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1.
Environ Int ; 133(Pt B): 105183, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31675559

RESUMO

Swine wastewater is an important reservoir of spread antibiotic resistance to the environment. Intra- and extracellular antibiotic resistance genes (iARGs and eARGs) were quantified during two typical swine wastewater treatment processes including a sequencing membrane bioreactor (SMBR) at pilot-scale and anaerobic-anoxic-oxic (A2O) at full-scale. The concentrations of iARGs and eARGs in raw wastewater were 3.42E+09 and 3.79E+07 copies/mL, respectively. The compositions were different between iARGs and eARGs. SMBR showed 0.63 log higher removals in the concentrations of iARG than A2O, while similar removal effects (3.01-3.44 log copies/mL) of eARGs were performed by the two processes. It suggested that membrane separation had advantages in the concentration removals of iARG rather than eARG. sul1 took the dominance in eARGs in effluent and had positive correlations with intI1, which indicated the risk of horizontal gene transfer of eARGs after wastewater discharge. Microbial community structures were estimated by 16S rRNA gene sequencing with both intra- and extracellular DNA (iDNA and eDNA). Compared between the effluent samples of the two treatment processes, microbial community structures estimated by iDNA had great differences, however which were similar for eDNA. Microbial community and water-quality parameters were the major influencing factors on ARG occurrences during swine wastewater treatment.

2.
Bioresour Technol ; 295: 122191, 2019 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-31634801

RESUMO

The dynamics of antibiotic resistance genes (ARGs) response to ammonia stress were evaluated using metagenomics and quantitative PCR (qPCR) in anaerobic digestion (AD). Ammonia stress reduced ARGs associated with antibiotic efflux, especially the major facilitator superfamily (MFS) of tet(L), due to free ammonia (FA) that changed the proton gradient of efflux system. Nonetheless, ARGs of antibiotic target alteration, especially ermB, were enriched under ammonia stress, which could be attributed to the initiation of the internal enhancer of the transferability of the broad host range plasmid, pAMbeta1. Statistical analysis elucidated the significant changes of ARGs are directly attributed to the mobile genetic elements (MGEs), but the little affected ARGs are mainly determined by the functional microbes reflected by nitrogen cycling genes (NCyc). This study deciphered the profiles of ARGs response to ammonia stress in AD, which indicated the importance of alleviation of ammonia inhibition for the mitigation of ARGs dissemination.

3.
J Vis Exp ; (150)2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31498325

RESUMO

This protocol provides a method for preparation of industrialized fermented fish product with sturgeon (Aquilaria sinensis) meat product. The procedures were: (1) pretreatment of farmed sturgeon including decapitation, evisceration, skinning-off, cleaning and cutting; (2) marinating fish cubes in 6-12% (w/v) salt solution (1:1, fish cube mass to solution volume); (3) drying fish cubes to a water content of 50-60% by hot air (40-60 °C) or by vacuum; (4) fermentation involving inoculating fish cubes with 0.4-1.6% (w/w) S. cerevisiae in flavor solution to fish cubes and fermenting at 25-35 °C for 6-10 h; (5) sealing fish cubes in vacuum packages with marinating and fermenting solutions; (6) sterilizing at 115-121 °C for 10-20 min. The sturgeon meat product prepared by this method has delicious taste which is mellow and thick, has various types and large amounts of volatile flavor compounds such as alcohols and esters which could mask musty and unpleasant odor from fish, has moderate salt content but good texture properties such as high springiness, gumminess and chewiness, and has bright russet color and attractive appearance. This new technique could also be applied in the processing of other fish to provide convenient fish snack foods which could be stored at room temperature. It is appropriate for both marine and freshwater fish.

