Antibacterial activity of Tagetes terniflora.

Methanol extracts of the leaves of Tagetes terniflora and ethyl acetate and aqueous fractions showed different degrees of activity against Gram positive and Gram negative strains.

Phosphatidylinositol-specific phospholipase C activity in Lactobacillus rhamnosus with capacity to translocate.

Phosphatidylinositol-specific phospholipase C (PI-PLC) activity was investigated in 25 different lactic acid bacteria (LAB) strains belonging to the genera Lactobacillus, Weisella, and Enterococcus. PI-PLC activity was detected in 44% of the strains studied in culture medium without carbon source. From the PI-PLC positive strains, Lactobacillus rhamnosus ATCC 7469 was selected for translocation studies. Healthy mice were orally administered with a daily dose of 2.0 x 10(9) of viable L. rhamnosus suspension. Viable bacteria were detected in liver and spleen of mice fed with LAB for 7 days. Bacterial colonies isolated from liver were biochemically characterized, and further subjected to randomly amplified polymorphic DNA. Amplification patterns of five strains displayed identical profiles to L. rhamnosus. PI-PLC activity was determined in the strains recovered from liver.

Antimicrobial activity of flowers from Anthemis cotula.

The flavonoid containing total extract of Anthemis cotula flowers, tested at the concentration of 200 microg/ml, showed interesting antimicrobial activity against both Gram-negative and Gram-positive microorganisms.

Influence of environmental conditions on hyphal morphology in pellets of Aspergillus niger: role of beta-N-acetyl-D-glucosaminidase.

The influence of modifications of the environmental conditions of growth on beta-N-acetyl-D-glucosaminidase (EC 3.2.1.30) activity and on hyphal morphological patterns in pellets of Aspergillus niger was studied. It was found that changes in the degree of branching and, to a lesser extent, in the number of bulbous cells were directly related to the activity of the enzyme. Nevertheless, since beta-N-acetyl-D-glucosaminidase is not the only enzyme involved in the lytic potential of the fungus, these findings do not exclude the possibility that other enzymes may be involved.

Purification and characterization of a thermostable and highly specific beta-N-acetyl-D-glucosaminidase from Aspergillus niger 419.

After a 10.5-fold purification, beta-N-acetyl-D-glucosaminidase (EC 3.2.1.52) produced by Aspergillus niger 419, showed the following main characteristics: maximum activity at 65 degrees C, pH 4.5; K(m) and kcat using p-nitrophenyl-N-acetyl-beta-D-glucosaminide as substrate, 0.2 mM and 0.93 x 10(4) min-1, respectively; Ea, 30.5 kJ/mol; molecular mass, 131,000 Da; pI 4.4. The activity after heating for 15 min at 70, 75 and 80 degrees C was 70, 28 and 13% of that found at 65 degrees C, respectively. The enzyme was active in reaction mixtures containing glycerol, ethanol, methanol, propan-2-ol, acetone or dioxan. The presence of Sr2+ or Ca2+ enhanced the activity, while it was inhibited by Cu2+ and Fe3+. The enzyme was highly specific for p-nitrophenyl N-acetyl-beta-D-glucosaminide and no activity was found when p-nitrophenyl derivatives of N-acetyl-beta-D-galactosaminide, beta-D-galactopyranoside and beta-D-N,N'-diacetylchitobiose were tested as substrates. Due to its thermostability, specificity and resistance to different organic solvents, the enzyme might be a potentially useful tool for the analysis and production of oligosaccharides.