Stress Responses And Metabolomics Under Cu²⁺ In Psychrophilic Microorganism

Under the heavy metal polluted circumstances, microbes certainly have somephysiological, biochemical and metabolic changes to adapt to the extremeenvironments. In this study, antioxidant characters and metabolic changes ofAntarctic bacterium stressed by Cu²⁺are analyzed. The results are expected to laidthe theoretical basis for the control of heavy metal environments.（1） A heavy metal resistance bacterium strain from160Antarctica strains isscreened by Atomic absorption spectrometry. Based on16S rDNA sequence andphysiological and biochemical properties, this strain is identified as Planococcus,named as Planococcus sp. O5.（2） Resistance of different concentration gradient heavy metal show that StrainO5has common resistance capacities to heavy metals, and the resistance to the orderfollowed by Pb²⁺>Cu²⁺>Cd²⁺>Hg²⁺>Zn²⁺, and the MICs is1.0mmol/L,0.8mmol/L,0.7mmol/L,0.6mmol/L,0.5mmol/L, respectively.（3） After CuSO4induction, bacterial cells produce a series of physiological andbiochemical changes. Increased conductivity and MDA show the heavy metal stressmake active oxygen species increase rapidly and cell membrane is destructed.Determination results of the antioxidant system indicate antioxidant enzymesactivity such as SOD, POD, GR and CAT increase, and antioxidant content ofcarotenoids and GSH improve, which can clear radicals effectively. Isozymesanalysis reveale that the new isozymes may play an important role in free radicalsscavenging.（4） By comparative metabolics method, the changes of metabolites areanalyzed in strain O5cells stressed by Cu²⁺. Firstly, OPLS-DA pattern recognitionmethod is defined from three different analysis ways. Using OPLS-DA and T-testanalysis,46kinds of different compounds are screened out from strain O5beforeand after Cu²⁺induced in the log growth phase and50different compounds in thestable growth phase. Phosphoric acid, glycine, lysine and an unknown compound areidentified as induced different substances in the two growth stages. The resultsexplain that the anti-metal mechanism of strain O5is achieved through thestrengthening of protein synthesis and increasing the stability of the cell membrane.The above studies are helpful for us to further understand how bacteria adapt toheavy metal contamination.