Isolation and characterization of a novel Acidithiobacillus ferrivorans strain from the Chilean Altiplano: attachment and biofilm formation on pyrite at low temperature

Microorganisms are used to aid the extraction of valuable metals from low-grade sulfide ores in mines worldwide, but relatively little is known about this process in cold environments. This study comprises a preliminary analysis of the bacterial diversity of the polyextremophilic acid River Aroma located in the Chilean Altiplano, and revealed that Betaproteobacteria was the most dominant bacterial group (Gallionella-like and Thiobacillus-like). Taxa characteristic of leaching environments, such Acidithiobacillus and Leptospirillum, were detected at low abundances. Also, bacteria not associated with extremely acidic, metal-rich environments were found. After enrichment in iron- and sulfur-oxidizing media, we isolated and identified a novel psychrotolerant Acidithiobacillus ferrivorans strain ACH. This strain can grow using ferrous iron, sulfur, thiosulfate, tetrathionate and pyrite, as energy sources. Optimal growth was observed in the presence of pyrite, where cultures reached a cell number of 6.5·10⁷ cells mL⁻¹. Planktonic cells grown with pyrite showed the presence of extracellular polymeric substances (10 °C and 28 °C), and a high density of cells attached to pyrite grains were observed at 10 °C by electron microscopy. The attachment of cells to pyrite coupons and the presence of capsular polysaccharides were visualized by using epifluorescence microscopy, through nucleic acid and lectin staining with Syto^®9 and TRITC-Con A, respectively. Interestingly, we observed high cell adhesion including the formation of microcolonies within 21 days of incubation at 4 °C, which was correlated with a clear induction of capsular polysaccharides production. Our data suggests that attachment to pyrite is not temperature-dependent in At. ferrivorans ACH. The results of this study highlight the potential of this novel psychrotolerant strain in oxidation and attachment to minerals under low-temperature conditions.     

胞外聚合物葡聚糖和DNA对粪肠球菌根管生物膜形成的影响

目的 研究胞外多糖和胞外DNA对粪肠球菌在人牙本质片上黏附并形成生物膜过程中的作用.方法 制备牙本质片,分成葡聚糖酶(Dextranase)组、DNA酶(DNaseI)组和对照组,体外培养获得粪肠球菌的牙本质生物膜标本.采用活菌菌落计数法、激光共聚焦扫描显微镜结合COMSTAT软件分析胞外聚合物对牙本质黏附菌量和生物膜三维结构的影响.结果 相同生物膜膜龄,Dextranase组和DNaseI组粪肠球菌牙本质黏附菌量均少于对照组,差异具有统计学意义(P＜0.05),其中1 h黏附菌量分别下降至对照组的15.61%、18.39%.激光共聚焦显微镜观察到Dextranase和DNaseI对粪肠球菌牙本质生物膜的形成有影响,处理后生物膜结构松散,生物量、底层覆盖率及平均厚度均下降,具有统计学意义(P＜0.0167),其中生物量由(3.95±0.09)μm3/μm2下降至(0.36±0.08)μm3/μm2、(1.05±0.06)μm3/μm2.DNaseI对成熟牙本质生物膜产生显著降解作用,而Dextranase对成熟牙本质生物膜作用不明显.结论 胞外多糖和胞外DNA是粪肠球菌生物膜的重要成分,对其初始黏附和生物膜三维结构起重要作用.     

Making sticky cells: effect of galactose and ferrous iron on the attachment of Leptospirillum ferrooxidans to mineral surfaces

The purpose of this study was to compare the efficacy of galactose and high initial ferrous iron concentrations as inducers for extracellular polymeric substances (EPS) production in planktonic cells of Leptospirillum ferrooxidans and to study cell attachment to a mineral surface in comparison to cells not exposed to such substances. L. ferrooxidans was successfully adapted to grow in a modified 9K medium at different concentrations of galactose (0.15, 0.25, 0.35%) and also at different initial ferrous iron concentrations (18, 27, 36 g/L), which are higher than 9K medium (9 g/L). The experiments were done in shake flasks using ferrous iron as energy source. A comparison of growth kinetics showed a decreasing of maximum specific growth rate of L. ferrooxidans with increasing concentrations of galactose and initial ferrous iron. The EPS content increased and the EPS chemical composition (relative abundance of carbohydrates, proteins and ferric iron) changed with increasing concentrations of galactose and initial ferrous iron. Results revealed that the increase of the bacterial adhesion rather depended on the chemical composition, i.e. relative abundance of the constituents of the EPS, than on the total amount of EPS. The EPS induced by galactose seemed to be “stickier” than the one induced by ferrous iron. Based on the results of this study it is proposed that galactose might enhance biooxidation processes which needs to be tested in future studies.     

