Biomedical subjects

F K Vogensen

Publications and source records attributed to F K Vogensen.

21 records · Page 2Linked to original sources

PubMed1993

LlaAI and LlaBI, two type-II restriction endonucleases from Lactococcus lactis subsp. cremoris W9 and W56 recognizing, respectively, 5'-/GATC-3' and 5'-C/TRYAG-3'.

Two type-II restriction endonucleases have been purified from Lactococcus lactis subsp. cremoris W9 and W56, the strains isolated from a mixed Cheddar starter. Their characterization showed that LlaAI was an isoschizomer of MboI from Morexella bovis with the cleaving sequence, 5'/GATC-3', being sensitive to methylation of the adenine residue; LlaBI was an isoschizomer to SfcI from Streptococcus faceium with the cleaving sequence, 5'-C/TRYAG-3'. Both LlaAI and LlaBI restriction-modification (R-M) systems are encoded by the plasmids, respectively, pFW094 and pJW563, protecting the harboring strain against phage attack.

Deoxyribonucleases, Type II Site-Specific↗

PubMed1993

Antimicrobial activity of lactic acid bacteria isolated from sour doughs: purification and characterization of bavaricin A, a bacteriocin produced by Lactobacillus bavaricus MI401.

Three hundred and thirty-five lactic acid bacteria were isolated from sour doughs and screened for antagonistic activity. Of these 145 showed activity against one or several of the indicator strains used in the screening. The antimicrobial activity of 18 isolates were due to a proteinaceous compound. These 18 isolates belonged to three different Lactobacillus species: Lactobacillus bavaricus, Lactobacillus curvatus and Lactobacillus plantarum. The spectrum of antimicrobial activity for the three species suggested that the inhibitory components were different. The inhibitory compound from Lact. bavaricus MI401 was chosen for further study. The proteinaceous nature, antimicrobial activity against closely-related species, heat resistance and sensitivity to alkaline treatment strongly indicated that this substance was a bacteriocin, which we designated bavaricin A. The bacteriocin was purified to homogeneity by ammonium sulphate precipitation, ion exchange, hydrophobic interaction and reverse-phase chromatography. The purification resulted in 193,000-fold increase in specific activity. SDS-PAGE of bavaricin A showed a molecular weight of 3500-4000 Da. By amino acid sequencing 41 amino acids were determined. Bavaricin A had a bactericidal mode of action and inhibited nine out of 10 Listeria monocytogenes. Lactobacillus bavaricus MI401 produced bavaricin A at temperatures from 4 degrees C to 30 degrees C. The production of active bavaracin A was inhibited at increasing sodium chloride concentration. In the presence of 3% sodium chloride at 4 degrees C no active bavaricin A could be detected. Nitrite (100 ppm) did not affect the production of active bavaricin A.

Amino Acid Sequence↗

PubMedDate not supplied

Sequence variation of the 16S to 23S rRNA spacer region in Salmonella enterica.

The possibility for identification of Salmonella enterica serotypes by sequence analysis of the 16S to 23S rRNA internal transcribed spacer was investigated by direct sequencing of polymerase chain reaction-amplified DNA from all operons simultaneously in a collection of 25 strains of 18 different serotypes of S. enterica, and by sequencing individual cloned operons from a single strain. It was only possible to determine the first 117 bases upstream from the 23S rRNA gene by direct sequencing because of variation between the rrn operons. Comparison of sequences from this region allowed separation of only 15 out of the 18 serotypes investigated and was not specific even at the subspecies level of S. enterica. To determine the differences between internal transcribed spacers in more detail, the individual rrn operons of strain JEO 197, serotype IV 43:z4,z23:-, were cloned and sequenced. The strain contained four short internal transcribed spacer fragments of 382-384 bases in length, which were 98.4-99.7% similar to each other and three long fragments of 505 bases with 98.0-99.8% similarity. The study demonstrated a higher degree of interbacterial variation than intrabacterial variation between operons for serotypes of S. enterica.

Base Sequence↗