PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from loc...PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim展开更多
This study has determined the portage of bacteria responsible for foodborne illness in the school canteen staff. 336 samples taken on the nose, mouth and hands were collected. Microbiological analyses were realized an...This study has determined the portage of bacteria responsible for foodborne illness in the school canteen staff. 336 samples taken on the nose, mouth and hands were collected. Microbiological analyses were realized and several pathogenic bacterial strains were isolated from the vendors: Staphylococcus aureus (26/122), sulphite-reducing clostridia (14/122) and Escherichia coli (10/122). The food vendors in the school canteen may be the vectors of germs that cause food poisoning among young students.展开更多
Four types of common seaweeds(Laminaria japonica,Undaria pinnatifida,Porphyra haitanensis,and Gracilaria lemaneiformis) were examined to remove Cr(Ⅵ) ions from aqueous solution.The experimental parameters that affect...Four types of common seaweeds(Laminaria japonica,Undaria pinnatifida,Porphyra haitanensis,and Gracilaria lemaneiformis) were examined to remove Cr(Ⅵ) ions from aqueous solution.The experimental parameters that affected the biosorption process including pH,biomass dosage,contact time and temperature were investigated via batch experiments.The surface characteristics of seaweeds before and after Cr(Ⅵ) adsorption were studied with scanning electron microscopy and Fourier transform infrared spectroscopy.The results show that an initial solution with the pH of 1.0 is most favorable for Cr(Ⅵ) adsorption.Rapid adsorption is observed in the initial stage and adsorption equilibrium state is reached within 1 h.The adsorption efficiency by Porphyra haitanensis is the maximum among four types of seaweed powders,followed by Laminaria japonica and Undaria pinnatifida with biosorption efficiency up to 90%.The removal rate of Gracilaria lemaneiformis is less than 60%.The kinetic data obtained using the seaweeds are found to follow pseudo-second order kinetic model.Experimental sorption data adequately correlate with the Langmuir model.FTIR indicates that amino and carboxyl groups play an important role in the process of Cr(Ⅵ) adsorption and a large percentage of Cr(Ⅵ) ions are reduced by reductive groups on the surface of seaweeds.展开更多
An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was express...An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities.展开更多
The effects of variety and tapping length on several physical, biochemical, nutritional and micro-biological parameters (viscosity, pH, Total Titratable Acidity (TTA), fermenting microorganisms, contaminants) of palm ...The effects of variety and tapping length on several physical, biochemical, nutritional and micro-biological parameters (viscosity, pH, Total Titratable Acidity (TTA), fermenting microorganisms, contaminants) of palm wine extracted from two varieties of palm oil tree (Dura and Tenera) were studied. Each variety presented its own palm wine specific characteristics regarding the chosen parameters. Microbiological and biochemical contents of palm wine were determined during the tapping of Dura and Tenera felled oil palm trees for 4 weeks. Some differences in chemical compositions between fresh palm wine samples of two palm trees varieties were observed. The exudates obtained during the first day of tapping of Dura palm wine were very sugary, less sour and did not contain substantial concentrations of alcohol but the highest loads of microorganisms were observed in Tenera palm wine. Throughout the tapping of palm wine, yeasts and lactic acid bacteria population changed with undoubtedly influence on the palm wine quality.展开更多
Emiliania huxleyi is the most prominent modern coccolithophore,a group of marine unicellular eukaryotes that play a critical role in ocean biogeochemistry.Coccolithoviruses are large double stranded DNA viruses,which ...Emiliania huxleyi is the most prominent modern coccolithophore,a group of marine unicellular eukaryotes that play a critical role in ocean biogeochemistry.Coccolithoviruses are large double stranded DNA viruses,which is responsible for the demise of large oceanic blooms formed by E.huxleyi.E.huxleyi virus(EhVs)acquired a series of enzyme-coding genes predicted to be involved in the sphingolipid biosynthesis by horizontal gene transfer between virus-host.Currently,there is limited experimental validation identifying the functions of these genes in EhV.Genetic transformation of eukaryotic cells is a powerful tool to get an insight into gene functions of the studied organisms.Serine palmitoyltransferase(SPT)catalyzes the first committed step in de novo sphingolipid biosynthetic pathway.Here,a novel vector system for the transformation of E.huxleyi was designed.It contained fragments of promoter and