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121.
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研究氯化钙(CaCl2)对食品腐败株荧光假单胞菌(Pseudomonas fluorescens)生物被膜形成特征的影响。采用结晶紫法、菌体计数、苯酚-硫酸法、共聚焦扫描显微镜和实时荧光定量聚合酶链式反应(polymerase chain reaction,PCR)检测Ca2+对荧光假单胞菌的生物被膜形成、多糖分泌、被膜结构及相关基因表达的影响。结果表明,0.1 mmol/L Ca2+刺激荧光假单胞菌生物被膜,随着浓度增加被膜形成增强,其中1 mmol/L促进最明显,而高于10 mmol/L作用减弱,并且Ca2+不影响浮游细菌生长;同时,0.1 mmol/L和1 mmol/L Ca2+对胞外多糖、薄膜和泳动性均呈现促进效果,而高浓度下呈现抑制;共聚焦扫描显微镜观察荧光假单胞菌对照组、1 mmol/L和20 mmol/L Ca2+处理组的成熟生物被膜厚度分别为20.0、40.0 μm和25.0 μm,其中添加1 mmol/L Ca2+显著增加PF07被膜厚度、菌体和胞外聚合物分泌量,使被膜结构更致密;实时荧光定量PCR检测显示,1 mmol/L Ca2+刺激菌体黏附素lapA、藻多糖alg、鞭毛flgA基因表达量增加3~4 倍,并且Ca2+均显著刺激AHLs合成酶luxI基因的表达,提示Ca2+影响生物被膜与群体感应密切相关。可见,食品介质中CaCl2通过影响菌体黏附行为、胞外分泌物、基因表达导致荧光假单胞菌生物被膜形成特征和结构的改变,该研究为复杂的食品介质中腐败菌生物被膜形成和黏附提供依据。 相似文献
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《International Journal of Hydrogen Energy》2019,44(50):27248-27258
Photofermentative hydrogen production at higher rate is desirable to make the technology of biological hydrogen production in practical application. An easy fabricating alveolar panel photobioreactor with high surface-to-volume ratio was proposed in this study to realize biofilm formation and used for developing a continuous bioprocess of hydrogen production. Effects of key operating parameters, i.e. variation in intensity of incident light, initial concentration of carbon substrate and flow rate on the rate of nitrogenase-based H2 production were investigated using response surface methodology (RSM) with Box-Behnken design. Surface and contour plots of the fitted regression model revealed that optimum H2 production rate of 57.6 mL/h/L was obtained at 125.9 μE/m2/s incident light intensity at 590 nm light wavelength, 52.4 mM initial concentration of carbon substrate and 209 mL/h flow rate. Regular groove surfaces within this photobioreactor were considered to have mutual effects on enhancement of continuous hydrogen production by enriching bacterial cell density, enhancing mass transfer of carbon substrate to facilitate release of protons and electrons, enhancing removal of molecular H2, and uniformly distribution of incident light within the photobioreactor for sufficient conversion into ATPs. 相似文献
125.
为分析碳纤维—微生物共生系统对水污染治理的效果及其水质净化机理,在武汉市东湖构建碳纤维—微生物共生系统水污染治理示范区,分别从其布设方式、挂膜特征、污染物去除规律等方面进行分析。研究表明,碳纤维表面48h左右可形成成熟的生物膜,挂膜量约为1.268g/g,约10d可形成活性污泥团;示范区建设初期东湖主湖水体为劣Ⅴ类,经过两到三个月,试验场水质由劣Ⅴ类上升为Ⅱ类,且有高效持久的控制作用;其净化水质过程主要包括材料本身的吸附以及微生物吸附两个阶段。未来碳纤维将会因其优异的性能在水污染治理方面应用前景广阔。 相似文献
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Nikola Mikušová Kateřina Nechvilová Andréa Kalendová Tereza Hájková Zdenka Capáková Ita Junkar 《国际聚合物材料杂志》2019,68(4):152-159
Functionality of polymeric coating, especially in terms of anti-corrosive properties and stability, can be negatively influenced by formation of either bacterial or fungal biofilm on its surface. Herein, the epoxy-ester resin based polymeric coating was filled with pigments (natural silicon dioxide diatomite, natural wollastonite, tungstate and molybdate). Pigments was modified by conducting polymers (polyaniline phosphate, polypyrrole phosphate, poly(p-phenylenediamine) phosphate and ZnFe2O4). Impact of modified pigments on the surface energy and formation of biofilm were tested. The use of various biofilm forming species of both the bacteria and fungi filled a knowledge gap about their behavior on polymeric coatings. 相似文献
128.
