[ Objective] This study aimed to clone and identify enterocin gene from Enterococcus. [ Method] The genomic DNA of 12 enterocecci was extracted, and separately amplified with specific primers. The amplified fragments ...[ Objective] This study aimed to clone and identify enterocin gene from Enterococcus. [ Method] The genomic DNA of 12 enterocecci was extracted, and separately amplified with specific primers. The amplified fragments were ligated into PGEM-T Easy vector, which was then transformed into DH5α competent cells. The positive clones were sequenced. [Result] Enterocin A gene was 274 bp long. It was obtained from six enterococci, and the amino acids encoded by the enterocin genes cloned from five object enterocecci were the same as that of type IIa reference strains except only one amino acid. The homology among them reached 99.76 - 100%, suggesting that the bacteriocin isolated from the enterococcis belonged to type II. Structure prediction by DNAstar indicated that 22nd - 30th amino acids of enterocin A formed ot region, which had a hydrophilic region at its N-terminal and a hydrophobic region at its C-terminal, a transmembrane helix structure. [ Conclusion] This study will provide basis for the heterologous expression and applications of enterocins. Key words Enterocin gene; Enterocecci; PCR; Sequence analysis展开更多
Current research aims to investigate the locally isolated enterococcal strains as probiotics and elaborate their associated biotechnological applications.The genus Enterococcus has ubiquitous distribution.Despite conc...Current research aims to investigate the locally isolated enterococcal strains as probiotics and elaborate their associated biotechnological applications.The genus Enterococcus has ubiquitous distribution.Despite concerns over antibiotic resistance and multiple virulence factors,this genus has been extensively studied for its probiotic potential and has identified many probiotic strains that are available commercially.In our previous study,we identified six(n=6)strains with potential probiotic properties via both phenotypic and genotypic assessments.Accordingly,this study aimed to investigate these lead enterococcal strains for further probiotic properties and to establish their potential biotechnological applications.We employ different in vitro validation assays that simulating the host physiological and industrial processes.These assays include stress tolerance,aggregation and clumping,enzyme production,cellular properties,survival,and shelf life at different storage conditions.The results obtained indicated their positive attributes for potential probiotic application.The test strains showed variable tolerance to saliva,lysozymes,pepsin,pancreatin,artificial intestinal juice,bile salts,and phenol.Furthermore,these strains also exhibit the production of aggregating agents,physiologically and biotechnologically relevant enzymes,and organic acids.Bile salt hydrolase activity was also detected in some strains.Importantly,the selected strains showed survivability(shelf life)for three months while kept at different temperatures.Similarly,the strains showed good survival potential at higher temperatures up to 50℃,while the effect of heat at 60℃ was found to reduce their growth exponentially.Under test conditions,our data highlights the diversity of enterococci genus and underscores their probiotic potential and future biotechnological applications.展开更多
Nowadays,as the interest in natural preservatives increases,research on bioprotective cultures that produce bacteriocins and studies on the use of these cultures in foods are also increasing day by day.Present study a...Nowadays,as the interest in natural preservatives increases,research on bioprotective cultures that produce bacteriocins and studies on the use of these cultures in foods are also increasing day by day.Present study aimed to investigate bacteriocin characterization and safety of Enterococcus faecium H108,H206 isolates and their potential utilization in the reduction of Listeria monocytogenes ATCC7644 in Beyaz cheese.Enterocin producing E.faecium H108 and H206 strains were isolated from raw cow’s milk and identified by 16S rRNA sequencing.Enterocin containing supernatants of E.faecium H108 and H206 were found to be stable to heat various chemicals used in food industry,wide pH range,lysozyme and catalase enzymes.On the other hand,activity of enterocins were inactivated by proteolytic enzymes.Maximum activity of E.faecium H108 was 6400 AU/mL,while that of H206 was 12800 AU/mL,and the activities remained stable for 24 h.Supernatant of both E.faecium H108 and H206 inhibited L.monocytogenes growth in vitro.E.faecium H108 and H206 did not show haemolytic and DN-ase activities and were susceptible to most of the antibiotics tested.The isolates were used in Beyaz cheese and were found to significantly,but not completely inhibit L.monocytogenes growth.The findings of this research suggest that E.faecium H108 and H206 isolates,after a detailed safety assessment,might be employed as bioprotective cultures in Beyaz cheese with starter culture or hurdle technologies.展开更多
