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11.
鼠李糖脂因其具有环境友好和卓越的物理化学特性,而有望成为化学合成表面活性剂的替代物。近年来鼠李糖脂得到了广泛的研究,其目的是利用低价的可再生资源进行大规模生产,但目前的研究成果仍不足以选育出更具商业竞争力的鼠李糖脂过量合成菌株。为此,进一步理解鼠李糖脂生物合成的复杂基因调控网络,探索降低生产成本的发酵工艺势在必行。综述了铜绿假单胞菌中鼠李糖脂的生物合成途径、群体感应对主要基因的调控、鼠李糖脂在生物膜形成中所发挥的作用,以及发酵优化对鼠李糖脂产量的影响。有助于加深对鼠李糖脂生物合成的认识,为提高鼠李糖脂产量提供重要参考信息。 相似文献
12.
《Saudi Journal of Biological Sciences》2020,27(10):2580-2585
Methicillin-Resistant Staphylococcus aureus (MRSA) biofilms are involved in various nosocomial infections, being in the limelight of academic research. The current study aimed to determine the antimicrobial effects of melittin on planktonic and biofilm forms of S. aureus. Following the identification of MRSA and SCCmec types (using PCR method), Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and fractional inhibitory concentration index (FICi), for melittin and mupirocin were determined by broth microdilution assay. Melittin anti-biofilm activity was determined, using a microtiter-plate test (MtP) and scanning electron microscope (SEM) methods. The quorum sensing inhibitory activity of ½ MIC melittin was examined using a quantitative real-time RT-PCR method, and melittin cytotoxicity on Vero cells was examined by tetrazolium-based colorimetric (MTT) test. The Results of our study showed that Geometric means of MIC values of the melittin and mupirocin were 4.4 and 14.22 μg/ml respectively. The geometric mean of the FICi for both melittin-mupirocin was 0.75. No S. aureus biofilm was formed and hld gene (as a biofilm regulator) expression down-regulated. It seems that melittin can be useful in the treatment of S. aureus infections (especially MRSA) by reducing the hld expression. Furthermore, synergistic growth-inhibitory effects of mupirocin with melittin could be considered as a promising approach in the treatment of MRSA isolates. 相似文献
13.
随着人们生活水平日益提高,口腔健康越来越受到关注。近年来,益生菌对口腔菌群和宿主健康的调节作用已成为广泛研究的话题。已有证据表明,益生菌可以竞争性地抑制口腔中致病细菌的黏附和定植,分泌抗菌物质以减少病原菌。本文综述了相关益生菌对变形链球菌这一公认的龋齿病原菌的作用,包括:(1)生物表面活性剂、细菌素、胞外多糖等益生菌代谢产物对变形链球菌牙菌生物膜的抑制作用;(2)刺激宿主免疫反应,调节口腔菌群组成;(3)下调或阻断变形链球菌细胞中与黏附在牙齿表面形成生物膜相关的基因表达。 相似文献
14.
Jamal M. Khaled Sami A. Alyahya C. Chenthis Kanisha Naiyf S. Alharbi Shine Kadaikunnan G. Ramachandran Khalid F. Alanzi G. Rajivgandhi RTV Vimala N. Manoharan 《Saudi Journal of Biological Sciences》2021,28(1):302-309
Urinary tract infections are second most important diseases worldwide due to the increased amount of antibiotic resistant microbes. Among the Gram negative bacteria, P. mirabilis is the dominant biofilm producer in urinary tract infections next to E. coli. Biofilm is a process that produced self-matrix of more virulence pathogens on colloidal surfaces. Based on the above fact, this study was concentrated to inhibit the P. mirabilis biofilm formation by various in-vitro experiments. In the current study, the anti-biofilm effect of essential oils was recovered from the medicinal plant of Solanum nigrum, and confirmed the available essential oils by liquid chromatography-mass spectroscopy analysis. The excellent anti-microbial activity and minimum biofilm inhibition concentration of the essential oils against P. mirabilis was indicated at 200 µg/mL. The absence of viability and altered exopolysaccharide structure of treated cells were showed by biofilm metabolic assay and phenol–sulphuric acid method. The fluorescence differentiation of P. mirabilis treated cells was showed with more damages by confocal laser scanning electron microscope. Further, more morphological changes of essential oils treated cells were differentiated from normal cells by scanning electron microscope. Altogether, the results were reported that the S. nigrum essential oils have anti-biofilm ability. 相似文献
15.
