Benoit Cudennec

Identification of lactobacilli with inhibitory effect on biofilm formation by pathogenic bacteria on stainless steel surfaces

Two hundred and thirty individual clones of microorganisms were recovered from milk tanks and milking machine surfaces at two distinct farms (Bejaja City, Algeria). Of these clones, 130 were identified as lactic acid bacteria (LAB). In addition Escherichia coli, Salmonella, Staphylococcus aureus and Pseudomonas aeruginosa species were identified in the remaining 100 isolates-spoilage isolate. These isolates were assayed for ability to form biofilms. S. aureus, Lactobacillus brevis strains LB1F2, LB14F1 and LB15F1, and Lactobacillus pentosus strains LB2F2 and LB3F2 were identified as the best biofilm formers. Besides, these LAB isolates were able to produce proteinaceous substances with antagonism against the aforementioned spoilage isolates, when grown in MRS or TSB-YE media. During the screening, L. pentosus LB3F2 exhibited the highest antibacterial activity when grown in TSB-YE medium at 30 °C. Additionally, L. pentosus LB3F2 was able to strongly hamper the adhesion of S. aureus SA3 on abiotic surfaces as polystyrene and stainless steel slides. LAB isolates did not show any hemolytic activity and all of them were sensitive to different families of antibiotic tested. It should be pointed out that LB3F2 isolate was not cytotoxic on the intestinal cells but could stimulate their metabolic activity. This report unveiled the potential of LB1F2, LB14F1, LB15F1, LB2F2, and LB3F2 isolates to be used as natural barrier or competitive exclusion organism in the food processing sector as well as a positive biofilm forming bacteria.

In vitro evidence for gut hormone stimulation release and dipeptidyl-peptidase IV inhibitory activity of protein hydrolysate obtained from cuttlefish (Sepia officinalis) viscera

Abstract Two cuttlefish ( Sepia officinalis ) viscera protein hydrolysates were obtained with different enzymes extracted from cuttlefish and smooth hound ( Mustellus mustellus ). Their ability to stimulate the secretion of cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1), using the enteroendocrine STC-1 cell line, and to inhibit the DPP-IV activity during a simulated gastrointestinal digestion was assayed. The physico-chemical parameters of hydrolysates and their effects on intestinal cell viability were also determined. The hydrolysate obtained with cuttlefish enzymes (CVPH1) appeared to be the most promising for all assessed bioactivities. Thus CVPH1 was able to stimulate CCK and active GLP-1 releasing activities of enteroendocrine cells without any cytotoxicity and to inhibit DPP-IV activity. Moreover, these actions were enhanced after gastrointestinal digestion and CVPH1 was also able to inhibit the intestinal DPP-IV activity of Caco-2 cells. These very promising findings highlight, via two different mechanisms, the positive effect of CVPH1 on GLP-1 actions.

Characterization of Candida famata Isolated from Poultry Feces for Possible Probiotic Applications.

We studied here the yeast content of poultry feces, collected randomly from a French farm located in the north of the country. Thus, 81 yeast colonies were isolated and clustered into 22 distinct groups using the rep-PCR method. A single colony was taken from each group and identified using biochemical (ID 32C system) and molecular (sequencing of the D1/D2 domain of 26S rDNA and ITS1-5.8-ITS2 rDNA region) methods. Both methods led to the identification of Candidafamata species. One isolate of C.famata strains, named strain Y5, was further studied for its cytotoxicity, adhesion, and surface properties, hemolytic activity, and its survival in simulated gastric and intestine environments. The data obtained advocate the probiotic potential of this isolate.

Particle-based photodynamic therapy based on indocyanine green modified plasmonic nanostructures for inactivation of a Crohn's disease-associated Escherichia coli strain

Particle-based photodynamic therapy (PPDT) holds great promise in theranostic applications. Herein, we demonstrate that PPDT based on gold nanorods coated with an indocyanine green (ICG)-loaded silica shell allows for the inactivation of the Crohns disease-associated adherent-invasive Escherichia coli strain LF82 (E. coli LF82) under pulsed laser light irradiation at 810 nm. Fine-tuning of the plasmonic structures together with maximizing the photosensitizer loading onto the nanostructures allowed optimizing the singlet oxygen generation capability and the PPDT efficiency. Using a nanoparticle concentration low enough to suppress photothermal heating effects, 6u2009log10 reduction in E. coli LF82 viability could be achieved using gold nanostructures displaying a plasmonic band at 900 nm. An additional modality of nanoparticle-based photoinactivation of E. coli is partly observed, with 3u2009log10 reduction of bacterial viability using Au NRs@SiO2 without ICG, due to the two-photon induced formation of reactive oxygen species. Interaction of the particles with the bacterial surface, responsible for the disruption of the bacterial integrity, together with the generation of moderate quantities of singlet oxygen could account for this behavior.

Simulated GI digestion of dietary protein: Release of new bioactive peptides involved in gut hormone secretion

Dietary proteins have been reported to induce a strong feeling of satiety that has been partially explained by gut hormone level increase. Up to date, various protein hydrolysates have demonstrated in vitro and in vivo their potential to stimulate gut hormone secretion related to food intake decrease and their mechanisms of action have just started to be resolved. In this context, this study aimed at identifying new peptide sequences involved in gut hormone secretion released by protein in vitro gastrointestinal digestion. Targeted gut hormones were Cholecystokinin (CCK) and Glucagon-Like Peptide 1 (GLP-1). The activity of DPP-IV was also considered as it strongly modulates GLP-1 action. In a previous study, simulated digestion of dietary protein has generated hydrolysates with enhancing effect on CCK and GLP-1 secretion in STC-1 cells as well as DPP-IV inhibitory properties. Successive purification steps were performed to isolate peptide fractions involved in these bioactivities whose sequence was determined by LC-MS-MS. Three peptide sequences ANVST, TKAVEH and KAAVT were pointed out for their stimulating effects on GLP-1 secretion. The sequence VAAA was isolated for its DPP-IV inhibitory properties. Two peptide groups were strongly involved in CCK release sharing a certain occurrence of aromatic amino acid residues.

