Nanotechnology is a rapidly developing toolbox that provides solutions to numerous challenges in ... more Nanotechnology is a rapidly developing toolbox that provides solutions to numerous challenges in the food industry and meet public demands for healthier and safer food products. The diversity of nanostructures and their vast, tunable functionality drives their inclusion in food products and packaging materials to improve their nutritional quality through bioactive fortification and probiotics encapsulation, enhance their safety due to their antimicrobial and sensing capabilities and confer novel sensorial properties. In this food nanotechnology state-of-the-art communication, matrix materials with particular focus on food-grade components, existing and novel production techniques, and current and potential applications in the fields of food quality, safety and preservation, nutrient bioaccessibility and digestibility will be detailed. Additionally, a thorough analysis of potential strategies to assess the safety of these novel nanostructures is presented.
The complete nucleotide sequences for pNAC1 (3538bp) from strain RW048 as well as for pNAC2 (3684... more The complete nucleotide sequences for pNAC1 (3538bp) from strain RW048 as well as for pNAC2 (3684bp) and pNAC3 (10,224bp) from strain RW041 of Bifidobacterium longum were determined. The largest ORF (repB) of pNAC1 encodes a putative protein similar to those involved in a rolling-circle (RC) replication mechanism, which was confirmed by demonstration of single-strand intermediates in the host cell. The putative RepB gene product of pNAC2 is most similar to the replication protein of pDOJH10L and pKJ36. A second gene (mob) is similar to mobilization proteins involved in conjugation. Plasmid pNAC3 is the largest bifidobacterial plasmid to be sequenced to date. Of the eight putative gene products coded by pNAC3, one is similar to replication proteins (RepB), and another (Orf2) to putative transfer proteins (Tra). Bifidobacterial plasmids were divided into five groups based on Rep amino acid sequence homology and the results suggest a new plasmid family for B. longum.
A coelectroporation method using a marker plasmid for indirect selection of lactococcal plasmids ... more A coelectroporation method using a marker plasmid for indirect selection of lactococcal plasmids with unassigned functions was evaluated. Cryptic plasmids were mixed with an erythromycin resistance (Eryr) marker plasmid and introduced into a recipient strain by electroporation, followed by plasmid extraction of erythromycin-resistant transformants. By optimizing the ratio between the marker plasmid and the cryptic plasmids, an average of 20% cotransformants was obtained, including combinations of more than one cryptic plasmid. The marker plasmid pSA3 was easily eliminated from the cotransformed cells by subculture without selective pressure. This cotransformation approach reduces the number of colonies that must be screened to find transformants harbouring cryptic plasmids. The method facilitates the isolation of cryptic plasmids, helps in assigning functions to unknown plasmids and allows construction of food-grade lactococcal strains with new combinations of wild-type plasmids.
The microbiota of silage is a key determinant of its quality. Although commercial inoculants are ... more The microbiota of silage is a key determinant of its quality. Although commercial inoculants are often used to improve silage quality, studies to analyze their impact on the microbiota of preserved forage at farm-scale facilities are scarce. We assessed the diversity of viable bacterial communities of hay (unfermented dry forage) and grass or legume (GL) and corn (C) silage to deepen our knowledge of how inoculant addition drives microbial occurrence patterns on dairy farms. Forage samples were collected from 24 dairy farms over two sampling periods. Samples were analyzed by high-throughput sequencing and quantitative PCR after being treated with propidium monoazide to account for viable cells. We found consistent significant differences between hay and silage community structures across sampling periods. Silage was generally dominated by lactic acid bacteria (LAB), while Pantoea and Sphingomonas were the main co-dominant genera in hay. The GL silage dominated by Pediococcus, Weisse...
Nanotechnology is a rapidly developing toolbox that provides solutions to numerous challenges in ... more Nanotechnology is a rapidly developing toolbox that provides solutions to numerous challenges in the food industry and meet public demands for healthier and safer food products. The diversity of nanostructures and their vast, tunable functionality drives their inclusion in food products and packaging materials to improve their nutritional quality through bioactive fortification and probiotics encapsulation, enhance their safety due to their antimicrobial and sensing capabilities and confer novel sensorial properties. In this food nanotechnology state-of-the-art communication, matrix materials with particular focus on food-grade components, existing and novel production techniques, and current and potential applications in the fields of food quality, safety and preservation, nutrient bioaccessibility and digestibility will be detailed. Additionally, a thorough analysis of potential strategies to assess the safety of these novel nanostructures is presented.
The complete nucleotide sequences for pNAC1 (3538bp) from strain RW048 as well as for pNAC2 (3684... more The complete nucleotide sequences for pNAC1 (3538bp) from strain RW048 as well as for pNAC2 (3684bp) and pNAC3 (10,224bp) from strain RW041 of Bifidobacterium longum were determined. The largest ORF (repB) of pNAC1 encodes a putative protein similar to those involved in a rolling-circle (RC) replication mechanism, which was confirmed by demonstration of single-strand intermediates in the host cell. The putative RepB gene product of pNAC2 is most similar to the replication protein of pDOJH10L and pKJ36. A second gene (mob) is similar to mobilization proteins involved in conjugation. Plasmid pNAC3 is the largest bifidobacterial plasmid to be sequenced to date. Of the eight putative gene products coded by pNAC3, one is similar to replication proteins (RepB), and another (Orf2) to putative transfer proteins (Tra). Bifidobacterial plasmids were divided into five groups based on Rep amino acid sequence homology and the results suggest a new plasmid family for B. longum.
A coelectroporation method using a marker plasmid for indirect selection of lactococcal plasmids ... more A coelectroporation method using a marker plasmid for indirect selection of lactococcal plasmids with unassigned functions was evaluated. Cryptic plasmids were mixed with an erythromycin resistance (Eryr) marker plasmid and introduced into a recipient strain by electroporation, followed by plasmid extraction of erythromycin-resistant transformants. By optimizing the ratio between the marker plasmid and the cryptic plasmids, an average of 20% cotransformants was obtained, including combinations of more than one cryptic plasmid. The marker plasmid pSA3 was easily eliminated from the cotransformed cells by subculture without selective pressure. This cotransformation approach reduces the number of colonies that must be screened to find transformants harbouring cryptic plasmids. The method facilitates the isolation of cryptic plasmids, helps in assigning functions to unknown plasmids and allows construction of food-grade lactococcal strains with new combinations of wild-type plasmids.
The microbiota of silage is a key determinant of its quality. Although commercial inoculants are ... more The microbiota of silage is a key determinant of its quality. Although commercial inoculants are often used to improve silage quality, studies to analyze their impact on the microbiota of preserved forage at farm-scale facilities are scarce. We assessed the diversity of viable bacterial communities of hay (unfermented dry forage) and grass or legume (GL) and corn (C) silage to deepen our knowledge of how inoculant addition drives microbial occurrence patterns on dairy farms. Forage samples were collected from 24 dairy farms over two sampling periods. Samples were analyzed by high-throughput sequencing and quantitative PCR after being treated with propidium monoazide to account for viable cells. We found consistent significant differences between hay and silage community structures across sampling periods. Silage was generally dominated by lactic acid bacteria (LAB), while Pantoea and Sphingomonas were the main co-dominant genera in hay. The GL silage dominated by Pediococcus, Weisse...
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Papers by Gisele LaPointe