4.
Mol Med Rep ; 20(4): 3131-3139, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432112

RESUMO

Advanced glycation end products (AGEs) have been reported to serve an important role in the stiffening of cardiac tissues and myocardial cell injury. Serious myocardial cell injury can result in various heart diseases with high mortality. Halofuginone (HF), which possesses marked anti­inflammatory and antifibrotic effects, has recently been applied to inhibit the effects of cardiac stress. The present study aimed to investigate the potential effects of HF and its underlying mechanism in the treatment of AGEs­induced H9C2 cardiomyocyte damage. The western blot results of the present study demonstrated that HF may reduce the expression levels of myocardial injury markers, including myoglobin, creatine kinase MB and cardiac troponin I. In addition, flow cytometric analysis indicated that the production of reactive oxygen species (ROS) was significantly decreased by HF. Additionally, endoplasmic reticulum (ER) stress was suppressed in response to treatment with HF, as observed by low expression levels of ER stress­associated proapoptotic proteins (CCAAT/enhancer­binding protein homologous protein and cleaved caspase­12); overexpression of prosurvival proteins (growth arrest and DNA damage­inducible protein GADD34 and binding immunoglobulin protein) was also reported. Furthermore, the expression levels of microtubule­associated proteins 1A/1B light chain 3B (LC3)II/LC3I and Beclin 1 were elevated, whereas P62 expression levels were reduced following treatment with HF. These findings, together with immunofluorescence staining of LC3, indicated that HF may induce autophagy. Finally, the protective effects of HF on AGEs­treated H9C2 cells were reversed following treatment with the inhibitor 3­methyladenine, as indicated by inhibition of autophagy, and increases in apoptosis, ROS production and the ER stress response. Collectively, the findings of the present study suggested that the protective effects of HF against AGEs­induced myocardial cell injury may be associated with the induction of autophagy and amelioration of ROS­mediated ER stress and apoptosis. These findings may contribute to the development of a novel therapeutic method to inhibit the progression of myocardial cell injury.

5.
Food Chem ; 301: 125278, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31387033

RESUMO

Softening is always a problem in fish preservation. This study was aimed to investigate the role of myofibrillar structural proteins degradation in fish softening. The changes of myofibrillar structural proteins, muscle ultrastructure, myofibril fragmentation, and shear force were studied. The results indicated that during the superchilled preservation of grass carp (Ctenopharyngodon idella), small (low-molecular-weight) myofibrillar structural proteins like desmin and troponin-T initiated textural deterioration, leading to Z-disk weakening and actin loosening. In contrast, giant (high-molecular-weight) myofibrillar structural proteins like titin and nebulin were degraded in more amount in the later storage, contributing to Z-disk and M-band disassembly and vague of light and dark regions (I and A bands). Compared to each other, desmin and titin played more important part in softening. All these changes were involved in the increase of muscle fibril segments and the sharp decrease of shear force.

6.
J Mol Neurosci ; 69(2): 235-245, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31201657

RESUMO

Cancer pain induced by pancreatic carcinoma is one of the most common symptoms and is difficult to endure, especially in the advanced stage. Evidence suggests that mast cells are recruited and degranulate in enteric disease-related visceral hypersensitivity. However, whether mast cells promote the visceral pain induced by pancreatic carcinoma remains unclear. Here, using toluidine blue staining and western blotting, we observed that mast cells were dramatically recruited to tissues surrounding pancreatic carcinoma, but not inside the carcinoma in patients with severe visceral pain. The levels of mast cell degranulation products, including tryptase, histamine, and nerve growth factor, were significantly increased in pericarcinoma tissues relative to their levels in normal controls, as evidenced by enzyme-linked immunosorbent assay. We determined that systemic administration of mast cell secretagogue compound 48/80 exacerbated pancreatic carcinoma-induced visceral hypersensitivity in a male BALB/c nude mouse model as assessed by measuring the hunching behavior scores and mechanical withdrawal response frequency evoked by von Frey stimulation. In contrast, the mast cell stabilizer ketotifen dose-dependently alleviated pancreatic cancer pain. In addition, we observed incomplete development of abdominal mechanical hyperalgesia and hunching behavior in mast cell-deficient mice with pancreatic carcinoma. However, ketotifen did not further attenuate visceral hypersensitivity in mast cell-deficient mice with carcinoma. Finally, we confirmed that intraplantar injection of pericarcinoma supernatants from BALB/c nude mice but not mast cell-deficient mice caused acute somatic nociception. In conclusion, our findings suggest that mast cells contribute to pancreatic carcinoma-induced visceral hypersensitivity through enrichment and degranulation in pericarcinoma tissues. The inhibition of mast cell degranulation may be a potential strategy for the therapeutic treatment of pancreatic carcinoma-induced chronic visceral pain.