Food peptidomics of in vitro gastrointestinal digestions of partially purified bovine hemoglobin: low‐resolution versus high‐resolution LC‐MS/MS analyses

Consumers and governments have become aware how the daily diet may affect the human health. All proteins from both plant and animal origins are potential sources of a wide range of bioactive peptides and the large majority of those display health‐promoting effects. In the meat production food chain, the slaughterhouse blood is an inevitable co‐product and, today, the blood proteins remain underexploited despite their bioactive potentiality. Through a comparative food peptidomics approach we illustrate the impact of resolving power, accuracy, sensitivity, and acquisition speed of low‐resolution (LR)‐ and high‐resolution (HR)‐LC‐ESI‐MS/MS on the obtained peptide mappings and discuss the limitations of MS‐based peptidomics. From in vitro gastrointestinal digestions of partially purified bovine hemoglobin, we have established the peptide maps of each hemoglobin chain. LR technique (normal bore C18 LC‐LR‐ESI‐MS/MS) allows us to identify without ambiguity 75 unique peptides while the HR approach (nano bore C18 LC‐HR‐ESI‐MS/MS) unambiguously identify more than 950 unique peptides (post‐translational modifications included). Herein, the food peptidomics approach using the most performant separation methods and mass spectrometers with high‐resolution capabilities appears as a promising source of information to assess the health potentiality of proteins.

Protein Digestion-Derived Peptides and the Peripheral Regulation of Food Intake

The gut plays a central role in energy homeostasis. Food intake regulation strongly relies on the gut–brain axis, and numerous studies have pointed out the significant role played by gut hormones released from enteroendocrine cells. It is well known that digestive products of dietary protein possess a high satiating effect compared to carbohydrates and fat. Nevertheless, the processes occurring in the gut during protein digestion involved in the short-term regulation of food intake are still not totally unraveled. This review provides a concise overview of the current data concerning the implication of food-derived peptides in the peripheral regulation of food intake with a focus on the gut hormones cholecystokinin and glucagon-like peptide 1 regulation and the relationship with some aspects of glucose homeostasis.

Using Caco-2 cells as novel identification tool for food-derived DPP-IV inhibitors

Dietary proteins have recently been investigated as a new source of DPP-IV inhibitory peptides with limited side effects and promising applications. Numerous studies have highlighted and identified peptide sequences able to inhibit DPP-IV activity in vitro, mostly from milk proteins. However, the correlation to in vivo studies remains scarce because standard in vitro assays with purified enzyme do not accurately simulate key factors impacting peptide bioactivity such as intestinal and brush border enzymes or cellular permeability. Therefore, a DPP-IV activity inhibition assay is here proposed using non differentiated confluent Caco-2 cells to rapidly assess food-derived peptide inhibitory potential in approaching intestinal conditions. DPP-IV gene expression was first checked and specific DPP-IV substrate was used to implement the assay. Using a specific DPP-IV inhibitor confirmed that non differentiated Caco-2 cells express measurable DPPIV activity. This in situ assay was then applied to digests which already demonstrated a DPP-IV inhibitory potential with a standard assay using purified enzyme. Bovine hemoglobin and cuttlefish hydrolysate digests from simulated gastrointestinal digestion exerted a dose response inhibition on DPP-IV activity but displayed different inhibitory potentials.

Biological Active Peptides from Marine Sources Related to Gut Hormones

Bioactive peptides obtained from marine species and marine by-products are showing these days a great interest in nutraceutical and pharmaceutical applications due to their wide range of biological activities. This mini-review focuses on the potential of marine peptides to be used as appetite suppressive molecules in the prevention and/or in the treatment of obesity syndrome. An important and promising aspect in the fight against obesity is the study of anorexigenic gut hormones, like cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1), that are synthetized by enteroendocrine cells in the presence of nutrients in the gastrointestinal tract. Recent works which have focused on the interaction between marine peptides and CCK and GLP-1 are here reviewed.

Required characteristics of Paenibacillus polymyxa JB-0501 as potential probiotic

AbstractnThe ability of Paenibacillus polymyxa to inhibit the growth of Escherichia coli generic ATCC 25922 (Escherichia coli ATCC 25922) and to adhere to monolayers of the enterocyte-like human cell line Caco-2 was evaluated. P. polymyxa JB-0501 (P. polymyxa JB-0501), found in a livestock feed probiotic supplement, was compared to P. polymyxa reference strain ATCC 43685 and ATCC 7070 (P. polymyxa ATCC) in terms of carbohydrate utilization and resistance to lysozyme, acid, bile salts, and hydrogen peroxide. JB-0501 grew at pH 4.5 and at H2O2 concentrations less than 7.3xa0μg/ml and presented a higher affinity to hexadecane and decane. Bile salts at 0.2xa0% inhibited the growth of all three strains. P. polymyxa JB-0501 and P. polymyxa ATCC 43865 adhered to Caco-2 cell monolayers. The percentage of cells that adhered ranged from about 0.35 to 6.5xa0% and was partially proportional to the number applied. Contact time (from 15xa0min to 1xa0h) had little impact on adhesion. P. polymyxa JB-0501 inhibited the growth of E. coli ATCC 25922, as proven by the diffusion tests in agar. Taken together, these results suggested that P. polymyxa JB-0501 has the potential probiotic properties to justify its consideration as a livestock feed supplement.