terminator sequences of E.huxleyi endogenic fucoxanthin chlorophyll a/c-binding protein gene“fcp”and harbored EhV-99B1 spt gene.The resultant recombinant transformation vectors pEhux-I-spt and pEhux-II were co-transferred into E.huxleyi BOF92 by electroporation.Transformants were obtained upon glufosinate-ammonium selection,and confirmed by Southern hybridization,genome PCR,qRT-PCR and Western blot screening of spt gene,which indicated that spt gene was integrated into the nuclear genome and was expressed at the mRNA and protein levels.The expression of the viral spt gene led to differences in lipid compositions analyzed using thin-layer chromatography(TLC).The results present the genetic transformation system for E.huxleyi,providing additional genetic resource with potential for exploring basic biological questions such as the virus-host interactions.展开更多
This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using erro...This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, two mutants of H260L and D84A/H260L showed enhanced thermal stability than the wild-type predecessor (WT). Site-directed mutagenesis demonstrated that only amino acid residue at Position 260 plays an important role in the thermostability of P. carrageenovora arylsulfatase. Thermal inactivation analysis showed that the half-life (t1/2) values at 55°C for H260L, H260I, H260Q, H260F and H260R were 40.6, 48.4, 30.9, 29.1 and 34.5 min, respectively, while that of WT was 9.1 min. Structure modeling demonstrated that the additional hydrogen bonds and/or optimization of surface charge-charge interactions could be responsible for the increased thermostability imparted by H260L, H260I, H260Q, H260F and H260R.展开更多
Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable supero...Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable superoxide dismutase (SOD) from this strain was purified to homogeneity by steps of fractional am-monium sulfate precipitation, DEAE-Sepharose chromatography, and Phenyl-Sepharose chromatography. SOD was purified 13.4 fold to homogeneity with a specific activity of 3 354 U/mg and 11.1% recovery. SOD fromGeobacillussp. EPT3 was of the Mn-SOD type, judged by the insensitivity of the enzyme to both KCN and H2O2. SOD was determined to be a homodimer with monomeric molecular mass of 26.0 kDa. It had high thermostability at 50°C and 60°C. At tested conditions,SOD was relatively stable in the presence of some inhibitors and denaturants, such asβ-mercaptoethanol (β-ME), dithiothreitol (DTT), phenylmethylsulfonyl fluoride (PMSF), urea, and guanidine hydrochloride.Geobacillussp. EPT3 SOD showed striking stability across a wide pH range from 5.0 to 11.0. It could withstand denaturants of extremely acidic and alkaline conditions, which makes it useful in the industrial applications.展开更多
Ionic liquids (ILs) with buffering and chelating abilities were designed and synthesized on the basis of ethylenediaminetetraacetic acid (EDTA) for the development of buffered enzymatic IL systems and for enzymatic re...Ionic liquids (ILs) with buffering and chelating abilities were designed and synthesized on the basis of ethylenediaminetetraacetic acid (EDTA) for the development of buffered enzymatic IL systems and for enzymatic reaction in heavy metal containing aqueous system. Transesterification activity of Candida antarctica lipase B dissolved in the hydroxyl-functionalized IL was buffer dependent. High activity and outstanding stability was obtained with the buffered enzymatic IL systems for the transesterification. In heavy metal containing aqueous system, EDTA IL buffers as Hg2+ chelators protected horseradish peroxidase (HRP) against Hg2+-induced denaturation and precipitation. Higher pH favored the protection, while at lower pH the protection diminished. We can conclude that the new ILs possess both buffering and chelating abilities.展开更多
The suitability of the abundant agro-industrial residues wheat straw(WS;control),barley and oats straw(BOS)and rice husk(RH),supplemented with various sources of oils(sunflower,corn oil),nitrogen(peptone,yeast extract...The suitability of the abundant agro-industrial residues wheat straw(WS;control),barley and oats straw(BOS)and rice husk(RH),supplemented with various sources of oils(sunflower,corn oil),nitrogen(peptone,yeast extract)and calcium salts(CaSO_(4)⋅2H_(2)O,CaCl2),as novel substrates in solid-state fermentation of selected Pleurotus ostreatus and P.eryngii mushrooms was investigated.The possible effect of different additives on mycelial growth rate,biomass production and endoglucanase,laccase and lipase biosynthesis were evaluated.Moreover,their impact on essential cultivation aspects(earliness,total mushroom yield,biological efficiency)and carposome quality parameters(weight,morphological characteristics)was assessed.Both fungi showed their highest growth rates on BOS substrates and the most positive implementation was