The impact of bacterial size on their survival in the presence of cationic particles of nano-silver

BackgroundMicrobial surface area is one of the battlegrounds for invading microbes and host defense. Hence, infectious diseases caused by drug resistant microbes with large surface area are more difficult to treat than small size microbes. Nanobiology offers opportunities to re-explore the biological properties of conventional drugs at molecular level to combat these microbes. The purpose of the present study was to examine size depended susceptibility of Gram-positive bacteria towards nano-silver particles.MethodsThis study investigated the growth, surface charge, and morphology of emerging B. megaterium MTCC 7192 and re-emerging S. aureus MTCC 3160 cells in order to observe the susceptibility of these bacteria towards cationic nano-silver particles. Nano-silver particles were applied into wells formed on the Nutrient agar plates containing 10⁸ CFU/mL of the bacteria. Surface potential of normal and treated cells was measured by Microtrac and the effects of nano-silver particles on bacterial cells were assessed by Scanning Electron Microscopy (SEM).ResultsIn this work, synthesized nano-silver particles were found to be more effective against B. megaterium MTCC 7192 than S. aureus MTCC 3160. For B. megaterium MTCC 7192, a 0.30 fold increase in inhibition zone was observed after the addition of nano-silver particles in the wells. From our studies, it is reasonable to state that alternation of zeta potential may affect the cell morphology, which was further confirmed by SEM.ConclusionThe present study concluded that nano-silver particles appears to interact with a larger surface area more effectively.     

Pegylated Eu-enabled submicron alumina spheres as potential theranostics agent RD cell line as model

ObjectivesThis study is aimed to synthesis and evaluate PEGylated Eu enabled spherical alumina submicron particles (s-Al₂O₃:Eu) for potential theranostic applications.MethodsThis study is bisected into two parts, a) synthesis of PEGylated Eu enabled spherical alumina submicron particles (s-Al₂O₃:Eu), and b) characterization of the synthesized particles to determine their efficacy for potential theranostic applications.The synthesis of the particles involved the following steps. In the first step, s-Al₂O₃:Eu is synthesized using solvothermal synthesis. In the next step, the particles undergo post synthesis water–ethanol treatment and calcination. The surface of the synthesized s-Al₂O₃:Eu particles is then coated by PEG to increase its biocompatibility.Once the particles are prepared, they are characterized using different techniques. The microstructure, composition and structure of the particles is characterized using SEM, EDX and XRD techniques. The detection of the functional groups is done using FTIR analysis. The photoluminescence emission spectrum of s-Al₂O₃:Eu is studied using Photoluminescence spectroscopy. And, finally, the biocompatibility is studied using MTT assay on RD cell lines.ResultsThe microstructure analysis, from the micrographs obtained from SEM, shows that the spherical alumina particles have a submicron size with narrow size distribution. The compositional analysis, as per EDX, confirms the presence of Oxygen, Aluminum and Europium in the particles. While, XRD analysis of s-Al₂O₃:Eu confirms the formation of alpha alumina phase after calcination at 700 °C. Emission peaks, obtained by Photoluminescence emission spectroscopy, show that the optimum emission intensities correspond to the transition from ⁵D₀ to ⁷F_j orbital of Eu⁺³. FTIR analysis confirms the successful coating of PEG. Finally, a cell viability of more than 86% is observed when the biocompatibility of the particles is studied, using MTT assay on RD cell lines.Conclusionss-Al₂O₃:Eu with narrow distribution are successfully synthesized. Structural and functional characterizations support the suitability of s-Al₂O₃:Eu as potential theranostic agent.     

The effect of long-term exposures to hypersaline particles originated from drying Urmia hypersaline Lake on the increased cardiovascular risks in the villagers around the Lake

Abstract

Background and Objectives: The world’s second largest permanent hypersaline lake, Lake Urmia, is drying in recent years and the dried bed of the Lake acts as a hypersaline particle emission source. Therefore, we aim to evaluate (for the first time to our knowledge) the association between hypersaline particles and biomarkers of inflammation and coagulation (hs-CRP and fibrinogen) in the residents around the Lake Urmia.

Methods: Three regions were selected as clean (region No.1) and polluted regions (region No.2 and No.3) for ambient particulate matter around the Urmia Lake from 2008 to 2015. In order to confirm the selected regions concentration of APM was measured in the selected regions for six months. Totally 123 participants were selected randomly, fibrinogen, hs-CRP and covariates were measured in the selected regions and were analyzed using multiple linear regression models.

