As a unique ecological system with low temperature and low nutrient levels, glaciers are considered a "living fossil" for the research of evolution. In this work, a lytic cold-active bacteriophage designated...As a unique ecological system with low temperature and low nutrient levels, glaciers are considered a "living fossil" for the research of evolution. In this work, a lytic cold-active bacteriophage designated VMY22 against Bacillus cereus MYB41-22 was isolated from Mingyong Glacier in China, and its characteristics were studied. Electron microscopy revealed that VMY22 has an icosahedral head(59.2 nm in length, 31.9 nm in width) and a tail(43.2 nm in length). Bacteriophage VMY22 was classified as a Podoviridae with an approximate genome size of 18 to 20 kb. A one-step growth curve revealed that the latent and the burst periods were 70 and 70 min, respectively, with an average burst size of 78 bacteriophage particles per infected cell. The pH and thermal stability of bacteriophage VMY22 were also investigated. The maximum stability of the bacteriophage was observed to be at pH 8.0 and it was comparatively stable at p H 5.0–9.0. As VMY22 is a cold-active bacteriophage with low production temperature, its characterization and the relationship between MYB41-22 and Bacillus cereus bacteriophage deserve further study.展开更多
Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the ...Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.展开更多
制备稳定的表面活性剂囊泡是进一步发展囊泡技术的关键.本工作制备了两种酰胺基分别在疏水链和连接基团的阳离子Gemini表面活性剂(C_(12)A-C_(2)-AC_(2)和C_(2)-AC_(12)A-C_(2))与阴离子谷氨酸表面活性剂(C_(2)Glu)混合体系囊泡,系统研...制备稳定的表面活性剂囊泡是进一步发展囊泡技术的关键.本工作制备了两种酰胺基分别在疏水链和连接基团的阳离子Gemini表面活性剂(C_(12)A-C_(2)-AC_(2)和C_(2)-AC_(12)A-C_(2))与阴离子谷氨酸表面活性剂(C_(2)Glu)混合体系囊泡,系统研究了酰胺基位置和羧基间氢键对囊泡形成与热稳定性的影响.结果表明,位于疏水链上的酰胺基通过氢键可有效促进表面活性剂混合体系囊泡形成和热稳定性,C_(12)A-C_(2)-AC_(2)&C_(2)Glu囊泡在升高温度过程中保持蓝色乳光不变,但对于酰胺基位于连接基团上的C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡溶液,其蓝色乳光随温度升高逐渐转变为乳白色或出现沉淀,降低温度溶液再次恢复蓝色乳光.含有两个羧基的C_(2)Glu的带电量及分子间氢键随p H此消彼长,p H 5.0时C_(2)Glu羧基形成的分子间氢键促进了C_(12)A-C_(2)-AC_(2)&C_(2)Glu和C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡的形成和热稳定性,在升温过程中混合体系囊泡溶液均没有产生沉淀,而p H 10.0时这两个体系形成的囊泡溶液随温度升高分别出现蓝色乳光加深和沉淀现象.这类具有温度响应性、高效形成囊泡的体系具有重要的实际应用价值.展开更多
Dear Editor,Viruses are the most abundant,diverse,and ubiquitous entities(approximately 1031)on Earth.They play major roles in horizontal gene transfer,the regulation of bacterial community structures,as well as nutri...Dear Editor,Viruses are the most abundant,diverse,and ubiquitous entities(approximately 1031)on Earth.They play major roles in horizontal gene transfer,the regulation of bacterial community structures,as well as nutrient and energy cycles of marine ecosystems(Danovaro et al.,2008).In particular,lytic bacteriophages(phages)can infect and kill bacteria without harming human or展开更多
基金supported by the National Natural Science Foundation of China (31160121)the Yunnan Provincial Education Fund project (2013Z138)funded by the Open Research Fund Program of the State Key Laboratory of Virology of China (2013002)
文摘As a unique ecological system with low temperature and low nutrient levels, glaciers are considered a "living fossil" for the research of evolution. In this work, a lytic cold-active bacteriophage designated VMY22 against Bacillus cereus MYB41-22 was isolated from Mingyong Glacier in China, and its characteristics were studied. Electron microscopy revealed that VMY22 has an icosahedral head(59.2 nm in length, 31.9 nm in width) and a tail(43.2 nm in length). Bacteriophage VMY22 was classified as a Podoviridae with an approximate genome size of 18 to 20 kb. A one-step growth curve revealed that the latent and the burst periods were 70 and 70 min, respectively, with an average burst size of 78 bacteriophage particles per infected cell. The pH and thermal stability of bacteriophage VMY22 were also investigated. The maximum stability of the bacteriophage was observed to be at pH 8.0 and it was comparatively stable at p H 5.0–9.0. As VMY22 is a cold-active bacteriophage with low production temperature, its characterization and the relationship between MYB41-22 and Bacillus cereus bacteriophage deserve further study.
基金supported by the National Natural Science Foundation of China (grant number 22078346)Beijing Nova Program of Science and Technology (Z201100006820141)+4 种基金Innovation Academy for Green Manufacture, CAS (IAGM2020C19)Natural Science Foundation of Beijing (2204097)Henan Key Research and Development Project (202102210046)Hebei Provincial Natural Science Foundation (B2020103010)the CAS Pioneer Hundred Program。
文摘Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.
文摘制备稳定的表面活性剂囊泡是进一步发展囊泡技术的关键.本工作制备了两种酰胺基分别在疏水链和连接基团的阳离子Gemini表面活性剂(C_(12)A-C_(2)-AC_(2)和C_(2)-AC_(12)A-C_(2))与阴离子谷氨酸表面活性剂(C_(2)Glu)混合体系囊泡,系统研究了酰胺基位置和羧基间氢键对囊泡形成与热稳定性的影响.结果表明,位于疏水链上的酰胺基通过氢键可有效促进表面活性剂混合体系囊泡形成和热稳定性,C_(12)A-C_(2)-AC_(2)&C_(2)Glu囊泡在升高温度过程中保持蓝色乳光不变,但对于酰胺基位于连接基团上的C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡溶液,其蓝色乳光随温度升高逐渐转变为乳白色或出现沉淀,降低温度溶液再次恢复蓝色乳光.含有两个羧基的C_(2)Glu的带电量及分子间氢键随p H此消彼长,p H 5.0时C_(2)Glu羧基形成的分子间氢键促进了C_(12)A-C_(2)-AC_(2)&C_(2)Glu和C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡的形成和热稳定性,在升温过程中混合体系囊泡溶液均没有产生沉淀,而p H 10.0时这两个体系形成的囊泡溶液随温度升高分别出现蓝色乳光加深和沉淀现象.这类具有温度响应性、高效形成囊泡的体系具有重要的实际应用价值.
基金supported by the National Natural Science Foundation of China(31160121,31360129)the China Scholarship Council
文摘Dear Editor,Viruses are the most abundant,diverse,and ubiquitous entities(approximately 1031)on Earth.They play major roles in horizontal gene transfer,the regulation of bacterial community structures,as well as nutrient and energy cycles of marine ecosystems(Danovaro et al.,2008).In particular,lytic bacteriophages(phages)can infect and kill bacteria without harming human or
