Quantitative characterization and dynamics of bacterial communities in ready-to-eat chicken using high-throughput sequencing combined with internal standard-based absolute quantification

Unlocking the structure-activity relationship of mangrove condensed and hydrolysable tannins: Unveiling their potential ecological significance in antioxidant and antibacterial functions

Tannins play key roles in regulating ecological processes within mangrove ecosystems, but the structures of mangrove condensed tannins (CT) and hydrolysable tannins (HT), as well as their antioxidant and antibacterial activities, are not well understood. In this study, MALDI-TOF MS was used to analyze the structural components of oligomers and polymers in phenolic extracts from Kandelia obovata, Aegiceras corniculatum, and Sonneratia apetala. Results identified two primary structural units: procyanidins (PC) and prodelphinidins (PD), with mass-to-charge ratios of 288 Da and 304 Da, respectively, and a 16 Da interval indicating differences in hydroxylation. Thiolysis degradation and acidic hydrolysis, combined with HPLC-ESI-MS, revealed significant variations in the mean degree of polymerization (mDP): oligomers had mDP values of 1.1-1.2, while polymers ranged from 7.8 to 9.1. Antioxidant assays (Folin-Ciocalteu, FRAP, TEAC, and DPPH) showed that PC < PD < HT in antioxidant capacity, with polymers exhibiting stronger activity than oligomers. Antibacterial tests revealed that A. corniculatum exhibited the weakest activity, while K. obovata and S. apetala showed similar efficacy against bacteria from Actinobacteria, Bacteroidetes, and Proteobacteria. This study enhances our understanding of mangrove phenolics' structural characteristics and their ecological roles in maintaining mangrove ecosystem functions.

Prediction of chicken breast meat freshness based on hyperspectral imaging technique and high-throughput sequencing

In this article, the hyperspectral imaging technique and the high-throughput sequencing were combined to construct prediction models for the freshness of chicken breast meat. The quality indicators including color, pH, TVC, TVB-N and TBARS were measured to reflect the freshness changes of chicken breast meat under 4 ℃ storage. Meanwhile, spectral images of chicken breast meat were obtained using visible near-infrared (400-1,000 nm) hyperspectral imaging. Through high-throughput sequencing, the major spoilage bacteria including Pseudomonas, Brochothrix and Escherichia were screened out to construct the models for predicting chicken freshness. After spectral preprocessing and characteristic wavelength selection, the prediction models were established using partial least squares regression (PLSR) and support vector machine (SVM). Among the models, the SNV-PLSR model based on characteristic wavelength for Pseudomonas content (Rp2=0.84, RMSEP=0.38, RPD=3.79) posed stronger predictive and generalization abilities. Therefore, the Pseudomonas count was chosen as a characteristic indicator for establishing an HSI-based prediction model to reflect the freshness of chicken breast meat.

Biofilm Compositions and Bacterial Diversity on Kitchen Towels in Daily Use

Towels with complex woven structures are susceptible to biofilm formation during daily use. The composition of biofilms formed on towels used under real-life conditions has yet to be studied. Thus, we investigated the color changes, structural integrity, and biofilm development on towels used continuously for 10 weeks by 12 volunteers in specific kitchen environments. Apparent biofilms composed of bacteria and extracellular polymeric substances (EPSs) were found on all used towels. The bacteria concentrations ranged from 4 to 7 log CFU/g. Proteins were the most abundant EPS, followed by polysaccharides and eDNA. A high-throughput sequencing method was employed to investigate the bacterial diversity on the towels. The predominant bacterial genera differed from towel to towel. Kocuria, Rothia, Psychrobacter, Enhydrobacter, and Pseudomonas are genera of relatively high abundance that may originate from the human body and foods. In addition, correlations among environmental factors, major bacterial genera, physical properties, and biofilm formation of the towels were analyzed, which could provide a scientific reference for maintaining towel hygiene.

Unraveling the spoilage characteristics of refrigerated pork using high-throughput sequencing coupled with UHPLC-MS/MS-based non-targeted metabolomics

The spoilage of refrigerated pork involves nutrient depletion and the production of spoilage metabolites by spoilage bacteria, yet the microbe-metabolite interactions during this process remain unclear. This study employed 16S rRNA high-throughput sequencing and non-targeted metabolomics based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to reveal the core microbiota and metabolite profiles of pork during refrigeration. A total of 45 potential biomarkers were screened through random forest model analysis. Metabolic pathway analysis indicated that eleven pathways, including biogenic amine metabolism, pentose metabolism, purine metabolism, pyrimidine metabolism, phospholipid metabolism, and fatty acid degradation, were potential mechanisms of pork spoilage. Correlation analysis revealed nine metabolites-histamine, tyramine, tryptamine, D-gluconic acid, UDP-d-glucose, xanthine, glutamine, phosphatidylcholine, and hexadecanoic acid-as spoilage biomarkers, with Pseudomonas, Serratia, and Photobacterium playing significant roles. This study provides new insights into the changes in microbial and metabolic characteristics during the spoilage of refrigerated pork.

Insights into microbial contamination and antibiotic resistome traits in pork wholesale market: An evaluation of the disinfection effect of sodium hypochlorite

Chlorine and its derivatives, such as sodium hypochlorite (NaClO) and chlorine dioxide, are frequently employed as disinfectants throughout the pork supply chain in China. Nevertheless, the extensive use of NaClO has the potential to cause the creation of 'chlorine-tolerant bacteria' and accelerate the evolution of antibiotic resistance. This study evaluated the efficacy of NaClO disinfection by examining alterations in the microbiome and resistome of a pork wholesale market (PWM), and bacteria isolation and analysis were performed to validate the findings. As expected, the taxonomic compositions of bacteria was significantly different before and after disinfection. Notably, Salmonella enterica (S. enterica), Salmonella bongori (S. bongori), Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Pseudomonas aeruginosa (P. aeruginosa) were observed on all surfaces, indicating that the application of NaClO disinfection treatment in PWM environments for pathogenic bacteria is limited. Correlations were identified between antibiotic resistance genes (ARGs) associated with aminoglycosides (aph(3'')-I, aph(6')-I), quinolone (qnrB, abaQ), polymyxin (arnA, mcr-4) and disinfectant resistance genes (emrA/BD, mdtA/B/C/E/F). Furthermore, correlations were found between risk Rank I ARGs associated with aminoglycoside (aph(3')-I), tetracycline (tetH), beta_lactam (TEM-171), and disinfectant resistance genes (mdtB/C/E/F, emrA, acrB, qacG). Importantly, we found that Acinetobacter and Salmonella were the main hosts of disinfectant resistance genes. The resistance mechanisms of the ARGs identified in PWM were dominated by antibiotic deactivation (38.7%), antibiotic efflux (27.2%), and antibiotic target protection (14.4%). The proportion of genes encoding efflux pumps in the PWM resistome increased after disinfection. Microbial cultures demonstrated that the traits of microbial contamination and antibiotic resistane were consistent with those observed by metagenomic sequencing. This study highlights the possibility of cross-resistance between NaClO disinfectants and antibiotics, which should not be ignored.