Identification,antifungal resistance profile,in vitro biofilm formation and ultrastructural characteristics of Candida species isolated from diabetic foot patients in Northern India

Purpose: Diabetic foot ulcers are a serious cause of diagnostic and therapeutic concern. The following study was undertaken to determine the fungal causes of diabetic foot ulcers, with their phenotypic and genotypic characterisation. Materials and Methods: A total of 155 diabetic foot ulcers were studied for 1 year. Deep tissue specimen was collected from the wounds, and crushed samples were plated on Sabouraud dextrose agar with chloramphenicol (0.05 g). Identification was done by growth on cornmeal agar, germ tube formation and urease test. For molecular identification, conserved portion of the 18S rDNA region, the adjacent internal transcribed spacer 1 (ITS1) and a portion of the 28S rDNA region were amplified, using the ITS1 and ITS2 primers. Antifungal susceptibility against voriconazole, fluconazole and amphotericin B was determined by standard broth microdilution method. Biofilm formation was studied in three steps. First, on the surface of wells of microtiter plates followed by quantification of growth by fungal metabolism measurement. Finally, biofilms were analysed by scanning electron microscopy (SEM). Results: Fungal aetiology was found in 75 patients (48.38%). All were identified as Candida species (100%). The prevalence of different species was Candida tropicalis (34.6%), Candida albicans (29.3%), Candida krusei (16.0%), Candida parapsilosis (10.6%), Candida glabrata (9.33%). All were susceptible to amphotericin B (100%). On microtiter plate, all the isolates were viable within 48 h showing biofilms. The metabolic activity of cells in the biofilm increased with cellular mass, especially in the first 24 h. On SEM, majority showed budding yeast form. Conclusion: Non-albicans Candida spp. with potential biofilm forming ability are emerging as a predominant cause of diabetic foot ulcers.     

XTT assay for evaluating the effect of alcohols, hydrogen peroxide and benzalkonium chloride on biofilm formation of Staphylococcus epidermidis

To analyze the degree of biofilm formation on three ica-positives Staphylococcus epidermidis as a function of biocides, the medium was supplemented with increasing concentrations of isopropanol, ethanol, and methanol at 0, 1, 4, 6, 8, 10, 12 and 14% (v/v), hydrogen peroxide (0, 0.125, 0.25, 0.5, 1, 2, 3, 4 and 5% v/v) and benzalkonium chloride (0, 0.125, 0.25, 0.5, 1, 2, 3, 4 and 6 μg ml⁻¹).     

Insights into the biology of acidophilic members of the Acidiferrobacteraceae family derived from comparative genomic analyses

The family Acidiferrobacteraceae (order Acidiferrobacterales) currently contains Gram negative, neutrophilic sulfur oxidizers such as Sulfuricaulis and Sulfurifustis, as well as acidophilic iron and sulfur oxidizers belonging to the Acidiferrobacter genus. The diversity and taxonomy of the genus Acidiferrobacter has remained poorly explored. Although several metagenome and bioleaching studies have identified its presence worldwide, only two strains, namely Acidiferrobacter thiooxydans DSM 2932^T, and Acidiferrobacter spp. SP3/III have been isolated and made publically available.Using 16S rRNA sequence data publically available for the Acidiferrobacteraceae, we herein shed light into the molecular taxonomy of this family. Results obtained support the presence of three clades Acidiferrobacter, Sulfuricaulis and Sulfurifustis. Genomic analyses of the genome sequences of A. thiooxydans^T and Acidiferrobacter spp. SP3/III indicate that ANI relatedness between the SPIII/3 strain and A. thiooxydans^T is below 95–96%, supporting the classification of strain SP3/III as a new species within this genus. In addition, approximately 70% of Acidiferrobacter sp. SPIII/3 predicted genes have a conserved ortholog in A. thiooxydans strains. A comparative analysis of iron, sulfur oxidation pathways, genome plasticity and cell-cell communication mechanisms of Acidiferrobacter spp. are also discussed.     

Phenotypic and genomic characterization of the antimicrobial producer Rheinheimera sp. EpRS3 isolated from the medicinal plant Echinacea purpurea: insights into its biotechnological relevance

In recent years, there has been increasing interest in plant microbiota; however, despite medicinal plant relevance, very little is known about their highly complex endophytic communities. In this work, we report on the genomic and phenotypic characterization of the antimicrobial compound producer Rheinheimera sp. EpRS3, a bacterial strain isolated from the rhizospheric soil of the medicinal plant Echinacea purpurea. In particular, EpRS3 is able to inhibit growth of different bacterial pathogens (Bcc, Acinetobacter baumannii, and Klebsiella pneumoniae) which might be related to the presence of gene clusters involved in the biosynthesis of different types of secondary metabolites. The outcomes presented in this work highlight the fact that the strain possesses huge biotechnological potential; indeed, it also shows antimicrobial effects upon well-described multidrug-resistant (MDR) human pathogens, and it affects plant root elongation and morphology, mimicking indole acetic acid (IAA) action.     

