Numerical Analysis of Bacterial Meningitis Stochastic Delayed Epidemic Model through Computational Methods

Based on theWorld Health Organization(WHO),Meningitis is a severe infection of the meninges,the membranes covering the brain and spinal cord.It is a devastating disease and remains a significant public health challenge.This study investigates a bacterial meningitis model through deterministic and stochastic versions.Four-compartment population dynamics explain the concept,particularly the susceptible population,carrier,infected,and recovered.The model predicts the nonnegative equilibrium points and reproduction number,i.e.,the Meningitis-Free Equilibrium(MFE),and Meningitis-Existing Equilibrium(MEE).For the stochastic version of the existing deterministicmodel,the twomethodologies studied are transition probabilities and non-parametric perturbations.Also,positivity,boundedness,extinction,and disease persistence are studiedrigorouslywiththe helpofwell-known theorems.Standard and nonstandard techniques such as EulerMaruyama,stochastic Euler,stochastic Runge Kutta,and stochastic nonstandard finite difference in the sense of delay have been presented for computational analysis of the stochastic model.Unfortunately,standard methods fail to restore the biological properties of the model,so the stochastic nonstandard finite difference approximation is offered as an efficient,low-cost,and independent of time step size.In addition,the convergence,local,and global stability around the equilibria of the nonstandard computational method is studied by assuming the perturbation effect is zero.The simulations and comparison of the methods are presented to support the theoretical results and for the best visualization of results.

Establishment of Molecular Biological Method for Identification of Bacteria by 16S rDNA and gyrB Gene

[Objectives]The paper was to establish a molecular biological method for identification of bacterial strains.[Methods]The thalli of standard bacterial strains existing in the laboratory were collected and genomic DNA was extracted for amplification of 16S rDNA and gyrB gene.The 16S rDNA and gyrB gene sequences were obtained after sequencing.Sequences were aligned and analyzed via EzBioCloud and NCBI database,and phylogenetic trees were constructed to determine the species relationship of strains.Meantime,they were compared with known strains.[Results]This method could identify 5 standard strains accurately to the species level.The 16S rDNA and gyrB gene sequences were aligned and analyzed in EzBioCloud database and NCBI database.The strain with the max score was consistent with the known strain.And the query cover and ident were both above 99%.[Conclusions]The established molecular biological method for identification of bacterial strains by 16S rDNA and gyrB gene has good accuracy,which effectively solves the problem that the laboratory identification of bacteria relies on traditional methods and the accuracy can not be guaranteed,and further improves the identification ability of laboratory bacterial strains.

On Solutions of Generalized Bacterial Chemotaxis Model in a Semi-Solid Medium

In this paper, the Adomian’s decomposition method has been developed to yield approximate solution of bacterial chemotaxis model of fractional order in a semi-solid medium. The fractional derivatives are described in the Caputo sense. The method introduces a promising tool for solving many linear and nonlinear fractional differential equations.

Seedling Petri-dish inoculation method:A robust,easy-to-use and reliable assay for studying plant-Ralstonia solanacearum interactions

Ralstonia solanacearum causes a lethal bacterial wilt disease in many crops,leading to huge losses in crop production every year.Understanding of plant-R.solanacearum interactions will aid to develop efficient strategies to control the disease.As a soilborne pathogen,R.solanacearum naturally infects plants via roots.A huge limitation in studying plant-R.solanacearum interactions is the large variation of R.solanacearum infection assay due to the variable soil conditions and uneven inoculum exposure.Here,we developed a robust and reliable Petri-dish inoculation method which allows consistent and stable infection in young plant seedlings.This method is easy to use,takes about only 10 days from seed germination to the completion of inoculation assay,and requires less inoculum of bacteria as well as growth chamber space.We proved the efficacy of the seedling Petri-dish inoculation method by analyzing plant defense primed by molecular patterns,resistance of defense-related plant mutants,and virulence of R.solanacearum mutants.Furthermore,we demonstrated that the seedling Petri-dish inoculation method can be applied to other host plants such as tobacco and has great potential for high-throughput screening of resistant plant germplasms to bacterial wilt in the future.

