the first isolated P450 gene. In addition to P450alk2, the existence of other P450alk-related genes is suggested by the hybridization pattern of P450alk1 and P450alk2 probes with the C. tropicalis genomic DNA. The P450LII gene family in C. tropicalis appears therefore to include several different members. This heterogeneity is presently a unique feature within yeast P450 gene families and resembles the situation existing in P450 gene families of higher eukaryotes