Penicillin G acylase from E. coli TA1 was immobilized by Cross-Linked Enzyme Aggregates (CLEA), a new method for immobilization. This biocatalyst and commercial immobilized penicillin G acylase (PGA-450) were used to study the effect of pH, temperature and substrate concentration on the synthesis of ampicillin from phenyl glycine methyl ester (PGME) and 6-aminopenicillanic acid (6-APA). Compare...

-Putrefactive hydrogen sulfide production in the upper 4 cm of sediment in two small freshwater and eutrophic Southeast Michigan, U.S.A., lakes ranged from 0.13 to 1.51 with an average of 0.46 mg S l-~ day-~. Sulfate reductive production of hydrogen sulfide at the same sites ranged from 0.7 to 3.2 with an average of 1.54 mg S 1~ dayt. Putrefactive hydrogen sulfide production represented 5.1-53°...

The aim of this study was the use of fish waste hydrolysate (FWH) as a substrate for alkaline protease production using isolated Bacillus sp. in a batch system. Then the fermentation kinetics of enzyme production was studied. The results show that with the addition of FWH to the fermentation medium with a final concentration of 4% (optimal concentration), alkaline protease value reached a maxim...

The ability of Neurospora crassa FGSC 4335 in the biotransformation of hydrocortisone was investigated. The microorganism produced two major metabolites after incubation with the substrate for seven days. Each microbial product was purified chromatographically and identified on the basis of spectral data. The products were identified as 11?,17?,20?,21-tetrahydroxypregn-4-en-3-one (II) and 11?-h...

Secondary substrate utilization of methylene chloride was analyzed by using Pseudomonas sp. strain LP. Both batch and continuously fed reactors demonstrated that this strain was capable of simultaneously consuming two substrates at different concentrations: the primary substrate at the higher concentration (milligrams per liter) and the secondary substrate at the lower concentration (micrograms...

This paper considers the possibility of spontaneous transition of aracemic mixture (composed of equal amounts of two enantiomeric species, say L and D) into a monochiral state (in which only one enantiomer, say L, is present). Transitions of this kind have been recently experimentally observed. A plausible approach to this phenomenon is a model put forward by Frank, based on simple laws of ...