Results: We found a statistically significant association between the hypersaline particles and fibrinogen in both polluted regions. This is while an association between hypersaline particles and hs-CRP was significant only in the polluted region No.2.

Conclusions: These results are consistent with our hypothesis that long-term exposure to hypersaline particles originated from drying Urmia hypersaline Lake is related to increased levels of hs-CRP and fibrinogen.     

生物磁谱分析技术在OA患者关节液磨屑颗粒评估中的初步应用

目的:随着人群的老龄化,骨关节炎(osteoarthritis,OA)已成为老年人最常见的疾病之一,严重影响老年人生活质量。而OA传统的诊断方法敏感性差,往往在确诊时,疾病已经发展到了晚期。本研究拟运用生物磁谱分析技术(bio-ferrography)来初步分析研究OA患者关节液中磨屑颗粒的参数,进而为OA的早期诊断提供依据。方法:选取符合纳入标准的2017年9月至2017年12月我科住院收治的OA患者。采集患者关节液后,运用bio-ferrography技术分离、收集关节液中的软骨磨屑颗粒和骨性磨屑颗粒,进一步通过扫描电镜(scanning electron microscope,SEM)观测磨屑颗粒的外形、数量和大小等参数。结果:随着患者OA等级的进展,软骨颗粒和骨性颗粒的数量均在增加,磨屑颗粒外形变得越来越锐利和不规则。在Kellgren-Lawrence(K-L)1级OA患者的关节液中,无骨性颗粒的存在,在K-L 1～3级OA患者的关节液中,软骨颗粒数量显著多于骨性颗粒。结论:我们初步探讨了通过bio-ferrography技术观测OA患者关节液中的磨屑颗粒,并评估了不同K-L分级OA患者关节液中磨屑颗粒的统计学特点,为今后建立以bio-ferrography技术为基础的OA早期诊断标准奠定了基础。     

Scan path optimization with/without clustering for active beam delivery in charged particle therapy

PurposeTo compare different algorithms to optimize the scanning path in charged particle therapy with quasidiscrete scanning. We implemented a Hybrid Genetic Algorithm with Heuristics (HyGA) and combined it with clustering techniques. The performance was compared to Simulated Annealing (SA) and to commercially available treatment planning system (TPS).MethodsPerformance and clinical implications were assessed using data from 10 patients treated at CNAO (Centro Nazionale di Adroterapia Oncologica). Clinical treatments are performed relying on beam deflection, avoiding irradiation for transitions between adjacent spots larger than 2 cm. A clustering method was implemented with HyGA (HyGA_Cl), which assumes beam deflection during transition between clusters. Clinical performance was determined as the total number of particles delivered during spot transitions and the number of particles wasted due to beam deflection. Results were compared to scan paths obtained with CNAO TPS.ResultsSA and HyGA produced on average shorter paths compared to the currently available TPS. This did not result in a reduction of transit particles, due to the concomitant effect of beam deflection out of the extraction line. HyGA_Cl achieved 2% average reduction in transit particles when compared to CNAO TPS. As a drawback, wasted particles increased, due to more frequent use of beam deflection. Both the SA and HyGA algorithms reduced the number of wasted particles.ConclusionSA and HyGA proved to be the most cost-effective methods in reducing wasted particles, with benefits in terms of shorter scan paths. A decrease in transit particles delivered with beam deflection can be achieved using HyGA_Cl.     

Particle size influence in an impaction bone grafting model. Comparison of fresh-frozen and freeze-dried allografts

BackgroundImpaction bone grafting with large particles is considered as mechanically superior to smaller morsels. Interest of freeze-dried irradiated bone for impaction bone grafting has been observed with small particles. Influence of bone process on other particle sizes still needed to be assessed.Material and methodsTwenty-four osteoarthrotic femoral heads were used to prepare fresh-frozen and freeze-dried irradiated cancellous bone. Each group was divided into four batches of different particle sizes, each batch containing 18 samples. The different particle sizes were obtained with a Retsch Cross Beater Mill SK 100, Noviomagus rotating bone mills with two sizes of rasps and a Luer bone rongeur. Bone grafts were impacted in a contained cylinder. Stiffness was monitored during impaction.ResultsFreeze-dried irradiated grafts showed higher stiffness than fresh-frozen bone whatever the size of the particles. Large particles obtained with the rongeur and the large rasp from the Noviomagus bone mill were mechanically superior than small particles up to 30 impactions.InterpretationLarge particles offer better mechanical performance as a greater magnitude of force would be required to deform and break the particles. Freeze-dried irradiated bone brittleness reduces this advantage after 30 impactions. Large particles embrittlement leads to similar mechanical results as small particles at higher impaction rate. This may account for partial collapse of the graft layer in clinical situation when impaction rate is lower. This model supports the use of small particles obtained with thin rasp bone mill when freeze-dried irradiated bone for impaction bone grafting and large particles obtained with the Rongeur when fresh-frozen bone is available.     

