Purification and characterization of intracellular and extracellular α-glucosidases from Geobacillus toebii strain E134.

Two different α-glucosidase-producing thermophilic E134 strains were isolated from a hot spring in Kozakli, Turkey. Based on the phenotypic, phylogenetic and chemotaxonomic evidence, the strain was proposed to be a species of G. toebii. Its thermostable exo-α-1,4-glucosidases also were characterized and compared, which were purified from the intracellular and extracellular fractions with estimated molecular weights of 65 and 45 kDa. The intracellular and extracellular α-glucosidases showed optimal activity at 65 °C, pH 7.0, and at 70 °C, pH 6.8, with 3.65 and 0.83 K(m) values for the pNPG substrate, respectively. Both enzymes remained active over temperature and pH ranges of 35-70 °C and 4.5-11.0. They retained 82 and 84% of their activities when incubated at 60 °C for 5 h. Their relative activities were 45-75% and 45-60% at pH 4.5 and 11.0 values for 15 h at 35 °C. They could hydrolyse the α-1,3 and α-1,4 bonds on substrates in addition to a high transglycosylation activity, although the intracellular enzyme had more affinity to the substrates both in hydrolysis and transglycosylation reactions. Furthermore, although sodium dodecyl sulfate behaved as an activator for both of them at 60 °C, urea and ethanol only increased the activity of the extracellular α-glucosidase. By this study, G. toebii E134 strain was introduced, which might have a potential in biotechnological processes when the conformational stability of its enzymes to heat, pH and denaturants were considered.

Antimicrobial activity of endemic Digitalis lamarckii Ivan from Turkey.

Antimicrobial activity of the methanolic extracts of leaves and flowers of D. lamarckii Ivan, (Scophulariaceae), an endemic plant species of Turkey, was tested on ten bacterial and four yeast strains. Effective antibacterial activity was observed in four bacterial strains. Minimum inhibitory concentration (MIC) was calculated by use of liquid culture tests and in all the four effective bacterial strains, the MIC was found to be > or = 199.5 mg/ml. The minimum bactericidal concentration (MBC) of B. subtilis, S. aureus, and L. monocytogenes was calculated to be > or = 199.5 mg/ml, and MBC value for Shigella was calculated as > or = 399 mg/ml.

Antimicrobial activity of endemic Crataegus tanacetifolia (Lam.) Pers and observation of the inhibition effect on bacterial cells.

Up to now an increasing number of antibiotic-resistant bacteria have been reported and thus new natural therapeutic agents are needed in order to eradicate these pathogens. Through the discovery of plants such as Crataegus tanacetifolia (Lam.) Pers that have antimicrobial activity, it will be possible to discover new natural drugs serving as chemotherapeutic agents for the treatment of nosocomial pathogens and take these antibiotic-resistant bacteria under control. The objective of the present study was to determine antimicrobial activity and the activity mechanism of C. tanacetifolia plant extract. The leaves of C. tanacetifolia, which is an endemic plant, were extracted using methanol and tested against 10 bacterial and 4 yeast strains by using a drop method. It was observed that the plant extract had antibacterial effects on Bacillus subtilis, Shigella, Staphylococcus aureus, and Listeria monocytogenes among the microorganisms that were tested. Minimum inhibitory concentration (MIC) results obtained at the end of an incubation of 24 h were found to be > or =6.16 mg ml(-1) for B. subtilis, < 394 mg ml(-1) for Shigella, and > or =3.08 mg ml(-1) for L. monocytogenes and S. aureus and minimum bactericidal concentration (MBC) were found as > or =24.63 mg ml(-1) for B. subtilis, > or =394 mg ml(-1) for Shigella, > or =6.16 mg ml(-1) for L. monocytogenes, and > or =98.5 mg ml(-1) for S. aureus. According to the MBC results, it was found that the plant extract had bactericidal effects and in order to explain the activity mechanism and cell deformation of bacterial strains treated with plant extract, the scanning electron microscopy (SEM) was used. The results of SEM showed that the treated cells appeared shrunken and there was degradation of the cell walls. This study, in which the antibacterial effect of C. tanacetifolia was demonstrated, will be a base for further investigations on advanced purification and effect mechanism of action of its active compounds.

Antimicrobial activity of various extracts of Ocimum basilicum L. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy.

The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Ocimum basilicum L. were studied. These extracts were tested in vitro against 10 bacteria and 4 yeasts strains by the disc diffusion method. The results indicated that the methanol extracts of O. basilucum exhibited the antimicrobial activity against tested microorganisms. While the chloroform and acetone extracts had no effect, the methanol extracts showed inhibition zones against strains of Pseudomonas aeruginosa, Shigella sp., Listeria monocytogenes, Staphylococcus aureus and two different strains of Escherichia coli. The cells of microorganisms, which were treated and untreated with plant extracts, were observed by using the scanning electron microscope. It was observed that the treated cells were damaged.

Antimicrobial activity of various extracts of ocimum basilicum l. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy

Abstract: The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Ocimum basilicum L. were studied. These extracts were tested in vitro against 10 bacteria and 4 yeasts strains by the disc diffusion method. The results indicated that the methanol extracts of O. basilucum exhibited the antimicrobial activity against tested microorganisms. While the chloroform and acetone extracts had no effect, the methanol extracts showed inhibition zones against strains of Pseudomonas aeruginosa, Shigella sp., Listeria monocytogenes, Staphylococcus aureus and two different strains of Escherichia coli. The cells of microorganisms, which were treated and untreated with plant extracts, were observed by using the scanning electron microscope. It was observed that the treated cells were damaged

Screening antimicrobial activity of various extracts of Artemisia dracunculus L.

The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Artemisia dracunculus L. were studied. These extracts were tested against nine bacteria and four yeasts strains by the disc diffusion method. The results indicated that the methanol extract of A. dracunculus is more effective against tested microorganisms than chloroform or acetone extracts. The chloroform and acetone extracts were inhibitory only towards Pseudomonas aeruginosa (ATCC 27853). While the methanol extract that was diluted with 10 ml distilled water showed inhibition zones against Shigella (RSHI), Listeria monocytogenes ATCC 7644, P. aeruginosa (ATCC 27853), the methanol extract that was diluted with 5 ml distilled water showed inhibition zones against two different strains of Escherichia coli (RSHI, ATCC 25922), Shigella (RSHI), L. monocytogenes (ATCC 7644), and P. aeruginosa ATCC 27853. The cells of microorganisms treated with plant extracts and normal microorganism cells were observed by scanning electron microscope. It was apparent that cells are damaged after treatment with A. dracunculus.