Comparison between a bovine and a human enterohaemorrhagic Escherichia coli strain of serogroup O26 by suppressive substractive hybridization reveals the presence of atypical factors in EHEC and EPEC strains

in FEMS Microbiology Letters (2012), 330(2), 132-139

Plasmid-associated bacteriocin production by Lactobacillus LMG21688 Listeria monocytogenes growth rebound in a food system.

in FEMS Microbiology Letters (2010), 306(1), 37-44

Genome comparison of Bifidobacterium longum strains NCC2705 and CRC-002 using suppression subtractive hybridization.

in FEMS Microbiology Letters (2008), 280(1), 50-6

Because probiotic effects are strain dependent, genomic explanations of these differences will contribute to understanding their mechanisms of action. The genomic sequence of the Bifidobacterium longum ... [more ▼]

Because probiotic effects are strain dependent, genomic explanations of these differences will contribute to understanding their mechanisms of action. The genomic sequence of the Bifidobacterium longum probiotic strain NCC2705 was determined, but little is known about the genetic diversity between strains of this species. Suppression subtractive hybridization (SSH) is a powerful method for generating a set of DNA fragments differing between two closely related bacterial strains. The purpose of this study was to identify genetic differences between genomes of B. longum strains NCC2705 and CRC-002 using PCR-based SSH. Strain CRC-002 produces exopolysaccharides whereas NCC2705 is not known for reliable exopolysaccharide production. Thirty-five and 30 different sequences were obtained from the SSH libraries of strains CRC-002 and NCC2705, respectively. Specific CRC-002 genes found were predicted to be involved in the biosynthesis of exopolysaccharides and metabolism of other carbohydrates, and these genes were not present in the genome of strain NCC2705. The identification of an endo-1,4-beta-xylanase gene in the CRC-002 SSH library is an important difference because xylanase genes have previously been proposed as a defining characteristic of the NCC2705 strain. The results demonstrate that the SSH technique was useful to highlight potential genes involved in complex sugar metabolism that differ between the two probiotic strains. [less ▲]

Mycoplasma bovis shares insertion sequences with Mycoplasma agalactiae and Mycoplasma mycoides subsp mycoides SC: Evolutionary and developmental aspects

in FEMS Microbiology Letters (2005), 245(2), 249-255

Three new insertion elements, IS Mbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma in mycoides subsp. in mycoides SC ... [more ▼]

Three new insertion elements, IS Mbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma in mycoides subsp. in mycoides SC), respectively, have been discovered in Mycoplasma bovis, an important pathogen of cattle. Southern blotting showed that the genome of M. bovis harbours 6-12 copies of ISMbov1, 11-15 copies of ISMbov2 and 4-10 copies of ISMbov3, depending on the strain. A fourth insertion element, the IS30-like element, is present in 4-8 copies. This high number of IS elements in AI bovis, which represent a substantial part of its genome, and their relatedness with IS elements of both M. agalactiae and M. mycoides subsp. mycoides SC suggest the occurrence of two evolutionary events: (i) a divergent evolution into ill. agalactiae and M. bovis upon infection of different hosts; (ii) a horizontal transfer of IS elements during co-infection with M. mycoides subsp. mycoides SC and Ad. bovis of a same bovine host. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. [less ▲]

Mycoplasma bovis shares insertion sequences with Mycoplasma agalactiae and mycoplasma mycoides subsp. mycoides: evolutionary and developmental aspects

in FEMS Microbiology Letters (2005), 245(2), 249-255

Three new insertion elements, ISMbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma mycoides subsp. mycoides SC), respectively, have ... [more ▼]

Three new insertion elements, ISMbov1, ISMbov2 and ISMbov3, which are closely related to ISMag1 (Mycoplasma agalactiae), ISMmy1 and IS1634 (both Mycoplasma mycoides subsp. mycoides SC), respectively, have been discovered in Mycoplasma bovis, an important pathogen of cattle. Southern blotting showed that the genome of M. bovis harbours 6-12 copies of ISMbov1, 11-15 copies of ISMbov2 and 4-10 copies of ISMbov3, depending on the strain. A fourth insertion element, the IS30-like element, is present in 4-8 copies. This high number of IS elements in M. bovis, which represent a substantial part of its genome, and their relatedness with IS elements of both M. agalactiae and M. mycoides subsp. mycoides SC suggest the occurrence of two evolutionary events: (i) a divergent evolution into M. agalactiae and M. bovis upon infection of different [less ▲]

Pleiotropic Mutants Hypersensitive to Heavy Metals and to Oxidative Stress in Chlamydomonas Reinhardtii

in FEMS Microbiology Letters (2001), 196(2),

Insertional mutagenesis was used in Chlamydomonas reinhardtii to isolate original mutants hypersensitive to multiple drugs and physical agents. Out of 5200 transformants analyzed, 13 mutants belonging to ... [more ▼]

