This work investigates the composition of whey protein phospholipid concentrate (WPPC), an underutilized dairy stream, and reveals that it is a source of many bioactive compounds that can benefit the ...immune system and gut health. Our glycoproteomics approach uncovered that proteins derived from the milk fat globule membrane (MFGM) represent 23% of the total protein relative abundance and identified 85 N-glycans. Released sialic acid, an additional marker of glycosylation, ranged from 1.2 to 2% of the total weight. Xanthine oxidase, a glycosylated marker of MFG bioactivity, was found in high abundance and displayed higher antimicrobial activity than bovine milk, despite its similar fat and solids content. An average MFG diameter of 2.64 ± 0.01 µm was found in liquid WPPC, compared to 4.78 ± 0.13 µm in bovine milk, which likely explains the unusually high presence of glycosylated membrane-bound proteins and phospholipids, whose total fatty acids accounted for 20% of the WPPC total fatty acid pool. Free and bound oxylipins (mainly derived from linoleic acid) were also identified, together with other less abundant anti-inflammatory lipid mediators derived from eicosapentaenoic acid and docosahexaenoic acid. Our study demonstrates that WPPC represents a promising starting material for bioactive compound extraction and a functional vehicle for the delivery of small MFGs.
Polydopamine (PDA) prepared in the form of a layer of polymerized dopamine (DA) in a weak alkaline solution has been used as a versatile biomimetic surface modifier as well as a broadly used ...immobilizing macromolecule. This review mainly discusses the progress of biomaterial surface modification inspired by the participation of PDA in bone tissue engineering. A comparison between PDA-assisted coating techniques and traditional surface modification applied to bone tissue engineering is first presented. Secondly, the chemical composition and the underlying formation mechanism of PDA coating layer as a unique surface modifier are interpreted and discussed. Furthermore, several typical examples are provided to evidence the importance of PDA-assisted coating techniques in the construction of bone biosubstitutes and the improvement of material biocompatibility. Nowadays, the application of PDA as a superior surface modifier in multifunctional biomaterials is drawing tremendous interests in bone tissue scaffolds to promote the osteointegration for bone regeneration.
Fungal spoilage of bread remains an unsolved issue in bread making. This work aims to identify alternative strategies to conventional preservatives in order to prevent or delay fungal spoilage of ...bread. The minimum inhibitory concentration (MIC) of bacterial metabolites and chemical preservatives was evaluated in vitro, and compared to their in situ activity in baking trials. Calcium propionate, sorbic acid, 3-phenyllactic acid, ricinoleic acid, and acetic acid were tested both individually and in combination at their MIC values against Aspergillus niger and Penicillium roqueforti. The combination of acetic acid with propionate and sorbate displayed additive effects against the two fungi. For these reasons, we introduced sourdough fermentation with specific strains of lactobacilli, using wheat or flaxseed, in order to generate acetate in bread. A combination of Lactobacillus hammesii and propionate reduced propionate concentration required for shelf life extension of wheat bread 7-fold. Flaxseed sourdough bread fermented with L. hammesii, excluding any preservative, showed a shelf life 2 days longer than the control bread. The organic acid quantification indicated a higher production of acetic acid (33.8 ± 4.4 mM) when compared to other sourdough breads. Addition of 4% of sucrose to sourdough fermentation with L. brevis increased the mould free shelf-life of bread challenged with A. niger by 6 days. The combination of L. hammesii sourdough and the addition of ricinoleic acid (0.15% or 0.08%) prolonged the mould free shelf-life by 7–8 days for breads produced with wheat sourdoughs. In conclusion, the in vitro MIC of bacterial metabolites and preservatives matched the in situ antifungal effect. Of the different bacterial metabolites evaluated, acetic acid had the most prominent and consistent antifungal activity. The use of sourdough fermentation with selected strains able to produce acetic acid allowed reducing the use of chemical preservatives.
•Sourdough baking can delay fungal spoilage.•Acetic acid is the most powerful antifungal metabolite of lactobacilli.•Sourdough enhances the antifungal activity of organic acids in bread.
Fungal spoilage limits the shelf life of fermented dairy products. To address the problem, this study explores the potential of lactic acid bacteria as antifungal adjunct cultures in dairy matrices. ...Strains of lactic acid bacteria (113) representing 19 species were screened for their activity against Penicillium caseifulvum, Aspergillus clavatus and Mucor racemosus in modified MRS medium, milk, and yogurt. Strains of Lactiplantibacillus plantarum, Furfurilactobacillus milii, and Lentilactobacillus parabuchneri inhibited the growth of mycelial fungi. The inhibitory effects of lactic acid bacteria against yeasts were also determined in yogurt with Candida sake, Saccharomyces bayanus, and Torulaspora delbrueckii as challenge strains. The inhibition of yeasts by lactic acid bacteria was strain-specific and unrelated to the activity towards mycelial fungi. Organic acids and hydroxy fatty acids were quantified by liquid chromatograph coupled with refractive index detector and tandem mass spectrometry, respectively. Principal component analysis indicated 10-OH 18: 1 fatty acids and acetate are the main antifungal metabolites and explained over 50 % of the antifungal activity. The correlation analysis of metabolites and mold-free shelf life of milk and yogurt confirmed the role of these compounds. The genomic study analysed genes related to the production of major antifungal metabolites and predicted the formation of 1,2-propanediol and acetate but not of hydroxy unsaturated fatty acids. The findings provide new perspectives on the selection of antifungal strains, the characterization of antifungal metabolites and the exploration of antifungal mechanisms among different species.
