Scientific Research Activity
The work of Prof. Patrizia Brigidi is documented by several
publications in international journals. The principal topics
covered in her work have been:
genetic improvement of industrial microorganisms;
molecular identification of probiotic strains;
study of the molecular mechanisms responsible for the
health promoting activities of probiotics;
characterization of human complex ecosystems (gut microbiota,
vaginal microflora);
fermentation processes for biomass production of Bacillus
stearothermophilus and Lactobacillus strains;
analysis of antimicrobial activity of traditional compounds and
new synthesized molecules.
1.Characterization of the human intestinal microbiota
by molecular techniques: set up of a microarray platform.
The recent development of culture-independent molecular
approacches allowed to characterize complex
ecosystems, such as the human gut microbiota. In particolar,
the molecular analysis allows to evaluate qualitative and
quantitative modifications of the predominant intestinal
microbial groups related to different
physio-pathological conditions of the subjects analyzed and
environmental stimuli, such as the intake of antibiotics and
functional foods. DNA microchips (Community Genome Arrays, CGAs)
represent a potent and robust genomic technology, commonly
used to study biological systems and processes.
However, up to now, this technology has not been widely
used for the characterization of microbial communities. In this
perspective, new chips, based on the employment of
microbial ribosomal DNA probes specific for the predominant
intestinal microbial groups, will be developed. 2.Genomic and
proteomic analysis of health promoting metabolic activities of
probiotics. The characterization of an increasing number
of genomes of bacterial probiotics allows
to identify putative genes which codify
for metabolic activities benificial for the host. In
Bifidobacterium and Lactobacillus strains we
have identified and characterized the oxc gene,
which codifies for oxalyl-decarboxilase, key
enzyme for the decarboxilation of oxalate, a toxic compound
assumed with the diet. The proteomic analysis allows to verify
the expression of putative genes envolved in probiotic activities
and study the bacterial metabolic responses in different
environmental conditions (stress, antibiotics). The proteomic
approach has been performed to identify bacterial
proteins involved in the bacterial adhesion to intestinal
epithelium. 3.Study of the mecchanisms of adhesion of
Bifidobacterium cells to human enterocytes. Despite the wide
employment of Bifidobacterium strains in probiotic dietary and
pharmaceutical preparations, the molecular mechanisms of
the interaction between probiotics and host, are still
unknown. On the the other hand, several are the
published studies about the interaction between
enteropathogens and host. By considering that enteropathogens and
probiotics colonize the same ecological niche, we hypothesed that
they use the same mechanisms for adhering to the intestinal
epithelium. In this perspective, we will study the capability of
cell wall proteins of Bifidobacterium to bind plaminogen,
fibronectin and laminin, which are proteins involved in
the cross-talk between enteropathogens and human enterocytes.
Different methodologies will be applied in this study, including
bidimensional electrophoresis, overlay assay using monoclonal
antibodies specific for plasminogen, fibronectin and laminin,
immunoelectronmicroscopy, and MALDI-TOF. 4. Analysis of the
intestinal metabolic profiles related to the intake of functional
foods. The metabolic activities of the gut microbiota strongly
impact on the health of the host. Therefore, the metabotyping
analysis of fecal samples will be performed, before and after
assumption of probiotics and prebiotics, by GC-MS-SPME
analysis, with particular attention to the detection
of metabolites markers of saccharolytic o proteolytic
activities, such as short chain fatty acids, cresols and indols.
Furthermore, microbial metabolites potentially involved in
gastroenteric pathologies (i.e. ethanol) will be studied.
