Transcriptomic analysis of biofilm formation by Bacillus cereus under different carbon source conditions

Background:Previous studies found differences in the utilization of different carbon sources during biofilm formation by Bacillus cereus.Illumina HiSeq high-throughput sequencing technology was used to investigate the changes in gene transcript levels in Bacillus cereus biofilm bacteria under different carbon source conditions.Results:Compared with the control group,the number of differentially expressed genes in the glucose,maltose,lactose,and skim milksupplemented groups was 351,1136,133,and 487,respectively.The results showed that the pathways involved in the differentially expressed genes were mainly distributed in glycolysis and pentose phosphate pathway,tricarboxylic acid cycle,amino acid metabolism,and fatty acid metabolism.The gene expression of enzymes related to acetoin synthesis from pyruvate was mostly upregulated in the glucose-supplemented group.The gene expression of enzymes related to pyruvate synthesis of branched-chain amino acids in the maltose-supplemented group was mostly upregulated.In the lactose-supplemented group,the gene expression of acetoin biosynthesis from pyruvate was upregulated.Pyruvate production through glycolysis pathway increased in the skim milk-supplemented group,but the metabolic capacity of the tricarboxylic acid cycle did not change significantly.Conclusion:The content of pyruvate stored by Bacillus cereus biofilm bacteria through glycolysis or pentose phosphate pathway increased,but the carbon flux into the tricarboxylic acid cycle did not increase,which suggested that carbon fluxes in the extracellular polysaccharide synthesis pathway of the biofilm may be increased,resulting in increased biofilm biomass formation.