Insertional mutagenesis was used in Chlamydomonas reinhardtii to isolate original mutants hypersensitive to multiple drugs and physical agents. Out of 5200 transformants analyzed, 13 mutants belonging to seven phenotypic classes were isolated. Five were exclusively sensitive to cadmium and represented two loci. The other mutants were pleiotropic and presented a cross sensitivity to several (2--6) of the following agents: cadmium, copper, lead, paraquat, hydrogen peroxide, UVC and light. In all mutants analyzed, the hypersensitive phenotype was most probably due to a single mutational event. The sensitivity of several pleiotropic mutants to a broad range of physical and chemical agents suggests that the disrupted genes are involved in multiple stress responses. [less ▲]

Arthrospira ('Spirulina') strains from four continents are resolved into only two clusters, based on amplified ribosomal DNA restriction analysis of the internally transcribed spacer

in FEMS Microbiology Letters (1999), 172(2), 213-22

We present the results of a phylogenetic study, based on amplified ribosomal DNA restriction analysis of the rDNA operon, of 37 Arthrospira ('Spirulina') cultivated clonal strains from four continents. In ... [more ▼]

We present the results of a phylogenetic study, based on amplified ribosomal DNA restriction analysis of the rDNA operon, of 37 Arthrospira ('Spirulina') cultivated clonal strains from four continents. In addition, duplicates from different culture collections or markedly different morphotypes of particular strains established as clonal cultures were treated as separate entries, resulting in a total of 51 tested cultures. The strain Spirulina laxissima SAG 256.80 was included as outgroup. The 16S rRNA genes appeared too conserved for discrimination of the strains by amplified ribosomal DNA restriction analysis, and thus the internally transcribed spacer was selected as molecular taxonomic marker. The internally transcribed spacer sequences situated between the 16S and the 23S rRNA were amplified by polymerase chain reaction and yielded amplicons of about 540 bp. Direct use of cells for polymerase chain reaction seemed to inhibit the amplification reaction. This was overcome by the design of a crude lysis protocol and addition of bovine serum albumin in the polymerase chain reaction mix. The amplicons were digested with four restriction enzymes (EcoRV, Hhal, Hinfl, Msel) and the banding patterns obtained were analyzed. Cluster analysis showed the separation of all the strains into two main clusters. No clear relationships could be observed between this division into two clusters and the geographic origin of the strains, or their designation in the culture collections, or their morphology. [less ▲]

Bovine Attaching and Effacing Escherichia Coli Possess a Pathogenesis Island Related to the Lee of the Human Enteropathogenic Escherichia Coli Strain E2348/69

in FEMS Microbiology Letters (1997), 154(2), 415-421

Attaching and effacing Escherichia coli (AEEC) has been described as a cause of diarrhea in calves. The molecular pathogenesis of AEEC was mainly studied in human enteropathogenic E. coli strain E2348/69 ... [more ▼]

Attaching and effacing Escherichia coli (AEEC) has been described as a cause of diarrhea in calves. The molecular pathogenesis of AEEC was mainly studied in human enteropathogenic E. coli strain E2348/69 in which the virulence correlated with the presence of a 35.4 kb pathogenesis island called LEE. We showed that several strains isolated from calves with diarrhea were able to produce attaching and effacing lesions in a rabbit ileal loop model and that they possess a pathogenesis island related to the LEE. Moreover, we showed that the LEE from bovine strains was inserted mainly at a different position in the chromosome compared to the human enteropathogenic E. coli strain E2348/69. [less ▲]

A Sequence-Specific DNA-Binding Protein Interacts with the Xlnc Upstream Region of Streptomyces Sp. Strain Ec3

in FEMS Microbiology Letters (1996), 142(1), 91-7

The alignment of the promoter region of several Streptomyces xylanases shows three conserved sequences which could be involved in gene regulation. By electromobility shift assays these specific sequences ... [more ▼]

The alignment of the promoter region of several Streptomyces xylanases shows three conserved sequences which could be involved in gene regulation. By electromobility shift assays these specific sequences, present only in Streptomyces xylanolytic strains, were identified as protein-binding sites. The sequence required for efficient recognition by the retarding protein appeared to be a 4-bp inverted repeat: 5'-CTTT-Nx-AAAG-3'. The DNA-protein affinity was influenced by the culture conditions. [less ▲]

Site-directed mutagenesis of penicillin-binding protein 3 of Escherichia coli: role of Val-545

in FEMS Microbiology Letters (1994), 121(2), 251-256

Val545 of the Escherichia coli penicillin-binding protein 3 is essential to the acyl transfer mechanism through which the active-site serine 307 is acylated by benzylpenicillin and cephalexin and to the ... [more ▼]

Val545 of the Escherichia coli penicillin-binding protein 3 is essential to the acyl transfer mechanism through which the active-site serine 307 is acylated by benzylpenicillin and cephalexin and to the mechanism through which the protein allows rapidly growing cells to divide. [less ▲]