EMbaRC: designing training and e-learning materials for biological resource centres

The European Consortium of Microbial Resource Centres (EMbaRC, www.embarc.eu) is a research infrastructure project gathering together major microbial Biological Resource Centres (BRCs) in Europe. These culture collections have a long and respected tradition in training people that are involved in microbial taxonomy, preservation and management. Advanced and bespoke courses on related topics add high value to the European educational community and create a knowledge-based training network. Under the framework of EMbaRC, the training programmes offered by the consortium were surveyed and schemes were proposed to establish an educational community to create a knowledge-based training network. This would implement lifelong educational and continuing professional development (CPD) schemes for those working within microbial resource centres (MiRC). In parallel, a European Masters Course on MiRC was designed to address the formal education path for strengthening competences in (1) Microbial Preservation Technologies, (2) MiRC: Organisation and Management, (3) QC Standards and International Regulations, (4) Microbial Biosafety and Biosecurity, and (5) IT Technologies and Database Management. Finally, to support these actions, materials for e-learning activities were developed such as videos related to microbial preservation techniques, the Gram-staining technique and, preparing microscopic slides of fungi. All activities developed under this EMbaRC task will support the MIRRI and other EU ESFRI-BMS and EMTRAIN projects

The Complete Genome of Propionibacterium freudenreichii CIRM-BIA1T, a Hardy Actinobacterium with Food and Probiotic Applications

Background: Propionibacterium freudenreichii is essential as a ripening culture in Swiss-type cheeses and is also considered for its probiotic use [1]. This species exhibits slow growth, low nutritional requirements, and hardiness in many habitats. It belongs to the taxonomic group of dairy propionibacteria, in contrast to the cutaneous species P. acnes. The genome of the type strain, P. freudenreichii subsp. shermanii CIRM-BIA1 (CIP 103027T), was sequenced with an 11-fold coverage. Methodology/Principal Findings: The circular chromosome of 2.7 Mb of the CIRM-BIA1 strain has a GC-content of 67% and contains 22 different insertion sequences (3.5% of the genome in base pairs). Using a proteomic approach, 490 of the 2439 predicted proteins were confirmed. The annotation revealed the genetic basis for the hardiness of P. freudenreichii, as the bacterium possesses a complete enzymatic arsenal for de novo biosynthesis of aminoacids and vitamins (except panthotenate and biotin) as well as sequences involved in metabolism of various carbon sources, immunity against phages, duplicated chaperone genes and, interestingly, genes involved in the management of polyphosphate, glycogen and trehalose storage. The complete biosynthesis pathway for a bifidogenic compound is described, as well as a high number of surface proteins involved in interactions with the host and present in other probiotic bacteria. By comparative genomics, no pathogenicity factors found in P. acnes or in other pathogenic microbial species were identified in P. freudenreichii, which is consistent with the Generally Recognized As Safe and Qualified Presumption of Safety status of P. freudenreichii. Various pathways for formation of cheese flavor compounds were identified: the Wood-Werkman cycle for propionic acid formation, amino acid degradation pathways resulting in the formation of volatile branched chain fatty acids, and esterases involved in the formation of free fatty acids and esters. Conclusions/Significance: With the exception of its ability to degrade lactose, P. freudenreichii seems poorly adapted to dairy niches. This genome annotation opens up new prospects for the understanding of the P. freudenreichii probiotic activity

