Enzyme surface concentration and permeate stream obtained in the membrane module with a dynamically formed biocatalyst layer were determined experimentally using two different, polymeric membranes. Correlations were formulated to calculate these values. It was found that their variability range was so big that when controlling the transmembrane pressure and turbulence of a retentate stream, the...

For L-aspartic acid biosynthesis, high production cells of Escherichia coli mutant B-715 and P1 were immobilized in chitosan gel using a technique developed in our laboratory. The immobilization process reduced initial activity of the intact cells, however, the biocatalyst produced was very stabile for long-term use in multi-repeated batch or continuous processes. Temperature influence on the c...

The paper explored the catalytic activity of a cell debris self-immobilized thermophilic lipase for polyester synthesis, using the ring-opening polymerization of ε-caprolactone as model. Effects of biocatalyst concentration, temperature, and reaction medium on monomer conversion and product molecular weight were systematically evaluated. The biocatalyst displayed high catalytic activity at high...

A lipase-catalyzed esterification of lignin model compounds in the ball mill was developed combining the advantages of enzyme catalysis and mechanochemistry. Under the described conditions, the primary aliphatic hydroxy groups present in the substrates were selectively modified by the biocatalyst to afford monoesterified products. Amongst the tested lipases, CALB proved to be the most effective...

Casein hydrolysis was carried out in PEG-dextran two-phase system by using a-chymotrypsin immobilized on a water soluble polymer Eudragit S-100. This biocatalyst along with the substrate casein was predominantly found to partition into the PEG phase. Under these optimized conditions, the product was found to partition (84%) in the dextran phase. Removal of dextran phase at an appropriate time i...

Biodesulfurization offers an attractive alternative to conventional hydrodesulfurization due to the mild operating conditions and reaction specificity afforded by the biocatalyst. The enzymatic pathway existing in Rhodococnrs has been demonstrated to oxidatively desulfurize the organic sulfur occurring in dibenzothiophene while leaving the hydrocarbon intact. In order for biodesulfurization to ...

Short-chain aliphatic esters are small volatile molecules that produce fruity and pleasant aromas and flavors. Most of these esters are artificially produced or extracted from natural sources at high cost. It is, however, possible to 'naturally' produce these molecules using biocatalysts such as lipases and esterases. A gene coding for a newly uncovered lipase was isolated from a previous metag...

The cells of filamentous fungus R. oryzae entrapped in the polyvinyl alcohol cryogel are capable of producing various extracellular hydrolytic enzymes (proteases, amylases, lipases) and are used for the treatment of complex wastewaters of food industry. Five types of media simulating the wastewater of various food enterprises were treated under batch conditions for 600 h. Fats containing mostly...

Directed evolution is being used increasingly in academic and industrial laboratories to modify and improve important biocatalysts. Significant advances during this period of review include compartmentalization of genes and the in vitro translation apparatus in emulsions, as well as several impressive demonstrations of catalyst improvement. Shuffling of homologous genes offers a new way to util...