CaSO_(4)⋅2H_(2)O 6%w/w(Kr=9.58 mm/day;P.ostreatus,Kr=9.42 mm/day;P.eryngii),while different additives led to enhancement of biomass production.Pleurotus species demonstrated minimal levels of endoglucanase activity,with values ranging from 0.01 to 0.42 U/g of dry weight,regardless of the substrate and the stage of colonization.On the contrary,the maximum values of laccase activity were observed at 50%of colonization on BOS and RH,while supplementation with nitrogen and calcium sources positively affected its biosynthesis.P.ostreatus and P.eryngii cultivated on BOS supplemented with peptone at 2 and 5%w/w,synthesized significant laccase amounts,i.e.,12,165.78 and 8,624.55 U/g d.w.,respectively.Satisfactory amounts of lipase were produced,especially in substrates supplemented with sunflower 2%w/w,in quantities up to 1.42 U/g d.w.,whereas the highest lipase activity was achieved by P.eryngii on WS supplemented with corn oil at 2%w/w,with a value of 4.25 U/g d.w.being recorded.Regarding fermentation of Pleurotus species in polypropylene bags,WS and BOS supported faster colonization and shorter earliness period than RH substrates,whereas supplementation did not seem to affect these culture parameters.Furthermore,oils supplementation had a positive effect on BE of both species,with values up to 100%for P.ostreatus and 80%for P.eryngii on WS and BOS,whereas on RH the lowest BE values were detected.Morphological characteristics were not significantly affected by the additives.Results indicate the positive impact that certain additives have on mushroom productivity and production of enzymes with great financial and environmental importance.展开更多
We report a colorimetric method for glucose detection based on Au nanoparticle-decorated WSe_(2)(Au@WSe_(2))hybrid nanostructures.These hybrid structures are easily synthesized by simply stirring HAuCl_(4) precursor w...We report a colorimetric method for glucose detection based on Au nanoparticle-decorated WSe_(2)(Au@WSe_(2))hybrid nanostructures.These hybrid structures are easily synthesized by simply stirring HAuCl_(4) precursor with WSe_(2) nanosheets in aqueous solution.Owing to strong synergistic catalytic effects of Au nanoparticles and WSe_(2) nanosheets,the Au@WSe_(2) hybrid nanostructures exhibit enhanced peroxidase-like activity(about 2-fold higher compared to WSe_(2) nanosheets alone)for 3,3',5,5'-tetramethylbenzidine oxidation by H_(2)O_(2).Based on the highly catalytical property,the colorimetric method for glucose detection is established by coupling glucose oxidase(GOx).The detection limit of glucose is 3.66 pM.Moreover,the proposed colorimetric method is applicable to glucose detection in serum samples and is promising for applications in biomedical fields.展开更多
A visual colorimetric detection strategy is reported for total antioxidant capacity(TAC)assay by using 3,3',5,5'-tetramethylbenzidine(TMB)oxidation as chromogenic substrate based on gold nanoparticle-decorated...A visual colorimetric detection strategy is reported for total antioxidant capacity(TAC)assay by using 3,3',5,5'-tetramethylbenzidine(TMB)oxidation as chromogenic substrate based on gold nanoparticle-decorated MoSe_(2) nanosheets(Au@MoSe_(2)).Au@MoSe_(2) nanostructures exhibit high peroxidase-like activity and can catalyze H_(2)O_(2)to oxidize TMB.Based on inhibition effect of ascorbic acid(AA)on TMB oxidation,a facile and sensitive colorimetric method was developed for AA detection.Under optimal conditions,the proposed method showed a sensitivity for AA in a concentration range from 2 to 120μM and limit of detection was 0.41μM.Furthermore,the method was employed for TAC assay in actual samples,including commercial beverages and vitamin C tablets.This work represents a model in nanostructure design and will lead to further development of TAC assay in evaluation of antioxidant food quality.展开更多
基金supported by a Grant-in-Aid for Scientific Research(No.25460532 and 26.04912)to Tadashi S.from the Ministry of Education,Culture,Sports,Science,and Technology of Japan
文摘PCR and DNA sequencing were used to screen and characterize integrons and resistance genes in Gram-negative bacteria isolated from seafood products in Japan.A total of 215 Gram-negative bacteria were isolated from local and imported seafood samples collected from retail markets in Hiroshima Prefecture.Class 1 integrons containing gene cassettes encoding resistance to trimethoprim
文摘This study has determined the portage of bacteria responsible for foodborne illness in the school canteen staff. 336 samples taken on the nose, mouth and hands were collected. Microbiological analyses were realized and several pathogenic bacterial strains were isolated from the vendors: Staphylococcus aureus (26/122), sulphite-reducing clostridia (14/122) and Escherichia coli (10/122). The food vendors in the school canteen may be the vectors of germs that cause food poisoning among young students.
