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Foods (Basel, Switzerland) Oct 2021In this study, high-throughput sequencing and culture-dependent and HPLC methods were used to investigate the contribution and regulation of biogenic amines (BAs) by...
In this study, high-throughput sequencing and culture-dependent and HPLC methods were used to investigate the contribution and regulation of biogenic amines (BAs) by dominant microorganisms during fish sauce fermentation. The results showed that the microbial composition constantly changed with the fermentation of fish sauce. (40.65%), (9.23%), (2.20%), (1.80%), (0.98%), (0.94%) and (0.16%) were the dominant microflora in fish sauce. The content of BAs gradually increased as the fermentation progressed. After 12 months of fermentation, the histamine content (55.59 mg/kg) exceeded the toxic dose recommended by the Food and Drug Administration (FDA). Correlation analysis showed that dominant microorganisms have a great contribution to the accumulation of BAs. By analyzing the BA production capacity of dominant isolates, the accumulation of BAs in fish sauce might be promoted by and . Moreover, four strains with high BA reduction ability were screened out of 44 low BA-producing dominant strains, and their influence on BA accumulation in fermented foods was determined. Results demonstrated that 5-5 and JCM 2418 might be the potential starters for BA control. The present study provided a new idea for the control of BAs in fermented foods.
PubMed: 34828853
DOI: 10.3390/foods10112572 -
Biomedical and Environmental Sciences :... Oct 2021
Topics: Animals; China; Chiroptera; Drug Resistance, Bacterial; Enterococcaceae; Genotype; Gram-Positive Bacterial Infections; Phenotype; Virulence; Whole Genome Sequencing
PubMed: 34782051
DOI: 10.3967/bes2021.114 -
Microorganisms Oct 2021Lactic acid bacteria (LAB) are probiotic candidates that may restore the balance of microbiota populations in intestinal microbial ecosystems by controlling pathogens...
Lactic acid bacteria (LAB) are probiotic candidates that may restore the balance of microbiota populations in intestinal microbial ecosystems by controlling pathogens and thereby promoting host health. The goal of this study was to isolate potential probiotic LAB strains and characterize their antimicrobial abilities against pathogens in intestinal microbiota. Among 54 LAB strains isolated from fermented products, five LAB strains (NSMJ15, NSMJ16, NSMJ23, NSMJ42, and NFFJ04) were selected as potential probiotic candidates based on in vitro assays of acid and bile salt tolerance, cell surface hydrophobicity, adhesion to the intestinal epithelium, and antagonistic activity. Phylogenetic analysis based on 16S rRNA genes showed that they have high similarities of 99.58-100% to strains NSMJ15 and NFFJ04, NSMJ16, NSMJ23, and NSMJ42. To characterize their antimicrobial abilities against pathogens in intestinal microbiota, the impact of cell-free supernatant (CFS) treatment in 10% (/) fecal suspensions prepared using pooled cattle feces was investigated using in vitro batch cultures. Bacterial community analysis using rRNA amplicon sequencing for control and CFS-treated fecal samples at 8 and 16 h incubation showed the compositional change after CFS treatment for all five LAB strains. The changed compositions were similar among them, but there were few variable increases or decreases in some bacterial groups. Interestingly, as major genera that could exhibit pathogenicity and antibiotic resistance, the members of , , , , and were decreased at 16 h in all CFS-treated samples. Species-level classification suggested that the five LAB strains are antagonistic to gut pathogens. This study showed the probiotic potential of the five selected LAB strains; in particular, their antimicrobial properties against pathogens present in the intestinal microbiota. These strains would therefore seem to play an important role in modulating the intestinal microbiome of the host.
PubMed: 34683462
DOI: 10.3390/microorganisms9102141 -
Food Science and Biotechnology Sep 2021Sufu is a common solid-state traditional fermented food made from soybean. Huase sufu is a typical type found in several provinces of China, especially in Hubei....
UNLABELLED
Sufu is a common solid-state traditional fermented food made from soybean. Huase sufu is a typical type found in several provinces of China, especially in Hubei. However, little is known about the bacterial community. High-throughput sequencing technology revealed that the dominant taxa at phylum level were: Firmicutes, Proteobacteria and Bacteroides, and at the genus level were: , , , etc. Additionally, LEfSe revealed that compared with the bacterial community of red sufu and white sufu, the biomarker genera for both huase sufu were , and . Moreover, there were twenty-eight hubs for the huase sufu samples, and four of them were dominant genera: , , , . These results provide a new insight into our understanding of the bacterial diversity of huase sufu, and will facilitate the isolation, screening, and development potential bacterial strains for production of huase sufu.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s10068-021-00963-3.
