SummaryThe enzyme 8-galactosidase (lactase) obtained from several microbial sources was immobilized on zirconia-coated porous glass particles. The immobilized enzymes were characterized by determining pH profiles, kinetic constants, thermal profiles, and operational half-lives in lactose and whey ultrafiltrate solutions. Studies were carried out on continuous reactor performance, and enzyme requirements for scale-up were estimated. Lactose or whey hydrolyzed by this technique could find use commercially as a sweetener in a number of dairy products.

SummaryA culture of R. rubrum cells apparently contaminated with K. pneumoniae were immobilized by entrapment in agar. This system was used as a model for hydrogen production by photometabolic means. Observed results indicated that the contaminant exerted a major influence on the observed results. This preparation, when immobilized and used in a specifically designed reactor with glucose substrate, showed operational half-lives of approximately lo00 hr. The feasibility of using this "mixed" culture for producing hydrogen from acid hydrolyzed cellulose and wood sawdust was also examined.

An enzyme which oxidizes 1 ,2-propanediol in the presence of NAD+ has been purified from lysates of Neisseria gonorrhoeae. The enzyme was activated by monovalent cations, had a pH optimum between 9 and 10, and showed a substrate specificity unlike any known alcohol or glycerol dehydrogenase. The enzyme had an apparent K, of 17 mM for 7,2-propanediol and 0.37 mM for NADf. When chromatographed on a Sephadex G-150 column, the enzyme eluted as a single peak in the molecular weight region of a bovine serum albumin marker. An antibody to the purified enzyme was prepared in goats. When antiserum was reacted with the enzyme in immunodiffusion experiments, a single precipitin band was detected. When the enzyme was mixed with an excess of antibody and then reacted with substrate, enzyme activity was completely inhibited.

SummaryA soluble fungal lactase (lactase-W) of greater activity that the previously available fungal lactase (lactase-M) has been covalently coupled to Zr02-coated porous glass particles and 1 mm diameter porous TiO, particles. The immobilized Iactase-W appears to give results similar to the lactase-M except for the operational half-life. At 30°C the half-life of the lactase-M appears to exceed that of the lactase-W by approximately 100 days under operational conditions.

The enzyme tannase has been immobilized on an inorganic sopport by covaleiit This immobilized enzyme was characterized and half-lives deter-Since this enzyme has application in the treatment of tea cream, experi-attachment. mined. ments were also carried out to determine the effect of tea on enzyme half-life.