Hongmei Zhang,Wenyuan Zhou,Wenyan Zhang,Anlin Yang,Yanlan Liu,Yan Jiang,Shaosong Huang,Jianyu Su
Biofilms are significant hazards in the food industry. In this study, we investigated the effects of food additive such as citral, cinnamaldehyde, and tea polyphenols on mixed biofilm formation by foodborne Staphylococcus aureus and Salmonella serotype Enteritidis. The adhesion rates of mixed strains in sub-MIC of additives were determined by a microtiter plate assay and bacterial communication signal autoinducer 2 (AI-2) production via a bioluminescence reporter Vibrio harveyi BB170. The structure of mixed biofilm was analyzed using scanning electron microscopy. The effect of the disinfectants hydrogen peroxide, sodium hypochlorite, and peracetic acid was tested on the mixed biofilm. Our results demonstrated that citral, cinnamaldehyde, and tea polyphenols were able to significantly inhibit mixed biofilm formation, while citral could reduce the synthesis of AI-2. Conversely, we observed a significant increase in AI-2 mediated by cinnamaldehyde. Tea polyphenols at lower concentrations induced AI-2 synthesis; however, AI-2 synthesis was significantly inhibited at higher concentrations (300 μg/ml). Food additives inhibited the adhesion of mixed bacteria on stainless steel chips and increased the sensitivity of the mixed biofilm to disinfectants. In conclusion, citral, cinnamaldehyde, and tea polyphenols had strong inhibitory effects on mixed biofilm formation and also enhanced the effect of disinfectant on mixed biofilm formation. This study provides a scientific basis for the application of natural food additives to control biofilm formation of foodborne bacteria.
The effects of the exogenous autoinducer-2 (AI-2) precursor, 4,5-dihydroxy-2,3-pentanedione (DPD; 0, 300, 600, and 900 nmol/L), on the degradation capacity of Lactiplantibacillus plantarum SH7 toward biogenic amines (BA) were investigated both in vitro and in a dry-sausage model. L. plantarum SH7 exhibited a significant increase in BA-degradation capacity (putrescine, cadaverine, and histamine) under DPD treatments compared to the absence of DPD treatment in vitro . Additionally, a significant increase in the production of AI-2 signal molecule and diamine oxidase in L. plantarum SH7 was observed with the addition of exogenous DPD ( p < 0.05). In the dry-sausage model, the contents of BAs (tryptamine, 2-phenethylamine, putrescine, cadaverine, and histamine) significantly decreased with the addition of DPD ( p < 0.05). Meanwhile, the sausage with 600-nM DPD exhibited the lowest cadaverine content (11.13 mg/kg), while the sausage with 900-nM DPD exhibited the lowest tryptamine, putrescine, and histamine contents (12.44, 11.15, and 13.21 mg/kg, respectively). Results suggest that an optimal concentration of exogenous DPD can enhance the capacity of L. plantarum SH7 to degrade BAs and that the degradation of BAs by L. plantarum SH7 may be dependent on the LuxS /AI-2 quorum sensing (QS) system. This study provides the theoretical basis for the development of functional starter cultures of lactic acid bacteria with BA-degradation ability based on targeted LuxS /AI-2 QS system regulation and reducing the accumulation of BAs in fermented meat products .
危险品化学品经营许可证（带存储）