Isolated And Diversity Analysis Of Deep Sea Actinobacteria In The South Atlantic

Recently, with the augmentation of the pathogen resistance, people’srequirements for new antibiotics are in badly needed. At the same time, with therapid development of microbiology, making Actinomycetes occupies an importantrole in the generation and filtering of natural products. Scientists’ study ofActinomycetes on land is almost mature, seeking isolation of Actinomycetes fromnew, unique environment becomes an important task. deep sea environment is quitedifferent from land and other environments, with low temperature and high pressurecharacters, so there might be many kinds of novel Actinomycetes that could beisolated.In this study, fifteen sediment samples, three seawater samples taken from theSouth Atlantic, were used to isolate Actinomycetes. And five kinds of pretreatmentmethods, fifteen kinds of culture medium, four different cultivation temperatures,two kinds of bacteriostatic agents, and five levels concentration of antimicrobialagent were utilized. The16S rDNA sequence analysis method was employed toisolated microorganism of36strains of Actinomycetes belonging to Dietzia,Mycobacterium, Gordonia, Micrococcus, Kocuria, Kytococcus, Dermacoccus,Microbacterium. With rich biodiversity, Dietzia, Micrococcus, Mycobacteriumoccupied a higher proportion.Diversity and quantity of Actinomycetes in deep sea samples taken fromdifferent stations existed difference. In sediment samples, diversity and quantity ofActinomycetes isolated from S052station were most, including two strains ofDietzia maris and one strain of Kocuria assamensis; one strain of Actinomyceteswas isolated from S012station, named Kytococcus schroeteri. In seawater samples,sampling at2700m, one strain of Actinomycetes was isolated from CTD06, namedMicrobacterium schleiferi. No Actinomycetes was isolated from CTD10, CTD11stations.Diversity and quantity of Actinomycetes from seawater samples at the same stationand sampling in different depths present divergence. Samples taken from CTD06station in different depths，of which Actinomycetes isolated from125m were themost; three strains were Microbacterium aquimaris, Microbacterium schleiferi andMycobacterium poriferae, repectively. No Actinomycetes was isolated fromseawater at seven depths including2500m.Results showed that the composition of the medium was one key factor onisolation of Actinomycetes. Raffinose-histidine medium and glycerol-argininemedium were better for Actinomycetes isolation, were the ideal mediums forActinomycetes from deep sea. Different inhibitors and their concentration also have impact on the isolationfor Actinomycetes. Potassium dichromate was better bacteriostat for Actinomycetesisolation than nalidixic acid and nystatin. On the Gause No.1medium, the effect ofaddition500μg/mL potassium dichromate or600μg/mL were almost same, oneActinomycetes belonging to Dietzia was isolated on starch casein culture medium,there was no Actinomycetes isolated in the concentration of200μg/mL potassiumdichromate.In the study of antifungal activity of Actinomycetes by treadmill confrontationmethod on GY freshwater medium showed33strains of Actinomycetes presentedantibacterial effect against both Aspergillus parasiticus mutant strains NFRI-95andpathogen fungi of Fusarium. On GY seawater medium,32strains of Actinomycetesexisted antibacterial activity against Aspergillus parasiticus mutant strains NFRI-95,all strains have no antibacterial effect against Aspergillus parasiticus mutant strainsNFRI-95, all Actinomycetes in seawater medium existed no antibacterial activityagainst pathogenic fungi of Fusarium. These finds indicated Actinomycetes couldproduce valuable metabolites presence in the deep sea environment of the SouthAtlantic, Actinomycetes strains isolated was less, so it is necessary to optimizeexperimental methods to study on their optimal growth environment further.