Fermentation of Inula britannica using Lactobacillus plantarum SY12 increases of epigallocatechin gallate and attenuates toxicity.

This study aimed to increase epigallocatechin gallate (EGCG) levels and attenuate the toxicity in Inulabritannica by fermentation using Lactobacillus plantarum SY12. The optimal medium was composed of 10 g of I. britannica, 4 g of xylose, 5 g of soytone, and 5 g of beef extract. The predicted value of EGCG was 237.327 µg/mL. To investigate damage in HepG2 cell lines by I. britannica extracts (IE) or fermented I. britannica extracts (FIE), cell viability, mitochondria membrane potential, the expression of apoptosis and autophagy genes, and chemical composition were measured. FIE increased cell viability, regulation of the gene expression (decreased p53, p62, p-ERK 1/2, and p-p38; increased CDK2 and CDK4) compared with IE. These results were explained by an increase in 1,3-dicaffeoylquinic acid and a decrease in 1-O-caffeoylquinic acid, 1-O-acetylbritannilactone, and ergolide in FIE. In conclusion, these results indicated that fermentation can mitigate the toxicity in I. britannica.

Synergistic antimicrobial activity of ε-polylysine, chestnut extract, and cinnamon extract against Staphylococcus aureus.

A mixed natural preservative composed of ε-polylysine (ε-PL), chestnut 70% ethanol extract (NE), and cinnamon hydrothermal extract (CW), was investigated for the reduction of Staphylococcus aureus. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of seven natural extracts were investigated against a cocktail of three strains of S. aureus (ATCC 25923, ATCC 33591, and ATCC 33594). Three important factors (ε-PL, NE, and CW) were selected by using the Plackett-Burman (PB) design for the response surface model (P < 0.001). Following a central composite design, S. aureus were treated with mixtures of natural preservatives that included ε-PL, NE, and CW. The MIC and MBC of ε-PL and the natural extracts and ranged from 1 to 16 mg/mL (R2 = 0.9857). The mixed natural preservative presented a synergistic antibacterial effect, at the optimum point. These results suggest that mixed natural preservatives of ε-PL, NE, and CW can lower the economic cost of food processing.

Optimization of an Industrial Medium and Culture Conditions for Probiotic Weissella cibaria JW15 Biomass Using the Plackett-Burman Design and Response Surface Methodology.

The objective of this study was to optimize industrial-grade media for improving the biomass production of Weissella cibaria JW15 (JW15) using a statistical approach. Eleven variables comprising three carbon sources (glucose, fructose, and sucrose), three nitrogen sources (protease peptone, yeast extract, and soy peptone), and five mineral sources (K2HPO4, potassium citrate, L-cysteine phosphate, MgSO4, and MnSO4) were screened by using the Plackett-Burman design. Consequently, glucose, sucrose, and soy peptone were used as significant variables in response surface methodology (RSM). The composition of the optimal medium (OM) was 22.35 g/l glucose, 15.57 g/l sucrose, and 10.05 g/l soy peptone, 2.0 g/l K2HPO4, 5.0 g/l sodium acetate, 0.1 g/l MgSO4·7H2O, 0.05 g/l MnSO4·H2O, and 1.0 g/l Tween 80. The OM significantly improved the biomass production of JW15 over an established commercial medium (MRS). After fermenting OM, the dry cell weight of JW15 was 4.89 g/l, which was comparable to the predicted value (4.77 g/l), and 1.67 times higher than that of the MRS medium (3.02 g/l). Correspondingly, JW15 showed a rapid and increased production of lactic and acetic acid in the OM. To perform a scale-up validation, batch fermentation was executed in a 5-l bioreactor at 37°C with or without a pH control at 6.0 ± 0.1. The biomass production of JW15 significantly improved (1.98 times higher) under the pH control, and the cost of OM was reduced by two-thirds compared to that in the MRS medium. In conclusion, OM may be utilized for mass producing JW15 for industrial use.

Antimicrobial and Antibiofilm Effect of ε-Polylysine against Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli in Tryptic Soy Broth and Chicken Juice.

ε-Polylysine (ε-PL) is a safe food additive that is used in the food industry globally. This study evaluated the antimicrobial and antibiofilm activity of antibacterial peptides (ε-PL) against food poisoning pathogens detected in chicken (Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli). The results showed that minimum inhibitory concentrations (MICs) ranged between 0.031-1.0 mg/mL, although most bacterial groups (75%) showed MICs of 1.0 mg/mL. The reduction in the cell viability of pathogens due to ε-PL depended on the time and concentration, and 1/2 × MIC of ε-PL killed 99.99% of pathogens after 10 h of incubation. To confirm biofilm inhibition and degradation effects, crystal violet assay and confocal laser scanning microscopy (CLSM) were used. The biofilm formation rates of four bacterial groups (Salmonella, Listeria, E. coli, and multi-species bacteria) were 10.36%, 9.10%, 17.44%, and 21.37% at 1/2 × MIC of ε-PL, respectively. Additionally, when observed under a CLSM, ε-PL was found to induce biofilm destruction and bacterial cytotoxicity. These results demonstrated that ε-PL has the potential to be used as an antibiotic and antibiofilm material for chicken meat processing.