Simulation of bacterial flagellar phase transition by non-convex and non-local continuum modeling

Bacterial flagellar filament can undergo a stress-induced polymorphic phase transition in both vitro and vivo environments.The filament has 12 different helical forms(phases) characterized by different pitch lengths and helix radii.When subjected to the frictional force of flowing fluid,the filament changes between a left-handed normal phase and a right-handed semi-coiled phase via phase nucleation and growth.This paper develops non-local finite element method(FEM) to simulate the phase transition under a displacement-controlled loading condition(controlled helix-twist).The FEM formulation is based on the Ginzburg-Landau theory using a one-dimensional non-convex and non-local continuum model.To describe the processes of the phase nucleation and growth,viscosity-type kinetics is also used.The non-local FEM simulation captures the main features of the phase transition:two-phase coexistence with an interface of finite thickness,phase nucleation and phase growth with interface propagation.The non-local FEM model provides a tool to study the effects of the interfacial energy/thickness and loading conditions on the phase transition.

Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) Profile of Bacterial Community from Agricultural Soils in Bauchi, North-East Nigeria

The population dynamics of bacterial community was investigated in three Agricultural soils, designated as Loamy sand (A), Peaty coarse (B) and Loamy coarse sand (C) in North-East, Nigeria. The soil chemical properties were characterized to fully understand their nature. Metagenomic approach was used to extract soil DNA using the fast DNA Spin Kit extraction technique. The PCR-electrophoresed DNA bands were excised and subjected to a full scale Denaturing Gradient Gel Electrophoresis (DGGE) analysis. DGGE fingerprinting for the PCR-16S rDNA product revealed a diverse profile of complex population of bacterial community in the study area. The study shows that more bacterial community can be fully investigated using molecular techniques rather than traditional culture method. The implication of the results obtained is discussed.

Computational Studies of Bacterial Colony Model

Microbiological experiments show that the colonies of the bacterium bacillus subtilis placed on a dish filled with an agar medium and nutrient form varied spatial patterns while the individual cells grow, reproduce and migrate on the dish in clumps. In this paper, we discuss a system of reaction-diffusion equations that can be used with a view to modelling this phenomenon and we solve it numerically by means of the method of lines. For the spatial discretization, we use the finite difference method and Galerkin finite element method. We present how the spatial patterns obtained depend on the spatial discretization employed and we measure the experimental order of convergence of the numerical schemes used. Further, we present the numerical results obtained by solving the model in a cubic domain.

李园杂草管理方式对土壤细菌群落和生态功能的影响

【目的】分析不同杂草管理方式对位于国家重点生态功能县的李园细菌群落结构和生态功能的影响,为李园土壤健康管理提供参考。【方法】以自然生草、人工生草、除草剂除草的李园和邻近天然槲栎次生林土壤为研究对象,提取土壤细菌DNA,对其ITS基因进行扩增,采用高通量测序和功能预测的方法研究细菌的多样性、群落结构及生态功能。【结果】不同处理OTU数量为2012~3522,细菌种类33门、108纲、242目、383科、667属。绿弯菌门、放线菌门、变形菌门和酸杆菌门为主要门类,在各处理中4个门的总丰度达到80%以上。多样性分析显示,天然林Ace和Chao指数显著低于李园的3个处理。群落组成和差异分析显示,天然林土壤酸杆菌优势比较大,病害细菌少,并有少量的有益细菌蛭弧菌;李园的鞘脂单胞菌相关病害的风险大,生草可在一定程度上提高芽孢杆菌等有益细菌的丰度,尤其自然生草比较明显。人工生草还有利于提高李园细菌的多样性,尤其是芽单胞菌的富集比较明显。使用除草剂的李园则主要富集了绿弯菌门的种类,而降低了苔藓杆菌的丰度。功能预测分析显示,土壤细菌新陈代谢最活跃,主要包括碳水化合物代谢和氨基酸代谢等,涉及化能异养、纤维素分解、固氮作用等功能。与其他处理比较,人工生草李园土壤硝酸还原功能较强、天然林土壤的木质素分解功能较强、除草剂处理的李园土壤甲基营养功能较强。【结论】天然林Ace和Chao指数显著低于李园,表现为土壤酸杆菌优势明显。不同杂草管理方式对李园土壤细菌群落结构和功能的影响较大,生草有利于李园有益细菌群落的建立。