基金supported by the Funds of National Natural Sciecne Foundation of China(41106143)Guangdong Natural Science Foundation(S2011040000377)China Postdoctoral ScienceFoundation(2011M500133)
基金Supported by General Project of Beijing Municipal Education Commissiona grant from the Schoolboard of Beijing,China(KM201110020005)
文摘[ Objective] This study aimed to clone and identify enterocin gene from Enterococcus. [ Method] The genomic DNA of 12 enterocecci was extracted, and separately amplified with specific primers. The amplified fragments were ligated into PGEM-T Easy vector, which was then transformed into DH5α competent cells. The positive clones were sequenced. [Result] Enterocin A gene was 274 bp long. It was obtained from six enterococci, and the amino acids encoded by the enterocin genes cloned from five object enterocecci were the same as that of type IIa reference strains except only one amino acid. The homology among them reached 99.76 - 100%, suggesting that the bacteriocin isolated from the enterococcis belonged to type II. Structure prediction by DNAstar indicated that 22nd - 30th amino acids of enterocin A formed ot region, which had a hydrophilic region at its N-terminal and a hydrophobic region at its C-terminal, a transmembrane helix structure. [ Conclusion] This study will provide basis for the heterologous expression and applications of enterocins. Key words Enterocin gene; Enterocecci; PCR; Sequence analysis
基金supported by the“Seed Fund”from ICCBS,University of Karachi,and Higher Education Commission of Pakistan(NRPU:20-151/Acad-R/0320-1339/R&D/09)to Syed Abid Ali.
文摘Current research aims to investigate the locally isolated enterococcal strains as probiotics and elaborate their associated biotechnological applications.The genus Enterococcus has ubiquitous distribution.Despite concerns over antibiotic resistance and multiple virulence factors,this genus has been extensively studied for its probiotic potential and has identified many probiotic strains that are available commercially.In our previous study,we identified six(n=6)strains with potential probiotic properties via both phenotypic and genotypic assessments.Accordingly,this study aimed to investigate these lead enterococcal strains for further probiotic properties and to establish their potential biotechnological applications.We employ different in vitro validation assays that simulating the host physiological and industrial processes.These assays include stress tolerance,aggregation and clumping,enzyme production,cellular properties,survival,and shelf life at different storage conditions.The results obtained indicated their positive attributes for potential probiotic application.The test strains showed variable tolerance to saliva,lysozymes,pepsin,pancreatin,artificial intestinal juice,bile salts,and phenol.Furthermore,these strains also exhibit the production of aggregating agents,physiologically and biotechnologically relevant enzymes,and organic acids.Bile salt hydrolase activity was also detected in some strains.Importantly,the selected strains showed survivability(shelf life)for three months while kept at different temperatures.Similarly,the strains showed good survival potential at higher temperatures up to 50℃,while the effect of heat at 60℃ was found to reduce their growth exponentially.Under test conditions,our data highlights the diversity of enterococci genus and underscores their probiotic potential and future biotechnological applications.
基金funded by Ataturk University Research Centre,grant number FHD-2023-13027.
文摘Nowadays,as the interest in natural preservatives increases,research on bioprotective cultures that produce bacteriocins and studies on the use of these cultures in foods are also increasing day by day.Present study aimed to investigate bacteriocin characterization and safety of Enterococcus faecium H108,H206 isolates and their potential utilization in the reduction of Listeria monocytogenes ATCC7644 in Beyaz cheese.Enterocin producing E.faecium H108 and H206 strains were isolated from raw cow’s milk and identified by 16S rRNA sequencing.Enterocin containing supernatants of E.faecium H108 and H206 were found to be stable to heat various chemicals used in food industry,wide pH range,lysozyme and catalase enzymes.On the other hand,activity of enterocins were inactivated by proteolytic enzymes.Maximum activity of E.faecium H108 was 6400 AU/mL,while that of H206 was 12800 AU/mL,and the activities remained stable for 24 h.Supernatant of both E.faecium H108 and H206 inhibited L.monocytogenes growth in vitro.E.faecium H108 and H206 did not show haemolytic and DN-ase activities and were susceptible to most of the antibiotics tested.The isolates were used in Beyaz cheese and were found to significantly,but not completely inhibit L.monocytogenes growth.The findings of this research suggest that E.faecium H108 and H206 isolates,after a detailed safety assessment,might be employed as bioprotective cultures in Beyaz cheese with starter culture or hurdle technologies.
