Recent progress in nanotechnology has provided high-performance nanomaterials for enzyme immobilization.Nanobiocatalysts combining enzymes and nanocarriers are drawing increasing attention because of their high cataly...Recent progress in nanotechnology has provided high-performance nanomaterials for enzyme immobilization.Nanobiocatalysts combining enzymes and nanocarriers are drawing increasing attention because of their high catalytic performance,enhanced stabilities,improved enzyme-substrate affinities,and reusabilities.Many studies have been performed to investigate the efficient use of cellulose nanocrystals,polydopamine-based nanomaterials,and synthetic polymer nanogels for enzyme immobilization.Various nanobiocatalysts are highlighted in this review,with the emphasis on the design,preparation,properties,and potential applications of nanoscale enzyme carriers and nanobiocatalysts.展开更多
A controlled release N fertilizer was developed by the carrier method using natural polysaccharides (PS)and urea. The results showed that mixing of PS and urea led to significant control of urea release. When a cross-...A controlled release N fertilizer was developed by the carrier method using natural polysaccharides (PS)and urea. The results showed that mixing of PS and urea led to significant control of urea release. When a cross-linker (boric acid or glutaraldehyde) was added, a better control effect was observed. During a 30 min leaching time the nitrogen release rate from the controlled release fertilizer was nearly constant, which was significantly different from normal urea. One of the controlled release mechanisms was related to space resistance from a large molecular structure. Infrared (IR) analysis indicated that interaction of PS with urea was through a hydrogen bond or a covalent bond. These bonds created an α-helix or high molecular network fertilizer carrier system, which was another reason for a controlled nutrient release. Pot experiment showed that nitrogen use efficiency could increase significantly with a carrier fertilizer.展开更多
Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared...Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared from the phage infecting Klebsiella K13. Treatment at 60℃ for 30 min could inactivate most of the K13 phage, with the titration decreasing from 6.4×10^8 PFU/mL to 1.6×10^6 PFU/mL. However, no obvious loss of phage enzyme activity was found after this treatment. The optimum hydrolytic temperature of phage enzyme was 60℃, with an activity 57 % higher than that at 30℃. The addition of phage enzyme could result in a rapid decrease of viscosity of exopolysaccharide （EPS） solution within minutes, indicating that K13 phage polysaccharide depolymerase acts as a kind of endo-glycanohydrolase. HPLC and reducing sugar analysis showed that the hydrolysis of EPS approached approximately the maxi-mum at 4h when the final concentration of phage was 6.0 x los PFU/mL. The results showed that K/eb-siella K13 phage depolymerase enzyme could be used as a good tool for the preparation of EPS oligosac- charide.展开更多
Antibiotics used for agricultural purpose has contributed to the increased prevalence of antibiotic-resistant bacteria. The goal of this study was to investigate the prevalence and antimicrobial resistance of ESBL-pro...Antibiotics used for agricultural purpose has contributed to the increased prevalence of antibiotic-resistant bacteria. The goal of this study was to investigate the prevalence and antimicrobial resistance of ESBL-producing E. coli in small-scaled poultry farms and retail chicken. The cultured E. coli isolates were subjected to phenotypic tests, susceptibility tests, and the polymerase chain reaction for detection of blacTX-M, blasHv, and blaTEM genes. From 120 samples each of chicken feces, retail chicken, soil and chicken feed, ESBL-producing E. coli isolates were detected in 75.9%, 63.6%, 39.2%, and 13.3% of the samples, respectively. Minimum inhibitory concentration （MICs） values indicated that ESBL-producing E. coli were resistance to ampicillin （MIC 〉 32 μg/mL）, gentamicin （M1C ≥ 16 μg/mL）, cefotaxime （MIC 〉 4 μg/mL） and cefhiaxone （MIC 〉 4 gg/mL）, respectively. The total resistance for imipenem was also observed at 1.0% （MIC ≥ 4 gg/mL） and none of the isolates were resistant