Diversity Of Culturable Microbial In The Indian Ocean,polyphasic Taxonomy Of Two New Marine Microbial Species And Application Value Analysis Of Esterases In Genomes

The Indian Ocean has a vast sea area,which is the third largest ocean in the world.It is closed in the north and connected with the Atlantic Ocean in the south.It has a 9074-meter Amirante Trench and a deep-sea hydrothermal area.The Indian Ocean is located in tropical and subtropical regions,and at the same time is connected to the Southern Ocean.In addition,a unique monsoon current is formed in the northern part of the Indian Ocean,which makes the Indian Ocean have a complicated temperature and ecological environment.Complicated geography,climate and humidity conditions have created the diversity of Indian Ocean microorganisms.In order to adapt to the complex and changeable environment,the microorganisms in this area not only need to change their own nutritional intake,but also need to change their metabolic pathways to perform energy metabolism faster or more economically.Therefore,microorganisms in this environment possess a variety of special metabolic enzymes.The above reasons have made the Indian Ocean a huge and rich treasure house of microbial resources.Therefore,the development of microbial resources in the Indian Ocean is very necessary,no matter from the protection and utilization of ecological resources,or from the perspective of industrial application.Firstly,based on the scientific investigation of DY52 and DY58 voyages,seawater and sediment samples from 37 stations were obtained in this paper.The samples were spread plate cultivation with Marine Broth 2216 medium,oliotrophic 2216 medium,STA medium,esterase medium and alginate medium.A total of 167 strains belonging to 49 genera and 24 families were isolated and the dominant genera was Pseudoalteromonas.Through the analysis of the bacterial genera obtained from the seawater and sediment samples collected on the two voyages,it is found that the microbial genera in the sediment samples and seawater samples are quite different,while the differences in the microbial genera in the seawater samples from different sea areas are slightly smaller.The results showed that the dominant strains in seawater samples were Thalassospira,and the dominant strains in sediment samples were Sulfitobacter,Pseudoalteromonas and Salinicola.Secondly,this paper carried out multi-phase taxonomic identification for the new species strain h42~T isolated from the 52nd voyage of Oceania and the suspected new species of strain ALG8 isolated from the intertidal zone seawaters of Zhoushan,Zhejiang Province.The 16S r RNA identity of the two strains reached 99.72%,which could be identified as different strains of the same species.A new genus(Suspensibacterium)and a new species(Suspensibacterium nitratireducens sp.nov.)have been established through morphological,physiological,biochemical and genome studies of strains h42~T and ALG8.The 16S r RNA phylogenetic tree and the genome phylogenetic tree have been constructed.Finally,in this paper,the novel h42~T and ALG8 genomes were annotated with functional genes,and the results of the annotations were analyzed and screened to obtain protein sequences with esterase function.Esterases with protein crystal structure and conserved amino acid residues were selected as the control,and four suspected esterase proteins in strains strains h42~T and ALG8 were selected for analysis.The secondary structure and three-dimensional structure of these four proteins were predicted,and the function of the suspected esterase protein was further speculated.This work provides theoretical support for the study of the relationship between the structure and function of microbial esterase protein,and provides a practical basis for the application of industrial microbial esterase in practical production.