| The composition of the polar marine sediments is complex and nutrient rich, which contains a large number of micro-organisms, the special habitat of the polar region has created a variety of microbial diversity and novelty. Screening of active strains and active metabolites against plant pathogenic fungi from polar microorganisms is of great significance for the research of the resource library and the development of the polar microbial pesticides.In this paper, the ocean sediment samples collected in the sixth Chinese Arctic scientific investigation were studied and mix it with Bacterial screening medium, from which 69 Arctic seabed sediment bacteria were separated, and we also carried out molecular identification and phylogenetic analysis of them. Phylogenetic analysis showed that 69 strains of bacteria were identified: they belonged to 18 genera, namely Pseudoalteromonas ? Shewanella ? Psychromonas ? Pseudomonas ? Marinomonas ?Halomonas?Psychrobacter?Loktanella?Microbacterium?Arthrobacter?Planomicrobium?Planococcus?Bacillus?Virgibacillus?Oceanobacillus?Flavobacterium?Maribacter?Olleya, among which Pseudoalteromona(14), Psychrobacter(14), Shewanella(10) are in the majority. At the same time, we adopted the method of agar diffusion, using Stemphylium solani and Phytophthora capsici as indicator bacteria, to screen antimicrobial strains from 69 strains of bacteria and obtain 4 strains bacteria which could inhibit the plant pathogenic fungi, their numbers were: R06-1, 2018, R11 and C13-2, and the phylogenetic analysis were performed and antibacterial spectrum were determined. Phylogenetic analysis results showed that: the 4 active strains were ?-Proteobacteria which belong to Proteobacteria of bacteria. The strain R06-1 belonged to the Shewanella genera, 2018 and C13-2 belonged to Pseudoalteromonas genera, R11-1 belonged to Psychrobacter genera.The results of antibacterial spectrum showed that, inhibition zone diameter of the selected 4 active strains against Stemphylium solani and Phytophthora capsici is more than 20.00 mm. The bacterial strain R06-1 and 2018 had the most obvious antimicrobial effect to the indicator bacteria, and the diameter of the inhibition zone reaches over 25.00 mm, and the strong inhibition effect was achieved, which will be achieved as target strains to further study the composition of their active substances.Strong antibacterial Arctic bacteria Shewanella sp.R06-1 was fermented, and traced its antibacterial activity. using ethyl acetate extraction, decompression silica gel column chromatography, Sephadex LH-20 column chromatography, RP-18 reversed-phase silica gel column chromatography and HPLC technique, antibacterial active substances in the Shewanella sp.R06-1 fermentation were separated and purified, which gave us a pure compounds(R06-01-3-1). Activity verification results showed that: compounds R06-01-3-1 had weak antibacterial effect against Phytophthora capsici. Meanwhile, the compounds were identified by mass spectrometry(MS), nuclear magnetic resonance spectroscopy(1H NMR) / carbon spectroscopy(13C NMR) and other techniques. The results showed that the structure of the compound R06-01-3-1 was Cyclo(D-Pro-L-Tyr), which was isolated from Shewanella sp. and reported on its effect against Phytophthora capsic for the first time.Another Arctic bacterium Pseudoalteromonas sp.2018 of strong antibacterial activity was fermented with a 50 L fermentor, by tracing its antibacterial activity, five compounds(1~5)were isolated from the ethyl acetate extract by using ethyl acetate extraction, ODS reversed-phase silica gel column chromatography, Sephadex LH-20 column chromatography, MPLC and HPLC method. At the same time, the structure identification of the compounds was carried out. The results showed that: five compounds respectively were Cyclo(D-Pro-L-Tyr)(1),Cyclo(R-Pro-R-Phe)(2),Cyclo(L-Ile-L-Pro)(3),Cyclo(L-Pro-L-Leu)(4)and phenylacetic acid(5). These compounds were isolated from Pseudoalteromonas sp. for the first time. |
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