to ceftazidime （MIC 〉 16 μg/mL）. ESBL-producing E. coli from chicken feces and retail chicken carried blasHv gene at a rate of 6.8% and 5.7%, respectively and blaCTX-M gene was also revealed at 2.9% in retail chicken. Moreover, ESBL-producing E. coli isolated from soil harbored blasnv and blaCTX-M genes at 5%. None of the feed samples yielded ESBLs genes. Twenty three resistance patterns were observed for multi-resistant ESBL-producing E. coli. This study highlights the prevalence of multi-antimicrobial resistant ESBL-producing E. coli in small-scaledpoultry farms and retail chicken, hence the need to review poultry management practices to minimize the occurrence.展开更多
Sea cucumbers are traditional marine food and Chinese medicine in Asia. The rapid expansion of sea cucumber market has resulted in various problems, such as commercial fraud and mislabeling. Conventionally, sea cucumb...Sea cucumbers are traditional marine food and Chinese medicine in Asia. The rapid expansion of sea cucumber market has resulted in various problems, such as commercial fraud and mislabeling. Conventionally, sea cucumber species could be distinguished by their morphological and anatomical characteristics; however, their identification becomes difficult when they are processed. The aim of this study was to develop a new convenient method of identifying and distinguishing sea cucumber species. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) analysis of mitochondrial cytochrome oxidase I gene(COI) was used to identifing five sea cucumber species(Apostichopus japonicus, Cucumaria frondosa, Thelenota ananas, Parastichopus californicus and Actinopyga lecanora). A 692 bp fragment of COI was searched for BamHI, KpnI, PstI, XbaI and Eco31 I restriction sites with DNAMAN 6.0, which were then used to PCR-RFLP analysis. These five sea cucumber species can be discriminated from mixed sea cucumbers. The developed PCR-RFLP assay will facilitate the identification of sea cucumbers, making their source tracing and quality controlling feasible.展开更多
基金supported by the National Natural Science Foundation of China(21336002,21222606,21376096)the Key Program of Guangdong Natural Science Foundation(S2013020013049)+2 种基金the Fundamental Research Funds for the Chinese Universities(2015PT002,2015ZP009)the Program of State Key Laboratory of Pulp and Paper Engineering(2015C04)the South China University of Technology Doctoral Student Short-Term Overseas Visiting Study Funding Project~~
文摘Recent progress in nanotechnology has provided high-performance nanomaterials for enzyme immobilization.Nanobiocatalysts combining enzymes and nanocarriers are drawing increasing attention because of their high catalytic performance,enhanced stabilities,improved enzyme-substrate affinities,and reusabilities.Many studies have been performed to investigate the efficient use of cellulose nanocrystals,polydopamine-based nanomaterials,and synthetic polymer nanogels for enzyme immobilization.Various nanobiocatalysts are highlighted in this review,with the emphasis on the design,preparation,properties,and potential applications of nanoscale enzyme carriers and nanobiocatalysts.
基金Project supported by the Innovational Project in Environment and Resources Fields from the Chinese Academy of Sciences (No. KZCX2-402) the National Natural Science Foundation of China (No. 39870431).
文摘A controlled release N fertilizer was developed by the carrier method using natural polysaccharides (PS)and urea. The results showed that mixing of PS and urea led to significant control of urea release. When a cross-linker (boric acid or glutaraldehyde) was added, a better control effect was observed. During a 30 min leaching time the nitrogen release rate from the controlled release fertilizer was nearly constant, which was significantly different from normal urea. One of the controlled release mechanisms was related to space resistance from a large molecular structure. Infrared (IR) analysis indicated that interaction of PS with urea was through a hydrogen bond or a covalent bond. These bonds created an α-helix or high molecular network fertilizer carrier system, which was another reason for a controlled nutrient release. Pot experiment showed that nitrogen use efficiency could increase significantly with a carrier fertilizer.
