In vivo transfer of pAM beta 1 from Lactobacillus reuteri to Enterococcus faecalis

Trials were conducted to determine the in vivo transferability of plasmid-mediated antibiotic resistance between two strains of enteric Gram-positive bacteria. Germ-free mice were associated with the donor Lactobacillus reuteri DSM 20016 strain, carrying the broad host range pAM beta 1 plasmid, and with the Enterococcus faecalis JH2SS recipient strain. Analysis of faecal content of associated mice demonstrated that the in vivo transfer of this plasmid did occur and that frequencies of conjugation were affected by the presence of subtherapeutic levels of antibiotic in the diet.     

Purification of Lactobacillus secreted proteins

Summary We describe a rapid and reliable one-step method for purification of Lactobacillus secreted proteins. With electroendosmotic preparative electrophoresis and a modified synthetic medium the L. plantarum aggregation promoting factor, a 32 kDa secreted protein, and the thermostable -amylase of Bacillus stearothermophilus cloned in L. reuteri were purified. Although the growth rate was reduced, the production of secreted proteins was not affected.     

Peptidase profiling of Lactobacillus casei

Summary Fifty four Lactobacillus casei strains were investigated and compared for their peptidase profiling by statistical analysis of aminoacids released from milk proteins. Forty one strains formed a homogeneous group; only two strains, not included in the above group, resulted the most suitable for grana cheese production either for their aminoacidic pattern or total aminoacid amount.     

Conjugal Transfer of Broad-Host-Range Plasmid pAMβ1 into Enteric Species of Lactic Acid Bacteria

The broad-host-range plasmid pAMβ1, which codes for erythromycin and lincomycin resistance, was transferred by conjugation into Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius. A novel 17-megadalton plasmid molecule was detected in the transconjugants, confirming the introduction of pAMβ1 into each species.     

Conjugal Transfer of Broad-Host-Range Plasmid pAMbeta1 into Enteric Species of Lactic Acid Bacteria

The broad-host-range plasmid pAMbeta1, which codes for erythromycin and lincomycin resistance, was transferred by conjugation into Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius. A novel 17-megadalton plasmid molecule was detected in the transconjugants, confirming the introduction of pAMbeta1 into each species.     

Anreicherung freier Diaminopimelinsäure in Lactobacillen

Zusammenfassung In Essigsäure-Extrakten einer größeren Zahl von Stämmen vonL. bulgaricus undL. helveticus konnten erhebliche Mengen an meso- undll-,-Diaminopimelinsäure nachgewiesen werden. Die Untersuchung der Zellwand zeigte, daß das Murein als Diaminosäure keine DAP, sondern nur Lysin enthält. Die Ursache für die ungewöhnliche Anreicherung freier DAP liegt vermutlich in einer Störung der Regulation der Lysinsynthese.

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Accumulation of diaminopimelic acid in lactobacilli

Summary Acetic acid extracts of several strains ofL. bulgaricus andL. helveticus contained a considerable amount of meso- andll-,-diaminopimelic acid. When the cell wall of this strains was studied, it was found that the murein did not contain DAP but lysine as the diamino acid. The unusual accumulation of free DAP could be caused by an upset regulation of lysine biosynthesis.

     

A likelihood method for the detection of selection and recombination using nucleotide sequences

Different regions along nucleotide sequences are often subject to different evolutionary forces. Recombination will result in regions having different evolutionary histories, while selection can cause regions to evolve at different rates. This paper presents a statistical method based on likelihood for detecting such processes by identifying the regions which do not fit with a single phylogenetic topology and nucleotide substitution process along the entire sequence. Subsequent reanalysis of these anomalous regions may then be possible. The method is tested using simulations, and its application is demonstrated using the primate psi eta-globin pseudogene, the V3 region of the envelope gene of HIV-1, and argF sequences from Neisseria bacteria. Reanalysis of anomalous regions is shown to reveal possible immune selection in HIV-1 and recombination in Neisseria. A computer program which implements the method is available.