In vitro assessment of the probiotic properties and bacteriocinogenic potential of Pediococcus pentosaceus MZF16, isolated from artisanal Tunisian meat « Dried Ossban »

International audienc

Evaluation of probiotic and bacteriocinogenic potential of Pediococcus pentosaceus MZF16 isolated from artisanal Tunisian meat "Dried Ossban"

International audiencePediococcus pentosaceus MZF16 has been isolated from artisanal Tunisian meat so called “Dried Ossban”, an original ecological niche, and identified by MALDI-TOF mass spectrometry and 16S rDNA sequencing. This bacterium showed a high tolerance to gastric stress conditions, and toward bile salts. P. pentosaceus MZF16 also demonstrated a hydrophobic surface profile (high adhesion to xylene), autoaggregation, and adhesive abilities to the human intestinal Caco-2/TC7 cell line. These properties may help the bacterium colonizing the gut. Furthermore, MZF16 was found to be resistant to gentamycin and chloramphenicol but did not harbor any transferable resistance determinants and/or virulence genes. The data also demonstrated absence of cytotoxicity of this strain. Conversely, P. pentosaceus MZF16 can slightly stimulate the immune system and enhance the intestinal epithelial barrier function. Moreover, this bacterium has been shown to be highly active against Listeria spp. due to bacteriocin production. Characterization of the bacteriocin by PCR amplification, sequencing and bioinformatic analyses revealed that MZF16 produces a bacteriocin 100% identical to coagulin, a pediocin-like inhibitory substance produced by Bacillus coagulans. To our knowledge, this is the first report that highlights the production of a pediocin 100% identical to coagulin in a Pediococcus strain. As coagulin, pediocin MZF16 has the consensus sequence YYGNGVXCXXXXCXVXXXXA (X denotes any amino acid), which confirms its belonging to class IIa bacteriocins, and its suitability to preserve foods from Listeria monocytogenes development. According to these results, P. pentosaceus MZF16 can be proposed as a probiotic and bioprotective agent for fermented foods, including Tunisian dry meat and sausages. Further investigations will aim to study the behavior of this strain in meat products as a component of functional food

BIOCHEMICAL PROFILE, ANTIOXIDANT ACTIVITY AND BIOMETHANISATION OF THE MICROALGA Chlorella vulgaris

Over the last decade, the use of microalgae for its high quality nutritional raw material and its ability to produce high amounts of lipids, proteins and different energy forms has become a challenge worldwide. The characterization of  the biochemical profile of a green microalgae Chlorella sp which was isolated from a Tunisian fresh water lagoon showed that this microalga accumulated 18% of lipid content (19% FA ω 3: 15% of C18:3 ω3, 3% EPA and 0.69% DPA) and a high protein content reaching up to 60%. of dry weight. Moderately producer of natural antioxidant, Chlorella sp. accumulates 3.7 mg AGE/ g DW and an inhibition concentration (IC 50) of 595µg/ ml. Finally, the anaerobic digestion of this microalgae provided 12.56% of CH4 biogas

Effect of seed maturation stages on physical properties and antioxidant activity in flaxseed (Linum usitatissimum L.)

AbstractThe changes in flaxseed constituents at different stages of maturity are reported. The physical properties and antioxidant activity of flaxseed oil during flaxseed development have been evaluated. Continuous decrease in total polyphenol content during flaxseed development. All the results showed no significant differences between HPLC-MS and TLC for quantitative determination of phospholipids classes. The fatty acid compositions of individual phospholipids were also reported. The antioxidant activity of oilseed was assessed by means of 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging assay. The test demonstrated that the antioxidant activity of the flaxseed oil was found to be harvesting time-dependant

Lipids, proteins, phenolic composition, antioxidant and antibacterial activities of seeds of peanuts (Arachis hypogaea l) cultivated in Tunisia

Fatty acid composition of peanut seed oil in four varieties cultivated in Tunisia showed that linoleic (C18:2), oleic (C18:1) and palmitic (C16) acids account for more than 84% for Chounfakhi and Massriya and for more than 85% of the total fatty acids of Trabilsia and Sinya seed oil respectively. Seed oil contents were significantly different (P ≤ 0.05) and did not exceed 48%. The study of total phenolics revealed that Chounfakhi contained more total phenolics (2.1 mg GAE/g DW), followed by the Massriya and Sinya cultivars (1.35 mg GAE/g DW for each); Trabilsia presented the lowest total phenolic content with 1 mg GAE/g DW. Considerable antiradical ability was found, especially in the Trabilsia peanut seed cultivar (IC50 = 1550 μg/ml), the Massriya and Sinya cultivars had, respectively, 720 and 820 mg/ml IC50. In the Massriya variety the sterol fraction showed antibacterial activity against Listeria ivanovii, Listeria inocua, Pseudomonas aeruginosa, Staphylococus aureus, Enterococcus hirae and Bacillus cereus