Exploring the antibacterial mechanism of essential oils by membrane permeability,apoptosis and biofilm formation combination with proteomics analysis against methicillin-resistant staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the important causes of food poisoning and infectious diseases worldwide, it can produce a large number of virulence factors, enhance the colonization ability of the host so that it can quickly colonize and spread on the surface of the objects. Essential oil (EO) is one of the natural products with antimicrobial properties, can be used as an important source of antibacterial agent discovery, and has a broad development prospect. However, the unclear mechanisms of antibacterial action have become an obstacle to its further development and use. Hence, the objective of the present study was to reveal the antibacterial mechanism of EO from Amomum villosum Lour (A villosum Lour) against MRSA using label-free quantitative proteomics, investigate the effect of EO on the bacterial proteome, enzymatic activities and leakage of bacterial intracellular biomacromolecule. Proteomic analysis of MRSA in the presence of EO found that a total of 144 differential expressed proteins (DEPs) between the control and treatment group, in which 42 proteins were distinctly up-regulated and 102 proteins were down-regulated. Besides, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, determination of cell membrane permeability and apoptosis, scanning electron microscopy (SEM) observations, bacterial surface hydrophobicity, and biofilm formation measurement were performed. Collectively, the above results indicated that the cell membrane damage by EO leads to the loss of membrane integrity and causes leakage of intracellular macromolecular substances, inhibition of protein, and biofilm synthesis. These findings manifested that EO exerts antibacterial effect by multiple avenues and expands our understanding of the antibacterial mechanism, it has potential application value in food preservative and pharmaceutical industries.     

Influence of extracellular fluid volume expansion on magnesium,calcium and phosphate handling along the rat nephron

Summary Renal tubular handling of P, Ca, Mg and Na was studied in the rat both before and during mild hypertonic NaCl loading (ECVE), using micropuncture and clearance techniques and electron microprobe analysis. Micropuncture was performed at the late proximal and early distal tubule sites. ECVE significantly increased the urinary output of all four elements. In the case of Mg, the increase was relatively small and dependend of reabsorption all along the entire length of the nephron. For Ca, it depended on the inhibition of proximal reabsorption, partially compensated by increased reabsorption along the loop. For P, it depended on proximal inhibition, no important net phosphate movement occuring in the loop during both periods. Ca reabsorption was highly correlated to that of sodium along the proximal tubule and Henle's loop. This was not the case for Mg and P. In the loop, Ca and Mg reabsorption were closely related to the load delivered at the beginning of the structure. These observations are compatible with the view that tubular reabsorption of Ca and Mg is concentration rather than Tm limited, and that reabsorption of Ca, unlike that of Mg, is linked to the movements of sodium. Following ECVE, the difference between early distal and urinary deliveries increased significantly for Ca and P, but not for Mg. For phosphate, this difference accounted for by 45% of the delivery at the early distal tubule site, at variance with microinjection data obtained in the rat under similar salt loading conditions, which indicated that 17% only of the phosphate distal delivery were reabsorbed along the terminal segments. This discrepancy is discussed in terms of nephron functional heterogeneity.Collaborateur temporaire de thèse C.E.A.     

Projections from the reticular formation of the medulla, the spinal trigeminal and lateral reticular nuclei to the inferior olive

Injections of tritiated L-leucine were placed in the reticular formation of the medulla, the spinal trigeminal and lateral reticular nuclei of cats and silver grain accumulations in the inferior olivary nucleus were demonstrated by autoradiography. Cells of the reticular formation located at the junction of nuclei reticularis magnocellularis and reticularis parvocellularis in the rostral medulla and within nucleus reticularis ventralis in the caudal medulla contribute four distinct projections to the olive. Three projections are distributed ipsilaterally in the caudal part of the medial accessory olive, at mid-level of the dorsal accessory olive and in the ventrolateral bend of the principal olive, at rostral levels. There is also a small controlateral projection to the caudal part of the medial accessory olive. the spinal trigeminal nucleus sends crossed projections to the rostral part of the dorsal accessory olive and adjacent ventral lamella as well as to the caudal part of the medial accessory olive. The lateral reticular nucleus sends an extensive ipsilateral projection to the caudal part of the medial accessory olive and provides a small contribution to the same subdivision, contralaterally. All these projections converge with other known afferents to the olive.     