响应面法优化红茶菌细菌纤维素生产条件

为提高红茶菌发酵细菌纤维素的产量,以红茶菌细菌纤维素干重为指标,采用响应面法对发酵条件进行优化,同时测定了细菌纤维素的基本理化性质。通过单因素试验及响应面法对确定红茶菌发酵生产BC的最佳培养条件为:茶汤体积分数0.83%、蔗糖质量分数10.42%、装液量70.22%、培养温度29.33℃。经验证试验,在此条件下实际得到细菌纤维素产量达4.21 g/L,较优化前(茶汤体积分数0.8%,蔗糖质量分数6%,装液量60%,培养温度30℃,产量2.63 g/L)提高了60.08%。对培养所得红茶菌纤维素干燥后进行理化性质测定,表明粗蛋白、粗淀粉、膳食纤维与灰分的质量分数分别为3.01%、1.01%、85.67%、6.1%;扫描电镜表明细菌纤维素具有超微网状结构,其纤维直径属于纳米级别;拉伸试验表明红茶菌纤维素强度约达2.28 MPa;X射线衍射分析细菌纤维素的结晶度为81.30%。利用响应面优化法有效提高了红茶菌细菌纤维的产量。

The Therapeutic Effect of Onion on the Pathogenic Bacteria of Gill Rot Disease in Grass Carp

[Objective] The curative effect of onion on bacterial rotted gill disease in grass carp was researched [Method] The combination method of taking medicine through oral and spraying was used to cure sick grass carp for 1 period of treatment in room under artificial conditions. [Result] Different concentrations of onion generated different cure rates. When the combination was adding 1.0% - 2.0% medicine into feed and spraying 2.0 g,/m3 - 5.0 g,/m3, the curative result was the best with cure rate was 70% -90% [ Conclusion] The onion was effective on curing bacterial rotted gill disease in grass carp and could be taken as curative medicine.

分光光度法与活菌计数法测定副鸡禽杆菌菌液浓度的相关性研究

为建立一种快速测定副鸡禽杆菌菌液浓度的方法,本研究选取副鸡禽杆菌血清A、B和C型代表性菌株(CVCC254株、CVCC257株和CVCC256株),培养制备菌液,分别在450、540、600、650 nm波长测定其吸光度值(OD值),同时测定活菌计数值。回归分析两组数据,获取回归方程及标准曲线,分析回归方程的测定系数(R^(2))和标准曲线的点线离散度,确定最适测定波长。再选取不同培养时间点(10、12、14、16、18、20 h)的菌液,在最适波长下测定其OD值并代入回归方程获取活菌数,同时采用活菌计数法获取活菌计数值,将两组数据使用SPSS 17.0软件进行统计分析,进一步验证分光光度法与活菌计数法测定菌液浓度的相关性。结果显示,3株菌液在600 nm波长测定的OD值与活菌计数值之间均呈最佳的线性关系,确定其菌液浓度最适测定波长均为600 nm,其回归方程分别为y=14.302x-0.1441(R^(2)=0.9962)、y=14.464x-0.2746(R^(2)=0.995)和y=14.681x-0.01326(R^(2)=0.9989),y为活菌计数值(×10^(8)CFU/mL),x为OD600值。3株培养至衰退期前的菌液在600 nm波长测定的OD值代入回归方程计算获得的活菌数值与其活菌计数值无显著差异(P>0.05)。研究结果表明,衰退期前副鸡禽杆菌菌液的分光光度法与活菌计数法具有良好的相关性。因此,该分光光度法可用于快速测定衰退期前副鸡禽杆菌菌液浓度。

