Electrophoretic Behavior Study of Bacteria of Pseudomonas aeruginosa, Edwardsiella tarda and Enteropathogenic Escherichia coli by Capillary Electrophoresis with UV and Fluorescence Detection

Capillary electrophoresis approaches have been utilized for the study of bacteria under specific experimental conditions. The main objective within our research work was to study electrophoretic behaviors of Pseudomonas aeruginosa by means of capillary electrophoresis with UV and fluorescence detection. Edwardsiella tarda and Enteropathogenic escherichia coli were also included in the study. The results showed that proper pretreatment (vortexing or sonication) for each bacterial sample before injection was necessary to disperse the clusters of cells, which is helpful to observe the single peaks and better peak shape of bacteria during electrophoresis. Apart from this, it was found that ionic strength of buffer affected mobilities of Pseudomonas aeruginosa as a result of increasing of buffer concentration from 25 mM to 150 mM. Moreover, sharp and single peaks were still observed without significant increase of noise in the concentration range. Eventually, mixtures of bacteria were well separated under optimized separation conditions with UV and fluorescence detection. In the mean time, comparison of concentration sensitivities for Pseudomonas aeruginosa by UV and fluorescence detection was made. Blue light emitting diode induced fluorescence detection was found to be more sensitive (8.5-fold higher) than UV detection with home-made fluorescence detection system. Generally, proposed CE methods for the analysis of bacteria could be potentially valuable for the monitoring of bacteria contamination in real life.     

Wound Healing,Antimicrobial and Antioxidant Properties of Clinacanthus nutans (Burm.f.) Lindau and Strobilanthes crispus (L.) Blume Extracts

Clinacanthus nutans is known to be an anticancer and antiviral agent, and Strobilanthes crispus has proven to be an antidiuretic and antidiabetic agent. However, there is a high possibility that these plants possess multiple beneficial properties, such as antimicrobial and wound healing properties. This study aims to assess the wound healing, antioxidant, and antimicrobial properties of Clinacanthus nutans and Strobilanthes crispus. The Clinacanthus nutans and Strobilanthes crispus leaves were dried, ground, and extracted with ethanol, acetone, and chloroform through cold maceration. In a modified scratch assay with co-incubation of skin fibroblast and Methicillin-resistant Staphylococcus aureus, Clinacanthus nutans and Strobilanthes crispus extracts were assessed for their wound healing potential, and the antimicrobial activities of Clinacanthus nutans and Strobilanthes crispus extracts were performed on a panel of Gram-positive and Gram-negative bacteria on Mueller–Hinton agar based on a disc diffusion assay. To assess for antioxidant potential, 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic and total flavonoid assays were conducted. In the modified scratch assay, Clinacanthus nutans extracts aided in the wound healing activity while in the presence of MRSA, and Strobilanthes crispus extracts were superior in antimicrobial and wound healing activities. In addition, Strobilanthes crispus extracts were superior to Clinacanthus nutans extracts against Pseudomonas aeruginosa on Mueller–Hinton agar. Acetone-extracted Clinacanthus nutans contained the highest level of antioxidant in comparison with other Clinacanthus nutans extracts.     

Inhibition of the Quorum Sensing System,Elastase Production and Biofilm Formation in Pseudomonas aeruginosa by Psammaplin A and Bisaprasin

Natural products derived from marine sponges have exhibited bioactivity and, in some cases, serve as potent quorum sensing inhibitory agents that prevent biofilm formation and attenuate virulence factor expression by pathogenic microorganisms. In this study, the inhibitory activity of the psammaplin-type compounds, psammaplin A (1) and bisaprasin (2), isolated from the marine sponge, Aplysinella rhax, are evaluated in quorum sensing inhibitory assays based on the Pseudomonas aeruginosa PAO1 lasB-gfp(ASV) and rhlA-gfp(ASV) biosensor strains. The results indicate that psammaplin A (1) showed moderate inhibition on lasB-gfp expression, but significantly inhibited the QS-gene promoter, rhlA-gfp, with IC₅₀ values at 14.02 μM and 4.99 μM, respectively. In contrast, bisaprasin (2) displayed significant florescence inhibition in both biosensors, PAO1 lasB-gfp and rhlA-gfp, with IC₅₀ values at 3.53 μM and 2.41 μM, respectively. Preliminary analysis suggested the importance of the bromotyrosine and oxime functionalities for QSI activity in these molecules. In addition, psammaplin A and bisaprasin downregulated elastase expression as determined by the standard enzymatic elastase assay, although greater reduction in elastase production was observed with 1 at 50 μM and 100 μM. Furthermore, the study revealed that bisaprasin (2) reduced biofilm formation in P. aeruginosa.     

