Lactobacillus plantarum R is the predominant bacterium widely used in food fermentation. However, it has a low tolerance to ethanol during fermentation, which restricts its broader application in the food industry. Although biofilm formation enhances bacterial resistance to various stresses, regulating biofilm formation in L. plantarum R remains challenging. In this study, we established a pathway for producing autoinducer 2 (AI-2), a quorum-sensing (QS) signaling molecule, by heterologously expressing pfs and LuxS in L. plantarum R. This approach aimed to modulate cell membrane structure and improve bacterial ethanol resistance. The findings showed that exogenous AI-2 significantly enhanced the growth of L. plantarum R under high-ethanol concentration and improved its biofilm formation at different ethanol concentrations. Furthermore, a multi-omics analysis revealed potential mechanisms by which AI-2 improved the tolerance of L. plantarum R to ethanol. Notably, the upregulation of the crr gene, a component of the phosphotransferase system (PTS), enhanced biofilm formation in response to ethanol stress. In addition, differential metabolites enriched in cysteine and methionine metabolic pathways further supported the role of QS in enhancing the tolerance of L. plantarum R to ethanol. These findings lay the groundwork for enhancing the fermentation performance of strains applied in the food fermentation industry, presenting a novel method for expanding the utilization of L. plantarum R in high-ethanol fermentation.
Jianhui Wu,Xiaobo Wu,Changdao Mu,Chunhua Wang,Wei Lin
The urgent requirement of replacement for solvent polyurethane (PU) makes waterborne polyurethane (WPU) coating more attractive and popular in many industrial areas. However, the simultaneous realization of good dispersion stability and high performance of the cured films especially water resistance remains challenging. Herein, we propose a novel and facile Pickering emulsion approach to fabricate WPU with enhanced abradability and water-resistance comparable to that of solvent-based PU coating. In this approach, the hydrophobic polyurethane synthesized by poly-addition reaction in ethyl acetate is directly dispersed into water with SiO 2 nanoparticles as Pickering stabilizer followed by subsequent evaporation of the remaining solvent to obtain Pickering waterborne polyurethane dispersion (PWPU dispersion). The ability of SiO 2 to stabilize emulsion can be modulated by hydrophobic modification with propyltriethoxysilane (PTS). SiO 2 nanoparticles with an optimal PTS-grafting rate of 2.8 wt% enables the PWPU dispersion with excellent long-term, chemical, thermal, and freeze-thaw stability. The highly-transparent composite films with honeycomb structures are readily formed by casting PWPU dispersion at room temperature. The thermal and mechanical properties of PWPU films are comparable to or superior to solvent-borne polyurethane (SPU) and self-emulsifying waterborne polyurethane (SWPU) films. Moreover, the water absorption of the PWPU-5 film is approximately 20 times lower than that of SWPU, demonstrating the excellent water-resistance. We further validated the coating performance of PWPU for leather finishing. The hydrophobicity , abrasion resistance and water vapor permeability of PWPU-coated leather are superior to those of SPU and SWPU-coated leather.
危险品化学品经营许可证（带存储）