基金Project(KLUEH201302) supported by Funded by the Key Laboratory of Urban Environment and Health,Institute of Urban Environment,Chinese Academy of SciencesProject(51004053) supported by the National Natural Science Foundation of China+2 种基金Project(3502Z20116008) supported by the Science and Technology Research Project of Xiamen City,ChinaProject(JA11146) supported by the Program for Fostering Distinguished Young Scholars in University of Fujian Province,ChinaProject(2011B003) supported by the Foundation for Young Professors of Jimei University,China
文摘Four types of common seaweeds(Laminaria japonica,Undaria pinnatifida,Porphyra haitanensis,and Gracilaria lemaneiformis) were examined to remove Cr(Ⅵ) ions from aqueous solution.The experimental parameters that affected the biosorption process including pH,biomass dosage,contact time and temperature were investigated via batch experiments.The surface characteristics of seaweeds before and after Cr(Ⅵ) adsorption were studied with scanning electron microscopy and Fourier transform infrared spectroscopy.The results show that an initial solution with the pH of 1.0 is most favorable for Cr(Ⅵ) adsorption.Rapid adsorption is observed in the initial stage and adsorption equilibrium state is reached within 1 h.The adsorption efficiency by Porphyra haitanensis is the maximum among four types of seaweed powders,followed by Laminaria japonica and Undaria pinnatifida with biosorption efficiency up to 90%.The removal rate of Gracilaria lemaneiformis is less than 60%.The kinetic data obtained using the seaweeds are found to follow pseudo-second order kinetic model.Experimental sorption data adequately correlate with the Langmuir model.FTIR indicates that amino and carboxyl groups play an important role in the process of Cr(Ⅵ) adsorption and a large percentage of Cr(Ⅵ) ions are reduced by reductive groups on the surface of seaweeds.
基金The Natural Science Foundation of Fujian Province of China under contract No.2016J01162the Program for New Century Excellent Talents in Fujian Province University,China under contract No.B15139
文摘An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities.
文摘The effects of variety and tapping length on several physical, biochemical, nutritional and micro-biological parameters (viscosity, pH, Total Titratable Acidity (TTA), fermenting microorganisms, contaminants) of palm wine extracted from two varieties of palm oil tree (Dura and Tenera) were studied. Each variety presented its own palm wine specific characteristics regarding the chosen parameters. Microbiological and biochemical contents of palm wine were determined during the tapping of Dura and Tenera felled oil palm trees for 4 weeks. Some differences in chemical compositions between fresh palm wine samples of two palm trees varieties were observed. The exudates obtained during the first day of tapping of Dura palm wine were very sugary, less sour and did not contain substantial concentrations of alcohol but the highest loads of microorganisms were observed in Tenera palm wine. Throughout the tapping of palm wine, yeasts and lactic acid bacteria population changed with undoubtedly influence on the palm wine quality.
基金Supported by the National Natural Science Foundation of China(Nos.41576166,21707042,31771972)the Fujian Province Natural Science Foundation of China(Nos.2019J01696,2017J01447,2017J01636)。
文摘Emiliania huxleyi is the most prominent modern coccolithophore,a group of marine unicellular eukaryotes that play a critical role in ocean biogeochemistry.Coccolithoviruses are large double stranded DNA viruses,which is responsible for the demise of large oceanic blooms formed by E.huxleyi.E.huxleyi virus(EhVs)acquired a series of enzyme-coding genes predicted to be involved in the sphingolipid biosynthesis by horizontal gene transfer between virus-host.Currently,there is limited experimental validation identifying the functions of these genes in EhV.Genetic transformation of eukaryotic cells is a powerful tool to get an insight into gene functions of the studied organisms.Serine palmitoyltransferase(SPT)catalyzes the first committed step in de novo sphingolipid biosynthetic pathway.Here,a novel vector system for the transformation of E.huxleyi was designed.It contained fragments of promoter and terminator sequences of E.huxleyi endogenic fucoxanthin chlorophyll a/c-binding protein gene“fcp”and harbored EhV-99B1 spt gene.The resultant recombinant transformation vectors pEhux-I-spt and pEhux-II were co-transferred into E.huxleyi BOF92 by electroporation.Transformants were obtained upon glufosinate-ammonium selection,and confirmed by Southern hybridization,genome PCR,qRT-PCR and Western blot screening of spt gene,which indicated that spt gene was integrated into the nuclear genome and was expressed at the mRNA and protein levels.The expression of the viral spt gene led to differences in lipid compositions analyzed using thin-layer chromatography(TLC).The results present the genetic transformation system for E.huxleyi,providing additional genetic resource with potential for exploring basic biological questions such as the virus-host interactions.
