Electric dipole moments of Escherichia coli HB 101.

The theoretical and experimental studies of the particles' electric dipole moments in the microscopic and submicroscopic size range show that in the case of polar and conductive media the interfacial components of the dipole moments are of greatest importance. While in the range of manometer's sizes there seems to be no important problems in the identification and in the estimation of the values of the dipole moments at present, in the micrometer range there are serious problems. In this communication these problems are considered and illustrated by electro-optic investigations of Escherichia coli HB 101.

Identification and in vitro characterisation of Lactobacillus plantarum strains from artisanal Bulgarian white brined cheeses.

Lactobacillus plantarum strains were isolated from fully ripened, white brined Bulgarian home-made cheeses. Strains were derived from phenotypically homogenous Lactobacillus group and were identified as L. plantarum based on both phenotypic and molecular identification (species-specific and multiplex PCR) methods. Heterogeneity of L. plantarum isolates was evaluated by Rep-PCR analysis. Further antimicrobial activity, antibiotic susceptibility and transit tolerance of the strains were evaluated. Most of them showed broad spectrum of activity against Gram-negative bacteria (including human pathogens) independent on the presence of organic acids or hydrogen peroxide. All strains were sensitive to amoxicillin and sulfamethoxazole/trimethoprim, resistant to clinically relevant beta -lactame antibiotics (penicillin and ampicillin) and to nalidixic acid, ciprofloxacin, streptomycin, and vancomycin. Significant variability in the sensitivity to tetracycline was noted. The tolerance to low pH, bile salts, pepsin and pancreatin at concentrations similar to those in the gastrointestinal tract was strain-dependent. The exposure to bile salts was less destructive than exposure to pH 2.0 for all tested strains. Based on their combined responses to the above selection criteria, four L. plantarum strains, RL29, RL34, RL36 and RL37, were selected as potential probiotics for in vivo studies.