Lysozyme activity of pneumococci]

Examination of 329 pneumococcal strains showed that 41.2 per cent of the cultures had lysozyme activity. The frequency of the lysozyme feature depended on the method used. The lysozyme active strains were more frequently isolated from patients than from healthy persons and characterized by antibiotic resistance. The lysozyme feature correlated with the pneumococcal virulence with respect to albino mice, capacity for capsule formaiton and resistance to phagocytosis.     

Lysozyme activity of fungi of the genus Candida

The capacity of fungi belonging to the genus Candida to produce lysozyme was studied. All 60 strains under study were found to possess pronounced muramidase activity. Among these cultures highly active lysozyme producers were discovered, which would make it possible to use them for production purposes in future.     

Lysozyme activity in the presence of nonionic detergent micelles

The effect of a nonionic surfactant, polyoxyethylenesorbitan monolaurate (Tween 20), on the hen egg-white lysozyme catalyzed lysis of a dried cell suspension of Micrococcus lysodeikticus is analysed. A rate enhancement of up to 70% is observed in the presence of surfactant at concentrations above the critical micelle concentration. This activity increase may be explained by postulating the existence of a micelle-enzyme complex in which enzyme molecules are bound to micelles with preferential orientation of their active sites. The reaction is found to be second order with respect to substrate. A mechanism is postulated in which a substrate particle is assumed to be an energy-furnishing collision partner to the enzyme-substrate complex. This mechanism correlated data over a wide range of enzyme and substrate concentrations. Data from kinetic, ultrafiltration, ultraviolet, and fluorescence studies provide convincing evidence for the existence of a micelle-lysozyme complex. The results suggest that it is possible that immobilized enzymes mat in general be more reactive than corresponding free enzymes.     

Lysozyme activity in six species of economically important astigmatid mites

• 1.1. Lysozyme activity was detected for the first time in populations of Acarus siro L., Glycyphagus destructor (Schrank), G. domesticus (De Geer), Rhizoglyphus callae Oudemans, R. robini Claparede and Tyrophagus longior (Gervais) (Arthropoda: Acari).
• 2.2. No significant differences between the activity in different populations was observed.

     

Collagenolytic activity of bacteria

Actively growing aerobic and anaerobic bacteria were screened by a plate assay, with reconstituted guinea pig collagen as a substrate, for their ability to produce a collagenolytic factor. Collagenolytic activity was not demonstrated among the aerobic organisms tested, with the exception of one strain of Staphylococcus aureus (only when grown under anaerobic conditions). Collagenolytic activity, however, was detected in cultures of Clostridium tetani and Bacteroides species other than B. melaninogenicus. Collagenolytic activity of these organisms could be confirmed by measuring the amount of hydroxyproline liberated from the collagen gel during growth. Although collagenase production by Pseudomonas aeruginosa has been suggested in previous reports, our results were negative. An extracellular fraction of P. aeruginosa was able to hydrolyze a synthetic hexapeptide Cbz-glycyl-l-prolyl-glycyl-glycyl-l-prolyl-l- alanine, but was without detectable effect on reconstituted collagen.     

Chitinolytic activity of bacteria

Chitinolytic bacteria play an important role in degradation of chitin, one of the most abundant biopolymers in nature. These microorganisms synthesize specific enzymes, that catalyze hydrolysis of beta-1,4-glycosidic bonds in low-digestible chitin polymers, turning it into low-molecular, easy to digest compounds. During last decades many bacterial chitinolytic enzymes have been studied and characterized, mainly for their potential applications in agriculture, industry and medicine. Several chitinase classifications have been proposed, either on the base of substrate specificity or amino acid sequence similarities. X-ray crystallography and NMR spectroscopy techniques enabled the determination of three dimensional structure of some chitinases, what was helpful in explaining their catalytic mechanism. Development of biotechnology and molecular biology enables a deep research in regulation and cloning of bacterial chitinase genes.     