High-frequency metabolite profiling and the incidence of recurrent cardiac events in patients with post-acute coronary syndrome

Abstract

Purpose: The aim of this study was to study temporal changes in metabolite profiles in patients with post-acute coronary syndrome (ACS), in particular prior to the development of recurrent ACS (reACS).

Methods: BIOMArCS (BIOMarker study to identify the Acute risk of a Coronary Syndrome) is a prospective study including patients admitted for ACS, who underwent high-frequency blood sampling during 1-year follow-up. Within BIOMArCS, we performed a nested case-cohort analysis of 158 patients (28 cases of reACS). We determined 151 metabolites by nuclear magnetic resonance in seven (median) blood samples per patient. Temporal evolution of the metabolites and their relation with reACS was assessed by joint modelling. Results are reported as adjusted (for clinical factors) hazard ratios (aHRs).

Results: Median age was 64 (25th–75th percentiles; 56–72) years and 78% were men. After multiple testing correction (p?<?0.001), high concentrations of extremely large very low density lipoprotein (VLDL) particles (aHR 1.60/SD increase; 95%CI 1.25–2.08), very large VLDL particles (aHR 1.60/SD increase; 95%CI 1.25–2.08) and large VLDL particles (aHR 1.56/SD increase; 95%CI 1.22–2.05) were significantly associated with reACS. Moreover, these longitudinal particle concentrations showed a steady increase over time prior to reACS. Among the other metabolites, no significant associations were observed.

Conclusion: Post-ACS patients with persistent high concentrations of extremely large, very large and large VLDL particles have increased risk of reACS within 1?year.     

Simulation of dose distribution and secondary particle production in proton therapy of brain tumor

AimThe aim of this study is simulation of the proton depth-dose distribution and dose evaluation of secondary particles in proton therapy of brain tumor using the GEANT4 and FLUKA Monte Carlo codes.BackgroundProton therapy is a treatment method for variety of tumors such as brain tumor. The most important feature of high energy proton beams is the energy deposition as a Bragg curve and the possibility of creating the spread out Bragg peak (SOBP) for full coverage of the tumor.Materials and methodsA spherical tumor with the radius of 1 cm in the brain is considered. A SNYDER head phantom has been irradiated with 30−130 MeV proton beam energy. A PMMA modulator wheel is used for covering the tumor. The simulations are performed using the GEANT4 and FLUKA codes.ResultsUsing a modulator wheel, the Spread Out Bragg Peak longitudinally and laterally covers the tumor. Flux and absorbed dose of secondary particles produced by nuclear interactions of protons with elements in the head are considerably small compared to protons.ConclusionsUsing 76.85 MeV proton beam and a modulator wheel, the tumor can be treated accurately in the 3-D, so that the distribution of proton dose in the surrounding tissues is very low. The results show that more than 99% of the total dose of secondary particles and protons is absorbed in the tumor.     

运用偏振光观测聚乙烯磨屑颗粒诱导人工关节假体无菌性松动

目的:探讨运用偏振光显微镜来观测无菌性松动人工关节假体周围的聚乙烯颗粒分布,评估其在研究磨屑颗粒诱导假体无菌性松动机制及防治措施等实验研究中的可行性。方法:我们用雌性新西兰大白兔建立动物模型,在左侧胫骨髓腔内植入羟基磷灰石(hydroxyapatite,HA)涂层假体。并分别于假体表面和膝关节腔内植入0.5×107超高分子量聚乙烯(Ultra-high molecular weight polyethylene,UHMWPE)颗粒。术后行四环素荧光双标记。膝关节滑膜组织苏木精-伊红(hematoxylin-eosin,HE)染色、骨组织改良丽春红染色后分别用普通光镜和偏振光镜观察,未染色的骨组织行荧光显微镜和偏振光镜观察。结果:在聚乙烯颗粒刺激下,膝关节滑膜组织增生明显,骨-假体结合差,假体周围骨小梁稀疏,偏振光显微镜可清晰显示双折光性的聚乙烯颗粒在膝关节分布于滑膜及其深层结缔组织中,在骨-假体间隙间大量充填,阻碍骨-假体整合。结论:运用偏振光显微镜可以清晰而简便地观察滑膜和假体周围的聚乙烯颗粒分布,与传统实验方法相比,更加直观、简便和经济。     

