A novel antibacterial peptide derived from Crocodylus siamensis haemoglobin hydrolysate induces membrane permeabilization causing iron dysregulation, oxidative stress and bacterial death

Aims A novel antibacterial peptide from Crocodylus siamensis haemoglobin hydrolysate (CHH) was characterized for antimicrobial activity. Methods and Results CHHs were hydrolysed for 2 h (2 h-CHH), 4 h (4h-CHH), 6 h (6 h-CHH) and 8 h (8 h-CHH). The 8 h-CHH showed antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa at concentrations of 20, 20, 20 and 10 mg ml−1 (w/v) respectively. Fluorescent microscopy revealed that the 8 h-CHH had bactericidal activity against E. coli and P. aeruginosa. β-galactosidase assay supported by RT-qPCR demonstrated that the 8 h-CHH resulted in differential expression of genes involved in iron homeostasis (ftnA and bfd) and oxidative stress (sodA, soxR and oxyR). Siderophore assay indicated that the 8 h-CHH also impaired siderophore production with diminished expression of pvdF. This pattern of gene expression suggests that the 8 h-CHH triggers the release of free ferric ions in the cytoplasm. However, decreased expression of genes associated with the SOS response (recA and lexA) in combination with neutral comet revealed that no DNA damage was caused by 8 h-CHH. Membrane permeabilization assay indicated that 8 h-CHH caused membrane leakage thought to mediate the antibacterial and iron-stress responses observed, due to loss of regulated iron transport. The novel active peptide from 8 h-CHH was determined as QAIIHNEKVQAHGKKVL (QL17), with 41% hydrophobicity and +2 net charge. Conclusions The QAIIHNEKVQAHGKKVL fragment of C. siamensis haemoglobin is antibacterial via a mechanism that likely relies on iron dysregulation and oxidative stress which results in bacterial death. Significance and Impact of the Study We have described for the first time, a novel peptide derived from C. siamensis haemoglobin hydrolysate that has the potential to be developed as a novel antimicrobial peptide

Antibacterial Activity of Some Lactic Acid Bacteria Isolated from an Algerian Dairy Product

In the present study, the antibacterial effect of 20 lactic acid bacteria isolates from a traditional cheese was investigated. 6 isolates showed antibacterial effect against Gram positive bacteria. Streptococcus thermophilus T2 strain showed the wide inhibitory spectrum against the Gram positive bacteria. Growth and bacteriocin production profiles showed that the maximal bacteriocin production, by S. thermophilus T2 cells, was measured by the end of the late-log phase (90 AU ml−1) with a bacteriocine production rate of 9.3 (AU ml−1) h−1. In addition, our findings showed that the bacteriocin, produced by S. thermophilus T2, was stable over a wide pH range (4–8); this indicates that such bacteriocin may be useful in acidic as well as nonacidic food. This preliminarily work shows the potential application of autochthonous lactic acid bacteria to improve safety of traditional fermented food

Bioactive peptides generated from meat industry by products

There is a large generation of meat by-products, not only from slaughtering but also in the meat industry from trimming and deboning during further processing. This results in extraordinary volumes of by-products that are primarily used as feeds with low returns or, more recently, to biodiesel generation. The aim of this work was to review the state of the art to generate bioactive peptides from meat industry by-products giving them an added value. Hydrolysis with commercial proteases constitutes the typical process and a variety of peptides result from such extensive proteolysis. This review focuses on the potential of meat by-products for the generation of bioactive peptides through enzymatic hydrolysis. The potential of some of the identified peptides to be used as bioactive supplements in foods has also been considered. (C) 2014 Elsevier Ltd. All rights reserved.Grant AGL2010-16305 from MINECO and FEDER funds are fully acknowledged. JAEDOC-CSIC postdoctoral contract to L.M. is also acknowledged. This work was developed under the Unidad Asociada IAD-UPV/IATA-CSIC framework.Mora, L.; Reig Riera, MM.; Toldra, F. (2014). Bioactive peptides generated from meat industry by products. Food Research International. 65:344-349. https://doi.org/10.1016/j.foodres.2014.09.014S3443496