Urease activity of adherent bacteria and rumen fluid bacteria

In experiments on six sheep fed on a low nitrogen diet (3.7 g N/day), urease (EC 3.5.1.5) activity (nkat X mg-1 bacterial dry weight) 3 h after feeding was found to be highest in the bacteria adhering to the rumen wall (13.25 +/- 2.10), lower in the rumen fluid bacteria (8.96 +/- 1.35) and lowest in the bacteria adhering to feed particles in the rumen (5.69 +/- 2.13). The urease activity of bacteria adhering to the rumen wall and of the rumen fluid bacteria of six sheep fed on a high nitrogen diet (21 g N/day) was significantly lower than in sheep with a low N intake and in both cases was roughly the same (3.81 +/- 1.37 and 3.76 +/- 1.02 respectively); it was lowest in bacteria adhering to feed particles in the rumen (1.92 +/- 0.90). It is concluded from the results that the urease activity of rumen fluid bacteria and of bacteria adhering to the rumen wall and to feed particles in the rumen is different and that it falls significantly in the presence of a high nitrogen intake. From the relatively high ureolytic activity of bacteria adhering to the rumen wall in the presence of a low nitrogen intake it is assumed that this is one of the partial mechanisms of the hydrolysis of blood urea entering the rumen across the rumen wall and of its reutilization in the rumen-liver nitrogen cycle in ruminants.     

Proteolytic activity of sourdough bacteria

Summary Proteolytic activity during the fermentation of sourdough results in an increase in amino acid content. The proteolysis is caused by flour enzymes, microbial enzymes of flour and by sourdough bacteria. The results indicate that the lactic acid bacteria of sourdough are important for proteolytic activity during the fermentation of sourdough. This proteolytic activity depends on the species of bacteria. Homo- and heterofermentative sourdough bacteria effect different amino acid spectra. Qualitative and quantitative differences in sulphur-containing, cyclic and hydroxy amino acids have been observed. The proteolytic process can be influenced by fermentation conditions, especially the temperature. A lesser effect is observed in the dough yield (flour-water relationship). From experiments with different strains and species of lactic acid bacteria, it is concluded that only one third of the proteolytic activity in sourdough is based on proteases from the flour.Publication-No. 5592 of Federal Research Centre for Cereal and Potato Processing, Detmold, Federal Republic of GermanyPaper presented at the Third International Conference Rye and Triticale, Poznan, Poland, 13–14 May 1987     

Cellulolytic activity of luminous bacteria

Summary The luminous bacteriaVibrio harveyi andV. fischeri degrade cellulose. Cellulase activity was high when carboxymethyl cellulose and cellobiose were used as substrates but low with cellulose powder. The role of these microbes in the digestion of food material in fish gut is also discussed.

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Resumen Las bacterias luminosasVibrio harveyi yV. fischeri degradan celulosa. La actividad celulásica fue alta cuando se utilizó Carboxy-metil-celulosa o celobiosa como sustrato y baja cuando se utilizó polvo de celulosa. Se discute el papel de estos microorganismos en la digestión intestinal de los alimentos en peces.

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Résumé Les bactéries lumineusesVibrio harveyi etV. fischeri dégradent la cellulose. L'activité cellulolytique était élevée lorsque la carboxméthylcellulose et la cellobiose servaient de substrats, mais elle était faible avec la poudre de cellulose. On discute également de rôle de ces microorganismes dans la digestion du matériau alimentaire.

     

Lysozyme activity in animal extracts after sodium dodecyl sulfate-polyacrylamide gel electrophoresis

1. Lysozyme activity was detected after electrophoresis in sodium dodecyl sulfate-polyacrylamide gels containing 0.2% (W/V) autoclaved Micrococcus lysodeikticus cells as substrate. 2. Lysozyme activity appeared as clear lysis zones after incubation of opaque gels at 37 degrees C in buffered Triton X-100. 3. As low as 0.1 pg of purified hen egg white lysozyme could be detected after 16 hr incubation at pH 6.5. 4. Bands with lytic activity from kidney and pancreas acetone powders, bird's egg whites and vitelline membranes, animal sera and human saliva corresponded to c-type (Mr 14,500), g-type (Mr 20,500) or both lysozymes as far as molecular weight is concerned. 5. Some extracts, like porcine kidney, exhibited more than two bands. 6. Bands with lytic activity migrating at the level of g-type lysozymes were detected in some kidney and pancreas extracts.     

Amidase activity of some bacteria

The amidase activity of bacteria possessing a high nitrilase activity was found to display the same spectrum although the bacteria may belong to different taxonomic groups,Bacillus, Bacteridium, Micrococcus, Brevibacterium. The spectrum of amidase activity, although very broad, is more restricted than that of nitrilase activity. Internal amides as well as vinyl-bound amides are not hydrolyzed.