Formation of biofilm changed the responses of Tetragenococcus halophilus to ethanol stress revealed by transcriptomic and proteomic analyses

Biofilms were found to promote the survival of Tetragenococcus halophilus, a functional halophilic lactic acid bacterium in the production of high-salt fermented foods under various environmental stresses including ethanol stress. Here, a comprehensive exploration of the response of T.halophilus biofilms and planktonic cells to ethanol stress was performed. Biofilms showed an ability to reduce death and damage of cell membrane and wall under 12% ethanol stress The formation of biofilm changed the characteristic of Fourier transformed infrared spec-troscopy (FT-IR). RNA-seq technology and iTRAQ technology revealed the differential expression of genes and proteins in biofilm and planktonic cells with or without ethanol treatment. The differentially expressed genes and proteins played positive roles in the biosynthesis of polysaccharides, proteins, and DNA, benefitting biofilm matrix production. The shelter provided by biofilms and the differential expression of genes and proteins involved in citrate formation, malate utilization, and the biosynthesis of tryptophan, fatty acid, lipoteichoic acid, and peptidoglycan might contribute to the stress tolerance of biofilm cells together. Results presented in this study may contribute to our understanding of biofilm formation by T. halophilus and the roles of bacterial biofilm in stress tolerance.

Automated summary

Biofilms were found to enhance the survival of Tetragenococcus halophilus in high-salt fermented foods production under various stresses, including ethanol stress. The study revealed that biofilms could protect cell membrane and wall from damage under ethanol stress and change the characteristic of Fourier transformed infrared spectroscopy (FT-IR). RNA-seq and iTRAQ analyses revealed differential gene and protein expressions in biofilms and planktonic cells with or without ethanol treatment, which were involved in biosynthesis and stress tolerance. This study contributes to understanding biofilm formation and the role of bacterial biofilms in stress tolerance.