A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively w...A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures.Over time,EPS became important as natural biotechnological additives because of their noncytotoxic,emulsifying,antioxidant,or immunostimulant activities.In this article,we unravelled a new EPS produced by Staphy-lococcus sp.BSP3 from an acidic(pH 6.03)San Pedro hot spring(38.1℃)located in the central Andean mountains in Chile.Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS),Atomic Force Microscopy(AFM),High-Performance Liquid Chromatography(HPLC),Gel permeation chromatography(GPC),Fourier Transform Infrared Spectroscopy(FTIR),1D Nuclear Magnetic Resonance(NMR),and Thermogravimetric analysis(TGA).It was confirmed that the amorphous surface of the BSP3 EPS,composed of rough pillar-like nanostructures,is evenly distributed.The main EPS monosaccharide constituents were mannose(72%),glucose(24%)and galactose(4%).Also,it is a medium molecular weight(43.7 kDa)heteropolysaccharide.NMR spectroscopy demonstrated the presence of a[→6)-α-d-Manp-(1→6)-α-d-Manp-(1→]backbone 2-O substituted with 1-α-d-Manp.A high thermal stability of EPS(287°C)was confirmed by TGA analysis.Emulsification,antioxidant,flocculation,water-holding(WHC),and oil-holding(OHC)capacities are also studied for biotechnological industry applications.The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes,like flocculation and natural additives in product formulation.展开更多
Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,red...Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.展开更多
Objective To develop a matrix assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） approach to identify Staphylococcus aureus （5. aureus） and differentiate methicillin-resistant 5. ...Objective To develop a matrix assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） approach to identify Staphylococcus aureus （5. aureus） and differentiate methicillin-resistant 5. aureus （MRSA） from methicillin-sensitive S. aureus （MSSA）. Methods A total of 100 5. aureus strains isolated from clinical specimens and farm workers were collected and analyzed by MALDI-TOF-MS. And data obtained were interpreted with biotyper software. Results Ninety-two strains were identified by MALDI-TOF-MS as 5. aureus at a level of secure genus and probable species, and 4 strains were identified at probable genus after their cultivation, spectral collection and data preprocessing. One strain was identified as 5. aureus with lower score. It was revealed that identification of 5. aureus by MALDI-TOF-MS was highly correlated with typing by biochemical and serological methods with an accuracy as high as 97%. The biotyper cluster analysis showed that 100 isolates were divided into 2 types at the distance level of 400. Higher peak intensity in the mass of both 3784 Da and 5700 Da was observed in MRSA, whereas that was absent from MSSA. Conclusion MALDI-TOF-MS is considered as a simple, high-throughput and accuracy for the identification of S from MSSA. rapid and highly reproducible technique with aureus and it can reliably differentiate MRSA展开更多
Objective： A direct-current, cold atmospheric-pressure air plasma microjet （PMJ） was performed to inactivate Staphylococcus aureus （S. aureus） and Enterococcusfaecalis （E. faecalis） in air. The process of steri...Objective： A direct-current, cold atmospheric-pressure air plasma microjet （PMJ） was performed to inactivate Staphylococcus aureus （S. aureus） and Enterococcusfaecalis （E. faecalis） in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods： In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum （OES） were used to understand the possible inactivation mechanisms of PMJ. Re- suits＂ The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion： The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances.展开更多
Objective:To isolate and characterize Staphylococcus aureus(S.aureus)β-hemolysinneutralizing dAbs from phage display library of Indian desert camel.Methods:Phage display library of 5×10 dAb clones of LPS-immuniz...Objective:To isolate and characterize Staphylococcus aureus(S.aureus)β-hemolysinneutralizing dAbs from phage display library of Indian desert camel.Methods:Phage display library of 5×10 dAb clones of LPS-immunized Indian desert camel constructed in our laboratory was used for selection of S.aureus exotoxin-specific clones by panning technique.Enrichment of Ag-specific clones in successive rounds of panning was assessed by phage-ELISA and phage titration.Different dAb clones binding to S.aureus exotoxin Ags were expressed with C-terminal 6×His tag in E.coli and purified by Ni-chelate chromatography.The expression was verified by SDS-PAGE and western blotting.The purified clones were tested for inhibition of ’hot-cold’ hemolytic activity in vitro.Resistance to thermal inactivation of the dAb clones was studied by observing the effect of heat treatment from 50℃to 99℃for 30 min on the ’hot-cold’ hemolytic activity in vitro.Results:Several dAb clones binding to S.aureus exotoxins were isolated and enriched by three rounds of panning.The soluble dAb clones were approximately～16 kDa in size and reacted with 6×His tag specific murine monoclonal antibody in western blot.One of the Ni-chelate affinity purified dAb.6×His clones,inhibited S.aureusβ-hemolysin activity in vitro and resisted thermal inactivation upto 991.Conclusions:An S.aureusβ-hemolysinneutralizing dAb clone of possible therapeutic potential has been isolated.展开更多
基金funded by FONDECYT Regular,Grant Number 1231917 by ANID,Govt.of Chile.