Deepening our understanding of HDL proteome

ABSTRACT

Introduction: High-density lipoprotein (HDL) particles are heterogeneous and their proteome is complex and distinct from HDL cholesterol. However, it is largely unknown whether HDL proteins are associated with cardiovascular protection.

Areas covered: HDL isolation techniques and proteomic analyses are reviewed. A list of HDL proteins reported in 37 different studies was compiled and the effects of different isolation techniques on proteins attributed to HDL are discussed. Mass spectrometric techniques used for HDL analysis and the need for precise and robust methods for quantification of HDL proteins are discussed.

Expert opinion: Proteins associated with HDL have the potential to be used as biomarkers and/or help to understand HDL functionality. To achieve this, large cohorts must be studied using precise quantification methods. Key factors in HDL proteome quantification are the isolation methodology and the mass spectrometry technique employed. Isolation methodology affects what proteins are identified in HDL and the specificity of association with HDL particles needs to be addressed. Shotgun proteomics yields imprecise quantification, but the majority of HDL studies relied on this approach. Few recent studies used targeted tandem mass spectrometry to quantify HDL proteins, and it is imperative that future studies focus on the application of these precise techniques.     

人工关节假体无菌性松动动物模型的快速建立

目的:人工关节置换手术发展至今,取得了非常大的成功,已在临床解决了许多终末期的关节疾患。研究表明,假体无菌性松动的患者,其假体周围处于高骨更新状态。因此骨-假体界面的早期整合对于阻止磨屑颗粒和细胞因子的迁移至关重要,而限制人工关节假体使用寿命的一个主要原因是磨屑颗粒诱导的假体无菌性松动。在本研究中,我们旨在尝试使用107个UHMWPE颗粒快速建立人工关节假体无菌性松动的兔动物模型,以便为进一步探讨假体无菌性松动的机制及防治奠定实验基础。方法:我们用雌性新西兰大白兔建立动物模型,随机均分为实验组和对照组,在两组动物的左侧胫骨髓腔内植入羟基磷灰石(hydroxyapatite,HA)涂层假体。在实验组中,分别于假体表面和膝关节腔内植入0.5×10~7超高分子量聚乙烯(Ultra-high molecular weight polyethylene,UHMWPE)颗粒。结果:同对照组相比,实验组动物的关节内压力更高、骨组织形态学参数更差、假体生物力学固定强度更低,同时,促炎细胞因子和骨更新标志均显著高于对照组。结论:我们使用很少的UHMWPE颗粒成功快速地建立了人工关节假体无菌性松动的兔动物模型,从而为今后人工关节假体无菌性松动的进一步研究奠定了实验基础。     

异化铁还原细菌LQ25还原重金属Cr (VI)的特性研究

[背景] 异化铁还原细菌能够在还原Fe （III）的同时将毒性较大的Cr （VI）还原成毒性较小的Cr （III）,解决铬污染的问题。[目的] 基于丁酸梭菌（Clostridium butyricum） LQ25异化铁还原过程制备生物磁铁矿,开展异化铁还原细菌还原Cr （VI）的特性研究。[方法] 构建以氢氧化铁为电子受体和葡萄糖为电子供体的异化铁培养体系。菌株LQ25培养结束时制备生物磁铁矿。设置不同初始Cr （VI）浓度（5、10、15、25和30 mg/L）,分别测定菌株LQ25对Cr （VI）还原效率以及生物磁铁矿对Cr （VI）的还原效率。[结果] 菌株LQ25在设置的Cr （VI）浓度范围内都能良好生长。当Cr （VI）浓度为15 mg/L时,在异化铁培养条件下,菌株LQ25对Cr （VI）的还原率为63.45%±5.13%,生物磁铁矿对Cr （VI）的还原率为87.73%±9.12%,相比菌株还原Cr （VI）的效率提高38%。pH变化能影响生物磁铁矿对Cr （VI）的还原率,当pH 2.0时,生物磁铁矿对Cr （VI）的还原率最高,几乎达到100%。电子显微镜观察发现生物磁铁矿表面有许多孔隙,X-射线衍射图谱显示生物磁铁矿中Fe （II）的存在形式是Fe （OH）₂。[结论] 基于异化铁还原细菌制备生物磁铁矿可用于还原Cr （VI）,这是一种有效去除Cr （VI）的途径。     