PubMed: 34603822
DOI: 10.1007/s10068-021-00963-3 -
Frontiers in Microbiology 2021Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its... (Review)
Review
Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its widespread presence in soil, sediment, and aquatic environments, which poses a threat to non-target crops, animals, humans, and ecosystems. Therefore, the removal of DUR from contaminated environments has been a hot topic for researchers in recent decades. Bioremediation seldom leaves harmful intermediate metabolites and is emerging as the most effective and eco-friendly strategy for removing DUR from the environment. Microorganisms, such as bacteria, fungi, and actinomycetes, can use DUR as their sole source of carbon. Some of them have been isolated, including organisms from the bacterial genera , , , , , , and and fungal genera , , , , , , and A number of studies have investigated the toxicity and fate of DUR, its degradation pathways and metabolites, and DUR-degrading hydrolases and related genes. However, few reviews have focused on the microbial degradation and biochemical mechanisms of DUR. The common microbial degradation pathway for DUR is transformation to 3,4-dichloroaniline, which is then metabolized through two different metabolic pathways: dehalogenation and hydroxylation, the products of which are further degraded cooperative metabolism. Microbial degradation hydrolases, including PuhA, PuhB, LibA, HylA, Phh, Mhh, and LahB, provide new knowledge about the underlying pathways governing DUR metabolism. The present review summarizes the state-of-the-art knowledge regarding (1) the environmental occurrence and toxicity of DUR, (2) newly isolated and identified DUR-degrading microbes and their enzymes/genes, and (3) the bioremediation of DUR in soil and water environments. This review further updates the recent knowledge on bioremediation strategies with a focus on the metabolic pathways and molecular mechanisms involved in the bioremediation of DUR.
PubMed: 34475856
DOI: 10.3389/fmicb.2021.686509 -
Life (Basel, Switzerland) Jul 2021Knowledge of the composition of the gut microbiota in freshwater fish living in their natural habitat has taxonomic and ecological importance. Few reports have been...
Knowledge of the composition of the gut microbiota in freshwater fish living in their natural habitat has taxonomic and ecological importance. Few reports have been produced on the composition of the gut microbiota and on the presence of LAB in the intestines of freshwater fish that inhabit river environments. In this study, we investigated the LAB community that was present in the gastrointestinal tract (GIT) of Mediterranean trout () that colonized the Biferno and Volturno rivers of the Molise region (Italy). The partial 16S rRNA gene sequences of these strains were determined for the species-level taxonomic placement. The phylogenetic analysis revealed that the isolated LABs belonged to seven genera ( and ). The study of the enzymatic activities showed that these LABs could contribute to the breakdown of polysaccharides, proteins, and lipids. In future studies, a greater understanding of how the LABs act against pathogens and trigger the fish immune response may provide practical means to engineer the indigenous fish microbiome and enhance disease control and fish health.
PubMed: 34357039
DOI: 10.3390/life11070667 -
Food Science & Nutrition Jul 2021According to the appearance and technology, traditional fermented Douchi can be divided into dried Douchi and wet Douchi. However, there are few reports on the...
According to the appearance and technology, traditional fermented Douchi can be divided into dried Douchi and wet Douchi. However, there are few reports on the difference of bacterial community structure between them or the influence of bacterial community on product flavor. In this study, high-throughput sequencing technology and electronic nose were used to measure the bacterial diversity and flavor of 40 Douchi samples, and the correlation between them was explored by multivariate statistical means combined with COG database. Results showed that the cumulative average relative abundance of Firmicutes and Proteobacteria in the samples was as high as 95.93%, and the former was the core bacteria phylum. On the whole, the dominant bacteria in Douchi were (50.67%), (14.07%), (2.54%), (1.61%), (1.46%), (1.26%), (1.24%), and (1.19%). LEfSe analysis indicated that can be used as a biomarker in dried fermented soybeans. Meanwhile, dried samples contained more intensive aromatic substances, but were significantly lower in W6S (selectivity to hydrogen) and W3S (methane-aliph) compared with the wet samples. and were helpful to the formation of aromatic flavor in Douchi, but and were the opposite. Gene and microbial phenotypic prediction showed that microorganisms in dried Douchi use protein more efficiently, while in wet Douchi, microbial energy metabolism was more vigorous. The pathogenic potential of microorganisms in dried samples was higher than that in wet. This study can sound the alarm for improving the safety of home-brewed Douchi and provide guidance for the subsequent screening of strains that enhance the flavor of fermented soybeans.
PubMed: 34262706
DOI: 10.1002/fsn3.2280 -
Plants (Basel, Switzerland) Jun 2021Antimicrobials are widely applied in aquaculture for treatment of infectious diseases in fish. The increased antimicrobial resistance of fish pathogens to conventional...
