Study On Microbial Diversity And Adaption In The Seamount Area Of Western Pacific Ocean

The deep ocean is special with physical and chemical characteristics,and is rich in biological resources.It is one of the best places to study the origin and evolution of life.The deep-sea seamount is rich in cobalt nodules and Fe-Mn crusts.There are large numbers of microbial resources that can produce new biological enzymes and active substances.In this study,DY56 ocean scientific survey was participated in person,and different kinds of samples were collected from the Western Pacific Ocean seamount area.Bacteria,especially heavy-metal resistant and iron and manganese redox bacteria were cultivated aboard the ship.Then polyphase taxonomic study of several new species was conducted.Based on the genome analysis of bacteria isolated from seamount samples,the adaptive mechanism of one nickel-resistant bacterium,three manganese-oxidizing bacteria,and the response of one zinc-tolerant bacterium under zinc stress at different growth time were discussed,which enriched seamount microbial resources and research about adaptive mechanism of marine microorganisms to heavy metal environment.739 strains,belonging to 76 genera and 116 different species,were isolated from the samples collected from 36 sites of Western Pacific Ocean.Most bacreria were belonging to Alaphaproteobacteria(62%)and Gammaproteobacteria(29%).Erythrobacter(15%),Alteromonas(6%)and Henriciella(6%)were the major genera,including 50 suspected new species,92 manganese-oxidizing bacteria and 23iron reduction bacteria.Bacterial diversity is different in seamount area and non-seamount area.The bacterial diversity of site PAC25,PAC30,PAC32 and PAC36 in seamount area was higher than that in other stations.Combing with environmental factors data,it was found that in different seawater samples from seamount areas,the influence of water depth,nitrate content,p H and active phosphate content on microbial diversity was higher than temperature,dissolved oxygen,salinity and nitrite content.The cell abundance and bacterial diversity of the stations near the shore were greater than stations from the open sea in the non-seamount area.According to systematic polyphase taxonomy,five suspected new marine microbial species were identified and established:Pseudooceannicola lipolyticus sp.nov.,Actibacterium pelagium sp.nov.,Muricauda maritima sp.nov.,Muricauda aequoris sp.nov.and Muricauda oceanensis sp.nov.(type strains are 157^T,JN33^T,72^T,NH166^T and 40DY170^T).Besides,Oceanicola flagellatus comb.nov was reclassified to genus Pseudooceannicola.Muricauda oceansis sp.nov 40DY170^T,which was isolated from the Western Pacific Ocean seamount area,contained multiple genes encoding metal resistance and effluent transport proteins.Experimental results showed that its minimum growth inhibition concentrations of Mn²⁺,Co²⁺,Cd²⁺,Ni²⁺and Zn²⁺were 20 m M,2 m M,5m M,5 m M and 5 m M,respectively.The adaptive mechanism of five marine bacteria was studied through physiological,biochemical experiments and genome analysis.Multiple csz CBA genes and high affinity nickel transport-related proteins similar to Nre B,Nre A and Rcn R were predicted in the genome of nickel resistant strain Sphingobium sp.DY56-G10,as well as heavy metal resistant transporters.Enzymes related to polycyclic aromatic hydrocarbon degradation was also predicted in its genome,which indicated it has the potential function of reconditioning heavy metal pollution.18 strains with manganese-oxidizing activity greater than 390?mol/L were selected from 31 strains using LBB and spectrophotometer.The draft genome of three strains in genus Pseudoalteromonas,DY56-GL-22,DY56-GL-68 and DY56-GL-79,were sequenced.P.shioyasakiensis JCM 18891^T,P.arabiensis JCM 17292^Tand P.gelatinilytica NH153^Twere selected as reference strains for comparative genome analysis.Result showed that the number of cytochrome oxidase genes encoded by strain DY56-GL-22and DY56-GL-68 was significantly higher than that of the reference strains.The number of unique homologous genes in DY56-GL-79 was much larger than other five strains.Although cop A gene was not annotated in DY56-GL-79,its manganese-oxidizing ability was high,which may be related to the complex multi-component regulation system of manganese-oxidizing process.Transcriptional analysis of Halomonas zincidurans B6^T with different growth times under zinc stress showed that the metabolic pathways involved in metal transportation,flagellum assembly,bacterial chemotaxis,oxidative stress response,amino acid metabolism and cell basic metabolism related variously expressed genes,were significantly enriched in B6^T.Among them,HALZIN?RS0102520,L-2,4aminobutyric aminotransferase gene HALZIN?RS0102525(doe D),threonine deaminase gene HALZIN?RS0102530,anaerobin synthase gene(icu C)HALZIN?RS0111510 and HALZIN?RS0111515(hpa I)had high different expression levels at various times,which may play a key role in regulating this process.