| Indian Ocean accounts for approximately 19.8%of the world's total ocean area.There are huge microbial resources in the Indian Ocean.And because of its complex and changeable environmental characteristics,functions and metabolism of these microbes are unique and diverse.Marine bacteria are involved in the transformation process of substances and elements,and marine fungi are an important source of natural products with special activities.Identification of marine microbial species,exploration the functional genes in bacteria,and finding secondary metabolites with novel structures and special activities have become the research focus of scientists on the development and utilization of deep-sea microbial diversity and marine biological resources.In this paper,625 strains of bacteria and 77 strains of fungi were isolated,purified and identified from seawater from the Indian Ocean.A bacterium Y33 with a 96.09%similarity to Algoriphagus sp.according to 16S r RNA was found.Four aspects of phenotypic characteristics,physiological and biochemical characteristics,cytochemical composition and molecular genetics were carried out.The taxonomic status of this bacterium was confirmed and the role of its functional genes in the Indian Ocean nitrogen cycle was explained.At the same time,77 strains of fungi were initially fermented by biological and chemical methods.The antibacterial and cytotoxic activities of the extracts were detected by the paper diffusion and MTT colorimetry,combined with HPLC fingerprint and thin layer chromatography.A fungus Penicillium sp.F13 with bacteriostatic and anti-tumor activity was screened out,and its secondary metabolites were studied.Strain Y33 was derived from seawater at a depth of 200 meters in the Indian Ocean.The Gram staining reaction is negative.Its cells are short rod-shaped,flagella-free,and strictly aerobic.The strain can grow in the temperature range of 7-43°C,the Na Cl concentration range is 0-8.0%(kg/L),and the p H range is 6.0-9.0.The main fatty acid components of the strain cells are iso-C15:0,C16:1?7c,anteiso-C15:0,and the main cellular respiratory quinone is MK-7.The cell polar lipid components of strain Y33include phosphatidylethanolamine(PE),phosphatidylglycerol(PG),diphosphatidylglycerol(DPG),phosphatidylcholine(PC),and glycosphingolipids.(Sphingoglycolipid,SGL).Based on 16S r RNA gene sequence analysis and phylogenetic tree construction,the strain Y33 was determined to be a member of the genus Algoriphagus sp.and formed an independent evolutionary branch.Whole-genome sequencing showed that the genome of strain Y33 consists of a 6,378,979 bp chromosome,with an average G+C content of 41.86%.The annotation of functional genes shows that the strain contains a large number of genes related to nitrate reduction,which further confirms its role in the Indian Ocean nitrogen cycle.Based on the above polyphasic taxonomy research data,strain Y33 represents a new species of Algoriphagus genus,and was named Algoriphagus sp.Y33.The strain is deposited in the China Collection of Microorganisms,with the preservation number of No.1.17378,and the registration number of its whole genome data in the Gen Bank database is CP061947.By optimizing the culture conditions,fungus Penicillium sp.F13 was fermented on a large scale,and its fermentation products were separated by various methods such as thin layer chromatography,silica gel column chromatography,gel column chromatography,and reversed-phase high pressure liquid phase.After separation and purification,4 monomer compounds(C1-C4)were isolated from the secondary metabolites of strain F13.Then,the chemical structures of these 4 compounds were explained through various spectroscopy methods(UV,MS,NMR,etc.).The antibacterial activity of the monomer compounds was tested by the paper diffusion method,and the results showed that compound C3 has inhibitory effects on Staphylococcus aureus,Escherichia coli,and Pseudomonas aeruginosa.The cytotoxic activity of the monomer compound was tested by the MTT colorimetry.The results showed that C1,C3,C4 have certain cytotoxic activity to SMC-7221,and C2 and C4have certain cytotoxicity inhibitory activity to T-47D.In summary,the polyphasic classification of Algoriphagus sp.Y33 from the Indian Ocean and the secondary metabolites of Penicillium sp.F13 were studied in this paper.The results show that marine microorganisms have great research potential and are an important source of discovering new functional genes and new active monomer compounds.This research provides a certain scientific basis for the study of marine microorganism diversity. |
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