Citric Acid Fermentation

Abstract

Dielectrophoresis is the motion of particles caused by electrical polarization effects in inhomogeneous (nonuniform) electric fields. Unlike electrophoresis, the particles do not require a net electrical charge for motion to occur and AC rather than DC fields are employed to exploit the dielectric properties of the particles. Factors controlling the effective dielectric properties of cells and microorganisms include electrical double layers associated with surface charges, the conductivity and permittivity of their membranes and any cell walls, and their morphologies and structural architectures. In recent years, several laboratories have developed separation and manipulation techniques for cells and microorganisms based on dielectrophoresis, using both static and traveling AC fields. In this article, the basic physical factors influencing the dielectrophoretic behavior of particles are outlined, and ways in which these can be employed to achieve selective separation of cells and microorganisms are described.     

Real-time monitoring of non-viable airborne particles correlates with airborne colonies and represents an acceptable surrogate for daily assessment of cell-processing cleanroom performance

Background aimsAirborne particulate monitoring is mandated as a component of good manufacturing practice. We present a procedure developed to monitor and interpret airborne particulates in an International Organization for Standardization (ISO) class 7 cleanroom used for the cell processing of Section 351 and Section 361 products.MethodsWe collected paired viable and non-viable airborne particle data over a period of 1 year in locations chosen to provide a range of air quality. We used receiver operator characteristic (ROC) analysis to determine empirically the relationship between non-viable and viable airborne particle counts.ResultsViable and non-viable particles were well-correlated (r² = 0.78), with outlier observations at the low end of the scale (non-viable particles without detectable airborne colonies). ROC analysis predicted viable counts ≥ 0.5/feet³ (a limit set by the United States Pharmacopeia) at an action limit of ≥ 32 000 particles (≥ 0.5 µ)/feet³, with 95.6% sensitivity and 50% specificity. This limit was exceeded 2.6 times during 18 months of retrospective daily cleanroom data (an expected false alarm rate of 1.3 times/year). After implementing this action limit, we were alerted in real time to an air-handling failure undetected by our hospital facilities management.ConclusionsA rational action limit for non-viable particles was determined based on the correlation with airborne colonies. Reaching or exceeding the action limit of 32 000 non-viable particles/feet³ triggers suspension of cleanroom cell-processing activities, deep cleaning, investigation of air handling, and a deviation management process. Our full procedure for particle monitoring is available as an online supplement.     

THE FRACTIONATION OF CLAY SIZED PARTICLES FROM THE WURAS DAM WATER PHASE

SUMMARY

The Coulter Counter has been employed with success to estimate the number and sizes of suspended particles in seawater. In the present study this method was applied to Wuras Dam, a turbid man made lake south of Bloemfontein.

High concentrations of larger clay sized particles occur in the inflow water as well as in the water of the dam proper. Fractionation of particles between ca 1 and 2 pm in diameter have been achieved, and a higher concentration of small sized particles (ca 1 μm) occurred in the dam water while the concentration of the larger particles (1,69 to 2,03 μm) was lower.

Surface area estimations were made for each size fraction. A considerable surface area (ca 163 m² m^?3) was associated with the investigated suspended particles in Wuras Dam. This might be of extreme importance for the physical, chemical and biological characteristics of the dam. The limnological importance of the suspended particles is briefly discussed.     

An Extended Gibbs Ensemble

Abstract

A general extended Gibbs ensemble, obtained by augmenting the standard Gibbs ensemble by intermediate states in the spirit of the scaled particle method of Nezbeda and Kolafa [Molec. Simul., 5, 391 (1991)], is introduced. The intermediate states span the states with different number of particles in the simulation boxes and facilitate the transfer of particles even in such complex systems as e.g., mixtures of very different components, systems of flexible polymeric molecules, or systems at very high densities. A general formulation of the ensemble is given and two implementations are considered in detail. The method is very general and is exemplified by studying the fluid-fluid coexistence in a dense binary mixture of the hard-sphere and square-well fluids. It is found that its efficiency is about by factor three greater in comparison with the standard Gibbs ensemble simulations.     

