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A traditional Thai fermented pork, nham, is a product popularly consumed in Thailand. Fermentation of the protein-rich product by uncontrolled bacterial community can result in high amounts of hazardous biogenic amines (BA). This study aimed to unveil dynamics of microbial community and its relation to BA accumulation in nham. Three batches of nham were analyzed for pH, lactic acid bacteria population, concentrations of organic acids and BA. Bacterial communities were analyzed by pyrosequencing of 16S rRNA gene amplicons. In all batches, pH dropped to the quality standard of nham (≤4.6) within 3-5 days by production of lactic acid and acetic acid. Initial BA levels varied batch-by-batch and increased with fermentation time. In the highest quality batch, levels of histamine, tyramine, and total BA were within the recommended safety limits (200, 100 and 1000 mg/kg, respectively) throughout the 10-days study. However, in other batches, unsafe levels of tyramine and total BA were found after 5 days of fermentation. The results indicated that over-fermentation and inferior conditions of ingredients increased risk due to high levels of BA. Lactobacillus, Lactococcus, Pediococcus and Weissella were prevalent and comprised >90% of total bacteria during fermentation. Weissella was predominant in the batch with low BA while Lactobacillus and Pediococcus were predominant in the higher BA batches. A negative correlation between Weissella dominance and total BA was observed (r = -0.90, p = .003). A 10% increase in dominance of Weissella was associated with 75-170 mg/kg decrease in total BA. W. hellenica was the species prevalent only in low BA batch. Therefore, W. hellenica isolates were suggested as subjects for future study to develop efficient starter culture securing safety of nham., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Aquaculture, the production of farm-raised fish, is a major industry that employs and feeds millions of individuals across the globe, but which may also be a nexus of emerging public health threats. This study examined potential health risks associated with integrated aquaculture operations by with One Health approach using a suite of tools to study water contamination sources, pathogens, antibiotic resistant bacteria, and bacterial community in the water from fishponds. Water samples from 27 fishponds across 9 villages were collected in Jiangmen City, China. Microbial source tracking, pathogens (including Salmonella and Arcobacter), toxin-producing Microcystis, and antibiotic resistant bacteria (ARB) resistant to tetracycline, sulfonamide, and carbapenem were quantified with qPCR. Bacterial community was determined with next-generation sequencing. All ponds exceeded E. coli single-day maximum criteria of US, and 67% ponds exceeded World Health Organization (WHO) waste-fed aquaculture guidelines for protecting consumers and pond workers, representing a high degree of fecal contamination and potential pathogen risks in these ponds. The majority of the ponds were positive for human- (84%) and pig- (41%) associated fecal contamination. Salmonella and microcystin-producing Microcystis were detected in 37% and 15% of the ponds, respectively, while Arcobacter was not detected in any ponds. ARB were highly prevalent. Among the measured factors, canonical correspondence analysis and network analysis demonstrated that secchi depth, temperature and conductivity were the major environmental elements impacting the bacterial community structure, while Proteobacteria and Actinobacteria were the major biological factor. This study demonstrated the presence of intersecting health risk factors in aquaculture facilities and can lay the foundation for addressing these risks in aquaculture management in rural China, with potential applicability in other developing regions dependent on aquaculture., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To assess interchangeability of estimates of bacterial abundance by different epifluorescence microscopy methods, total bacterial numbers (TBNs) determined by most widely accepted protocols were statistically compared. Bacteria in a set of distinctive samples were stained with acridine orange (AO), 4'-6-diamidino-2-phenylindole (DAPI), and BacLight and enumerated by visual counting (VC) and supervised image analysis (IA). Model II regression and Bland-Altman analysis proved general agreements between IA and VC methods, although IA counts tended to be lower than VC counts by 7% on a logarithmic scale. Distributions of cells and latex beads on polycarbonate filters were best fitted to negative binomial models rather than to Poisson or log-normal models. The fitted models revealed higher precisions of TBNs by the IA method than those by the VC method. In pairwise comparisons of the staining methods, TBNs by AO and BacLight staining showed good agreement with each other, but DAPI staining had tendencies of underestimation. Although precisions of the three staining methods were comparable to one another (intraclass correlation coefficients, 0.97 to 0.98), accuracy of the DAPI staining method was rebutted by disproportionateness of TBNs between pairs of samples that carried 2-fold different volumes of identical cell suspensions. It was concluded that the TBN values estimated by AO and BacLight staining are relatively accurate and interchangeable for quantitative interpretation and that IA provides better precision than does VC. As a prudent measure, it is suggested to avoid use of DAPI staining for comparative studies investigating accuracy of novel cell-counting methods.