Evaluation of the Membrane Damage Mechanism of Chlorogenic Acid against Yersinia enterocolitica and Enterobacter sakazakii and Its Application in the Preservation of Raw Pork and Skim Milk

Spore germination and lactic acid combined treatment: A new processing strategy for the shelf-life extension of instant wet noodles

Bacillus amyloliquefaciens (BAM) was identified as the predominant spoilage bacteria in instant wet noodles (IWNs). The utilization of industrial acid treatment as a long shelf-life strategy resulted in reduced consumer acceptance due to the acidic taste of the products. This study proposed a processing strategy that integrated spore germination (SG) and lactic acid (LA) treatment to effectively reduce the spore survival rate and extend the shelf life of IWNs. L-histidine, d-glucose, and sodium chloride were highly efficient and safe germinants for BAM spores. In IWNs, compound germinants (1.0 % L-histidine, 0.5 % d-glucose, and 1.0 % sodium chloride) boosted the SG rate by 3.61 times. With synergistic LA treatment, the spore lethality increased by 34.41 % -41.68 %. Under the SG and reduced acid-heat conditions of pH 2.30-2.50, the mortality of spores could reach 92.00 %-93.17 %, which was 14.11 %-15.28 % higher than the industrial acid-heat condition of pH 2.10. DPA, ATP, and membrane potential showed that germinants reduced the spore membrane permeability and promoted the occurrence of spore membrane damage under acid-heat conditions. Moreover, this strategy significantly extended the shelf-life of IWNs by 3.00-5.50 times and controlled the pH ≥ 5.50. Additionally, it improved color, texture, and overall sensory evaluation. Accordingly, this strategy solved the contradiction between the long shelf-life of IWNs and the unacceptable acidification in industrial production.

Comparison of the effects of chlorogenic acid isomers and their compounds on alleviating oxidative stress injury in broilers

The development of large-scale and intensive breeding models has led to increasingly prominent oxidative stress issues in animal husbandry production. Chlorogenic acid (CGA) is an important extract with a variety of biological activities. It is an effective antioxidant drug and shows different antioxidant capacities due to its different chemical structures. Therefore, it is a new research target to determine the proportion of chlorogenic acid isomers with high antioxidant activity to resist the damage caused by oxidative stress. In this experiment, the antioxidant activities of the chlorogenic acid monomer and its compounds were compared by a series of in vitro antioxidant indexes. Based on the above experiments, it was found that LB and LC have superior antioxidant abilities (P < 0.05). Subsequently, 300 healthy 1-day-old Arbor Acres (AA) male broilers with no significant difference in body weight (about 44 g) were randomly selected and randomly divided into 5 groups with 6 replicates in each group and 10 chickens in each replicate. One group was the control group, 1 group was the model group, and the remaining 3 groups were the experimental groups. At 37 d of age, animals in the control group were injected with normal saline, and animals in the other 4 groups were injected with 1 mL/kg 5% hydrogen peroxide (H2O2) through the chest muscle before the supplementation. The control group (control) and the model group (PC) were fed a standard diet. The remaining 3 groups included the CGA group, LB group (CIB), and LC group (CIC). In these groups, 50 g/t chlorogenic acid, LB compound, or LC compound were added to the basal diet, respectively, and the other feeding conditions remained consistent. The addition of the LB complex to the diet could significantly improve the growth performance and antioxidant performance of broilers (P < 0.05), upregulate the expression of Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related genes in liver and jejunum (P < 0.05), regulate the disordered intestinal flora, and alleviate the damage caused by oxidative stress. These results suggested for the first time that the LB complex exhibited superior effects in vitro and vivo.

Restoring Ampicillin Sensitivity in Multidrug-Resistant Escherichia coli Following Treatment in Combination with Coffee Pulp Extracts

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.

Chlorogenic Acid Inhibits Rahnella aquatilis KM25 Growth and Proteolytic Activity in Fish-Based Products

This work verified the antiproliferative and antiproteolytic activities of chlorogenic acid against Rahnella aquatilis KM25, a spoilage organism of raw salmon stored at 4 °C. Chlorogenic acid limited the growth of R. aqatilis KM25 in vitro at a concentration of 2.0 mg/mL. The dead (46%), viable (25%), and injured (20%) cell subpopulations were identified by flow cytometry following treatment of R. aquatilis KM25 with the examined agent. The exposure of R. aquatilis KM25 to chlorogenic acid altered its morphology. Changes in cell dimensions, mostly in length parameters from 0.778 µm to 1.09 µm, were found. The length of untreated cells ranged from 0.958 µm to 1.53 µm. The RT-qPCR experiments revealed changes in the expression of genes responsible for the proliferation and proteolytic activity of cells. Chlorogenic acid caused a significant reduction in the mRNA levels of the ftsZ, ftsA, ftsN, tolB, and M4 genes (-2.5, -1.5, -2.0, -1.5, and -1.5, respectively). In situ experiments confirmed the potential of chlorogenic acid to limit bacterial growth. A similar effect was noted in samples treated with benzoic acid, where the growth inhibition of R. aquatilis KM25 was 85-95%. Reduction of microbial R. aquatilis KM25 proliferation significantly limited total volatile base nitrogen (TVB-N) and trimethylamine (TMA-N) formation during storage, extending the shelf life of model products. The TVB-N and TMA-N parameters did not exceed the upper levels of the maximum permissible limit of acceptability. In this work, the TVB-N and TMA-N parameters were 10-25 mg/100 g and 2.5-20.5 mg/100 g, respectively; for samples with benzoic acid-supplemented marinades, the parameters TVB-N and TMA-N were 7.5-25.0 mg/100 g and 2.0-20.0 mg/100 g, respectively. Based on the results of this work, it can be concluded that chlorogenic acid can increase the safety, shelf life, and quality of fishery products.

Sandwich capture ultrasensitive sensor based on biohybrid interface for the detection of Cronobacter sakazakii

A simple, rapid and ultrasensitive visual sensing method for the detection of Cronobacter sakazakii (C. sakazakii) based on a biohybrid interface was established. During the entire sensing process, quadruple-cascade amplification showed its superior sensing performance. First, the prepared immunomagnetic beads (IMB) were used to isolate and enrich specific targets from the food matrix. After adding the fusion aptamer, the aptamer sequence specifically recognized the target and formed the immune sandwich structure of antibody-target-fusion aptamer. In addition, the fusion aptamer also included the template sequence of exponential amplification reaction (EXPAR), which contained the antisense sequence of the G-rich sequence. Therefore, a large number of G-rich sequences can be generated after EXPAR can be triggered in the presence of Bst. DNA polymerase, nicking endonuclease, cDNA, and dNTP. They were self-assembled into G-quadruplex structures and then combined with hemin to form G4/hemin DNAzyme, resulting in visible coloration and measuring absorbance at 450 nm for quantitative detection. The assay showed a limit of detection (LOD) of 2 CFU/mL in pure culture and 12 CFU/g in milk powder in optimal conditions. This method provides a promising strategy for rapid and point-of-care testing (POCT) since it does not require DNA extraction, medium culturing, and expensive instrumentation. KEY POINTS: •Single-cell level detection of C. sakazakii with ultrasensitive and rapidness •The fusion aptamer integrated recognition and amplification •Sensing analysis of C. sakazakii based on cascade amplification of biohybrid interface.