Lactic Acid and Peroxyacetic Acid Inhibit Biofilm of Escherichia coli O157:H7 Formed in Beef Extract

Ferrous sulfate combined with ultrasound emulsified cinnamaldehyde nanoemulsion to cause ferroptosis in Escherichia coli O157:H7

The purpose of this study was to investigate ferroptosis in Escherichia coli O157:H7 caused by ferrous sulfate (FeSO4) and to examine the synergistic effectiveness of FeSO4 combined with ultrasound-emulsified cinnamaldehyde nanoemulsion (CALNO) on inactivation of E. coli O157:H7 in vitro and in vivo. The results showed that FeSO4 could cause ferroptosis in E. coli O157:H7 via generating reactive oxygen species (ROS) and exacerbating lipid peroxidation. In addition, the results indicated that FeSO4 combined with CALNO had synergistic bactericidal effect against E. coli O157:H7 and the combined treatment could lead considerable nucleic acids and protein to release by damaging the cell membrane of E. coli O157:H7. Besides, FeSO4 combined with CALNO had a strong antibiofilm ability to inhibit E. coli O157:H7 biofilm formation by reducing the expression of genes related on biofilm formation. Finally, FeSO4 combined with CALNO exhibited the significant antibacterial activity against E. coli O157:H7 in hami melon and cherry tomato.

Propionate and Butyrate Inhibit Biofilm Formation of Salmonella Typhimurium Grown in Laboratory Media and Food Models

Salmonella is among the most frequently isolated foodborne pathogens, and biofilm formed by Salmonella poses a potential threat to food safety. Short-chain fatty acids (SCFAs), especially propionate and butyrate, have been demonstrated to exhibit a beneficial effect on promoting intestinal health and regulating the host immune system, but their anti-biofilm property has not been well studied. This study aims to investigate the effects of propionate or butyrate on the biofilm formation and certain virulence traits of Salmonella. We investigated the effect of propionate or butyrate on the biofilm formation of Salmonella enterica serovar Typhimurium (S. Typhimurium) SL1344 grown in LB broth or food models (milk or chicken juice) by crystal violet staining methods. Biofilm formation was significantly reduced in LB broth and food models and the reduction was visualized using a scanning electron microscope (SEM). Biofilm metabolic activity was attenuated in the presence of propionate or butyrate. Meanwhile, both SCFAs decreased AI-2 quorum sensing based on reporter strain assay. Butyrate, not propionate, could effectively reduce bacterial motility. Bacterial adhesion to and invasion of Caco-2 cells were also significantly inhibited in the presence of both SCFAs. Finally, two SCFAs downregulated virulence genes related to biofilm formation and invasion through real-time polymerase chain reaction (RT-PCR). These findings demonstrate the potential application of SCFAs in the mitigation of Salmonella biofilm in food systems, but future research mimicking food environments encountered during the food chain is necessitated.

Control of bacterial biofilms in red meat - A systematic review

Biofilm formation is a serious threat in the meat industry, mainly since it aids food-borne pathogen survival. Biofilms are often difficult to eliminate, and it is essential to understand the best possible deployable measures to remove or inactivate biofilms. We systematically reviewed the published in vitro studies that investigated various methods for removing biofilms in red meat. Publicly available databases, including Google Scholar and PubMed, were queried for relevant studies. The search was restricted to articles published in the English language from 2010 to 2021. We mined a total of 394 studies, of which 12 articles were included in this review. In summary, the studies demonstrated the inhibitory effect of various methods, including the use of bacteriophages, dry heat, cold atmospheric pressure, ozone gas, oils, and acids, on red meat extract or red meat culture. This systematic review suggests that in addition to existing sanitation and antibiotic procedures, other methods, such as the use of phage cocktails and different oils as nanoparticles, yield positive outcomes and may be taken from the in vitro setting to industry with prior validation of the techniques.