Antimicrobials are widely applied in aquaculture for treatment of infectious diseases in fish. The increased antimicrobial resistance of fish pathogens to conventional antimicrobial treatment highlights the need for research on the antibacterial properties of natural products-in this case, essential oils (EOs). The aim of the present study was to detect the antimicrobial activity of the essential oils on pathogenic microorganisms found in freshwater fish. Freshwater fish isolates of spp., spp., spp., spp., spp., spp., spp., and spp. were tested for antimicrobial resistance and antimicrobial activity against 14 commercially available essential oils. Antimicrobial resistance was identified in spp. isolates against cefepime and ciprofloxacin; while all , , and isolates were fully susceptible. All tested EOs revealed antimicrobial activity against the tested freshwater fish isolates at different extents. exhibited strong antimicrobial activity against spp. (3.12 μL/mL), spp. (0.78-1.56 μL/mL), and spp. with the MIC method. EOs of and showed strong antibacterial activity against spp. and spp. (6.25 μL/mL). The study shows the antimicrobial activity of EOs against the most relevant freshwater fish pathogens and indicates the application opportunities in aquaculture.
PubMed: 34206270
DOI: 10.3390/plants10071265 -
Proceedings of the National Academy of... Jun 2021While it is well recognized that the environmental resistome is global, diverse, and augmented by human activities, it has been difficult to assess risk because of the...
While it is well recognized that the environmental resistome is global, diverse, and augmented by human activities, it has been difficult to assess risk because of the inability to culture many environmental organisms, and it is difficult to evaluate risk from current sequence-based environmental methods. The four most important criteria to determine risk are whether the antibiotic-resistance genes (ARGs) are a complete, potentially functional complement; if they are linked with other resistances; whether they are mobile; and the identity of their host. Long-read sequencing fills this important gap between culture and short sequence-based methods. To address these criteria, we collected feces from a ceftiofur-treated cow, enriched the samples in the presence of antibiotics to favor ARG functionality, and sequenced long reads using Nanopore and PacBio technologies. Multidrug-resistance genes comprised 58% of resistome abundance, but only 0.8% of them were plasmid associated; fluroquinolone-, aminoglycoside-, macrolide-lincosamide-streptogramin (MLS)-, and β-lactam-resistance genes accounted for 2.7 to 12.3% of resistome abundance but with 19 to 78% located on plasmids. A variety of plasmid types were assembled, some of which share low similarity to plasmids in current databases. Enterobacteriaceae were dominant hosts of antibiotic-resistant plasmids; physical linkage of extended-spectrum β-lactamase genes (, , , and ) was largely found with aminoglycoside-, MLS-, tetracycline-, trimethoprim-, phenicol-, sulfonamide-, and mercury-resistance genes. A draft circular chromosome of was assembled; it carries MLS-, tetracycline- (including and on an integrative conjugative element), and trimethoprim-resistance genes flanked by many transposase genes and insertion sequences, implying that they remain transferrable.
Topics: Animals; Anti-Bacterial Agents; Base Sequence; Cattle; Drug Resistance, Microbial; Environmental Microbiology; Feces; Gene Regulatory Networks; Genes, Bacterial; Genetic Linkage; Genetic Variation; Host Specificity; Microbiota; Phylogeny; Plasmids; Sequence Analysis, DNA
PubMed: 34161269
DOI: 10.1073/pnas.2024464118 -
Food Science and Biotechnology Mar 2021The effects of vacuum package combined with 0.1% ε-polylysine and 0.2% rosemary extract (V + RP) on the quality attributes and microbial communities of large yellow...
The effects of vacuum package combined with 0.1% ε-polylysine and 0.2% rosemary extract (V + RP) on the quality attributes and microbial communities of large yellow croaker () during ice storage were investigated. The quality was evaluated by chemical characteristics (total volatile basic nitrogen (TVB-N), K-value and biogenic amines (BAs)), microbiological indexes (Total viable counts (TVC), bacteria counts, bacteria counts, Psychrophilic bacteria counts (PBC)), changes in microbial composition were analyzed using high-throughput sequencing. Results showed that the increase of TVB-N, K-value, microorganisms and BAs could be inhibited by V + RP. and were detected in all samples. increases rapidly in the middle of storage. and were related to the decomposition of ATP, the formation of BAs, and TVB-N, respectively. In conclusion, V + RP presented the optimal effects, which could extend the shelf life of large yellow croaker for another 9 days compared with the control.
PubMed: 33868757
DOI: 10.1007/s10068-021-00880-5