| Microorganism is generally considered to be efficient producers of biologically active substances and new compounds in today. Microorganisms survive in the polar where the climate is extremely harsh, which means that from polar microorganisms biologically active substances for humans may have special significance. The polar microorganisms (sea ice microalgae and bacteria) produce large amounts of extracellular polysaccharides (EPS). These substances gathered in the channel of sea ice where the ice algae and bacteria survive, organic carbon in sea ice and ice water interface is the main substance of the energy transfer. Plant and animal species in Antarctica is less, but it contains very rich microbial resources, and it is an important treasure house of microbial resources. Including psychrophilic and cold-adapted microbes, these microbes can produce many new active substances and lead compounds, such as polysaccharides, proteins, enzymes, antibiotics and lipids. Basic research and development applications in the future of these active substances will provide tremendous help. Sugars such as monosaccharides, oligosaccharides, polysaccharides etc, are the energy source of human survival, and are an important component of many plants, animals and micro-organisms substances. Oligosaccharides with different physiological activity because of its molecular structure and size of different degree of polymerization, in many areas of molecular biology, food science, medicine and health science has a broad development prospects and market value. China’s24th Antarctic scientific visits Uruguay stations acquisition of sea ice samples Psychrobacter sp. B-3psychrotrophic bacilli as the original strain, Obtained by fermentation and separation and purification molecular weight1000Da extracellular oligosaccharides pure and followed the extracellular oligosaccharides structural composition and antioxidant activity, and use the response surface methodology and the strains fermented sugar-producing conditions were optimized to obtain the results and conclusions are as follows:Antarctic bacterium Psychrobacter sp.B-3extracellular oligosaccharide separation and purification:2216E liquid fermentation medium for the fermentation of the Antarctic Psychrophile B-3, centrifuged fermentation supernatant, added three times the volume of95%ethanol overnight ethanol precipitation, centrifugation and precipitation, then alcohol precipitation Seveage law in addition to protein, reconstituted freeze-dried to obtain the extracellular crude sugar products; And then the extracellular raw sugar samples isolated and purified using Sephadex G-75gel column, after the detection of two peaks, take No. I peak sugar-like freeze-dried after the Q-Sepharose Fast Flow ion-exchange chromatography, before the peak Ⅱ collection standby, after ion exchange chromatography to obtain a sample for testing collection; The sample obtained from the chromatographed twice detection, HPLC and HP-GPC, measured sample molecular weight of1000Da, high purity to meet the requirements for the next experiment, named EPS-1, and protein samples and the starch test results were negative, contain other impurities.Antarctic bacteria Psychrobacter sp.B-3extracellular oligosaccharide structure analysis: By GC analysis, the results showed that, The Antarctic Psychrobacter sp. B-3extracellular oligosaccharide sample ESP-1is composed of glucose, mannose and galactose, after another further MS and NMR analysis obtained the extracellular oligosaccharide The structure of the EPS-1as follows:-(β-D-Man-β-D-Man-α-D-Glu)2-Antarctic bacterium Psychrabacler sp. B-3fermentation of sugar Response Surface Methodology:temperature, pH, different carbon sources, nitrogen sources, metal ions and seawater ratio as the only variable for single-factor experiments, screened out of the sugar-producing significant single factor range; On this basis, three major factors affect the production of polysaccharides screened using Plackett-Burman experimental design, are yeast powder, Chen seawater ratio and medium volume. Then Box-Behnken experimental design and response surface analysis regression analysis, the Antarctic bacterium Psychrabacler sp.B-3optimized fermentation conditions:Yeast extract1.1g/L, Chen seawater and tap water ratio is2:1, the liquid volume was50%, peptone3.0g/L, inoculation amount of1.5%, the incubation time64h, of BaCl20.03g/L, the temperature10℃, rotation speed of150r/min, the pH was7.0. Optimized the amount of sugar in the fermentation broth from444μg/ml to624μg/ml, Compared to the initial sugar production increased nearly1.4times. The results show that the response surface method can significantly optimize Antarctic bacterium Psychrobucter sp.B-3the extracellular sugar-3liquid fermentation conditions.Antioxidant activity studies Antarctic bacterium Psychrabacter sp. B the-3extracellular oligosaccharides:Hydroxyl radical scavenging capacity, DPPH radical scavenging, superoxide anion scavenging and anti-lipid peroxidation ability to experiment analysis extracellular oligosaccharides sample antioxidant capacity of the Antarctic Psychrabacler sp. B-3, The results showed that the antioxidant capacity of the purified sample was separated after two EPS-1is the strongest, the antioxidant capacity of the total sugars EPS-3, followed by the minimum peak Ⅱ sample portion EPS-2anti-oxidation activity, the total sugar EPS-3only after removing protein, chromatographic separation has not been. The activity related to the structure factor of the sugar substituent, such as polysaccharides, the type of sugar units and glycosidic bond configuration, and these factors lead to different sugars having a different activity.This article is the first time to study the antioxidant activity of the B-3extracellular oligosaccharides Antarctic psychrotrophic bacteria, and analysis of the oligosaccharide structure of the sample, for the "Ocean sugar Library provides novel structural features of oligosaccharides. And experiment with response surface optimization for the bacteria to find the best fermented sugar-producing conditions, laid the theoretical foundation for the Antarctic microbial metabolites development application. |
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