Molecular Epidemiology of Enteroaggregative Escherichia coli (EAEC) Isolates of Hospitalized Children from Bolivia Reveal High Heterogeneity and Multidrug-Resistance

Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen frequently associated with acute diarrhea in children and travelers to endemic regions. EAEC was found the most prevalent bacterial diarrheal pathogen from hospitalized Bolivian children less than five years of age with acute diarrhea from 2007 to 2010. Here, we further characterized the epidemiology of EAEC infection, virulence genes, and antimicrobial susceptibility of EAEC isolated from 414 diarrheal and 74 non-diarrheal cases. EAEC isolates were collected and subjected to a PCR-based virulence gene screening of seven virulence genes and a phenotypic resistance test to nine different antimicrobials. Our results showed that atypical EAEC (a-EAEC, AggR-negative) was significantly associated with diarrhea (OR, 1.62, 95% CI, 1.25 to 2.09, p < 0.001) in contrast to typical EAEC (t-EAEC, AggR-positive). EAEC infection was most prevalent among children between 7–12 months of age. The number of cases exhibited a biannual cycle with a major peak during the transition from warm to cold (April–June). Both typical and a-EAEC infections were graded as equally severe; however, t-EAEC harbored more virulence genes. aap, irp2 and pic were the most prevalent genes. Surprisingly, we detected 60% and 52.6% of multidrug resistance (MDR) EAEC among diarrheal and non-diarrheal cases. Resistance to ampicillin, sulfonamides, and tetracyclines was most common, being the corresponding antibiotics, the ones that are frequently used in Bolivia. Our work is the first study that provides comprehensive information on the high heterogenicity of virulence genes in t-EAEC and a- EAEC and the large prevalence of MDR EAEC in Bolivia.     

Discriminative graph convolution networks for hyperspectral image classification

Recently, the proposal of graph convolutional networks (GCN) has successfully implemented into hyperspectral image data representation and analysis. In spite of the great success, there are still several major challenges in hyperspectral image classification, including within-class diversity, and between-class similarity, which generally degenerate hyperspectral image classification performance. To address the problems, we propose a discriminative graph convolution networks (DGCN) for hyperspectral image classification. This method introduces the concepts of within-class scatter and between-class scatter, which respectively reflect the global geometric structure and discriminative information of the input space. The experimental results on the hyperspectral data sets show that the proposed method has good classification performance.     

浓香型白酒窖泥放线菌的原位分离及代谢特性研究

以川南某浓香型白酒生产企业50年窖龄且发酵正常的窖泥为研究对象。通过高通量测序技术分析细菌群落结构以及放线菌群落结构,利用原位分离法从中分离得到2株放线菌,结合形态鉴定、生理生化和16S rRNA基因序列比对分析确定菌种属,并对其进行耐酸、耐乙醇特性研究,基于风味导向思路,分别对2株菌进行液态培养和固态培养,采用顶空固相微萃取法和气相色谱质谱联用对发酵挥发性产物进行分析,为放线菌的相关研究和应用提供理论参考。结果显示,放线菌在该窖泥样品含有较高操作分类单元(operational taxonomic unit,OTU),相对丰度达(10.7±3.4)%,且主要分布于链霉菌亚目(Streptomycineae)和科里氏杆菌亚目(Coriobacterineae)。采用原位分离法分离放线菌,将分离得到的2株菌编号为A1、A2,菌株A1鉴定为桑氏链霉菌(Streptomyces sampsonii),菌株A2鉴定为鲁地链霉菌(Streptomyces rutgersensis)。菌株A1、A2均可在pH>4.3或乙醇体积分数<6%的环境中生长。菌株A1在液态和固态发酵条件下都会产生大量土臭素以及萜烯类物质,菌株A2在液态条件下能产生多种酯类,其中己酸乙酯相对含量(5.384%)较高,而固态条件下能够检测出大量的3-羟基-2丁酮、2,3-丁二醇和吡嗪类物质。     