7.
Genome Biol ; 20(1): 103, 2019 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-31126313

RESUMO

BACKGROUND: Inherited factors contribute to lung cancer risk, but the mechanism is not well understood. Defining the biological consequence of GWAS hits in cancers is a promising strategy to elucidate the inherited mechanisms of cancers. The tag-SNP rs753955 (A>G) in 13q12.12 is highly associated with lung cancer risk in the Chinese population. Here, we systematically investigate the biological significance and the underlying mechanism behind 13q12.12 risk locus in vitro and in vivo. RESULTS: We characterize a novel p53-responsive enhancer with lung tissue cell specificity in a 49-kb high linkage disequilibrium block of rs753955. This enhancer harbors 3 highly linked common inherited variations (rs17336602, rs4770489, and rs34354770) and six p53 binding sequences either close to or located between the variations. The enhancer effectively protects normal lung cell lines against pulmonary carcinogen NNK-induced DNA damages and malignant transformation by upregulating TNFRSF19 through chromatin looping. These variations significantly weaken the enhancer activity by affecting its p53 response, especially when cells are exposed to NNK. The effect of the mutant enhancer alleles on TNFRSF19 target gene in vivo is supported by expression quantitative trait loci analysis of 117 Chinese NSCLC samples and GTEx data. Differentiated expression of TNFRSF19 and its statistical significant correlation with tumor TNM staging and patient survival indicate a suppressor role of TNFRSF19 in lung cancer. CONCLUSION: This study provides evidence of how the inherited variations in 13q12.12 contribute to lung cancer risk, highlighting the protective roles of the p53-responsive enhancer-mediated TNFRSF19 activation in lung cells under carcinogen stress.


Assuntos
Cromossomos Humanos Par 13 , Elementos Facilitadores Genéticos , Neoplasias Pulmonares/genética , Receptores do Fator de Necrose Tumoral/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Apoptose , Linhagem Celular Tumoral , Reparo do DNA , Regulação da Expressão Gênica , Predisposição Genética para Doença , Células HEK293 , Humanos , Desequilíbrio de Ligação , Neoplasias Pulmonares/metabolismo , Polimorfismo de Nucleotídeo Único
8.
Cell Mol Life Sci ; 76(22): 4525-4538, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31139846

RESUMO

Dosage compensation, which is achieved by X-chromosome inactivation (XCI) in female mammals, ensures balanced X-linked gene expression levels between the sexes. Although eutherian mammals commonly display random XCI in embryonic and adult tissues, imprinted XCI has also been identified in extraembryonic tissues of mouse, rat, and cow. Little is known about XCI in pigs. Here, we sequenced the porcine XIST gene and identified an insertion/deletion mutation between Asian- and Western-origin pig breeds. Allele-specific analysis revealed biallelic XIST expression in porcine ICSI blastocysts. To investigate the XCI pattern in porcine placentas, we performed allele-specific RNA sequencing analysis on individuals from reciprocal crosses between Duroc and Rongchang pigs. Our results were the first to reveal that random XCI occurs in the placentas of pigs. Next, we investigated the H3K27me3 histone pattern in porcine blastocysts, showing that only 17-31.8% cells have attained XCI. The hypomethylation status of an important XIST DMR (differentially methylated region) in gametes and early embryos demonstrated that no methylation is pre-deposited on XIST in pigs. Our findings reveal that the XCI regulation mechanism in pigs is different from that in mice and highlight the importance of further study of the mechanisms regulating XCI during early porcine embryo development.

9.
Crit Rev Food Sci Nutr ; : 1-13, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30924360

RESUMO

Fishery products are delicious, nutritional and healthy foods, and their popularity in today's market is growing. With the changes in consumer consumption expectations as well as the development of reliable cold-chains, fresh preprocessed fishery products such as fillets are more popular with consumers and producers because of their convenience for processing and cooking. However, fishery products after being removed from water have a short shelf life due to their intrinsic characteristics. Therefore, developing effective preservation technology to extend postmortem shelf life of fishery products has been an on-going area of study. This review summarizes the patterns of quality deterioration and external factors that affect postmortem quality of fishery products, and then updates the recent advances with preservation methods for fishery products including superchilling, modified atmosphere packaging, active packaging, edible coatings, irradiation and high hydrostatic pressure. Moreover, the advantages and disadvantages of each technology are discussed, and future trends for improving the preservation of fishery products are also discussed.

