基于多波长透射光谱法的水体细菌微生物检测能力初步研究

搭建的水体细菌微生物多波长透射光谱快速测量实验系统,实验获取了肺炎克雷伯菌、金黄色葡萄球菌和大肠杆菌在不同浓度下220～900 nm范围内的多波长透射光谱,研究建立了三种细菌基于不同波长点及全光谱波段的浓度校准曲线,计算了肺炎克雷伯菌、金黄色葡萄球菌和大肠杆菌的检测限,并与紫外-可见分光光度计测量分析结果进行了对比。结果表明,实验系统与紫外-可见分光光度计测量光谱线性相关系数在0.999 8以上,具有非常好的一致性,且30次光谱信号采集时间仅需15 s;基于实验系统分析得到三种细菌在220,258,300,350,400,450,500和550 nm不同波长点以及全光谱波段的检测限结果均优于紫外-可见分光光度计,且利用多波长透射光谱全光谱波段计算得到的细菌检测限均最低,其中：肺炎克雷伯菌、金黄色葡萄球菌和大肠杆菌的检测限分别为1.60×104,1.06×104和1.16×104 cells·mL-1。研究结果为进一步发展水体细菌微生物的多波长透射光谱快速定量检测技术提供了基础数据。     

半导体纳米粒子SERS基底对大肠杆菌的无损检测研究

很多致命的疾病都与细菌感染密切相关,快速、准确地检测和鉴定细菌及微生物,一直是微生物学家及有关科研工作者追求的目标,拉曼光谱可以提供丰富的谱图信息,而表面增强拉曼光谱(SERS)有很高的检测灵敏度,然而一些贵金属SERS基底却容易使蛋白质变性,影响检测结果。以大肠杆菌(E.Coli)作为目标检测细菌,首先检测到大肠杆菌的拉曼光谱,之后采用两种不同的SERS基底(ZnO,Ag溶胶)进行检测。结果表明Ag溶胶基底有很强且较丰富的SERS信号,但是相对于E.Coli的本体拉曼谱峰有较大位移,说明与银溶胶相互作用的细菌存在一定的蛋白质变性过程;而ZnO纳米粒子与细菌作用的SERS信号虽然较弱,但是与E.Coli的本体拉曼信号较为相似,说明ZnO纳米粒子对E.Coli本体基本无损,这将有利于SERS在生物体系的无损检测。该结果可以为利用生物相容性好的半导体SERS基底进行细菌的检测提供有益的参考。     

微波辅助细菌纤维素酯的制备及对Pb(Ⅱ)的高效去除

以细菌纤维素(BC)为原料,通过微波辅助酯化改性的方法制得了两种改性细菌纤维素,细菌纤维素黄原酸酯(XMBC)和细菌纤维素硫酸酯(SMBC)。对所制备的样品进行X射线衍射(XRD)、扫描电镜-电子能谱(SEM-EDS)、傅里叶变换红外(FT-IR)光谱和BET比表面积分析,通过续批式实验考察其对Pb(Ⅱ)的去除效果。研究了pH值、反应时间、温度、污染物初始浓度、离子强度对其吸附能力的影响以及材料再生性能。结果表明,改性细菌纤维素的比表面积和孔容均有上升,其对Pb(Ⅱ)的吸附量随反应温度和离子强度的增加而降低,最优pH值为5.0。巯基的引入增强了细菌纤维素对Pb(Ⅱ)的吸附能力,改性后的吸附剂显示出比原始BC更优异的吸附性能,其中XMBC和SMBC的最大吸附量分别为144.93和126.58 mg·g^-1,该吸附过程符合准二级速率方程和Langmuir等温吸附模型。材料对Pb(Ⅱ)的吸附是自发的放热过程,且吸附剂易于再生和重复回收。因此, SMBC和XMBC作为从水中富集分离重金属的新型材料具有及大应用前景。     

Bacterial Cellulose Nanopaper as Reinforcement for Polylactide Composites: Renewable Thermoplastic NanoPaPreg

Bacterial cellulose (BC) is often regarded as a prime candidate nano‐reinforcement for the production of renewable nanocomposites. However, the mechanical performance of most BC nanocomposites is often inferior compared with commercially available polylactide (PLLA). Here, the manufacturing concept of paper‐based laminates is used, i.e., “PaPreg,” to produce BC nanopaper reinforced PLLA, which has been called “nanoPaPreg” by the authors. It is demon­strated that high‐performance nanoPaPreg (v_f = 65 vol%) with a tensile modulus and strength of 6.9 ± 0.5 GPa and 125 ± 10 MPa, respectively, can be fabricated. It is also shown that the tensile properties of nanoPaPreg are predominantly governed by the mechanical performance of BC nanopaper instead of the individual BC nanofibers, due to difficulties impregnating the dense nanofibrous BC network.

