Transcriptomics reveals differentially expressed genes related to ectoine metabolism in Halomonas campaniensis XH26 under Fe3O4 nanoparticle stress
[Objective]To studyhydroxyl radical the differentially expressed genes(DEGs)in Halomonas campaniensis XH26 after co-culture with Fe3O4 nanoparticles(NPs),and clarify the molecular mechanism of Fe3O4 NPs in increasing the ectoine accumulation in strain XH26.[Methods]Strain XH26 was co-cultured with low-,medium-,and high-concentration(0.01,0.10,and 0.50 g/L respectively in L,M,and H groups)Fe3O4 NPs,and the strain cultured without Fe3O4 NPs(0 g/L)was taken as the control group(C).Transcriptome sequencing was performed by Illumina HiSeq 300PE.The DEGs between different groups were mined,and key genes were screened for RT-qPCR verification.[Results]Compared with group C,group M showed an increase of 55.67％(708.87 mg/L)in ectoine accumulation,and groups M and H showed increased ferrous ions and antioxidant capacity.The hydroxyl radical content in group H was higher than that in group M.The transcriptomics analysis showed that the DEGs between groups M and C were enriched in arginine/proline metabolism(13),nitrogen metabolism(11),and sulfur metabolism(10)pathways.They were mainly related to the ectoine synthesis pathways(11),electron transport pathways(7),and antioxidant enzyme systems(5).RT-qPCR was employed to verify the expression of lysC,asd,and ectABC involved in ectoine synthesis,astA/B/D/E in arginine metabolic pathway,and argE/H in urea cycle,which showed the results consistent with the results of RNA-seq.[Conclusion]Ectoine is an important stable protective agent for bacterial cells and biomacromolecules.Strain XH26 exposed to the stress of Fe3O4 NPs showed increased intracellular reactive oxygen species and altered amino acid/nitrogen metabolism processes.Strain XH26 increased the accumulation of ectoine to cope with the stress of Fe3O4 NPs by improving the antioxidant capacity.
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