Staphylococcus aureus (S. aureus) is the most common pathogen causing infections from skin to systemic infections. The success of S. aureus infections can partially be attributed to its antibiotic resistance and to its ability to form biofilm. An increasing prevalence of methicillin-resistant S. aureus (MRSA) becomes a global public health problem in recent decades. Here, the effects of tea catechin extracts on the growth and biofilm formation of three MRSA strains were investigated. The results revealed that tea catechin extracts potently suppressed MRSA growth, and the minimal inhibitory concentration of tea catechin extracts against these MRSA strains was 0.1g/L. Then, tea catechin extracts inhibited biofilm formation of these strains in a dose-dependent manner measured with a colorimetric method, and the inhibitory effect was also demonstrated by scanning electron microscopy assay. Moreover, adhesin genes biofilm-associated protein (bap), bone sialoprotein-binding protein (bbp), collagen-binding protein (cna), clumping factors A (clfA), fibronectin binding protein A and B (fnbA and fnbB), and intercellular adhesion gene BC (icaBC) were scanned, and the results shown that fnbA and icaBC were present in these three strains. Furthermore, tea catechin extracts depressed fnbA and icaBC expression in the strains. Therefore, inhibition of biofilm formation by tea catechin extracts probably was associated with downregulation of fnbA and icaBC expression in these strains.

Non-Saccharomyces (NSc) yeasts have great potential in improving wine qualities. In this study, two NSc and two Saccharomyces cerevisiae (Sc) samples were tested on their performance of mono-inoculated and composite culture in the fermentation of Chunjian citrus wine. The cell count, Brix degree, total sugar, total acidity, alcohol level, pH value, color intensity (CI), and tonality were determined to evaluate the contribution of NSc to the quality of citrus wine in the mixed fermentation. Volatile compounds were analyzed by HS-SPME-GC-MS, and sensory evaluation was carried out. During the 9-day fermentation, the mixed-culture wine exhibited a higher cell concentration than the pure culture. After the fermentation, mixed-culture wine specifically decreased the concentrations of unfavorable volatile compounds, such as isobutanol and octanoic acid, and increased favorable volatile compounds, including ethyl octanoate, ethyl decanoate, and phenylethyl acetate. The quality category of the citrus wine was improved compared with the Sc mono-inoculated wines, mainly in regard to aroma, retention, and sweetness. The study shows that the mixed fermentation of NSc and Sc has positive impacts on reducing alcohol level and total acidity and increasing CI. The present work demonstrates that the mixed fermentation of NSc and Sc has enormous beneficial impacts on improving the quality of citrus wine.

Staphylococcus aureus is a major food‐borne pathogen and easy to be induced into a viable but nonculturable state under stress conditions from food processing, causing a significant and potential risk to public health. In this study, the primers for femB gene were examined to be specific to S. aureus. 10 μM of PMA was determined as the optimal treatment concentration to minimize the PCR amplification signal produced by dead bacterial DNA. When ∼10⁷ CFU/mL of S. aureus was treated with sorbic acid, about 85% of S. aureus ATCC 6538 cells and 76% S. aureus‐1 cells were induced into VBNC state after 6 days, respectively. 1 mg/mL of Fe₃O₄ nanomagnetic beads, at 37°C for 10 min were determined as the optimal condition to separate VBNC S. aureus cells. The detection capability of Fe₃O₄‐PMA‐qPCR for VBNC S. aureus in rice, chicken, and milk was comparable with DNeasy PowerFood Microbial Kit‐PMA‐qPCR, and the detection efficiency of Fe₃O₄‐PMA‐qPCR was comparatively more excellent. Compared to commercial Kit‐PMA‐qPCR, the established Fe₃O₄‐PMA‐qPCR combined with plating assay was applied to quantify VBNC S. aureus inoculated into food samples, with advantages of specificity to S. aureus, short time, low cost, and sensitive results.