一例输入性非典型肺炎患者病原体的分离鉴定及其变异性研究

目的 对一例输入性非典型肺炎病例的病原体进行分离鉴定，研究其变异情况，为该病的诊断和防治提供依据。方法 用Vero E6细胞对病人的咽拭标本进行分离培养，并对分离物使用电镜、间接免疫荧光(IFA)、巢式PCR及S基因核苷酸序列测定等方法进行分析。结果 在该病人的咽拭标本中，成功地分离到一株冠状病毒(R69)，将部分S基因测序并与不同地区非典型肺炎病人分离株进行比较，表明分离到的毒株为一种新型冠状病毒。结论 目前存在冠状病毒的变异株，病毒核苷酸序列与广东省原发性SABS病人分离到的冠状病毒有所不同。     

基于Scopus数据分析多能干细胞研究领域的文章、作者及高影响力机构

文题释义： 文献计量学：是以文献体系和文献计量特征为研究对象,采用数学、统计学等计量研究方法,研究文献情报的分布结构、数量关系、变化规律和定量管理,进而探讨科学技术的某些结构、特征和规律的一门学科。主要应用于科学出版物评价、科研工作评价、学科发展评价、机构评价等。 CiteScore(CS)：即Scopus数据库的核心指标,CS被定义为某期刊前3年发表的文献在统计当年被引用次数除以该刊前3年发表的文献数。CS和JCR中的核心指标影响因子(IF)是同类指标,都是某期刊一定引证时间窗口内论文的篇均被引频次。二者的主要区别有3个方面：①引证时间窗口不同：IF的引证时间窗口为2年,而CS为3年;②IF和CS的分子和分母所包含的文献类型不同：IF分子为期刊所有类型文献被引频次,分母仅计数可被引文献(论文和综述),而CS分母为期刊所有类型文献;③引证数据来源不同：计算IF所用的被引频次来源于WoS,而计算CS所用被引频次来源于Scopus。 背景：多能干细胞为许多疾病治疗带来了新的曙光,各国对该领域的投入和重视都在加强。 目的：为从事多能干细胞研究的中国机构或作者提供参考,促进该研究领域的质量提升与国际竞争力。 方法：利用Elsevier公司出版的Scopus数据库,使用关键词“pluripotent stem cell”OR“pluripotential stem cell”OR“multipotent stem cell”OR“multipotential stem cell”对2014至2018年发表的多能干细胞研究领域的文献进行了回顾性检索,并将检索得到的文献利用分析工具SciVaL和微软软件Excel2007做统计分析,揭示了全球文献产出学者、机构、高影响力论文以及中国的研究现状。 结果与结论：①2014至2018年Scopus数据库共收录多能干细胞研究领域文献18 508篇,领域加权影响因子为1.43,其中医学学科产出6 398篇,领域加权影响因子为1.38,27.7%的文章处于高被引地位,48.4%的文章发表在高影响力期刊上,27%的文献是国际合作完成;②发文量最多的机构是哈佛大学805篇,共有1 732位作者,总被引21 654次。中国科学院发文量排在第4位,一共发表394篇,1 139位作者,总被引5 313次;③发文量最多的个人是来自斯坦福大学的JOSEPH教授117篇,总被引2 878次,H指数74;④5篇被引大于500的论文中,有2篇是综述文献,3篇研究论文;日本有6个机构进入亚洲机构前10位,中国紧随其后有3个,印度1个;中国发文最多的作者是裴端卿教授45篇,总被引864次;⑤结果表明,2014至2018年美国哈佛大学处于领先地位,其产出和影响力都显著,在全球发文最多的10名学者中美国和日本各占3席,德国占据2席,中国在该领域有影响力的学者或机构还有待努力。通过综合分析高影响力研究机构、研究作者、研究文章,为多能干细胞领域的科学研究提供前瞻性思考。 ORCID: 0000-0002-9470-0440(何林) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Confirmed Zika virus infection in a Belgian traveler returning from Guatemala,and the diagnostic challenges of imported cases into Europe

We report the first laboratory-confirmed Zika virus (ZIKV) infection in a Belgian traveler after a three week holiday in Guatemala, December 2015. This case along with other imported cases into Europe emphases once again the need for accurate diagnostic tools for this rapidly emerging virus. The challenge is to diagnose patients in the acute phase, which appears short, as serological testing is complicated by cross-reactivity, vaccination status and scarce availability of specific ZIKV tests.