10.
Int J Biol Sci ; 15(2): 481-492, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30745836

RESUMO

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious disease and the most economically important disease of the swine industry worldwide. Highly pathogenic-PRRS virus (HP-PRRSV) is a variant of PRRSV, which caused high morbidity and mortality. Scavenger receptor CD163, which contains nine scavenger receptor cysteine-rich (SRCR) domains, is a key entry mediator for PRRSV. A previous study demonstrated that SRCR domain 5 (SRCR5), encoded by exon 7, was essential for PRRSV infection in vitro. Here, we substituted exon 7 of porcine CD163 with the corresponding exon of human CD163-like 1 (hCD163L1) using a CRISPR/Cas9 system combined with a donor vector. In CD163Mut/Mut pigs, modifying CD163 gene had no adverse effects on hemoglobin-haptoglobin (Hb-Hp) complex clearance or erythroblast growth. In vitro infection experiments showed that the CD163 mutant strongly inhibited HP-PRRSV replication by inhibiting virus uncoating and genome release. Compared to wild-type (WT) pigs in vivo, HP-PRRSV-infected CD163Mut/Mut pigs showed a substantially decreased viral load in blood and relief from PRRSV-induced fever. While all WT pigs were dead, there of four CD163Mut/Mut pigs survived and recovered at the termination of the experiment. Our data demonstrated that modifying CD163 remarkably inhibited PRRSV replication and protected pigs from HP-PRRSV infection, thus establishing a good foundation for breeding PRRSV-resistant pigs via gene editing technology.

11.
Food Chem ; 278: 452-459, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-30583396

RESUMO

Obscure pufferfish (Takifugu obscurus) softening during frozen storage remains to be solved. This study was therefore aimed to provide explanations by differentiate the roles of three potential factors in fish softening. The influences of ice crystal, endogenous proteolytic activities, and oxidization were distinguished by treatment of fish fillets with liquid nitrogen, iodoacetic acid, and tea polyphenol with ascorbic acid, respectively. This distinguishing method was verified to be effective by investigation in ice crystal microstructure, endogenous proteolytic activities and lipid and protein oxidation. In comparison of three factors, it showed that the shear force of fish fillets with smaller ice crystals was about 15.5% and 13.7% higher than those with the inhibition of endogenous proteolytic activities and oxidation respectively, indicating the dominant role of ice crystal in frozen fish softening. Besides, quality decline of frozen fish was initially fast and then slowed down during the storage.


Assuntos
Congelamento , Alimentos Marinhos/análise , Takifugu/metabolismo , Animais , Ácido Ascórbico/química , Cristalização , Gelo/análise , Ácido Iodoacético/química , Nitrogênio/química , Oxirredução , Peptídeo Hidrolases/química , Peptídeo Hidrolases/metabolismo , Polifenóis/química , Proteólise , Resistência ao Cisalhamento
12.
Proc Natl Acad Sci U S A ; 115(47): E11071-E11080, 2018 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-30381455

RESUMO

Substantial rates of fetal loss plague all in vitro procedures involving embryo manipulations, including human-assisted reproduction, and are especially problematic for mammalian cloning where over 90% of reconstructed nuclear transfer embryos are typically lost during pregnancy. However, the epigenetic mechanism of these pregnancy failures has not been well described. Here we performed methylome and transcriptome analyses of pig induced pluripotent stem cells and associated cloned embryos, and revealed that aberrant silencing of imprinted genes, in particular the retrotransposon-derived RTL1 gene, is the principal epigenetic cause of pregnancy failure. Remarkably, restoration of RTL1 expression in pig induced pluripotent stem cells rescued fetal loss. Furthermore, in other mammals, including humans, low RTL1 levels appear to be the main epigenetic cause of pregnancy failure.

13.
J Cell Physiol ; 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30362550

RESUMO

Excess reactive oxygen species (ROS) generated in embryos during in vitro culture damage cellular macromolecules and embryo development. Glutathione (GSH) scavenges ROS and optimizes the culture system. However, how exogenous GSH influences intracellular GSH and improves the embryo developmental rate is poorly understood. In this study, GSH or GSX (a stable GSH isotope) was added to the culture media of bovine in vitro fertilization embryos for 7 days. The cleavage rate, blastocyst rate, and total cell number of blastocysts were calculated. Similarly to GSH, GSX increased the in vitro development rate and embryo quality. We measured intracellular ROS, GSX, and GSH for 0-32-hr postinsemination (hpi) in embryos (including zygotes at G1, S, and G2 phases and cleaved embryos) cultured in medium containing GSX. Intracellular ROS significantly decreased with increasing intracellular GSH in S-stage zygotes (18 hpi) and cleaved embryos (32 hpi). γ-Glutamyltranspeptidase ( GGT) and glutathione synthetase ( GSS) messenger RNA expression increased in zygotes (18 hpi) and cleaved embryos treated with GSH, consistent with the tendency of overall GSH content. GGT activity increased significantly in 18 hpi zygotes. GGT and GCL enzyme inhibition with acivicin and buthionine sulfoximine, respectively, decreased cleavage rate, blastocyst rate, total cell number, and GSH and GSX content. All results indicated that exogenous GSH affects intracellular GSH levels through the γ-glutamyl cycle and improves early embryo development, enhancing our understanding of the redox regulation effects and transport of GSH during embryo culture in vitro.

