Multi-omics Analysis Of The Michanisms Of A Deep-sea Bacterium Shewanella Sp. F12 Adapting To The Low-temperature And High-pressure Environments

The deep-sea,which accounts for 75% of the total ocean,is a typical extreme environment.Bacteria living in the deep-sea must have a series of physiological adaptation and metabolic characteristics to the environment.Therefore,the research on the adaptability mechanism of deep-sea microbes in extreme environment is farreaching and significant in its meaning.In this study,the growth characteristics experiment of a deep-sea strain Shewanella sp.F12 was conducted under different temperatures,pressures and p H conditions.The results are shown as below: The survival temperature of strain F12 ranged from 4 to 20?(optimum 15?);F12 could still grow under 50 MPa(optimum 0.1 MPa);p H range of strain F12 was p H 6-9(optimum p H=7).In a word,Strain F12 is characteristic of psychrophilic,piezo resistance and alkali tolerance.What is more,the multi-omics study based on genomics,transcriptomics and metabolomics was carried out to explore the adaptation mechanisms of strain F12 under low-temperature and high-pressure.According to the results of genomic analysis,with single chromosome and 5502 coding genes,Shewanella sp F12,does not contain plasmids,and its genome size is about 6.23 Mb,GC content is 43.59 mol%,average gene density is 0.88 / kb.In the genome of strain F12,the genes related to low-temperature adaptation are mainly relevant to cell membrane,flagella and pili,compatible solute,protein / enzyme and molecular chaperone,ribosome function,DNA damage repair,nucleotide metabolism,antioxidant stress,transcriptional regulatory factors and so on;Likewise,genes related to high-pressure adaptation are mainly related to flagella and pili,cell respiration,proteins / enzymes and molecular chaperones,as well as several related genes.Probably by encoding these genes,Shewanella sp.F12 adapt to deep-sea low-temperature and high-pressure environments.On the basis of the transcriptomic analysis results,Shewanella sp.F12 may responds to stress of deep-sea low-temperature and high-pressure by regulating the expression of related metabolic pathways or genes.The main strategies are as follows:regulating the pathways related to amino acid metabolism,nucleotide metabolism,energy metabolism and carbohydrate metabolism;Adopting different repair mechanisms to deal with DNA damage caused by low-temperature and high-pressure;Up-regulating biofilm formation and reducing cell division and proliferation of strains under low-temperature and high-pressure;Weakening the flagellum-related movement and partially depending on rubbing movement under high-pressure.However enhancing its flagellum-related movement at low-temperature;Up-regulating the secretion of compatible solutes such as betaine-proline at low-temperature and the expression of proteins related to type ? secretory system under low-temperature and high-pressure.In light of the metabolomics analysis results,the metabolic pattern of Shewanella sp.F12 changed when it was exposed to low-temperature or high-pressure environment.Besides,a total of 34 metabolites of strain F12 were identified in the NMR(Nuclear Magnetic Resonance)spectroscopy,which were involved in carbohydrate,nucleotide,amino acid and other metabolic pathways.Furthermore,What the results of metabolomic analysis suggest can be shown as below: Glycine,serine,tyrosine,threitol,betaine and glycerol may be compatible solutes at low-temperature,meanwhile F12 was provided energy mainly by glycolysis and down-regulates nucleotide metabolism;Alanine,glycine,isoleucine,serine and valine are associated with high-pressure adaptation of F12,and it may be supplied by multiple anaerobic respiratory systems;In the condition of low-temperature and high-pressure,Alanine,glycine,serine and glycerol may be used as compatible solutes,and F12 may derives energy by glycolysis and oxidative phosphorylation together.Moreover,strain F12 is disordered in intracellular pyrimidine metabolism and the pathways related to biofilm synthesis are regulated.This study preliminarily elucidated the adaptive mechanism of the deep-sea bacteria Shewanella sp.F12 in the environment of deep-sea low-temperature and highpressure,which lays a foundation for further exploration of the adaptive mechanism of deep-sea microorganisms in extreme environments.