Is Pseudobutyrivibrio xylanivorans strain Mz5T suitable as a probiotic? An in vitro study.

Rumen bacterium Pseudobutyrivibrio xylanivorans strain Mz5T possessed a potent xylanolytic enzyme system consisting of at least 7 different xylan hydrolases with molar mass 27-145 kDa. Three of them were successfully isolated in active native form. This strain produced butyrate and lactate on different saccharides. cis-9, trans-11-Conjugated linoleic acid was also detected in the culture medium. Bacteriocin-like inhibitory substances of Mz5T were active against some strains of rumen bacteria and against selected Salmonella and E. coli isolates from poultry meat. The strain Mz5T retained viability and xylanolytic activity also under not fully anaerobic conditions; its cells attached to the Caco-2 cells so that its successful association with gut epithelial cells may be expected. These in vitro results confirmed several probiotic traits of the isolate Mz5T and justified further in vivo experiments to test its ability to improve animal health and performance.

Reliable identification of Prevotella and Butyrivibrio spp. from rumen by fatty acid methyl ester profiles.

Data for bacterial identification were provided by culturing anaerobic bacteria under standardized conditions followed by extraction and methylation of cellular long-chain fatty acids and gas chromatographic analysis. The databases of fatty acid methyl ester (FAMEs) profiles for two predominant ruminal genera, Prevotella and Butyrivibrio, were created. Major long-chain cellular fatty acids found in the 23 analyzed Prevotella strains were 15:0 (anteiso), 15:0, 15:0 (iso) and 16:0. The strains of Prevotella could be well identified on species level by the characteristic ratios among major fatty acids and by acids unique fatty for each species. The 45 Butyrivibrio strains were grouped into 4 major and 2 minor groups according to FAMEs profiles. The major fatty acids for the bulk of the Butyrivibrio strains were 14:0, 15:1, 16:0 and 16:0 (iso). This groups corresponded to those based on 16S rDNA sequences.

Multiple endoxylanases of Butyrivibrio sp.

Butyrivibrio sp. Mz 5 with a high xylanolytic activity was isolated. Four major xylanases were detected in the cell-associated fraction using the zymogram technique. The xylanolytic activity was inducible with the oat spelts xylan; two endoxylanases (51 and 145 kDa) were formed constitutively. The bulk of the xylanolytic activity was cell-bound and growth-phase dependent; the maximum activity in the cell-associated fraction was achieved after 16 h of incubation. The highest xylanolytic activity was determined in a medium with 0.5% oat spelts xylan. Under optimum conditions (the highest xylanolytic activity produced), the two cell-bound xylanases (51 and 58 kDa) were isolated by anion exchange chromatography on CIM DEAE 8 tubes attached to a MPLC system, and gel filtration.

Effect of vinblastine on cell membrane fluidity in vinblastine-sensitive and -resistant HeLa cells.

The electron paramagnetic resonance method (EPR) was used to study the effects of vinblastine (VLB) on cell membrane fluidity in wild-type HeLa cells (HeLa K) and its subclone, which is resistant to several drugs (HeLa CA). HeLa CA cells, obtained by treatment of HeLa K with CDDP, were found to be more resistant to VLB than to CDDP. The experimentally observed EPR spectra were correlated with the calculated spectra obtained by computer simulation. The results indicate that the cell membrane of HeLa K and HeLa CA cells is heterogeneous and can be described with at least three types of coexisting domains with different fluidity characteristics. The two more fluid domains of HeLa CA cells were found to be more fluid than in HeLa K cells. The fluidity of the less fluid domain remained unchanged but its portion in the membrane was increased. VLB treatment did not affect the membrane fluidity of HeLa CA cells significantly. On the other hand, 1 h of treatment of HeLa K cells with 1 ng/ml VLB did not change the fluidity characteristics of membrane domains but decreased the portion of the less fluid domains. This was also reflected in an average increase of the entire membrane fluidity. The observed changes were detected at VLB concentrations which were far below the cytotoxic level.