14.
Cell Mol Life Sci ; 75(24): 4619-4628, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30259067

RESUMO

Insulin-like growth factor 2 (IGF2) is an important growth factor, which promotes growth and development in mammals during fetal and postnatal stages. Using CRISPR-Cas9 system, we generated multiple founder pigs containing 12 different mutant alleles around a regulatory element within the intron 3 of IGF2 gene. Crossing two male founders passed four mutant alleles onto F1 generation, and these mutations abolished repressor ZBED6 binding and rendered this regulatory element nonfunctional. Both founders and F1 animals showed significantly faster growth, without affecting meat quality. These results indicated that editing IGF2 intron 3-3072 site using CRISPR-Cas9 technology improved meat production in Bama pigs. This is the first demonstration that editing non-coding region can improve economic traits in livestock.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Fator de Crescimento Insulin-Like II/genética , Íntrons , Sequências Reguladoras de Ácido Nucleico , Suínos/genética , Alelos , Criação de Animais Domésticos/métodos , Animais , Cruzamento/métodos , Feminino , Genótipo , Masculino , Carne/análise , Mutação , Fenótipo
15.
Bioresour Technol ; 270: 328-336, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30241066

RESUMO

Livestock manure is a reservoir of antibiotic resistance genes (ARGs). The endogenous inhibitors that emerge during high solid anaerobic digestion (HSAD) greatly influence the bioprocess performance and the ARGs. The effect of endogenous inhibitors including volatile fatty acids (VFAs) and free ammonia (FA) on the ARG occurrences during HSAD of swine manure was investigated in this study. The ARG properties during HSAD (8%-14% total solids (TS)) largely differed from the low TS control (4%). The endogenous inhibitors and microbial communities greatly contributed to the three-phase changes in ARGs. The concentrations of VFAs and abundances of Proteobacteria and intI1 were correlated with the changes in ARGs. FA inhibition and VFA accumulation (especially propionate) delayed and restricted the decline of ARGs. The relatively slow rate of changes in ARGs and high ARGs in the end product suggested the high risk of the HSAD digestate for land application.

16.
Bioresour Technol ; 269: 300-308, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30195222

RESUMO

The hydrodynamics in the membrane module of a full-scale sMBR at 500 m3/d was simulated by computational fluid dynamics (CFD) in this study. Several key indexes, including membrane distance (d), aeration design, height of gas-liquid dispersion hm, and freeboard height hf and operational conditions, including SADp and liquid viscosity, were optimized through investigating their impacts on water velocity distribution and membrane shear stress. The CFD model was validated by comparing the simulated trace element RTD curves with experimental results. The optimal design and operational parameters for the full scale sMBR are as following: membrane distance d = 35 mm, air diffusers parallel located 75-100 mm under the bottom of the membrane module, the free board height hf adjusted to 400 mm, and the SADp recommended as 20 in the full-scale MBR studied.


Assuntos
Reatores Biológicos , Hidrodinâmica , Membranas Artificiais , Modelos Teóricos , Estresse Mecânico , Eliminação de Resíduos Líquidos
17.
Bioresour Technol ; 269: 57-66, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30149255

RESUMO

Biochemical biogas upgrading retaining more CO2 from biogas to form biomethane opens new avenues for sustainable biofuel production. For developing this technology, maintaining sustain pH for CO2·H2O is fundamental. This study proposes an innovative control strategy for in-situ biogas upgrading retaining and converting the CO2 in the biogas into CH4, via hydrogenotrophic methanogenesis without external agent. The Biogas-pH strategy limited pH drop over 7.4 by stop feeding and maintained the methanogenesis activity by biogas flow rate over 98 ml·h-1. Low pH (7.37-7.80) decrease CO2·H2O as a substrate in stage-I, higher pH (7.40-8.41) enhances CO2 to CO2·H2O transfer by 6.29 ±â€¯2.20% in stage-II. Because of that 95% CO2·H2O converts to HCO3- and CO32- when pH > 7.9, higher pH > 7.9 did not further upgrading the biogas. The carbonate buffer system shown open and close system characteristics in gas and liquid phase. The biogas CH4 was upgraded from 67.27 ±â€¯5.21% to 73.56 ±â€¯5.01%.