Simultaneous bioelectricity generation and pollutants removal of sediment microbial fuel cell combined with submerged macrophyte

A submerged macrophyte sediment microbial fuel cell (SP-SMFC) was constructed in this study. Ceratophyllum demersum L., Vallisneria natans, Hydrilla verticillate were chosen as the submerged plants to form cer-SMFC, val-SMFC, hyd-SMFC systems. Plant groups showed the advantage of bioelectricity generation and pollutants removal compared with the unplanted system. The cer-SMFC group stood out with the maximum power density as 24.56 mW m^?2 and the average pollutants removal in overlying water (COD: 81.16%, TN: 65.27%, TP: 79.10%) and in sediments (TN: 26.40%, TP: 21.79%). The determination of root exudates and radial oxygen loss (ROL) demonstrated that C. demersum L. was superior to other studied submerged macrophytes. More root exudates may contribute to an increase in available substrates for electrochemically active bacteria and other microorganisms. Higher enzyme activities were obtained in three SP-SMFCs (especially in cer-SMFC). ATPase and APA activities in cer-SMFC group were increased by over 40% compared with the control. The results indicated that the presence of plants enhanced the microorganism activities, thereby improving bioelectricity generation and pollutants removal. This study will facilitate the application of SP-SMFC technology as an alternative for in situ remediation of polluted sediments.     

Informative and corrective responsive packaging: Advances in farm-to-fork monitoring and remediation of food quality and safety

Microbial growth and fluctuations in environmental conditions have been shown to cause microbial contamination and deterioration of food. Thus, it is paramount to develop reliable strategies to effectively prevent the sale and consumption of contaminated or spoiled food. Responsive packaging systems are designed to react to specific stimuli in the food or environment, such as microorganisms or temperature, then implement an informational or corrective response. Informative responsive packaging is aimed at continuously monitoring the changes in food or environmental conditions and conveys this information to the users in real time. Meanwhile, packaging systems with the capacity to control contamination or deterioration are also of great interest. Encouragingly, corrective responsive packaging attempting to mitigate the adverse effects of condition fluctuations on food has been investigated. This packaging exerts its effects through the triggered release of active agents by environmental stimuli. In this review, informative and corrective responsive packaging is conceptualized clearly and concisely. The mechanism and characteristics of each type of packaging are discussed in depth. This review also summarized the latest research progress of responsive packaging and objectively appraised their advantages. Evidently, the mechanism through which packaging systems respond to microbial contamination and associated environmental factors was also highlighted. Moreover, risk concerns, related legislation, and consumer perspective in the application of responsive packaging are discussed as well. Broadly, this comprehensive review covering the latest information on responsive packaging aims to provide a timely reference for scientific research and offer guidance for presenting their applications in food industry.     

Bacterial community succession and biogenic amine changes during fermentation of fish-chili paste inoculated with different commercial starter cultures

The microbial dynamics, diversity and succession characterisation during the fermentation of fish-chili paste, with and without starter cultures by high-throughput sequencing, were investigated to identify the relationship between microbial composition and the accumulation of biogenic amines. Results showed that Firmicutes was the predominant phylum, and Lactobacillus and Weissella were the main genera during fermentation process, regardless of the inclusion of starter cultures. Compared with naturally fermented samples (NS; no starter cultures), Pediococcus and Staphylococcus flourished in samples inoculated with SBM-52 starter culture (Staphylococcus xylosus + Staphylococcus carnosus + Pediococcus pentosaceus + Pediococcus acidilactici). Staphylococcus also accounted for a larger proportion in samples inoculated with WBX-43 starter culture (Staphylococcus xylosus + Staphylococcus carnosus). Furthermore, Enterobacter was inhibited in inoculated samples. Unweighted pair-group method with arithmetic means and principal component analyses revealed that microbiota structures were different among NS, SBM and WBX samples. In case of biogenic amines, the concentration of putrescine, cadaverine and tyramine increased to higher levels in NS samples compared with inoculated samples. Our work also investigated the relationship between core bacterial communities and biogenic amines. This study provided an improved understanding for the effects of starter cultures on the microbial community and the quality of fish-chili paste.     

