107 strains producing protease were screened from 260 strains of Antarctic psychrophilic bacteria, among which proteolytic activity of five strains was more than 45 U ml^-1. The 16S rRNA gcne sequences homology and ph...107 strains producing protease were screened from 260 strains of Antarctic psychrophilic bacteria, among which proteolytic activity of five strains was more than 45 U ml^-1. The 16S rRNA gcne sequences homology and phylogcnetic analysis of five Antarctic psychrophillc bacteria showed that NJ276, NJS-9, NJ16-70,NJ345 belonged tO the described genus Pseudoalteromonas and NJ341 belonged to the genus Colwellia. The growth and the protease characteristic of four Antarctic psychrophilic bacteria had been studied, and the result showed that the 6ptimal temperature for growth and protease-produeing of four strains was about 10℃. Their growth and protease-produeing were still high during incubatlng 2-5 days. The maximum proteolytic activity occurred at pH 9 for four Antarctic psychrophilic bacteria. The optimal temperature of protease action of both strains NJ276 and NJ5-9 was about 50℃, however, the optimal temperature of protease aetlon of both strains NJ341 and NJ345 was about 40 ℃, and their proteolytic activity under 0℃ exhibited nearly 30% of the maximum activity, but their thermal stabilities were weaker. These results indicated that proteases from NJ341 and NJ345 were low-temperature proteases.展开更多
The neolithic ruins of rice cultivation play an important role in the study on origin,evolution and propagation of cultivated rice. There are more than one hundred neolithicsites in China. where the ruins of rice have...The neolithic ruins of rice cultivation play an important role in the study on origin,evolution and propagation of cultivated rice. There are more than one hundred neolithicsites in China. where the ruins of rice have been found. and 80 percent of them and allthe earlier ones (Hemudu and LuoJiajiao. about 7 ka B.P.: Pengtoushan. about 7.5—9 kaB. P.) are distributed over the areas of the Yangtze River. Are there the earlier. cultivatedrice in the areas of the Yellow River and Huaihe River? This problem has received展开更多
The clay minerals in the surface sediments from 354 stations have been analyzed qualita-tively and semiquantitatively. The obtained data are dealt mathematically. According to thecalculated results, the distribution l...The clay minerals in the surface sediments from 354 stations have been analyzed qualita-tively and semiquantitatively. The obtained data are dealt mathematically. According to thecalculated results, the distribution laws and the trends of content changes of clay mineralsare discussed. The studied area is divided into four main provinces of sediments with differ-ent sources. Finally the author approached the laws of the migration and dispersal of thefine-grained matter carried into the seas by the Huanghe River, the Changjiang River, theZhujiang River and the Philippine Archipelagoes, and set up the transport model of the fine-grained matter in the China Sea and adjacent seas.展开更多
基金supported by Program of National Natural Science Foundation of China.(No.40406003)
文摘107 strains producing protease were screened from 260 strains of Antarctic psychrophilic bacteria, among which proteolytic activity of five strains was more than 45 U ml^-1. The 16S rRNA gcne sequences homology and phylogcnetic analysis of five Antarctic psychrophillc bacteria showed that NJ276, NJS-9, NJ16-70,NJ345 belonged tO the described genus Pseudoalteromonas and NJ341 belonged to the genus Colwellia. The growth and the protease characteristic of four Antarctic psychrophilic bacteria had been studied, and the result showed that the 6ptimal temperature for growth and protease-produeing of four strains was about 10℃. Their growth and protease-produeing were still high during incubatlng 2-5 days. The maximum proteolytic activity occurred at pH 9 for four Antarctic psychrophilic bacteria. The optimal temperature of protease action of both strains NJ276 and NJ5-9 was about 50℃, however, the optimal temperature of protease aetlon of both strains NJ341 and NJ345 was about 40 ℃, and their proteolytic activity under 0℃ exhibited nearly 30% of the maximum activity, but their thermal stabilities were weaker. These results indicated that proteases from NJ341 and NJ345 were low-temperature proteases.
基金Project supported by the National Natural Science Foundation of China.
文摘The neolithic ruins of rice cultivation play an important role in the study on origin,evolution and propagation of cultivated rice. There are more than one hundred neolithicsites in China. where the ruins of rice have been found. and 80 percent of them and allthe earlier ones (Hemudu and LuoJiajiao. about 7 ka B.P.: Pengtoushan. about 7.5—9 kaB. P.) are distributed over the areas of the Yangtze River. Are there the earlier. cultivatedrice in the areas of the Yellow River and Huaihe River? This problem has received
文摘The clay minerals in the surface sediments from 354 stations have been analyzed qualita-tively and semiquantitatively. The obtained data are dealt mathematically. According to thecalculated results, the distribution laws and the trends of content changes of clay mineralsare discussed. The studied area is divided into four main provinces of sediments with differ-ent sources. Finally the author approached the laws of the migration and dispersal of thefine-grained matter carried into the seas by the Huanghe River, the Changjiang River, theZhujiang River and the Philippine Archipelagoes, and set up the transport model of the fine-grained matter in the China Sea and adjacent seas.
