Simone Guglielmetti

Publications (41) View all

• Article: Luteibacter rhizovicinus MIMR1 promotes root development in barley (Hordeum vulgare L.) under laboratory conditions.

  Simone Guglielmetti, Roberto Basilico, Valentina Taverniti, Stefania Arioli, Claudia Piagnani, Andrea Bernacchi
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  ABSTRACT: In order to preserve environmental quality, alternative strategies to chemical-intensive agriculture are strongly needed. In this study, we characterized in vitro the potential plant growth promoting (PGP) properties of a gamma-proteobacterium, named MIMR1, originally isolated from apple shoots in micropropagation. The analysis of the 16S rRNA gene sequence allowed the taxonomic identification of MIMR1 as Luteibacter rhizovicinus. The PGP properties of MIMR1 were compared to Pseudomonas chlororaphis subsp. aurantiaca DSM 19603(T), which was selected as a reference PGP bacterium. By means of in vitro experiments, we showed that L. rhizovicinus MIMR1 and P. chlororaphis DSM 19603(T) have the ability to produce molecules able to chelate ferric ions and solubilize monocalcium phosphate. On the contrary, both strains were apparently unable to solubilize tricalcium phosphate. Furthermore, the ability to produce 3-indol acetic acid by MIMR1 was approximately three times higher than that of DSM 19603(T). By using fluorescent recombinants of strains MIMR1 and DSM 19603(T), we also demonstrated that both bacteria are able to abundantly proliferate and colonize the barley rhizosphere, preferentially localizing on root tips and in the rhizoplane. Finally, we observed a negative effect of DSM 19603(T) on barley seed germination and plant growth, whereas MIMR1, compared to the control, determined a significant increase of the weight of aerial part (+22 %), and the weight and length of roots (+53 and +32 %, respectively). The results obtained in this work make L. rhizovicinus MIMR1 a good candidate for possible use in the formulation of bio-fertilizers.
  MIRCEN Journal of Applied Microbiology and Biotechnology 05/2013; · 1.08 Impact Factor
• Article: Impact of Bifidobacterium bifidum MIMBb75 on mouse intestinal microbes.

  Natasha Singh, Stefania Arioli, Angela Wang, Christopher R Villa, Raha Jahani, Ye Seul Song, Diego Mora, Simone Guglielmetti, Elena M Comelli
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  ABSTRACT: Bifidobacterium bifidum MIMBb75 is a recently identified probiotic. However, its distribution along the intestine and impact on resident microbiota is unknown. Herein, we established a quantitative real-time PCR assay targeting the B. bifidum-specific BopA region for the quantification of B. bifidum in feces and used this assay to investigate transit of B. bifidum MIMBb75 through the murine intestine. We also analyzed the consequential impact on resident microbial cohorts. C57BL/6J mice were daily gavaged with 0.2 mL of either sterile PBS or PBS containing 10(8) CFU of B. bifidum MIMBb75 for two weeks, after which intestinal contents and fecal samples were analyzed for microbial compositional changes. B. bifidum MIMBb75 was able to transiently colonize the murine intestine with the predominant niche being the caeco-promixal colonic region. Region-specific effects on host microbiota were observed including decreased levels of Clostridium coccoides in the caecum, increased levels of bifidobacteria in the proximal and distal colon, total bacteria and Clostridium leptum in the proximal colon, and of C. coccoides in the feces. These findings suggest that probiotic properties of B. bifidum MIMBb75 may partially depend on its ability to at least transiently colonize the intestine and impact on the resident microbial communities at various intestinal loci. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
  FEMS Microbiology Ecology 03/2013; · 3.41 Impact Factor
• Article: Evaluation of adhesion properties and antibacterial activities of the infant gut commensal Bifidobacterium bifidum PRL2010.