•The antifungal activity of lactobacillus was strain- and species-specific.•The activity against mycelial fungi and yeasts was unrelated.•Acetate and hydroxy unsaturated fatty acids were identified as major antifungal metabolites.•The antifungal activity is only partially predicted from genome sequences.
Strains of Limosilactobacillus reuteri are used as starter and bioprotective cultures and contribute to the preservation of food through the production of fermentation metabolites lactic and acetic ...acid, and of the antimicrobial reuterin. Reuterin consists of acrolein and 3-hydroxypropionaldehyde (3-HPA), which can be further metabolized to 1,3-propanediol and 3-hydroxypropionic acid (3-HP). While reuterin has been the focus of many investigations, the contribution of 3-HP to the antimicrobial activity of food related reuterin-producers is unknown. We show that the antibacterial activity of 3-HP was stronger at pH 4.8 compared to pH 5.5 and 6.6. Gram-positive bacteria were in general more resistant against 3-HP and propionic acid than Gram-negative indicator strains including common food pathogens, while spoilage yeast and molds were not inhibited by ≤ 640 mM 3-HP. The presence of acrolein decreased the minimal inhibitory activity of 3-HP against E. coli indicating synergistic antibacterial activity. 3-HP was formed during the growth of the reuterin-producers, and by resting cells of L. reuteri DSM 20016. Taken together, this study shows that food-related reuterin producers strains synthesize a second antibacterial compound, which might be of relevance when strains are added as starter or bioprotective cultures to food products.
•The food microbe Limosilactobacillus reuteri has the potential to produce the antibacterial 3-hydroxypropionic acid.•The antibacterial activity against food pathogens of 3-hydroxypropionic acid was pH dependent.•The antibacterial activity of acrolein and 3-hydroxypropionic acid both produced by L. reuteri was synergistic.•Growth of spoilage yeast and mycelial fungi was only inhibited by propionic acid at low pH.
The quality of fermented sausage is strongly influenced by its fatty acid (FA). However, the role of a defined starter culture in modifying sausage FA composition, and especially in the production of ...hydroxy FAs (HFAs), has not been determined. In this study, the FA compositions of sausages fermented with Latilactobacillus sakei, with L. sakei plus Staphylococcus carnosus, and with an aseptic control were characterized by liquid chromatography–mass spectrometry (MS)/MS and gas chromatography–MS. The sausages fermented with L. sakei, and with L. sakei plus S. carnosus, showed a reduced accumulation of poly and/or diunsaturated FAs and distinct composition of HFAs compared to the aseptic control. 2-HFAs were enriched via high-speed counter-current chromatography and identified uniquely in the L. sakei plus S. carnosus fermented sausage. Through lipid analyses, this study illustrated how the choice of a defined starter culture affected the observed FA metabolism in fermented sausages, facilitating the development of starter cultures or additives that impart desirable characteristics to sausage.
•Counter-current chromatography (CCC) was used to collect ganglioside fractions.•The selected CCC solvent system was 2:4:3:8 butanol/MTBE/acetonitrile/H2O.•0.5% (v/v) acetic acid was added to the ...lower phase in dual-mode elution CCC.•CCC separated mg levels of (d36:1) & (d38:1) homologues of porcine GM1, GD1a & GD1b.•The purity of ganglioside fractions was estimated using LC-MS/MS.
Gangliosides play critical roles in the development of many progressive diseases. Due to their structural diversity, efficient methods are needed to separate individual gangliosides for studies of their functions, and for use as standards in the analysis of ganglioside mixtures. This proof-of-concept study reports a useful analytical-semi-preparative scale counter-current chromatography (CCC) enrichment of multiple ganglioside homologues of various species and classes at the milligram level.
Since few individual ganglioside standards were available, this research aimed to achieve analytical-semi-preparative scale separation of gangliosides by differences in saccharide monomer compositions (classes), their arrangements (species), or ceramide compositions (homologues), using CCC. The solvent system composition, addition of solvent modifiers, and elution modes were all adjusted to separate porcine gangliosides, mainly GM1 (d36:1), GD1a (d36:1), GD1b (d36:1) and their (d38:1) homologues as a demonstration. The eluted compounds were analyzed by flow-injection analysis (FIA)-MS and LC-MS/MS.