Chemical composition and antimicrobial activity of essential oils from Acantholippia deserticola,Artemisia proceriformis,Achillea micrantha and Libanotis buchtormensis against phytopathogenic bacteria and fungi

Essential oils from aerial parts of Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis were analysed by GC–MS. The major compounds identified were β-thujone (66.5 ± 0.2%), and trans-sabinyl acetate (12.1 ± 0.2%) in A. deserticola; α-thujone (66.9 ± 0.4%) in A. proceriformis; 1,8-cineole (26.9 ± 0.5%), and camphor (17.7 ± 0.3%) in A. micrantha and cis-β-ocimene (23.3 ± 0.3%), and trans-β-ocimene (18.4 ± 0.2%) in L. buchtormensis. The oils showed a weak antimicrobial effect (MIC₁₀₀ > 1.5 mg/ml) on most phytopathogens tested. A moderate antimicrobial activity (MIC₁₀₀ between 0.5 and 1.5 mg/ml) was displayed by the oils of A. deserticola, A. micrantha and L. buchtormensis on Septoria tritici and by the oil of A. deserticola on Septoria glycine. The antimicrobial activity was associated to the contents of β-thujone, trans-sabinyl acetate and trans-sabinol. Our results indicate that the tested essential oils have little inhibitory potency not suitable for use as plant protection products against the phytopathogens assayed.     

New MSPQC Method for Rapid Identification and Quantification of Pseudomonas aeruginosa

Abstract

A new method for the rapid identification and quantification of Pseudomonas aeruginosa using multichannel series piezoelectric quartz crystal (MSPQC) was proposed. The identification of P. aeruginosa was based on the development of acetamide broth, which can selective culture P. aeruginosa and performed perfectly in MSPQC. The quantitative detection of P. aeruginosa was based on the fact that the frequency detection time (FDT) detected by MSPQC in developed medium had a linear relationship with the logarithm of its initial concentration in the range of 10–10⁸ colony ? forming units (cfu) ml^–1 (R=?0.984). The detection limit was 10 cfu ml^–1.     

Total syntheses of (+)- and (−)-syringolides 3 and of (+)- and (−)-syributins 1, 2 and 3

The first total syntheses of (−)-syringolide 3, (+)-syributin 3 and their unnatural enantiomers (+)-syringolide 3 and (−)-syributin 3 using a common intermediate as starting material are described. In addition, total syntheses of (−)- and (+)-syributins 1 and 2 were accomplished by means of the same methodology.     

纳米银对荧光假单胞菌生物膜形成的影响

分别以空白和0.4%纳米银乙烯醋酸乙烯酯(EVA)塑料片作为载体培养荧光假单胞菌生物膜,通过菌落计数法测定生物膜的变化曲线,分别采用普通显微镜观察生物膜形成并计算覆盖率(BCR),扫描电镜观察生物膜的微观结构,激光共聚焦显微镜观察生物膜中的细菌状态并计算死亡率.结果表明,空白、纳米银EVA表面生物膜分别在12和24 h达到稳定状态,各时间点的纳米银EVA表面菌数及BCR均显著低于空白EVA(p<0.05);在10000倍的视野下,空白EVA表面的荧光假单胞菌通过胞外产物和菌体形成致密生物膜,纳米银EVA表面多为分散菌体;在24,48 h时,纳米银EVA表面的死亡菌体数显著高于空白EVA(p<0.05);纳米银通过抑制荧光假单胞菌生长和减少胞外产物的分泌而影响生物膜的形成.     

绿脓素对降解原油的微生物菌群的影响

铜绿假单胞菌WJ-1是从蒙古林油田油水样中分离得到的一株能够以原油为唯一碳源, 通过合成某些代谢产物增加其环境竞争力和存活率的烃降解菌. 用氯仿从WJ-1LB培养液中萃取绿脓素, 气相色谱-质谱法(Gas chromatograph-Mass Spectrometry, GC-MS)分析得该物质为1-羟基吩嗪. 通过在原油培养基中加入和未加入0.2 g/L绿脓素, 培养32 d来研究绿脓素对烃降解菌群T2的群落结构和原油降解能力的影响. 变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis, DGGE)分析结果表明: 在32 d的原油降解中, 含有绿脓素的培养液中T2菌群多样性减少. 气相色谱和棒薄层层析分析得: 含有绿脓素的培养液中原油的芳香族烃等非烃类和正构烷烃中长链组分的降解率比未加入绿脓素的要低. 超氧化物歧化酶(SOD)和过氧化氢酶(catalase)活性检测结果表明: 不同菌体的过氧化氢酶和超氧化物歧化酶含量与活性不同, 引起对绿脓素抗性的差异. 可见绿脓素对烃降解菌群的结构和原油降解能力有负面影响.     

Biphenyl-cis-diol chemistry to access enantiopure aryl-substituted organoiron complexes

The endo face selectivity of the complexation of the biologically derived 3-phenyl-1,2-dihydroxycyclohexa-3,5-diene ligand has been proved by an X-ray crystallographic study of the enantiopure (1R,2S,3S) η⁴ tricarbonyliron complex, and the correlation between the absolute configuration of the complex and its circular dichroism curve has been established to provide a basis on which to assign absolute configurations in the synthetically important [‘-(Ar)CCH-CHCH-’]Fe(CO)₃ series.