基金The National Natural Science Foundation of China under contract No.31401632the Program for New Century Excellent Talents in Fujian Province University,China under contract No.B15139
文摘This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, two mutants of H260L and D84A/H260L showed enhanced thermal stability than the wild-type predecessor (WT). Site-directed mutagenesis demonstrated that only amino acid residue at Position 260 plays an important role in the thermostability of P. carrageenovora arylsulfatase. Thermal inactivation analysis showed that the half-life (t1/2) values at 55°C for H260L, H260I, H260Q, H260F and H260R were 40.6, 48.4, 30.9, 29.1 and 34.5 min, respectively, while that of WT was 9.1 min. Structure modeling demonstrated that the additional hydrogen bonds and/or optimization of surface charge-charge interactions could be responsible for the increased thermostability imparted by H260L, H260I, H260Q, H260F and H260R.
基金The National Natural Science Foundation of China under contract No.31371751the Science and Technology Program of Xiamen,China under contract No.201303120001the Foundation for Innovative Research Team of Jimei University,China under contract No.2010A006
文摘Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermo-phileGeobacillussp.EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermo-stable superoxide dismutase (SOD) from this strain was purified to homogeneity by steps of fractional am-monium sulfate precipitation, DEAE-Sepharose chromatography, and Phenyl-Sepharose chromatography. SOD was purified 13.4 fold to homogeneity with a specific activity of 3 354 U/mg and 11.1% recovery. SOD fromGeobacillussp. EPT3 was of the Mn-SOD type, judged by the insensitivity of the enzyme to both KCN and H2O2. SOD was determined to be a homodimer with monomeric molecular mass of 26.0 kDa. It had high thermostability at 50°C and 60°C. At tested conditions,SOD was relatively stable in the presence of some inhibitors and denaturants, such asβ-mercaptoethanol (β-ME), dithiothreitol (DTT), phenylmethylsulfonyl fluoride (PMSF), urea, and guanidine hydrochloride.Geobacillussp. EPT3 SOD showed striking stability across a wide pH range from 5.0 to 11.0. It could withstand denaturants of extremely acidic and alkaline conditions, which makes it useful in the industrial applications.
文摘Ionic liquids (ILs) with buffering and chelating abilities were designed and synthesized on the basis of ethylenediaminetetraacetic acid (EDTA) for the development of buffered enzymatic IL systems and for enzymatic reaction in heavy metal containing aqueous system. Transesterification activity of Candida antarctica lipase B dissolved in the hydroxyl-functionalized IL was buffer dependent. High activity and outstanding stability was obtained with the buffered enzymatic IL systems for the transesterification. In heavy metal containing aqueous system, EDTA IL buffers as Hg2+ chelators protected horseradish peroxidase (HRP) against Hg2+-induced denaturation and precipitation. Higher pH favored the protection, while at lower pH the protection diminished. We can conclude that the new ILs possess both buffering and chelating abilities.
基金the European Regional Development Fund of the European Union and Greek national funds(European Social Fund-ESF)through the Operational Program Competitiveness,Entrepreneurship and Innovation,under the call RESEARCH-CREATE-INNOVATE(project code:Τ1EDK-05027),scientifically coordinated by the Hellenic Agricultural Organization-Dimitra(Institute of Technology of Agricultural Products/Laboratory of Edible Fungi).