Comparative Study on Biochemical Properties and Antioxidative Activity of Cuttlefish (<i>Sepia officinalis</i>) Protein Hydrolysates Produced by Alcalase and<i>Bacillus licheniformis</i>NH1 Proteases

Antioxidative activities and biochemical properties of protein hydrolysates prepared from cuttlefish (Sepia officinalis) using Alcalase 2.4 L andBacillus licheniformisNH1 proteases with different degrees of hydrolysis (DH) were determined. For the biochemical properties, hydrolysis by both enzymes increased protein solubility to above 75% over a wide pH range. The antioxidant activities of cuttlefish protein hydrolysates (CPHs) increase with increasing DH. In addition, all CPHs exhibited antioxidative activity in a concentration-dependent manner. NH1-CPHs generally showed greater antioxidative activity than Alcalase protein hydrolysates (P&lt;0.05) as indicated by the higher 1,1-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity and ferrous chelating activity. Both Alcalase and NH1 protein hydrolysates were able to retard lipid peroxidation andβ-carotene-linoleic acid oxidation. Alcalase-CPH (DH = 12.5%) and NH1-CPH (DH = 15%) contained 75.36% and 80.11% protein, respectively, with histidine and arginine as the major amino acids, followed by glutamic acid/glutamine, serine, lysine, and leucine. In addition, CPHs have a high percentage of essential amino acids made up 48.85% and 50.04%. Cuttlefish muscle protein hydrolysates had a high nutritional value and could be used as supplement to poorly balanced dietary proteins.</jats:p

Etude des profils des bandes d'absorption infrarouge V3 du dioxyde de carbone et du protoxyde d'azote dissous dans une serie d'alcanes liquides

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 81296 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Stabilisation de l'hemoglobine par les solvants organiques: etude de l'auto-oxydation et de la denaturation thermique

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 79638 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Préparation de peptides antimicrobiens à partir de l'hydrolyse enzymatique de deux protéines (l'hémoglobine bovine et l'a-lactalbumine bovine)

Vingt quatre peptides antimicrobiens ont été isolés par CLHP à partir d'un hydrolysat pepsique d'hémoglobine bovine à 3% de degré d'hydrolyse. Cinq peptides antimicrobiens : a 107141, a 107-136, a 133-141, a 137-141 et b 126-145 ont été purifiés en une seule étape de CLHP. Leurs CMI, effet hémolytique ainsi que quelques propriétés structurales ont pu être déterminés. L'amélioration des méthodes de préparation de ces peptides antimicrobiens a montré que: l'augmentation de la température d'incubation permettait d'augmenter les concentrations des peptides antimicrobiens, et que le pH d'incubation avait un effet sur la sélectivité de l'enzyme en favorisant les coupures en Cterminal de la Leucine lors de l'hydrolyse en conditions dénaturantes. En conditions natives, le pH 3,5 a permis l'obtention de peptides antimicrobiens absents lors de l'hydrolyse menée à pH 4,5. La mise en place d'un système biphasique eau/butan-2-ol a permis d'extraire sélectivement plusieurs peptides antimicrobiens. Un nouveau modèle d'étude a été mis en place à partir de l'a-Lactalbumine. Après avoir étudié différents paramètres d'hydrolyse, le choix s'est porté sur l'hydrolyse chymotrypsique de l'apoforme de l'a-Lactalbumine dans le tampon phosphate de sodium 100 mM pH 7,4 pour rechercher des peptides antimicrobiens. La population peptidique au cours de cette cinétique d'hydrolyse.a été établie par différentes techniques de spectrométrie de masse. Une activité antimicrobienne a été mise en évidence au sein de plusieurs hydrolysats chymotrypsique de l'a-Lactalbumine. Deux hydrolysats se sont montrés particulièrement actifs: l'hydrolysat de 30 minutes et celui de 12H.LILLE1-BU (590092102) / SudocSudocFranceF