The effect of reaction milieu on synthesis of esters of higher fatty acids by Mucor javanicus T45 lipase was investigated. The folloving factors were studied: a temperature, an organic solvent, concentrations of substrates and their molar ratios, a solvent concentration, pH of water present in the lipase preparation and a concentration of diethanoloamine (DEtA) applied to modifity the essential water layer of the enzyme. It was revelated that M. javanicus lipase, immobilized in situ in its mycelium, preserves from 48 to 92 percent of the initial activity after heating for 1 houer at 100oC in nonpolar solvents. The modification of the enzyme essential water layer with DEtA increases the synthetic activity of the enzyme by about 70 percent.
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Chitosan is a linear N-deacetylated derivative of chitin, soluble in acetic solutions. The deacetylation of chitin can be achieved enzymatically using chitin deacetylase (ChDa) (EC 3.5.1.41), which hydrolyses the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin and chitosan. Complementary DNA (cDNA), which encodes ChDa, was isolated from M. rouxii s well as other fungi. Chitin deacetylase activity was detected in partially purified and concentrated crude extract of the protein from Mucor circinelloides IBT-83. Additionally, two open reading frames (ORF), putatively encoding ChDa, were identified and amplified from cDNA of this strain. Each ORF was molecularly cloned and sequenced. Amino acid sequences of ChDaI and ChDaII were predicted, using nucleotide sequences of these cDNA clones, and analysed by means of bioinformatics tools.
A continuous production of oligoaminosaccharides from chitosan was achieved with a column reactor packed with chitosanolytic enzymes-containing mycelia of Mucor circinelloides and Mucor racemosus immobilized in porous carriers. The efficient work of the bed used for chitosan hydrolysis in a column reactor lasted for several or more than 10 days and depended on a type of a carrier and substrate concentration. Because a crucial parameter for large scale applications of enzymes is their operating stability, presented research intended to improve it through stabilization of proteins and elimination of their leakage from the carrier. Cross-linking of mycelial preparations of chitosanolytic enzymes with 1% glutaraldehyde did not increase their stability and further process optimization is necessary.
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