文摘The suitability of the abundant agro-industrial residues wheat straw(WS;control),barley and oats straw(BOS)and rice husk(RH),supplemented with various sources of oils(sunflower,corn oil),nitrogen(peptone,yeast extract)and calcium salts(CaSO_(4)⋅2H_(2)O,CaCl2),as novel substrates in solid-state fermentation of selected Pleurotus ostreatus and P.eryngii mushrooms was investigated.The possible effect of different additives on mycelial growth rate,biomass production and endoglucanase,laccase and lipase biosynthesis were evaluated.Moreover,their impact on essential cultivation aspects(earliness,total mushroom yield,biological efficiency)and carposome quality parameters(weight,morphological characteristics)was assessed.Both fungi showed their highest growth rates on BOS substrates and the most positive implementation was CaSO_(4)⋅2H_(2)O 6%w/w(Kr=9.58 mm/day;P.ostreatus,Kr=9.42 mm/day;P.eryngii),while different additives led to enhancement of biomass production.Pleurotus species demonstrated minimal levels of endoglucanase activity,with values ranging from 0.01 to 0.42 U/g of dry weight,regardless of the substrate and the stage of colonization.On the contrary,the maximum values of laccase activity were observed at 50%of colonization on BOS and RH,while supplementation with nitrogen and calcium sources positively affected its biosynthesis.P.ostreatus and P.eryngii cultivated on BOS supplemented with peptone at 2 and 5%w/w,synthesized significant laccase amounts,i.e.,12,165.78 and 8,624.55 U/g d.w.,respectively.Satisfactory amounts of lipase were produced,especially in substrates supplemented with sunflower 2%w/w,in quantities up to 1.42 U/g d.w.,whereas the highest lipase activity was achieved by P.eryngii on WS supplemented with corn oil at 2%w/w,with a value of 4.25 U/g d.w.being recorded.Regarding fermentation of Pleurotus species in polypropylene bags,WS and BOS supported faster colonization and shorter earliness period than RH substrates,whereas supplementation did not seem to affect these culture parameters.Furthermore,oils supplementation had a positive effect on BE of both species,with values up to 100%for P.ostreatus and 80%for P.eryngii on WS and BOS,whereas on RH the lowest BE values were detected.Morphological characteristics were not significantly affected by the additives.Results indicate the positive impact that certain additives have on mushroom productivity and production of enzymes with great financial and environmental importance.
基金supported by the National Natural Science Foundation of China(Nos.22004032 and 21804050)the Fundamental Research Funds for the Central Universities(No.531118010569)the Natural Science Foundation of Fujian Province of China(No.2019J05098).
文摘We report a colorimetric method for glucose detection based on Au nanoparticle-decorated WSe_(2)(Au@WSe_(2))hybrid nanostructures.These hybrid structures are easily synthesized by simply stirring HAuCl_(4) precursor with WSe_(2) nanosheets in aqueous solution.Owing to strong synergistic catalytic effects of Au nanoparticles and WSe_(2) nanosheets,the Au@WSe_(2) hybrid nanostructures exhibit enhanced peroxidase-like activity(about 2-fold higher compared to WSe_(2) nanosheets alone)for 3,3',5,5'-tetramethylbenzidine oxidation by H_(2)O_(2).Based on the highly catalytical property,the colorimetric method for glucose detection is established by coupling glucose oxidase(GOx).The detection limit of glucose is 3.66 pM.Moreover,the proposed colorimetric method is applicable to glucose detection in serum samples and is promising for applications in biomedical fields.
基金the National Natural Science Foundation of China(Nos.21804050 and 22004032)Hunan Provincial Natural Science Foundation of China(No.2021JJ20020).
文摘A visual colorimetric detection strategy is reported for total antioxidant capacity(TAC)assay by using 3,3',5,5'-tetramethylbenzidine(TMB)oxidation as chromogenic substrate based on gold nanoparticle-decorated MoSe_(2) nanosheets(Au@MoSe_(2)).Au@MoSe_(2) nanostructures exhibit high peroxidase-like activity and can catalyze H_(2)O_(2)to oxidize TMB.Based on inhibition effect of ascorbic acid(AA)on TMB oxidation,a facile and sensitive colorimetric method was developed for AA detection.Under optimal conditions,the proposed method showed a sensitivity for AA in a concentration range from 2 to 120μM and limit of detection was 0.41μM.Furthermore,the method was employed for TAC assay in actual samples,including commercial beverages and vitamin C tablets.This work represents a model in nanostructure design and will lead to further development of TAC assay in evaluation of antioxidant food quality.
基金supported by the National Natural Science Foundation of China(Nos.31371826 and 31571808)the China Postdoctoral Science Foundation Funded Project(No.2016M592002)