Research

Research in the field of probiotics

We have several years of experiences in the probiotic research which was started already in the 90s. Our activities in this field include isolation of unique strains with probiotic properties from different environments, tracing and quantification of individual strains during the passage through the digestive tract and in probiotic products and determination of the safety and functionality of probiotic bacteria in vitro and in vivo.


The acquisition of new probiotic bacterial strains from different environments

Environments from which the potential probiotic bacterial strains can be isolated include  faeces of babies and animals, human colostrum and milk, intestinal mucosa, etc.... Candidates for probiotics are stored in our own collection of microorganisms, which is part of the Slovenian national collection ZIM - Culture Collection of Industrial Microorganisms, also registered as WDCM810 (WFCC-MIRC World Data Centre for Microorganisms (WDCM)). Our best studied strain is Lactobacillus gasseri K7. The results of the studies of this strain have been published in numerous scientific articles. Its entire genome has already been sequenced. In collaboration with industrial partners, we have developed the products in powder form or oily suspension containing viable K7 cells. Among the particularly interesting isolates are also those derived from the intestinal mucosa of children, which were obtained in collaboration with the industrial partner (Medis) in the frame of the project KC-BRIN - The competence centre for Biotechnological Development and Innovation. Individual isolates are capable of anti-inflammatory activity and/or affecting the intestinal barrier function, and are therefore useful for the prevention or support in the treatment of chronic inflammatory bowel diseases.

Tracing and quantification of probiotics in different environments

In order to develop specific methods for detection and quantification of probiotics we are looking for the strain-specific fragments of the genome, which represent a suitable target for  PCR or hybridization. Methods are adapted to different needs, such as tracing of particular strains during the passage through the digestive tract or detection of strains in different probiotic products.

Determination of safety and functionality of probiotic bacteria

Determination of safety and functionality of probiotic bacteria can be carried out in vitro - with cultivation methods, on cell cultures (Caco2 - epithelial cells model, THP-1 - macrophage model, ...) and in vivo on animals and humans.
Among the most important features that are tested are the following:

  • Safety: lack of resistance to clinically important antibiotics;
  • Confirmation of the species – probiotics have to belong to the species that are considered safe (QPS status by EFSA);
  • Inhibition of pathogenic bacteria;
  • Effects on the immune system of the host (the impact on cytokines’ genes expression and secretion of cytokines, effects on the transcriptome of the host’s immune cells, ...) and on the intestinal barrier function (in collaboration with prof. Dr. Mojca Narat, Chair of Genetics, Animal Biotechnology and Immunology, Department of Animal Science, Biotechnical Faculty, University of Ljubljana);
  • Effects of bacteriocins secreted by probiotics in the gut of the host.
In the context of the assessment of safety and functionality of probiotic bacteria in vivo, we participated in the planning and execution of the following clinical studies:

  • A clinical study on the effects of probiotic fermented milk products with probiotics in patients with IBS - Irritable bowel syndrome (project KC-BRIN - The competence centre for Biotechnological Development and Innovation, collaboration with the industrial partners Celeia and Clinres); this study also comprised next generation sequencing (NGS) of the intestinal microbiota of subjects (in collaboration with researchers of the Chair of Microbiology and Microbial Ecology, Department of Animal Science, Biotechnical Faculty, University of Ljubljana);
  • A clinical study on the effects of probiotic strains Lactobacillus fermentum and Bifidobacterium animalis isolated from the intestinal mucosa, in patients with IBS - Irritable bowel syndrome (KC-BRIN, in collaboration with the industrial partner Medis);
  • A completed prospective observational clinical study in lactating / pregnant Slovenian women and their children - some of them have consumed a probiotic Lb. gasseri K7 during the last month of pregnancy; in collaboration with the University Medical Centre Ljubljana (www.moje-mleko.si). It is expected that the statistical analyzes which are in progress will show the links between diet (breast-feeding, milk composition) and the microbiota of infants.

Selected publications:

  • SAGAYA, F. M., HACIN, Biljana, TOMPA, Gorazd, IHAN, Alojz, ŠKRAJNAR, Špela, ČERNE, Manica, HURRELL, Richard, BOGOVIČ MATIJAŠIĆ, Bojana, ROGELJ, Irena, VERGÈRES, G. Lactobacillus gasseri K7 modulates the blood cell transcriptome of conventional mice infected with Escherichia coli O157:H7. Journal of applied microbiology, 2014, vol. 116, issue 5, str. 1282-1296. doi:10.1111/jam.12440.
  • TREVEN, Primož, TURKOVÁ, Kristýna, TRMČIĆ, Aljoša, OBERMAJER, Tanja, ROGELJ, Irena, BOGOVIČ MATIJAŠIĆ, Bojana. Detection and quantification of probiotic strain Lactobacillus gasseri K7 in faecal samples by targeting bacteriocin genes. Folia microbiologica, 2013, vol. 58, no. 6, str. 623-630, doi:10.1007/s12223-013-0252-8.
  • BOGOVIČ MATIJAŠIĆ, Bojana, ROGELJ, Irena. Bacteriocins of probiotics and enteric cytoprotection. V: MALAGO, J.J. (ur.), KONINKX, J.F.J.G. (ur.), MARINŠEK-LOGAR, Romana (ur.). Probiotic bacteria and enteric infections : cytoprotection by probiotic bacteria. Dordrecht [etc.]: Springer, cop. 2011, str. 313-354. doi:10.1007/978-94-007-0386-5.
  • MAVRIČ, Anja, TOMPA, Gorazd, TRMČIĆ, Aljoša, ROGELJ, Irena, BOGOVIČ MATIJAŠIĆ, Bojana. Bacteriocins of Lactobacillus gasseri K7-Monitoring of gassericin K7 A and B genesʼ expression and isolation of an active component. Process biochemistry, 2014, vol. 49, no. 8, str. 1251-1259. doi:10.1016/j.procbio.2014.04.022.
  • ČITAR, Manuela, HACIN, Biljana, TOMPA, Gorazd, ŠTEMPELJ, Mateja, ROGELJ, Irena, DOLINŠEK, Jernej, NARAT, Mojca, BOGOVIČ MATIJAŠIĆ, Bojana. Human intestinal mucosa-associated Lactobacillus and Bifidobacterium strains with probiotic properties modulate IL-10, IL-6 and IL-12 gene expression in THP-1 cells. Beneficial microbes, 2015, vol. 6, no. 3, str. 326-336, doi:10.3920/BM2014.0081.