     

Multimodal approach for diagnosis of bacterial etiology in brain abscess

Background and purpose

Proton magnetic resonance spectroscopy (PMRS) has high sensitivity and specificity for the detection of pyogenic brain abscess and the categorization of bacteria. But the metabolite patterns failed to evaluate the etiology of disease when the culture results are sterile. The aim of the present study is to compare the multimodality techniques viz., conventional culture, MR spectroscopy and 16S rRNA PCR and sequencing for rapid diagnosis of etiology in brain abscess and evaluate the PMRS in culture sterile samples and also demonstrate the sensitivity and specificity of these techniques.

Methods

Thirty five patients underwent MRI on a 3 T MRI and in-vivo PMRS for the diagnosis and evaluation of various resonances of metabolites such as lipid (LIP), lactate (LAC), acetate (AC), amino acid (AC), succinate (SUC). Pus was collected for identification of etiologic agents by culture and molecular method.

Results

In 35 samples, metabolite patterns were as follows: LIP/LAC/AA, n = 17, LIP/LAC/AA/SUC with or without AC, n = 17 and LIP/LAC/AA/AC, n = 1. Culture showed bacterial growth in 22 samples (18 aerobic/facultative anaerobic, 9 anaerobic) whereas molecular method was detected 26 aerobic/facultative anaerobic, 13 anaerobic, 4 microaerophilic bacteria. Among the 13 sterile samples, molecular method detected 16 microorganisms along with 3 mixed infections and PMRS recognized metabolite patterns as LIP/LAC/AA, n = 5 and LIP/LAC/AA/SUC with or without AC, n = 8. The sensitivity of in-vivo PMRS in sterile samples was 100% and 75%, and specificity was 75% and 100% for aerobic and anaerobic organisms respectively.

Conclusion

Based on metabolite resonances, PMRS can detect slow growing and fastidious organisms and classify them into aerobic and anaerobic bacteria which are difficult to culture by conventional method. It can categorize microorganisms even in culture sterile samples with rational sensitivity and specificity which may allow early choice of targeted therapy.     

Production of bacterial cellulose from alternate feedstocks

Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents in cluded low-solids (LS) and high-solids (HS) potato effluents, cheese whey permeate (CW), or sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did strain 10821 and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, and LS was unsuitable for production by strain 10821. However, strain 23770 produced 17% more cellulose from LS than from glucose, indicating that unamended LS could serve as a feedstock for bacterial cellulose.     

家兔注射兔瘟疫苗对药品热原检测结果影响的研究

探讨家兔注射兔瘟疫苗后对细菌内毒素发热灵敏度的影响因素,实验结果表明：家兔注射兔疫苗后对细菌内毒素发热灵敏度未见明显影响。但家兔注射免疫瘟疫苗后有一升温过程,可持续５天,无合格证的家兔,对细菌内毒素发热的灵敏度个体差异很大,可影响药品热原检测结果的准确性。     

Stereochemical differentiation and simultaneous analysis of 3-, 4-, and 5-hydroxyalkanoic acids from biopolyesters by multidimensional gas chromatography

The direct enantioselective analysis of 3-, 4-, and 5-hydroxy fatty acids from biological material has been achieved by enantioselective multidimensional gas chromatography (enantio-MDGC) with heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)- or (2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. All the bacteria investigated produced polyesters of enatiomerically pure (R) configured compounds.     

Electrochemical attachment of motile bacterial cells to gold

Selective attachment of Escherichia coli K-12 bacterial cells to charged gold surfaces was demonstrated. Electrostatic binding of E. coli K-12 bacterial cells to positively charged surfaces was observed starting at +750 mV. The binding of E. coli K-12 cells to positively charged gold surfaces is proposed to occur due to long-range electrostatic interactions between the negatively charged O-chain of lipopolysaccharide (LPS) molecules protruding the bacterial cell body and the electrode surface. Removing LPS alters the cellular surface charge and results in cellular attachment to negatively charged surfaces. Thus, applying an electrical potential allows for the direct, real time detection of live, dead or damaged bacterial cells. The attachment of E. coli K-12 bacterial cells to surfaces with an applied potential substantiates the hypothesis that an electrostatic interaction is responsible for the binding of bacterial cells to positively charged molecular assemblies on surfaces used for building bacterial microarrays.