页岩气生产液细菌计数方法对比研究

针对部分油气田服务企业以平板计数法、ATP荧光快速检测法代替绝迹稀释法(MPN)进行页岩气生产液中细菌含量检测的现象,将这三种细菌计数方法对相同样品的测定结果进行了对比研究。平板计数法与ATP荧光法操作均比MPN法简便,但是对于页岩气生产液,这两种方法均存在检测出的细菌类型不明确、计数结果不准确、线性关系差等缺点。平板计数法检测出的细菌主要为好氧或耐氧菌腐生菌,无法检测和鉴别与腐蚀密切相关的硫酸盐还原菌。ATP荧光法通过总菌的ATP含量换算得到细菌含量,该法目前更多用于医疗与食品行业的限制类细菌含量的快速检测,尚无明确标准可依,且无法区分菌体的死活。而MPN法可通过鉴别培养基将与腐蚀相关的硫酸盐还原菌(SRB)、铁细菌(IB)和腐生菌(TGB)分别培养后计数,且其检测限远低于另外两种方法,因此更适用于页岩气生产液中特定腐蚀菌种的检测。

ZIF-8改性细菌纤维素膜的制备及对盐酸四环素吸附性能研究

使用生物基有机材料细菌纤维素(BC)作为载体,沸石咪唑骨架-8(ZIF-8)为客体材料,采用一步真空抽滤法,制备BC/ZIF-8复合纤维膜。通过FT-IR、XRD、SEM、EDS、BET等对制备的复合纤维膜进行了结构表征,考察了接触时间、温度、离子浓度,底物的初始浓度对复合纤维膜吸附盐酸四环素(TC)的影响。结果表明改性后的复合纤维膜较初始BC膜具有更丰富的孔结构,氮气吸附-脱附曲线测得比表面积从6.2415 m^(2)/g增加到265.8820 m^(2)/g。吸附实验表明,离子浓度对吸附影响较小,吸附过程符合准二级动力学模型和Langmuir等温吸附模型,TC主要以单层吸附的形式吸附到在BC/ZIF-8复合纤维膜上,理论最大吸附量为438.59 mg/g。

新型抗生素筛选的研究进展

抗生素耐药性是一个重要的公共卫生问题,由于细菌耐药性的不断进化和传播,尤其是“超级细菌”的出现,导致传染病发病率和死亡率不断增加,治疗也变得更具挑战性,因此,新型抗生素的研究至关重要。进入抗生素后时代以来,大批新技术、新方法为新型抗生素的筛选提供了思路。本文对新型抗生素筛选和替代方法的进展进行了总结,包括从天然产物中筛选、采用化学合成或合成生物学方法筛选、基于组学技术的筛选、人工智能辅助筛选、药物再利用和联合用药以及抗生素的替代疗法如单克隆抗体疗法、噬菌体疗法。新型抗生素的筛选对于应对多耐药菌、治疗新兴疾病、提高治疗效果都具有重要意义,药物再利用、联合用药及抗生素的替代疗法可以降低药物开发的时间和成本,为医疗领域带来更多的创新和进步。

食品中菌落总数的测定分析

随着我国社会经济的持续发展,国民的物质生活水平显著提升,对食品安全的关注度也日益提高。在此背景下,相关职能部门越来越重视食品中微生物的检测,并将食品中菌落总数测定确立为一项强制性任务,以保障公众的食品安全。对此,文章首先阐述了菌落总数测定的定义和方法,然后分析了食品菌落总数测定中常见的问题,并探讨了主要的测定思路及质量控制措施,以期为保障食品中菌落总数测定工作的顺利开展提供有益参考。

基于营养琼脂培养基保温后浑浊问题与对策研究

营养琼脂培养基在50℃条件下保温18 h后,会出现浑浊现象,给无菌判定带来困难,同时也会影响菌落计数等微生物实验的准确性。为查明营养琼脂培养基在保温后出现浑浊现象的原因,以提高涉及该培养基的所有实验的准确性,文章通过复融法、磷酸盐沉淀法和初始菌控制法对其原因进行研究分析。实验结果表明,导致营养琼脂培养基在保温过程中出现浑浊现象的主要原因是培养基中初始菌含量过高,在121℃灭菌15 min的条件下无法全部灭活。针对验收过程中出现的保温浑浊问题,可以采用辐照灭菌的方法,将培养基以15~18 kgy的剂量进行辐照灭菌,降低初始菌含量,并在121℃的条件下灭菌15 min。

