Application Of Metabolomics Analyses In Biofilm Formation Of Desulfovibrio Vulgaris Hildenborough

Sulfate reducting bacteria were the main anaerobic population in the anaerobic biocorrosion.Desulfovibrio vulgaris Hildenborough was one model bacterium of sulfate reducting bacteria,which was mainly observed as biofilm in nature.Biofilm formation was a dynamic,complex and highly regulated process.The fully developed biofilms had a three-dimensional structure composed of a polysaccharide matrix that contains water channels for the transfer of nutrients and the removal of the wastes.In this study,the D.vulgaris biofilm on steel surface in anaerobic serum bottles was first generated.We first applied the qPCR to determine the growth curve of biofilm cells and planktonic cells of D.vulgaris.In order to elucidate the mechanism of biofilm formation in metabolism level and decipher the interaction between D.vulgaris and the steel,in this work,a metabolomics approach combining both GC-MS and LC-MS was carried out to determine the time-series metabolic changes among the biofilm cells,planktonic populations and pure culture cells of D.vulgaris.Finally principal components analysis(PCA),volcano plot and pathway enrichment analyses were used to discriminate and assess the responsive metabolites and metabolic pathways associated with the different cellular status.There were 58 metabolites identified by GC-MS,and 22 metabolites related to central carbohydrate and energy metabolism were selected for LC-MS based on the targeted metabolite analysis in this study.Score plots of PCA of both LC-MS and GC-MS showed that an obvious clustering pattern for cell samples of the same time point and condition,indicating the overall good reproducibility indicating the reliability of the study.The GC-MS results showed that the fatty acids were up-regulated in biofilm cells when compared to other conditions at both exponential and stationary phases,such as lauric acid,mysistic acid,palmitoleic acid and stearic acid.Furthermore,pathway enrichment analysis indicated that fatty acid biosynthesis was up-regulated.Notably,the LC-MS results showed that the metabolic state of biofilm cells was down-regulated,especially metabolites related to the central carbon metabolism,relative to the other two conditions,such as PEP,3PG,AMP,G6 P and ADP-GCS.This study offered a valuable view of metabolic dynamics of D.vulgaris biofilm,and provided new information important for future biocorrosion control.