Understanding mechanisms of controlling the bacteria growth and degradation of pollutants is critical for effective improvements in water treatment and bioremediation in porous media. In this study, we developed an integrated model of individual-based model and multicomponent lattice Boltzmann method to study interactions of oxygen, bioclogging, chemical oxygen demand (COD) removal, and their influence on growth and permeability of microbial biofilms. We found biofilm growth to be very heterogeneous on the surface of the solid matrix and pores. There is a biofilm porosity threshold. Beyond this threshold, the porosity of biofilm has no obvious influence on the flow rate and COD removal. We also studied the influence of initial cell populations, bulk oxygen concentration and biofilm permeability on the flow rate and COD removal. It demonstrated the capability of the present model to investigate biofilm growth, clogging and contaminants degradation in porous media, and its potential applications in water treatment. 相似文献
129.
Robert Riedl Nicole Dünzer Maximilian Michel Fritz Jacob Mathias Hutzler 《Journal of the Institute of Brewing》2019,125(2):250-260
Lactobacillus brevis is the most significant beer spoilage bacteria worldwide. It is found as a contaminant at all stages of brewing, including during primary and secondary fermentation, storage, filtration and the packaging process. In production with flash pasteurisation and subsequent hygienic filling, avoiding and tracing secondary contaminations is the key to a microbiologically stable product. However, L. brevis strains vary in their spoilage potential and can grow in many different beer types. This study presents a physiological test scheme for growth potential and biofilm formation in various media. It was determined that a large number of L. brevis strains can form biofilms as a first coloniser. The identification of the species alone is therefore not enough to be sure of the spoilage risk, which shows the need for a more in depth differentiation. DNA fingerprint techniques are crucial to differentiate isolates of this species at strain level. The rep‐PCR fingerprint system (GTG)5 was used to differentiate a selected collection of 20 isolates, which were characterised in growth and biofilm formation in various media. The data showed a high variation within the selected isolates. As second step, generated fingerprint clusters of L. brevis were traced back to contamination sources in a German brewery, revealing a high number of isolates with potentially varying growth, spoilage and biofilm potential. L. brevis being the demonstrator species, the PCR system used is a powerful and compatible tracing and troubleshooting tool for all kinds of spoilage bacteria in the brewing industry. © 2019 The Institute of Brewing & Distilling 相似文献
130.
有害片球菌是啤酒酿造环境中较为常见且危害较大的腐败菌。作者比较了啤酒腐败有害片球菌生物被膜和浮游细胞进入活的不可培养(VBNC)状态的能力差异。将5种有害片球菌的浮游细胞和生物被膜细胞在啤酒中于26 ℃下进行培养,结果发现,生物被膜细胞和浮游细胞均可以被诱导进入VBNC状态,但形成VBNC状态的时间有所不同。生物被膜细胞进入VBNC状态至少需要70 d,而浮游细胞进入VBNC状态的时间为126~189 d。作者还用单叠氮丙啶与PCR相结合来扩增16S rDNA和horA基因,以证实生物被膜中VBNC细胞的存在。另外,与浮游细胞相比,生物被膜细胞对0.025 mol/L NaOH具有更强的抵抗力,而VBNC状态生物被膜又比同样状态下的浮游细胞具有更强的耐受力。综上所述,在啤酒酿造过程中,相比于浮游细胞,有害片球菌生物被膜在低pH、高浓度的啤酒花苦味物质、乙醇等压力条件下更易被诱导进入VBNC状态,而且还拥有更强的碱耐受力。 相似文献