| The oxygen reducing membrane fractions were found in E. coli E-8 and in acetic acid producing oxidative bacteria (Gluconobacter oxydans and Acetobacter xylinum). The maximum activities of membrane fractions were obtained from 24-h old E. coli E-8, 24-h old Gluconobacter, and 36-h old Acetobacter under aerobic growth. Oxyrase was very active using lactate as the hydrogen donor reducing oxygen in 3.5 mL solution completely in 5 min. E. coli E-8 membrane fraction depleted oxygen in less than 1 min with formate. Gluconobacter and Acetobacter were effective with pyruvate (also alcohol) and lactate, respectively. Oxyrase and E. coli E-8 membrane fractions were active at basic pH (7.0-9.0) and high temperature (37-45;The membrane fraction significantly stimulated growth of facultative and anaerobic pathogenic bacteria such as Listeria monocytogenes, E. coli O157:H7, Salmonella typhimurium, Yersinia enterocolitica, Clostridium perfringens, Campylobacter jejuni, and Campylobacter coli. The stimulatory effect increased as the concentrations of membrane fractions increased. The membrane fraction lowered the detection limit of the bacteria by increasing a faster growth of very small number to the detectable level (10;Oxyrase, E. coli E-8 membrane fractions and food grade membrane fractions from the acetic acid bacteria significantly enhanced growth and production formation of many fermented foods (yogurt, buttermilk, wine, beer, bread dough, and summer sausage). The food grade membrane fractions were more suitable for foods not only they originally food producing organisms but they also very active at lower pH which most of food fermentations usually generate.;Membrane fractions contained several dehydrogenase enzymes that responsible to the utilization of dissolved oxygen. The absorption spectra, native gel and SDS gel electrophoreses of both sediments and supernatants from ultracentrifuged samples showed that they contained slightly different patterns and types of proteins leading to having different substrate specificities. |