Zymogram and Preliminary Characterization of Lactobacillus helveticus Autolysins

The autolysins of Lactobacillus helveticus ISLC5 were detected and partially characterized by renaturing sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis with substrate-containing gels (zymogram). By using lyophilized Micrococcus luteus cells or heated whole cells of L. helveticus ISLC5 (0.2% [wt/vol]) as a substrate, several lytic activities were detected in the whole-cell SDS extract of strain ISLC5 (i) one activity at 42.4 kDa, which was named autolysin A, and (ii) six other activities having very similar molecular weights (29.1, 29.6, 30, 30.8, 31.7, and 32.8 kDa), which were named autolysins B (B1 through B6, respectively). As regards the temporal distribution of the enzymes, autolysins A and B were detected in the cells harvested from the beginning of the exponential growth phase. Autolysin A appeared to be associated only with viable cells, whereas the autolysins B remained associated with the cell envelope several days after the complete loss of culture viability. When SDS-treated walls of L. helveticus ISLC5 were used as a substrate, a supplementary lytic activity appeared at 37.5 kDa; it was considered a peptidoglycan hydrolase, since it was not able to induce lysis of whole-cell substrate. The autolysins of 30 other strains of L. helveticus from various geographical origins were also analyzed by zymogram; all the activity profiles obtained were similar to that of strain ISLC5 in terms of the number of lytic bands and their apparent molecular weights. Only the relative intensities of the lytic bands corresponding to autolysins A and B were variable depending on the strains. This observation suggested that autolysins are highly conserved enzymes. A concentrated crude lysate of the virulent bacteriophage 832-B1 infecting L. helveticus was also analyzed by zymogram; one lytic activity with an apparent molecular weight of 31.7 kDa, very close to the weights of the autolysins B, was observed. Finally, the autolysins of L. helveticus ISLC5 were successfully extracted from whole cells by using a 1 M lithium chloride solution; they were partially purified by precipitation, selective resolubilization, and gel filtration chromatography, which led to a 20-fold increase in specific activity

X-ray Photoelectron-spectroscopy and Biochemical-analysis of the Surface of Lactobacillus-helveticus Atcc-12046

The cell wall of Lactobacillus helveticus ATCC 12046 was investigated: intact cells were compared to cells stripped of their surface layer (S-layer) by treatment with LiCl. The protein profile and the amino acid composition of isolated cell walls were compared with those of LiCl-treated walls. The S-layer-forming-protein was tested for the presence of glycosidic residues. Finally, the overall elemental composition of the surface of intact cells, LiCl-treated cells and isolated S-layer-forming-protein was determined by X-ray photoelectron spectroscopy. The data collected by the ensemble of methods employed indicate that the surface of intact cells consists mainly of proteins. with some polysaccharides and teichoic or lipoteichoic acids. The exposed surface of LiCl-treated bacteria is rich in peptidoglycan, teichoic acids (or lipoteichoic acids) and polysaccharide. The extracted material is practically pure protein with traces of some glycosidic residues

Autolysis of dairy propionibacteria: isolation and renaturing gel electrophoresis of the autolysins of Propionibacterium freudenreichii CNRZ 725

International audienc

prtH2, Not prtH, Is the Ubiquitous Cell Wall Proteinase Gene in Lactobacillus helveticus▿

Lactobacillus helveticus strains possess an efficient proteolytic system that releases peptides which are essential for lactobacillus growth in various fermented dairy products and also affect textural properties or biological activities. Cell envelope proteinases (CEPs) are bacterial enzymes that hydrolyze milk proteins. In the case of L. helveticus, two CEPs with low percentages of amino acid identity have been described, i.e., PrtH and PrtH2. However, the distribution of the genes that encode CEPs still remains unclear, rendering it difficult to further control the formation of particular peptides. This study evaluated the diversity of genes that encode CEPs in a collection of strains of L. helveticus isolated from various biotopes, both in terms of the presence or absence of these genes and in terms of nucleotide sequence, and studied their transcription in dairy matrices. After defining three sets of primers for both the prtH and prtH2 genes, we studied the distribution of the genes by using PCR and Southern blotting experiments. The prtH2 gene was ubiquitous in the 29 strains of L. helveticus studied, whereas only 18 of them also exhibited the prtH gene. Sequencing of a 350-bp internal fragment of these genes revealed the existence of intraspecific diversity. Finally, expression of these two CEP-encoding genes was followed during the growth in dairy matrices of two strains, ITG LH77 and CNRZ32, which possess one and two CEP-encoding genes, respectively. Both genes were shown to be expressed by L. helveticus at each stage of growth in milk and at different stages of mini-Swiss-type cheese making and ripening