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Wang F.,Henan Agricultural University | Xu B.,Henan Agricultural University | Sun Y.,Henan Agricultural University | Zang J.,Key Laboratory of Marine Bioactive Substances | And 2 more authors.
Journal of Chinese Institute of Food Science and Technology

A fungus named WNF-15A which secreted a special amaranthine pigment was isolated from soil collected from Antarctic. It was determined as a member of Geomyces based on colony morphologic characteristics, microscopic morphology and the phylogenetic analysis of ITS. And it was a psychrophiles which has optimum growth temperature between 15~20°C. The hydro soluble amaranthine pigment produced by WNF-15A has the maximum absorption at 533 nm. Its thermal degradation dynamics corresponded with Arrhenius empirical formula and the activation energy was 65.4~81.2 kJ/mol, and this pigment has a nearly higher thermostability than monacolin K and betacyanin. Changes of pH had little effect on the stability of the pigment that was most stable under pH3~9 condition. Although the pigment was faded quickly when it exposed to sunlight, scattered light was almost ineffective on its stability. This pigment was nontoxic determined by LD50>15000 mg/kg observed from mice toxicity test. This pigment could be largely exploited as a natural pigment. Source

Li J.,First Institute of Oceanography | Li J.,Key Laboratory of Marine Bioactive Substances | Sha Y.,First Institute of Oceanography | Sha Y.,Key Laboratory of Marine Bioactive Substances | And 5 more authors.
Journal of Microbiology and Biotechnology

An extracellular agarase was purified from Bacillus sp. BI-3, a thermophilic agar-degrading bacterium isolated from a hot spring in Indonesia. The purified agarase revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular mass of 58 kDa. The optimum pH and temperature of the agarase were 6.4 and 70°C, respectively. The activity of the agarase was stable at high temperatures, and more than 50% activity was retained at 80°C for 15 min. Furthermore, the enzyme was stable in the pH range of 5.8-8.0, and more than 60% of the residual activity was retained. Significant activation of the agarase was observed in the presence of K+, Na+, Ca2+, Mg2+, and Sr2+; on the other hand, Ba2+, Zn2+, Cu2+, Mn2+, Co2+, Fe2+, and EDTA inhibited or inactivated the enzyme activity. The components of the hydrolytic product analyzed by thin-layer chromatography showed that the agarase mainly produced neoagarobiose. This study is the first to present evidence of agarolytic activity in aerobic thermophilic bacteria. © 2014 by The Korean Society for Microbiology and Biotechnology. Source

Shuo-Shuo C.,First Institute of Oceanography | Shuo-Shuo C.,Key Laboratory of Marine Bioactive Substances | Xue-Zheng L.,First Institute of Oceanography | Xue-Zheng L.,Key Laboratory of Marine Bioactive Substances | And 2 more authors.
Protein Expression and Purification

The cold-active lipase gene Lip-948, cloned from Antarctic psychrotrophic bacterium Psychrobacter sp. G, was ligated into plasmid pColdI. The recombinant plasmid pColdI + Lip-948 was then transformed into Escherichia coli BL21. SDS-PAGE analysis showed that there was substantive expression of lipase LIP-948 in E. coli with a yield of about 39% of total protein, most of which was present in the inclusion body. The soluble protein LIP-948 only consisted of 1.7% of total LIP-948 with a specific activity of 66.51 U/mg. Co-expression of molecular chaperones with the pColdI + Lip-948 were also carried out. The results showed that co-expression of different chaperones led to an increase or decrease in the formation of soluble LIP-948 in varying degrees. Co-expression of pColdI + Lip-948 with chaperone pTf16 and pGro7 decreased the amount of soluble LIP-948, while the soluble expression was enhanced when pColdI + Lip-948 was co-expressed with "chaperone team" plasmids (pKJE7, pG-Tf2, pG-KJE8), respectively. LIP-948 was most efficiently expressed in soluble form when it was co-expressed with pG-KJE8, which was up to 19.8% of intracellular soluble proteins and with a specific activity of 108.77 U/mg. The soluble LIP-948 was purified with amylase affinity chromatography and its enzymatic characters were studied. The optimal temperature and pH of LIP-948 was 35 °C and 8, respectively. The activity of LIP-948 dropped dramatically after incubation at 50 °C for 15 min and was enhanced by Sr2+, Ca 2+. It preferentially hydrolyzed 4-nitrophenyl esters with the shorter carbon chain. © 2011 Elsevier Inc. All rights reserved. Source