Glass Transition and Delocalization in a Binary Hard-Sphere Mixture

Abstract

The glass transition of a disparate-size binary liquid and the delocalization of small particles in a glassy matrix are studied within a mode-coupling theory. The density-relaxation functions together with their long-time limits are investigated by solving space- and time-dependent mode-coupling equations numerically. We focus our attention on the effective-potential fluctuations produced by the glassy matrix, which the small particles will experience when they move through the matrix. It is found that in a strongly localized state the spatial correlations of effective-potential fluctuations are well represented by a Gaussian function. For the small particles with a long localization length, on the other hand, the effective potential is no longer Gaussian, reflecting the structure of the glassy matrix established by the big particles. The time-dependence of the effective potential is also investigated.     

The Use of Nanotrap Particles in the Enhanced Detection of Rift Valley Fever Virus Nucleoprotein

BackgroundRift Valley fever virus (RVFV) is a highly pathogenic arthropod-borne virus that has a detrimental effect on both livestock and human populations. While there are several diagnostic methodologies available for RVFV detection, many are not sensitive enough to diagnose early infections. Furthermore, detection may be hindered by high abundant proteins such as albumin. Previous findings have shown that Nanotrap particles can be used to significantly enhance detection of various small analytes of low abundance. We have expanded upon this repertoire to show that this simple and efficient sample preparation technology can drastically improve the detection of the RVFV nucleoprotein (NP), the most abundant and widely used viral protein for RVFV diagnostics.ResultsAfter screening multiple Nanotrap particle architectures, we found that one particle, NT45, was optimal for RVFV NP capture, as demonstrated by western blotting. NT45 significantly enhanced detection of the NP at levels undetectable without the technology. Importantly, we demonstrated that Nanotrap particles are capable of concentrating NP in a number of matrices, including infected cell lysates, viral supernatants, and animal sera. Specifically, NT45 enhanced detection of NP at various viral titers, multiplicity of infections, and time points. Our most dramatic results were observed in spiked serum samples, where high abundance serum proteins hindered detection of NP without Nanotrap particles. Nanotrap particles allowed for sample cleanup and subsequent detection of RVFV NP. Finally, we demonstrated that incubation of our samples with Nanotrap particles protects the NP from degradation over extended periods of time (up to 120 hours) and at elevated temperatures (at 37ºC).ConclusionThis study demonstrates that Nanotrap particles are capable of drastically lowering the limit of detection for RVFV NP by capturing, concentrating, and preserving RVFV NP in clinically relevant matrices. These studies can be extended to a wide range of pathogens and their analytes of diagnostic interest.     

The Detailed Balance Energy-scaled Displacement Monte Carlo Algorithm

Abstract

The Detailed Balance Energy-scaled Displacement Monte Carlo method that stems from the previously published Energy Scaled Displacement Monte Carlo method is presented. The results of tests performed on a dense Lennard-Jones liquid and on two particles in one dimension are reported.     

Liquid culture of the entomopathogenic nematode,Steinernema colombiense: evolution of the nematode concentration,particles volume fraction,rheological properties and surface tension

ABSTRACT

The rheological properties and surface tension (σ) of culture broths with suspended particles are factors that affect the performance of fermentation processes. This article presents the first report concerning the evolution of suspended particles, rheological properties and σ of culture broths during the liquid culture of Steinernema colombiense and its symbiont bacterium, in a medium containing 1.25% (w/v) egg yolk. Cultures started with 1087?infective-juveniles/mL and finished with 53,583?individuals/mL after 10 days. Culture broths were moderately concentrated suspensions with total particles volume fraction in the range 0.08–0.14. The suspended particles were nematodes of different sizes depending on their developmental stage, and egg yolk particles. Rheological properties corresponded to pseudoplastic fluids with flow behaviour index values ?0.3 (dimensionless), greatly determined by the symbiotic bacterium activity. After nematode inoculation, the apparent viscosity values (η_a; Pa s) for the whole culture broth and its supernatants were in the ranges 0.010–0.018 and 0.008–0.015, respectively. Concerning σ, their values were in the range 31.22–37.74?mN/m, probably determined by the contents of egg yolk.