细菌内毒素检查微量凝胶法的研究

目的通过研究微量凝胶法确定其能否满足《中华人民共和国药典》(2020年版)(简称“《中国药典》”)要求,作为现有细菌内毒素检查法的补充。方法依据《中国药典》四部“9101药品质量分析方法验证指导原则”规定,按照其项下“杂质测定”中“限度”项目具体要求,对微量凝胶法(5μL样品+50μL鲎试剂)进行专属性、检测限、耐用度3项内容进行验证,并采用凝胶法和微量凝胶法对85批样品进行品种适用性比较研究,对384批样品进行一致性比对研究。结果经方法学验证,微量凝胶法符合《中国药典》对定性方法的要求,微量凝胶法与凝胶法相比,品种适用性与一致性比对具有等效结果。结论微量凝胶法可以作为凝胶法的补充方法在我国推广。

右旋兰索拉唑原料药的细菌内毒素检查方法研究

目的为难溶性原料药右旋兰索拉唑建立细菌内毒素检测方法。方法使用3种方法建立右旋兰索拉唑的内毒素检查方法。①乙腈溶解供试品至10 mg·mL^(-1),稀释100倍,使用凝胶法、灵敏度为0.25 EU·mL^(-1)的鲎试剂进行检测;②使用1.4 mg·mL^(-1)氢氧化钠溶解样品至10 mg·mL^(-1),稀释600倍,使用凝胶法、灵敏度为0.03 EU·mL^(-1)的鲎试剂进行细菌检测;③使用三氯甲烷溶解供试品,然后采用萃取的方法进行内毒素检测。结果3批供试品使用乙腈和1.4 mg·mL^(-1)氢氧化钠溶液溶解样品后采用检查用水稀释的方法,均可排除溶剂及供试品对细菌内毒素检测的干扰,干扰试验结果符合要求,且供试品细菌内毒素含量小于限值。符合《中华人民共和国药典》(2020年版)规定。但三氯甲烷萃取的方法存在较大干扰,结果不成立。结论建立右旋兰索拉唑原料药的细菌内毒素检测方法,解决了样品的检测难点,为其他难溶性样品建立细菌内毒素检测方法提供参考。

检验用鲎试剂及重组试剂的现状与思考

目的通过研究检验用鲎试剂及重组试剂的使用及管理现状,为细菌内毒素检测和鲎试剂使用的科学有序发展提供参考。方法结合日常医疗产品检测和管理工作实践,梳理检测用鲎试剂的相关历史沿革和国内外监管现状,分析在鲎资源短缺情况下,细菌内毒素检测主要替代方法及其所用重组试剂的基本情况。结果与结论对目前在无菌医疗产品细菌内毒素检测领域可能面临的原材料短缺、监管方式有待进一步完善等主要问题进行总结,建议明确鲎试剂的管理归属、对医疗产品检验用鲎试剂的质量标准开展标准提高及生产质量管理的研究工作、加强鲎试剂检测替代方法相关试剂的监管等。

注射用单磷酸阿糖腺苷细菌内毒素检查方法研究

目的:建立注射用单磷酸阿糖腺苷的细菌内毒素检测方法并进行方法学验证,以期对该品种的质量控制标准进行统一规范。方法:按照《中国药典》2020年版四部通则1143“细菌内毒素检查法”,确定细菌内毒素的限值,进行干扰试验,并进行内毒素检查。结果:按经验拟定的限值标准(每1mg单磷酸阿糖腺苷中含内毒素的量应小于0.06EU)对15个厂家提供的25个批次的供试品进行细菌内毒素检查,结果均符合规定。结论:本文建立的细菌内毒素检查法检查,可用于注射用单磷酸阿糖腺苷的质量控制。