Song W.,First Institute of Oceanography | Song W.,Key Laboratory of Marine Bioactive Substances | Lin X.,First Institute of Oceanography | Lin X.,Key Laboratory of Marine Bioactive Substances | And 2 more authors.
Polar Biology

Low temperature is one of the major environmental challenges that Antarctic bacteria must face. Detailed studies of cold shock responses of cold-adapted microorganisms are still insufficient. Here, we cloned three cold shock protein (CSP) genes (Csp1137, Csp2039, and Csp2531) in the Antarctic bacterium Psychrobacter sp. G and their regulatory sequences were identified. The three CSPs were highly conserved with other known CspAs. qRT-PCR was performed to evaluate their expression characteristics under stress conditions, and the potential influence of regulatory sequences also was analyzed. The expression of Csp1137 was enhanced both by low (0, 10 °C) and high temperature (30 °C). The expression of Csp2039 was enhanced by low temperature (0 °C), but was lower than that of Csp1137. This can be explained by the absence in Csp2039 of the AT-rich UP element. Different from Csp1137, the expression of Csp2531 was inhibited by low temperature (0 °C), even with the presence of AT-rich UP element, and it was not sensitive to high temperature (30 °C). The expression of Csp1137 was enhanced by high salinity (90, 120), whereas that of Csp2531was enhanced by low salinity (0, 15). At 0 °C and a salinity of 15, the expression of Csp1137 was repressed initially, but then it increased greatly during the next 10 h. The expressions of Csp2039 and Csp2531 were repressed significantly under four different combinations of stress conditions. Our results showed that the role of the upstream regulation sequences were much more complex than previously thought. Also, gene expressions were also affected by the environmental salinity. These are helpful in further clarification of the adaptation mechanism of Psychrobacter sp. G. © 2012 Springer-Verlag. Source

Yi-Bin W.,State Oceanic Administration | Yi-Bin W.,Key Laboratory of Marine Bioactive Substances | Fang-Ming L.,State Oceanic Administration | Fang-Ming L.,Key Laboratory of Marine Bioactive Substances | And 10 more authors.
Journal of the Marine Biological Association of the United Kingdom

Ice algae have successfully adapted to the extreme environmental conditions in the Antarctic, however the underlying mechanisms involved in the regulation and response of thylakoid membranes and chloroplast to low-temperature stress are still not well understood. In this study, changes in pigment concentrations, lipids, fatty acids and pigment protein complexes in thylakoid membranes and chloroplast after exposure to low temperature conditions were investigated using the Antarctic ice algae Chlamydomonas sp. ICE-L. Results showed that the chloroplasts of Chlamydomonas sp. ICE-L are distributed throughout the cell except in the nuclear region in the form of thylakoid lamellas which exists in the gap between organelles and the starch granules. Also, the structure of mitochondria has no obvious change after cold stress. Concentrations of Chl a, Chl b, monogalactosyl diacylglycerol, digalactosyl diacylglycerol and fatty acids were also observed to exhibit changes with temperature, suggesting possible adaptations to cold environments. The light harvesting complex, lutein and β-carotene played an important role for adaptation of ICE-L, and increasing of monogalactosyl diacylglycerol and digalactosyl diacylglycerol improved the overall degree of unsaturation of thylakoid membranes, thereby maintaining liquidity of thylakoid membranes. The pigments, lipids, fatty acids and pigment-protein complexes maintained the stability of the thylakoid membranes and the normal physiological function of Chlamydomonas sp. ICE-L. Copyright © Marine Biological Association of the United Kingdom 2016 Source

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