Fohad Mabood Husain Kahkashan Perveen Faizan Abul Qais Iqbal Ahmad Ahmed H. Alfarhan Mohamed A. El-Sheikh 《Saudi Journal of Biological Sciences》2021,28(1):333-341
Food producing animals harbouring bacteria carrying drug resistance genes especially the metallo-beta-lactamase (MBL) pose high risk for the human population. In addition, formation of biofilm by these drug resistant pathogens represents major threat to food safety and public health. In this study, metallo-β-lactamases (MβLs) producing Pseudomonas spp. from camel meat were isolated and assessed for their biofilm formation. Further, in vitro and in silico studies were performed to study the effect of flavone naringin on biofilm formation against isolated Pseudomonas spp. A total of 55% isolates were found to produce metallo-β-lactamase enzyme. Naringin mitigated biofilm formation of Pseudomonas isolates up to 57%. Disturbed biofilm architecture and reduced the colonization of bacteria on glass was observed under scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). The biofilm related traits such as exopolysaccharides (EPS) and alginate production was also reduced remarkably in the presence of naringin. Eradication of preformed biofilms (32–60%) was also observed at the respective 0.50 × MICs. Molecular docking revealed that naringin showed strong affinity towards docked proteins with binding energy ranging from −8.6 to −8.8 kcal mol−1. Presence of metallo-β-lactamase producers indicates that camel meat could be possible reservoir of drug-resistant Pseudomonas species of clinical importance. Naringin was successful in inhibiting biofilm formation as well as eradicating the preformed biofilms and demonstrated strong binding affinity towards biofilm associated protein. Thus, it is envisaged that naringin could be exploited as food preservative especially against the biofilm forming food-borne Pseudomonas species and is a promising prospect for the treatment of biofilm based infections. 相似文献
16.
Lilia Montoya Lourdes B. Celis Marisol Gallegos‐García Elías Razo‐Flores Ángel G. Alpuche‐Solís 《Engineering in Life Science》2013,13(3):302-311
Sulfate reduction is an appropriate approach for the treatment of effluents with sulfate and dissolved metals. In sulfate‐reducing reactors, acetate may largely contribute to the residual organic matter, because not all sulfate reducers are able to couple the oxidation of acetate to the reduction of sulfate, limiting the treatment efficiency. In this study, we investigated the diversity of a bacterial community in the biofilm of a laboratory scale down‐flow fluidized bed reactor, which was developed under sulfidogenic conditions at an influent pH between 4 and 6. The sequence analysis of the microbial community showed that the 16S rRNA gene sequence of almost 50% of the clones had a high similarity with Anaerolineaceae. At second place, 33% of the 16S rRNA phylotypes were affiliated with the sulfate‐reducing bacteria Desulfobacca acetoxidans and Desulfatirhabdium butyrativorans, suggesting that acetotrophic sulfate reduction was occurring in the system. The remaining bacterial phylotypes were related to fermenting bacteria found at the advanced stage of reactor operation. The results indicate that the acetotrophic sulfate‐reducing bacteria were able to remain within the biofilm, which is a significant result because few natural consortia harbor complete oxidizing sulfate‐reducers, improving the acetate removal via sulfate reduction in the reactor. 相似文献
17.
AbstractThis work investigated chloroform extracts from culture supernatants of two human probiotic bacteria, Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730 for the production of virulence factors and quorum sensing (QS) interference against three Pseudomonas aeruginosa strains. Both extracts inhibited biofilm biomass (up to 50%), biofilm metabolic activity (up to 39%), the production of the enzyme elastase (up to 63%) and pyocyanin (up to 77%), and decreased QS, without presenting any antibacterial acgivity. In addition, the chloroform extracts of both strains disrupted preformed biofilms of the three strains of P. aeruginosa analyzed (up to 40%). GC-MS analysis revealed that the major compounds detected in the bioactive extracts were four diketopiperazines. This study suggests that the metabolites of L. casei and L. acidophilus could be a promising alternative to combat the pathogenicity of P. aeruginosa. 相似文献
18.
Daoyuan Yang 《Biofouling》2020,36(4):389-402
AbstractMost studies dealing with monitoring the dynamics of biofilm formation use microbial suspensions at high concentrations. These conditions do not always represent food or water distribution systems. A continuous flow system capable of controlling the concentration of the microbial suspension stream from 104 to 106 CFU ml?1 is reported. Pseudomonas putida biofilms formed using 100-fold, 1,000-fold or 10,000-fold diluted bacterial suspensions were monitored in-line by electrochemical impedance spectroscopy (EIS) and total plate counts. Randles equivalent circuit model and a modified Randles model with biofilm elements were used to fit the EIS data. In Randles equivalent circuit, the charge transfer resistance decreased as the biofilm formed. The log colony counts of the biofilm correlated to the charge transfer resistance. In the biofilm model, the biofilm resistance and the double layer capacitance decreased as the biofilm formed. The log colony counts of the biofilm correlated to the biofilm resistance. 相似文献
19.
AbstractThis work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10?mg l?1 of free chlorine for 10?min, an increased shear stress (a fluid velocity of 1.5?m s?1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure. 相似文献
20.
《Biochemical and biophysical research communications》2020,521(3):555-561
Uropathogenic Escherichia coli (UPEC) is a major pathogen that causes urinary tract infection (UTI), a common bacterial infectious disease. This bacterium invades the urinary tract cells, where it aggregates, and subsequently forms multicellular colonies termed intracellular bacterial communities (IBCs). The motility of the bacteria plays a key role in the mechanism of virulence in the host bladder. Here, we show that CytR is a modulator of bacterial internalization and aggregation within the bladder epithelial cells sustained by CRP in UPEC. Mutational analyses and gel-shift assays indicated that CytR represses the expression of flhD, thereby encoding a master regulator for flagellar expression that is responsible for bacterial motility when CRP is present, whereas CRP is an activator of flhD expression. Thus, elevated flagellar expression was involved in promoted virulence in the cytR mutant. These combined observations suggest another regulatory layer of flagellar expression and the role of CytR in UPEC virulence. 相似文献