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
Strain of Pseudomonas Lip35 producing lipase was isolated in a refrigerator. Lipase production and characterization of this strain were investigated under different conditions. The Pseudomonas was cultivated in shakin...Strain of Pseudomonas Lip35 producing lipase was isolated in a refrigerator. Lipase production and characterization of this strain were investigated under different conditions. The Pseudomonas was cultivated in shaking flasks in a fermentation medium in various nutritional and physical environments. Lipase production has been influenced by the presence of yeast-extract, soybean powder, NaCI, and Tween-80. Maximum lipase productivity was obtained when the physical environment of the fermentation medium was optimal for 67 h. The production of lipase reached 58.9 U·mL^-1. The lipase of Pseudomonas Lip35 can be considered to be inducible, but the inducer had little influence on the production of lipase. The lipase was characterized and showed high lipolytic activity from pH 7.5-8.0. The optimum temperature was observed at 20℃ and the thermal inactivation of lipase was obvious at 60℃. The lipase activity was inhibited by K＋, stimulated by Ca^2＋, and thermostability decreased in the presence of Ca^2＋, therefore the lipase was Ca^2＋ -dependent cold-adapted enzyme.展开更多
The filamentous fungi from the Huanghai sea sludge were screened according to their ability to produce cold-active α-amylase. The strain with the highest amylase activity was identified as Penicillium species. The ...The filamentous fungi from the Huanghai sea sludge were screened according to their ability to produce cold-active α-amylase. The strain with the highest amylase activity was identified as Penicillium species. The α-amylase purified by ammonium sulphate precipitation and column chromatography on DEAE-sepharose and sephadex G-100 shows a molecular weight of about 55000 and a pI of 4.38. The enzyme is stable in a pH range of 5.5—8.0 and has a maximum activity at pH 6.0. Compared with the α-amylase from mesophiles and thermophiles, the cold-active enzyme shows a high enzyme activity at lower temperatures and a high sensitivity at temperatures higher than 50 ℃. The optimal temperature is 40 ℃ and the activity decreases dramatically at temperatures above 50 ℃. Ca 2+ shows a significant effect on maintaining the structure and the activity of the enzyme. EDTA and Cu 2+ are its inhibitors. The products from the hydrolysis of soluble starch with the cold-active enzyme are maltose and other oligosaccharides.展开更多
To find new extradiol dioxygenases（EDOs,EC 1.13.11.2）,a metagenomics library was constructed from polychlorinated biphenyl-contaminated soil and was screened for some dioxygenase with aromatic ring cleavage activity...To find new extradiol dioxygenases（EDOs,EC 1.13.11.2）,a metagenomics library was constructed from polychlorinated biphenyl-contaminated soil and was screened for some dioxygenase with aromatic ring cleavage activity.A novel EDO,designated as BphC_A,was identified and heterologously expressed in Escherichia coli.The deduced amino acid sequence of BphC_A exhibited a homology of less than 60% with other known EDOs.Phylogenetic analysis of BphC_A suggests that the protein is a novel member of the EDO family.The enzyme exhibits higher substrate affinity and catalytic efficiency toward 3-methylcatechol than toward 2,3-dihydroxybiphenyl or catechol,the preferred substrate of other known EDOs.The optimum activity of purified BphC_A occurred at pH=8.5 and 35 °C,and BphC_A showed more than 40% of its initial activity at 5 °C.The activity of purified BphC_A was significantly induced by Mn^2＋ and slightly reduced by Al^3＋,Cu^2＋ and Zn^2＋.展开更多