Assuntos
Biocombustíveis , Reatores Biológicos , Águas Residuárias , Dióxido de Carbono , Metano , Amido
18.
Int J Food Microbiol ; 285: 61-68, 2018 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-30031352

RESUMO

The effects of a chitosan-based coating on the inhibition of microbial spoilage of grass carp (Ctenopharyngodon idellus) fillets were studied during refrigerated storage for 15 days in terms of pH, total volatile base nitrogen (TVB-N), trimethylamine (TMA), adenosine triphosphate (ATP)-related compounds, K value, microbial enumeration and high-throughput sequencing. The results indicated that the fillets treated with chitosan-based coating enriched with 0.3% glycerol monolaurate and 0.5% clove essential oil had lower values of TVB-N, TMA, hypoxanthine riboside (HxR), hypoxanthine (Hx) and K value with the significant reductions (P < 0.05) of nearly 34, 73, 32, 74 and 38%, respectively, when compared to the control at day 15 of storage. Using high-throughput sequencing analysis, the major bacteria phyla of Firmicutes, Cyanobacteria and Bacteroidetes and the bacteria family of Lachnospiraceae and Bacteroidaceae were observed in fresh grass carp. As storage time increased, the coated samples retained bacterial diversity. However, Shewanellaceae, Pseudomonadaceae and Flavobacteriaceae increased and became the predominant microbiota in spoiled control samples. The significant difference between the bacteria species in the control and coated samples showed that the coating had the potential to inhibit microbial growth, especially spoilage microorganisms, and reduced quality deterioration caused by bacteria during refrigerated storage of grass carp fillets.

19.
Food Res Int ; 111: 565-573, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30007719

RESUMO

The main goal of this study was to investigate the dynamics, diversity and succession of microbial community present during the preparation of Suan yu (fermented fish), with and without starter cultures by high-throughput sequencing of 16S rRNA and ITS1 genes. Firmicutes and Ascomycota were the predominant phyla of bacteria and fungi, respectively, in all samples. At the genus level, Lactobacillus, Macrococcus and Staphylococcus were the predominating bacteria throughout the fermentation process, regardless of the inclusion of starter cultures. Saccharomyces was the predominating fungal genus in the early-fermentation stage of samples that inoculated starter cultures (MS), while the final product was dominated by Candida and Wickerhamomyces. Compared with naturally-fermented samples (NS; no starter cultures), Lactococcus, Leuconostoc, Enterococcus, Vibrio, Fusicolla and Torulaspora were inhibited and Aureobasidium emerged in samples inoculated with starter cultures (P < .05). Unweighted pair-group and principal component analyses of bacterial and fungal compositions revealed that microbiota structures differed between NS and MS samples. Redundancy analysis indicated that water content and pH might be important factors influencing the dominant bacterial and fungal community. Results indicated that microbial community were dynamic during fermentation process and the inoculation of mixed starter culture inhibited the growth of many organisms associated with food spoilage and contributed to the improvement of the quality of Suan yu products.

20.
Artigo em Inglês | MEDLINE | ID: mdl-29970829

RESUMO

A lab-scale anaerobic membrane bioreactor (AnMBR) with a side stream tubular membrane was developed to treat synthetic domestic sewage to evaluate its performance and the dynamic shift of bacterial and archaeal communities during the start-up, steady-state, overloading and recovery periods of operation at mesophilic temperatures. During the start-up period, the bacterial and archaeal communities changed drastically, and Proteobacteria and Bacteroidetes predominated. During the steady-state period, the AnMBR exhibited excellent COD removal above 91%, and COD of the effluent was below 50 mg/L. High-throughput sequencing analysis results revealed that bacterial and archaeal communities shifted significantly from the start-up to the steady-state period, and that the Proteobacteria phylum predominated on days 140, 162 and 190, and the archaea community hydrogenotrophic methanogen genus Methanolinea (1.5⁻6.64%) predominated over the aceticlastic methanogen genus Methanothrix (1.35⁻3.07%). During the overloading period, significant changes occurred in microbial community on day 210, e.g., the phyla Bacteroidetes (30%), Proteobacteria (23%) and Firmicutes (18%) predominated and the archaeal community was completely suppressed, and Methanobrevibacter (0.7%) was the only methanogen genus that emerged in the overloading period. After a shock loading period, the microbial communities exhibited significant changes within the ranks of methanogens and shifted to dominance of the aceticlastic methanogen pathway. In addition, the TVFAs to alkalinity ratio in this study was suitable as an indicator of monitoring performance in the AnMBR operation.

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