Investigation of diverse bacteria encoding histidine decarboxylase gene in Sichuan-style sausages by culture-dependent techniques, polymerase chain reaction-denaturing gradient gel electrophoresis, and high-throughput sequencing

The diverse bacteria encoding histidine decarboxylase gene during the fermentation of Sichuan-style sausages were investigated by culture-dependent techniques, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and high-throughput sequencing. All microbial indicators exhibited the advantages of mixed starter culture and the stability of microecosystem was more in the inoculation group than in the control group. DGGE and selected band sequencing were used to investigate the bacterial diversity of these sausages. Weissella were the main lactic acid bacteria (LAB) in the initial fermentation stage, whereas Weissella and Lactobacillus were the dominant bacteria in the later fermentation stage. After sequence alignment analysis, Enterobacter aerogenes and Citrobacter freundi were the two main bacteria encoding histidine decarboxylase gene and could produce histamine. These findings facilitate the better understanding of bacteria producing histidine decarboxylase during sausage fermentation and provide a theoretical basis for the control of histamine-producing bacteria in the process of fermented sausage processing.Peer reviewe

Effects of lipids with different oxidation levels on protein degradation and biogenic amines formation in Sichuan-style sausages

ABS T R A C T We evaluated the effects of different oxidation levels of lipids on protein degradation and biogenic amines (BAs) formation during Sichuan-style sausages processing. Lipids with varying degrees of oxidation were obtained through storage at different temperatures and added as raw materials of Sichuan-style sausages, followed by the analyses of lipid oxidation, protein degradation, biogenic amine content, and other indicators. During the pro-cessing, with increasing degree of lipid oxidation, the contents of peroxide value (POV), thiobarbituric acid reactive substances (TBARs), protein degradation index (PI), amino acid nitrogen (AAN), free amino acids (FAAs), and BAs increased. Based on the protein electrophoresis results, the higher the oxidation degree of pig backfat, the higher degree of sarcoplasmic protein oxidation, and the greater myofibril protein degradation. Pearson correlation revealed that lipid oxidation, protein degradation, and BAs content correlated significantly (P < 0.05).Peer reviewe

Metagenomic Analysis of Bacteria, Fungi, Bacteriophages, and Helminths in the Gut of Giant Pandas

To obtain full details of gut microbiota, including bacteria, fungi, bacteriophages, and helminths, in giant pandas (GPs), we created a comprehensive microbial genome database and used metagenomic sequences to align against the database. We delineated a detailed and different gut microbiota structures of GPs. A total of 680 species of bacteria, 198 fungi, 185 bacteriophages, and 45 helminths were found. Compared with 16S rRNA sequencing, the dominant bacterium phyla not only included Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria but also Cyanobacteria and other eight phyla. Aside from Ascomycota, Basidiomycota, and Glomeromycota, Mucoromycota, and Microsporidia were the dominant fungi phyla. The bacteriophages were predominantly dsDNA Myoviridae, Siphoviridae, Podoviridae, ssDNA Inoviridae, and Microviridae. For helminths, phylum Nematoda was the dominant. In addition to previously described parasites, another 44 species of helminths were found in GPs. Also, differences in abundance of microbiota were found between the captive, semiwild, and wild GPs. A total of 1,739 genes encoding cellulase, β-glucosidase, and cellulose β-1,4-cellobiosidase were responsible for the metabolism of cellulose, and 128,707 putative glycoside hydrolase genes were found in bacteria/fungi. Taken together, the results indicated not only bacteria but also fungi, bacteriophages, and helminths were diverse in gut of giant pandas, which provided basis for the further identification of role of gut microbiota. Besides, metagenomics revealed that the bacteria/fungi in gut of GPs harbor the ability of cellulose and hemicellulose degradation

The Optimization of Emergency Evacuation from Nuclear Accidents in China

An emergency evacuation route is an important component of emergency rescue of for nuclear accidents. A reasonable evacuation route can reduce evacuation times and protect people&rsquo;s life. The evacuation route of the nuclear power plant is abstracted into a network diagram and a mathematical model of evacuation optimization route based on the graph theory and the parity of spot diagram method in this paper. Road traffic capacity and other external factors that may affect emergency evacuation are considered in the time weight factor for each road. Finally, an example is given to verify the feasibility of the model

Evaluation of Emergency Response Measures for the LOCA of A Marine Reactor

In this study, a technical index system for nuclear accident emergency response measures was established and comprehensively evaluated by studying the impact of time, ventilation speed, and leakage speed on the radiation consequences after a loss of coolant accident (LOCA) in a marine reactor. The weight of each index was calculated by the analytic hierarchy process (AHP), and the weight of the radiation protection measure in the second-level index emergency measure was 0.625, accounting for the maximum proportion. The weights of improving radionuclide detection technology in chambers, improving detection capability, and improving the diagnosis efficiency of radiation damage in the three-level indicator emergency measures were 0.4442, 0.4384, and 0.4521, respectively, accounting for the maximum proportions. The fuzzy comprehensive evaluation method was used to quantify and comprehensively evaluate the index system of emergency measures. The quantitative evaluation result was 82.8 points, indicating that the evaluation result was adequate. Therefore, the nuclear emergency response measure based on the radiation consequences of a marine reactor LOCA is reasonable and feasible. It provides valuable measures and practical guidance for the emergency response of a marine reactor LOCA, and dramatically reduces the harm of radiation to staff and the environment

Evaluation of Emergency Response Measures for the LOCA of A Marine Reactor

In this study, a technical index system for nuclear accident emergency response measures was established and comprehensively evaluated by studying the impact of time, ventilation speed, and leakage speed on the radiation consequences after a loss of coolant accident (LOCA) in a marine reactor. The weight of each index was calculated by the analytic hierarchy process (AHP), and the weight of the radiation protection measure in the second-level index emergency measure was 0.625, accounting for the maximum proportion. The weights of improving radionuclide detection technology in chambers, improving detection capability, and improving the diagnosis efficiency of radiation damage in the three-level indicator emergency measures were 0.4442, 0.4384, and 0.4521, respectively, accounting for the maximum proportions. The fuzzy comprehensive evaluation method was used to quantify and comprehensively evaluate the index system of emergency measures. The quantitative evaluation result was 82.8 points, indicating that the evaluation result was adequate. Therefore, the nuclear emergency response measure based on the radiation consequences of a marine reactor LOCA is reasonable and feasible. It provides valuable measures and practical guidance for the emergency response of a marine reactor LOCA, and dramatically reduces the harm of radiation to staff and the environment

Evolutionary Game Model of Internal Threats to Nuclear Security in Spent Fuel Reprocessing Plants Based on RDEU Theory

The internal threat to nuclear security is one of the most serious problems in the physical protection supervision of spent fuel reprocessing plants. Both insiders and nuclear security departments have obvious characteristics of situational decision making and even irrational decision making. Combined with Game theory and RDEU theory, the RDEU Game model of insiders and nuclear security departments was constructed to analyze the existence of equilibrium solutions of two-way strategies under different emotional states. From a dynamic point of view, the influence and change process of emotion on participants’ decision-making behavior were analyzed. Then, the model was numerically simulated to verify its accuracy and effectiveness, which showed that different emotional states and intensities would not only affect the final result of evolutionary equilibrium, but also change the evolution speed of the strategies. In addition, compared with insiders, the intensity of pessimism in the nuclear security department had a greater impact on the game equilibrium. Finally, we present some reasonable recommendations to prevent and protect nuclear security events at spent fuel reprocessing plants by strengthening the emotional supervision and guidance of insiders and the nuclear security department