试验分离鉴定黑龙江省鹤岗地区玉米根围冻土中生防菌株wswshg^(-1)0,并检测其低温生长特性、分泌活性物质能力、拮抗病原菌活性及催芽促生特性。综合形态和理化特性、16S r DNA和gyr B基因序列分析将其鉴定为甲基营养型芽孢杆菌Bacillus...试验分离鉴定黑龙江省鹤岗地区玉米根围冻土中生防菌株wswshg^(-1)0,并检测其低温生长特性、分泌活性物质能力、拮抗病原菌活性及催芽促生特性。综合形态和理化特性、16S r DNA和gyr B基因序列分析将其鉴定为甲基营养型芽孢杆菌Bacillus me thylotrophicus。该菌株在4~15℃低温及20~30℃常温范围内可正常生长,是一株耐冷生防菌株,分泌几丁质酶、纤维素酶、蛋白酶、嗜铁素、吲哚乙酸、抗菌蛋白等多种活性物质,抑制烟草角斑病菌、玉米茎基腐病菌、黄瓜枯萎病菌、大豆菌核病菌、水稻恶苗和稻曲病菌、番茄灰霉病菌以及刺五加根腐病菌生长,抑制率74.3%~89.2%。菌液处理玉米种子能促进种子萌发及幼苗生长,根长和茎长显著增加。该菌株具有低温生长、抗菌促生特性,为低温菌剂研发提供菌株资源。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 Major Program of the Hebei Province Commission of Science and Technology during the 11 th Five-Year-Plan period,China(06220106D)
文摘Strain of Pseudomonas Lip35 producing lipase was isolated in a refrigerator. Lipase production and characterization of this strain were investigated under different conditions. The Pseudomonas was cultivated in shaking flasks in a fermentation medium in various nutritional and physical environments. Lipase production has been influenced by the presence of yeast-extract, soybean powder, NaCI, and Tween-80. Maximum lipase productivity was obtained when the physical environment of the fermentation medium was optimal for 67 h. The production of lipase reached 58.9 U·mL^-1. The lipase of Pseudomonas Lip35 can be considered to be inducible, but the inducer had little influence on the production of lipase. The lipase was characterized and showed high lipolytic activity from pH 7.5-8.0. The optimum temperature was observed at 20℃ and the thermal inactivation of lipase was obvious at 60℃. The lipase activity was inhibited by K＋, stimulated by Ca^2＋, and thermostability decreased in the presence of Ca^2＋, therefore the lipase was Ca^2＋ -dependent cold-adapted enzyme.
文摘The filamentous fungi from the Huanghai sea sludge were screened according to their ability to produce cold-active α-amylase. The strain with the highest amylase activity was identified as Penicillium species. The α-amylase purified by ammonium sulphate precipitation and column chromatography on DEAE-sepharose and sephadex G-100 shows a molecular weight of about 55000 and a pI of 4.38. The enzyme is stable in a pH range of 5.5—8.0 and has a maximum activity at pH 6.0. Compared with the α-amylase from mesophiles and thermophiles, the cold-active enzyme shows a high enzyme activity at lower temperatures and a high sensitivity at temperatures higher than 50 ℃. The optimal temperature is 40 ℃ and the activity decreases dramatically at temperatures above 50 ℃. Ca 2+ shows a significant effect on maintaining the structure and the activity of the enzyme. EDTA and Cu 2+ are its inhibitors. The products from the hydrolysis of soluble starch with the cold-active enzyme are maltose and other oligosaccharides.
基金Supported by the National Natural Science Foundation of China(Nos.41101226,50879029)the Technology Development Project of Jilin Province,China(Nos.201101020,20090415)
文摘To find new extradiol dioxygenases（EDOs,EC 1.13.11.2）,a metagenomics library was constructed from polychlorinated biphenyl-contaminated soil and was screened for some dioxygenase with aromatic ring cleavage activity.A novel EDO,designated as BphC_A,was identified and heterologously expressed in Escherichia coli.The deduced amino acid sequence of BphC_A exhibited a homology of less than 60% with other known EDOs.Phylogenetic analysis of BphC_A suggests that the protein is a novel member of the EDO family.The enzyme exhibits higher substrate affinity and catalytic efficiency toward 3-methylcatechol than toward 2,3-dihydroxybiphenyl or catechol,the preferred substrate of other known EDOs.The optimum activity of purified BphC_A occurred at pH=8.5 and 35 °C,and BphC_A showed more than 40% of its initial activity at 5 °C.The activity of purified BphC_A was significantly induced by Mn^2＋ and slightly reduced by Al^3＋,Cu^2＋ and Zn^2＋.
文摘试验分离鉴定黑龙江省鹤岗地区玉米根围冻土中生防菌株wswshg^(-1)0,并检测其低温生长特性、分泌活性物质能力、拮抗病原菌活性及催芽促生特性。综合形态和理化特性、16S r DNA和gyr B基因序列分析将其鉴定为甲基营养型芽孢杆菌Bacillus me thylotrophicus。该菌株在4~15℃低温及20~30℃常温范围内可正常生长,是一株耐冷生防菌株,分泌几丁质酶、纤维素酶、蛋白酶、嗜铁素、吲哚乙酸、抗菌蛋白等多种活性物质,抑制烟草角斑病菌、玉米茎基腐病菌、黄瓜枯萎病菌、大豆菌核病菌、水稻恶苗和稻曲病菌、番茄灰霉病菌以及刺五加根腐病菌生长,抑制率74.3%~89.2%。菌液处理玉米种子能促进种子萌发及幼苗生长,根长和茎长显著增加。该菌株具有低温生长、抗菌促生特性,为低温菌剂研发提供菌株资源。