文摘A type of high molecular weight bioactive polymers called exopolysaccharides(EPS)are produced by thermophiles,the extremophilic microbes that thrive in acidic environmental conditions of hot springs with excessively warm temperatures.Over time,EPS became important as natural biotechnological additives because of their noncytotoxic,emulsifying,antioxidant,or immunostimulant activities.In this article,we unravelled a new EPS produced by Staphy-lococcus sp.BSP3 from an acidic(pH 6.03)San Pedro hot spring(38.1℃)located in the central Andean mountains in Chile.Several physicochemical techniques were performed to characterize the EPS structure including Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS),Atomic Force Microscopy(AFM),High-Performance Liquid Chromatography(HPLC),Gel permeation chromatography(GPC),Fourier Transform Infrared Spectroscopy(FTIR),1D Nuclear Magnetic Resonance(NMR),and Thermogravimetric analysis(TGA).It was confirmed that the amorphous surface of the BSP3 EPS,composed of rough pillar-like nanostructures,is evenly distributed.The main EPS monosaccharide constituents were mannose(72%),glucose(24%)and galactose(4%).Also,it is a medium molecular weight(43.7 kDa)heteropolysaccharide.NMR spectroscopy demonstrated the presence of a[→6)-α-d-Manp-(1→6)-α-d-Manp-(1→]backbone 2-O substituted with 1-α-d-Manp.A high thermal stability of EPS(287°C)was confirmed by TGA analysis.Emulsification,antioxidant,flocculation,water-holding(WHC),and oil-holding(OHC)capacities are also studied for biotechnological industry applications.The results demonstrated that BSP3 EPS could be used as a biodegradable material for different purposes,like flocculation and natural additives in product formulation.
文摘Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.
文摘Objective To develop a matrix assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） approach to identify Staphylococcus aureus （5. aureus） and differentiate methicillin-resistant 5. aureus （MRSA） from methicillin-sensitive S. aureus （MSSA）. Methods A total of 100 5. aureus strains isolated from clinical specimens and farm workers were collected and analyzed by MALDI-TOF-MS. And data obtained were interpreted with biotyper software. Results Ninety-two strains were identified by MALDI-TOF-MS as 5. aureus at a level of secure genus and probable species, and 4 strains were identified at probable genus after their cultivation, spectral collection and data preprocessing. One strain was identified as 5. aureus with lower score. It was revealed that identification of 5. aureus by MALDI-TOF-MS was highly correlated with typing by biochemical and serological methods with an accuracy as high as 97%. The biotyper cluster analysis showed that 100 isolates were divided into 2 types at the distance level of 400. Higher peak intensity in the mass of both 3784 Da and 5700 Da was observed in MRSA, whereas that was absent from MSSA. Conclusion MALDI-TOF-MS is considered as a simple, high-throughput and accuracy for the identification of S from MSSA. rapid and highly reproducible technique with aureus and it can reliably differentiate MRSA
基金supported by Bioelectrics Inc.(USA),Peking University Biomed-X Foundation and China International Science and Technology Cooperation(No.2008KR1330)
文摘Objective： A direct-current, cold atmospheric-pressure air plasma microjet （PMJ） was performed to inactivate Staphylococcus aureus （S. aureus） and Enterococcusfaecalis （E. faecalis） in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods： In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum （OES） were used to understand the possible inactivation mechanisms of PMJ. Re- suits＂ The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion： The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances.
基金Financial support by Department of Biotechnology,Government of India,New Delhi for construction of phage display library and its applications, and Indian Council of Agricultural Research,New Delhi for infrastructure assistance
文摘Objective:To isolate and characterize Staphylococcus aureus(S.aureus)β-hemolysinneutralizing dAbs from phage display library of Indian desert camel.Methods:Phage display library of 5×10 dAb clones of LPS-immunized Indian desert camel constructed in our laboratory was used for selection of S.aureus exotoxin-specific clones by panning technique.Enrichment of Ag-specific clones in successive rounds of panning was assessed by phage-ELISA and phage titration.Different dAb clones binding to S.aureus exotoxin Ags were expressed with C-terminal 6×His tag in E.coli and purified by Ni-chelate chromatography.The expression was verified by SDS-PAGE and western blotting.The purified clones were tested for inhibition of ’hot-cold’ hemolytic activity in vitro.Resistance to thermal inactivation of the dAb clones was studied by observing the effect of heat treatment from 50℃to 99℃for 30 min on the ’hot-cold’ hemolytic activity in vitro.Results:Several dAb clones binding to S.aureus exotoxins were isolated and enriched by three rounds of panning.The soluble dAb clones were approximately～16 kDa in size and reacted with 6×His tag specific murine monoclonal antibody in western blot.One of the Ni-chelate affinity purified dAb.6×His clones,inhibited S.aureusβ-hemolysin activity in vitro and resisted thermal inactivation upto 991.Conclusions:An S.aureusβ-hemolysinneutralizing dAb clone of possible therapeutic potential has been isolated.