基金the National Natural Science Foundation of China(No40506027 and No30771646)the Doctoral Foundation of Shandong Province(No2005BS02015)
文摘Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared from the phage infecting Klebsiella K13. Treatment at 60℃ for 30 min could inactivate most of the K13 phage, with the titration decreasing from 6.4×10^8 PFU/mL to 1.6×10^6 PFU/mL. However, no obvious loss of phage enzyme activity was found after this treatment. The optimum hydrolytic temperature of phage enzyme was 60℃, with an activity 57 % higher than that at 30℃. The addition of phage enzyme could result in a rapid decrease of viscosity of exopolysaccharide （EPS） solution within minutes, indicating that K13 phage polysaccharide depolymerase acts as a kind of endo-glycanohydrolase. HPLC and reducing sugar analysis showed that the hydrolysis of EPS approached approximately the maxi-mum at 4h when the final concentration of phage was 6.0 x los PFU/mL. The results showed that K/eb-siella K13 phage depolymerase enzyme could be used as a good tool for the preparation of EPS oligosac- charide.
文摘Antibiotics used for agricultural purpose has contributed to the increased prevalence of antibiotic-resistant bacteria. The goal of this study was to investigate the prevalence and antimicrobial resistance of ESBL-producing E. coli in small-scaled poultry farms and retail chicken. The cultured E. coli isolates were subjected to phenotypic tests, susceptibility tests, and the polymerase chain reaction for detection of blacTX-M, blasHv, and blaTEM genes. From 120 samples each of chicken feces, retail chicken, soil and chicken feed, ESBL-producing E. coli isolates were detected in 75.9%, 63.6%, 39.2%, and 13.3% of the samples, respectively. Minimum inhibitory concentration （MICs） values indicated that ESBL-producing E. coli were resistance to ampicillin （MIC 〉 32 μg/mL）, gentamicin （M1C ≥ 16 μg/mL）, cefotaxime （MIC 〉 4 μg/mL） and cefhiaxone （MIC 〉 4 gg/mL）, respectively. The total resistance for imipenem was also observed at 1.0% （MIC ≥ 4 gg/mL） and none of the isolates were resistant to ceftazidime （MIC 〉 16 μg/mL）. ESBL-producing E. coli from chicken feces and retail chicken carried blasHv gene at a rate of 6.8% and 5.7%, respectively and blaCTX-M gene was also revealed at 2.9% in retail chicken. Moreover, ESBL-producing E. coli isolated from soil harbored blasnv and blaCTX-M genes at 5%. None of the feed samples yielded ESBLs genes. Twenty three resistance patterns were observed for multi-resistant ESBL-producing E. coli. This study highlights the prevalence of multi-antimicrobial resistant ESBL-producing E. coli in small-scaledpoultry farms and retail chicken, hence the need to review poultry management practices to minimize the occurrence.
基金supported by National Natural Science Foundation of China (Nos. 31101281 and 31071525)National Marine Public Welfare Scientific Research Project of China (No. 201105029)
文摘Sea cucumbers are traditional marine food and Chinese medicine in Asia. The rapid expansion of sea cucumber market has resulted in various problems, such as commercial fraud and mislabeling. Conventionally, sea cucumber species could be distinguished by their morphological and anatomical characteristics; however, their identification becomes difficult when they are processed. The aim of this study was to develop a new convenient method of identifying and distinguishing sea cucumber species. Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) analysis of mitochondrial cytochrome oxidase I gene(COI) was used to identifing five sea cucumber species(Apostichopus japonicus, Cucumaria frondosa, Thelenota ananas, Parastichopus californicus and Actinopyga lecanora). A 692 bp fragment of COI was searched for BamHI, KpnI, PstI, XbaI and Eco31 I restriction sites with DNAMAN 6.0, which were then used to PCR-RFLP analysis. These five sea cucumber species can be discriminated from mixed sea cucumbers. The developed PCR-RFLP assay will facilitate the identification of sea cucumbers, making their source tracing and quality controlling feasible.