A two-phase solvent system, consisting of butanol/methyl t-butyl ether/acetonitrile/water at a ratio of 2:4:3:8 (v/v/v/v) with 0.5% (v/v) acetic acid added to the lower phase, was used to separate mg-levels of porcine gangliosides under dual-mode elution. The relative abundances of the above 6 gangliosides increased from 10 to 21% in the ganglioside extract to 55–73% in the collected fractions through the purification.
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•Some plant seed oils contain antifungal hydroxy fatty acids (HUFA).•Antifungal activity of HUFA depends on the site of hydroxylation.•HUFA with substitution at the centre of the ...carbon chain are antifungal.•Mycelial fungi but not yeasts are susceptible to HUFA with MIC’s below 1 g/L.•Resistance to HUFA relates to the ergosterol content of the cytoplasmic membrane.
This study investigated the relationships between the structures of hydroxy unsaturated fatty acids (HUFA) and their antifungal activities. Structurally diverse HUFA, including four monohydroxy-18:1 isomers, two monohydroxy 18:2 isomers and two monohydroxy 18:2 isomers were extracted from seeds of plants (Coriaria nepalensis, Thymus vulgaris, Mallotus philippensis and Dimorphotheca sinuata) for which information was available on PlantFAdb database, and from culture supernatants of lactobacilli. They were purified by high-speed counter current chromatography (HSCCC) and identified by LC-MS/MS. The minimum inhibitory concentrations of HUFA were tested against a panel of five yeasts and five mycelial fungi. The membrane phase changes under HUFA treatment and the content of ergosterol were both measured to differentiate HUFA-sensitive and HUFA-resistant fungi. HUFA with a hydroxyl group near the center of the 18-carbon fatty acid chains were found to contribute strongly to HUFA antifungal activity. Antifungal HUFA targeted filamentous fungi but not yeasts. HUFA didn’t alter the overall membrane fluidity of sensitive fungi, but the most HUFA-sensitive fungi had a lower average ergosterol content compared to the resistant yeasts. This indicates the possible interaction of HUFA with fungal membrane with low sterol content, which partially support the previous proposed mode of action. Findings here provide insight on further development of HUFA application in food products.
Hydroxy unsaturated fatty acids (HUFA) can function as antifungal agents. To investigate the antifungal spectrum, that is, the scope of the in vitro fungal-inhibition activities of HUFA and their ...potential applications, three HUFA were produced by microbial transformation or extracted from plant-seed oils; these compounds included coriolic acid (13-hydroxy-9,11-octadecadienoic acid) from Coriaria seed oil, 10-hydroxy-12-octadecenoic acid from cultures of Lactobacillus hammesii, and 13-hydroxy-9-octadecenoic acid from cultures of Lactobacillus plantarum TMW1.460Δlah. HUFA were purified by high-speed counter-current chromatography (HSCCC), characterized by LC-MS and MS/MS, and their antifungal activities were evaluated with 15 indicator fungal strains. The HUFA had different antifungal spectra when compared with unsaturated fatty acids with comparable structures but without hydroxy groups. The inhibitory effects of HUFA specifically targeted filamentous fungi, including Aspergillus niger and Penicillium roqueforti, whereas yeasts, including Candida spp. and Saccharomyces spp., were resistant to HUFA. The findings here support the development of food applications for antifungal HUFA.
Lipoprotein metabolism is critical to inflammation. While the periphery and central nervous system (CNS) have separate yet connected lipoprotein systems, impaired lipoprotein metabolism is implicated ...in both cardiometabolic and neurological disorders. Despite the substantial investigation into the composition, structure and function of lipoproteins, the lipoprotein oxylipin profiles, their influence on lipoprotein functions, and their potential biological implications are unclear. Lipoproteins carry most of the circulating oxylipins. Importantly, lipoprotein-mediated oxylipin transport allows for endocrine signaling by these lipid mediators, long considered to have only autocrine and paracrine functions. Alterations in plasma lipoprotein oxylipin composition can directly impact inflammatory responses of lipoprotein metabolizing cells. Similar investigations of CNS lipoprotein oxylipins are non-existent to date. However, as APOE4 is associated with Alzheimer's disease-related microglia dysfunction and oxylipin dysregulation, ApoE4-dependent lipoprotein oxylipin modulation in neurological pathologies is suggested. Such investigations are crucial to bridge knowledge gaps linking oxylipin- and lipoprotein-related disorders in both periphery and CNS. Here, after providing a summary of existent literatures on lipoprotein oxylipin analysis methods, we emphasize the importance of lipoproteins in oxylipin transport and argue that understanding the compartmentalization and distribution of lipoprotein oxylipins may fundamentally alter our consideration of the roles of lipoprotein in cardiometabolic and neurological disorders.
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