  Fausta Serafini, Francesco Strati, Patricia Ruas-Madiedo, Francesca Turroni, Elena Foroni, Sabrina Duranti, Francesco Milano, Alessio Perotti, Alice Viappiani, Simone Guglielmetti, Annamaria Buschini, Abelardo Margolles, Douwe van Sinderen, Marco Ventura
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  ABSTRACT: Bifidobacteria are extensively exploited by the food industry as health-promoting microorganisms. However, very little is known about the molecular mechanisms responsible for these beneficial activities, or the molecular players that sustain their ability to colonize and persist within the human gut. Here, we have investigated the enteric adaptation features of the gut commensal Bifidobacterium bifidum PRL2010, originally isolated from infant feces. This strain was able to survive under gastrointestinal challenges, while it was shown to adhere to human epithelial intestinal cell monolayers (Caco 2 and HT-29), thereby inhibiting adhesion of pathogenic bacteria such as Escherichia coli and Cronobacter sakazakii.
  Anaerobe 03/2013; · 2.41 Impact Factor
• Article: Mobilome and genetic modification of bifidobacteria.

  S Guglielmetti, B Mayo, P Alvarez-Martín
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  ABSTRACT: Until recently, proper development of molecular studies in Bifidobacterium species has been hampered by growth difficulties, because of their exigent nutritive requirements, oxygen sensitivity and lack of efficient genetic tools. These studies, however, are critical to uncover the cross-talk between bifidobacteria and their hosts' cells and to prove unequivocally the supposed beneficial effects provided through the endogenous bifidobacterial populations or after ingestion as probiotics. The genome sequencing projects of different bifidobacterial strains have provided a wealth of genetic data that will be of much help in deciphering the molecular basis of the physiological properties of bifidobacteria. To this end, the purposeful development of stable cloning and expression vectors based on robust replicons - either from temperate phages or resident plasmids - is still needed. This review addresses the current knowledge on the mobile genetic elements of bifidobacteria (prophages, plasmids and transposons) and summarises the different types of vectors already available, together with the transformation procedures for introducing DNA into the cells. It also covers recent molecular studies performed with such vectors and incipient results on the genetic modification of these organisms, establishing the basis that would allow the use of bifidobacteria for future biotechnological applications.
  Beneficial microbes. 12/2012;
• Article: S-layer protein mediates the stimulatory effect of Lactobacillus helveticus MIMLh5 on innate immunity.

  Valentina Taverniti, Milda Stuknyte, Mario Minuzzo, Stefania Arioli, Ivano De Noni, Christian Scabiosi, Zuzet Martinez Cordova, Ilkka Junttila, Sanna Hämäläinen, Hannu Turpeinen, Diego Mora, Matti Karp, Marko Pesu, Simone Guglielmetti
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  ABSTRACT: The ability to positively affect host health through the modulation of the immune response is a feature of increasing importance in measuring the probiotic potential of a bacterial strain. However, the identities of the bacterial cell components involved in cross-talk with immune cells still remain elusive. In this study, we characterized the dairy strain Lactobacillus helveticus MIMLh5 and its surface layer protein (SlpA) using in vitro and ex vivo analyses. We found that MIMLh5 and SlpA exert anti-inflammatory effects by reducing the activation of NF-κB on the intestinal epithelial Caco-2 cell line. On the contrary, MIMLh5 and SlpA act as stimulators of the innate immune system by triggering the expression of pro-inflammatory factors TNF-α and COX-2 in the human macrophage cell line U937 via recognition through TLR-2. In the same experiments, SlpA protein did not affect the expression of the anti-inflammatory cytokine IL-10. A similar response was observed following stimulation of macrophages isolated from mouse bone marrow or the peritoneal cavity. These results suggest that SlpA plays a major role in mediating bacterial immune-stimulating activity, which could help to induce host's defenses against and responses towards infections. This study supports the concept that the viability of bacterial cells is not always essential to exert immunomodulatory effects, thus permitting the development of safer therapies for the treatment of specific diseases according to a paraprobiotic intervention.
  Applied and environmental microbiology 12/2012; · 3.69 Impact Factor