Digital inclusion of people with disabilities: a qualitative study of intra-disability diversity in the digital realm

ABSTRACT

This paper presents an in-depth study of intra-disability diversity in the digital realm and the related role of individuality and selectiveness in the digital choices and experiences of people with disabilities (PwD). The study adopts the interactionist model of disability and problematises conceptual uniformity in research that focuses on the medical and socially-constructed features of disability as those determining digital constraints and affordances for PwD. Through primary qualitative evidence, it argues that individuality and selectiveness shape a complex terrain of intra-disability diversity, which forms the nuances and experiences of digital inclusion for PwD. Thus, it invites researchers to move beyond disability-fixed categorisations and offers a 3-tier recommendation for future research to explain the range of PwD’ perceptions and experiences in the digital realm.     

人工湿地-微生物电解池耦合系统的脱氮特性

实验构建了人工湿地-微生物电解池耦合系统（CW-MEC），并考察了CW-MEC在阴极有无曝气及不同水力停留时间（HRT）的条件下对生活污水的处理效果。实验结果显示，降低HRT会让CW-MEC阴极、阳极的COD去除率由91.11%±7.76%、86.58%±9.54%降低为77.81%±14.84%、81.44%±11.11%，氨氮去除率由58.54%±5.80%、58.22%±5.03%降低为48.04%±12.94%、48.27%±13.40%；阴极增加曝气会让CW-MEC阴极、阳极的COD去除率分别提高到89.51%±3.92%、82.40%±1.63%，阴极氨氮去除率提高到71.51%±16.44%，而阳极氨氮去除率不受影响；增加阴极曝气条件后，系统阴、阳极开始有硝酸盐氮积累，而CW-MEC阴极的硝酸盐氮含量明显低于对照组（CW-MFC）；通过电化学性能分析，相对于CW-MFC系统，CW-MEC具有更低的内阻；通过微生物多样性分析，CW-MEC系统具有更丰富的微生物多样性。     

以风化煤为底物制取生物甲烷的潜力分析

我国拥有丰富的风化煤储量,因其高度被氧化的独特性质,可应用的领域极为有限,目前主要被作为改善土壤性质的肥料和制取腐殖酸的来源。以风化煤为底物制取生物甲烷是一种具有探索性的全新生物发酵工艺,探究其可行性及模拟实验过程中风化煤的物性特征变化有利于拓宽风化煤的资源利用和环境改善,并可以进一步丰富煤生物产气理论。实验选取内蒙古乌海和山西晋城两地不同风化程度煤样,以煤层矿井水为菌种来源,在适宜环境条件下开展模拟产气实验,通过生物产气模拟和红外光谱测试,分析不同风化程度煤的生物产气能力及其内在因素,以揭示其产气潜力及物性变化特征。结果表明:①随着煤的风化程度加深,可燃基CH 4产气量明显增加,两组煤样中可燃基CH 4生成量最高分别达到7.13,4.20 mL/g;②不同风化程度的煤样均出现了产气高峰,时间基本都出现在15~30 d,各组中随着煤样风化程度不断加深,产气高峰出现时间也越来越早;③随着煤的风化程度加深,煤中芳环被不断打开,大分子结构被破坏,同时煤中羟基、氨基等基团含量趋于降低,脂碳结构逐渐解体,含氧官能团成为主要结构,氧含量比例不断增高,更容易被微生物降解;④菌群鉴定表明风化煤不仅含有大量产生生物气所需的第1阶段和第2阶段细菌,更含有甲烷杆菌属、甲烷球菌属等多种类型的产甲烷菌群,具有把风化煤转化为生物甲烷的环境条件。实验结果最终反映了风化煤具有转化为生物甲烷的潜力,并有利于提高我国风化煤的资源利用率。