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41.
Mingxu Zhou Zhiyan Guo Yang Yang Qiangde Duan Qi Zhang Fenghua Yao Jun Zhu Xinjun Zhang Philip R. Hardwidge Guoqiang Zhu 《Veterinary microbiology》2014
Bacteria that form biofilms are often highly resistant to antibiotics and are capable of evading the host immune system. To evaluate the role of flagellin and F4 fimbriae on biofilm formation by enterotoxigenic Escherichia coli (ETEC), we deleted the fliC (encoding the major flagellin protein) and/or the faeG (encoding the major subunit of F4 fimbriae) genes from ETEC C83902. Biofilm formation was reduced in the fliC mutant but increased in the faeG mutant, as compared with the wild-type strain. The expression of AI-2 quorum sensing associated genes was regulated in the fliC and faeG mutants, consistent with the biofilm formation of these strains. But, deleting fliC and/or faeG also inhibited AI-2 quorum sensing activity. 相似文献
42.
Muhammad?Ashraf Shahida?Hasnain Odile?Berge Tariq?MahmoodEmail author 《Biology and Fertility of Soils》2004,40(3):157-162
A pot experiment was conducted to elucidate the effects of inoculating five exopolysaccharide- (EPS-) producing bacterial strains on the dry matter yield and the uptake of K+, Na+, and Ca2+ by wheat seedlings grown in a moderately saline soil. The bacteria were isolated from the rhizosphere soil (RS) of wheat grown in a salt-affected soil and included Aeromonas hydrophila/caviae (strain MAS-765), Bacillus insolitus (strain MAS17), and Bacillus sp. (strains MAS617, MAS620 and MAS820). The inoculation substantially increased the dry matter yield of roots (149–527% increase) and shoots (85–281% increase), and the mass of RS (176–790% increase). All the strains, except MAS617, also increased the RS mass/root mass ratio as well as the population density of EPS bacteria on the rhizoplane, and both these parameters were significantly correlated with the content of water-insoluble saccharides in the RS. Inoculation restricted Na+ uptake by roots, which was not attributable to the binding of Na+ by the RS, or to the ameliorative effects of Ca2+ under salinity. The decreased Na+ uptake by roots of inoculated than uninoculated plants was probably caused by a reduced passive (apoplasmic) flow of Na+ into the stele due to the higher proportion of the root zones covered with soil sheaths in inoculated treatments. Among the strains tested, MAS820 was the most efficient in all respects, whereas MAS617 was the least effective. Results suggested that inoculating selected EPS-producing bacteria could serve as a useful tool for alleviating salinity stress in salt-sensitive plants. 相似文献
43.
利用三维白光干涉形貌仪对滴灌系统中光滑毛管管壁、未使用过的毛管管壁、附生生物膜的毛管管壁3种壁面进行表面形貌测试,在此基础上借助相位多普勒粒子分析仪研究了3种壁面条件下,3种粒径颗粒与壁面碰撞规律。结果表明:生物膜管壁的比表面积(212%)显著高于毛管管壁(4.37%)及光滑管壁(0.196%);细颗粒(粒径为10μm)与光滑管壁碰撞的平均速度低于生物膜管壁,且表现出光滑管壁、毛管管壁、生物膜管壁速度概率分布逐渐变宽的趋势,而中(粒径为50μm)、粗(粒径为100μm)两种颗粒物平均速度接近于零,概率密度分布未出现明显变宽趋势,说明附生生物膜对粒径高于50μm的颗粒物运移影响不显著。 相似文献
44.
Helena Khatoon Sanjoy Banerjee Mohamed Shariff Japar Sidik Bujang 《Aquaculture (Amsterdam, Netherlands)》2007,273(4):470-477
Periphyton grown on substrates is known to improve water quality in aquaculture ponds. Five different substrates, (i) bamboo pipe (ii) plastic sheet (iii) polyvinylchloride (PVC) pipe (iv) fibrous scrubber, and, (v) ceramic tile were evaluated for the formation of biofilm in this experiment. The substrates were suspended 25 cm below the water surface. Each type of substrate was collected fortnightly to analyze the abundance and biomass of different periphytic algae and of the biofouling organism. The study was terminated after 60 days due to severe fouling by polychaete. Results showed that pond water nutrients were high on day 60 with mean total ammonia-N, nitrite-N and soluble reactive phosphorus concentrations of 309.6 ± 8.6 μg L− 1, 26.0 ± 2.7 μg L− 1 and 87.2 ± 7.1 μg L− 1 respectively. During the first two weeks the substrates were colonized by 19 periphytic algae. The most abundant family was Bacillariophyta (8 genera) followed by Chlorophyta (7 genera) and Cyanophyta (4 genera). Periphyton colonization on bamboo pipe showed the highest (p < 0.05) biomass in terms of chlorophyll a amongst all the substrates used. The biomass varied from 179 to 1137 μg m− 2 with mean values of 1137.2 ± 0.6, 929.6 ± 0.6, 684.2 ± 1.2, 179.1 ± 0.6 and 657.0 ± 0.6 μg m− 2 on bamboo pipe, PVC pipe, plastic sheet, fibrous scrubber and ceramic tile respectively for the first 15 days. From 3rd week, polychaetes began to form tubes on the substrate. By day 60, the whole surface of all substrates was covered with tightly packed polychaete tubes with mean densities of 168.0 ± 15.4, 121.0 ± 13.5, 72.8 ± 9.8, 72.4 ± 7.4 and 56.0 ± 6.8 polychaete tubes cm− 2 for bamboo, PVC, plastic, fibrous scrubber and ceramic tile respectively. This study illustrated the invasive nature of attached polychaete thus hampering the formation of periphyton biofilm on substrates which could have been used for improving water quality in enriched brackishwater shrimp ponds. 相似文献
45.
Yi Zou Saixiang Feng Chenggang Xu Bin ZhangSuming Zhou Lingyun ZhangXianhui He Jingyi LiZhen Yang Ming Liao 《Veterinary microbiology》2013
In our previous study, an ompP2 mutant of a Haemophilus parasuis SC096 strain showed sensitivity to serum bactericidal activity. In this study, we inactivated two gal genes, galU and galE, and these mutants were found to be serum sensitive to porcine sera. Furthermore, the galE mutant exhibited greater sensitivity than the galU mutant in serum sensitivity assays. Biofilm formation ability was also investigated. The galU mutant is unable to form biofilms, while more biofilm mass was produced by the galE mutant compared with SC096. Lack of expression of GalU protein by the galU mutant increased its tendency to autoagglutinate. The results indicated that the galU plays a role in autoagglutination and biofilm formation, while galE may affect the biofilm production indirectly. Both genes are significant for serum resistance in the H. parasuis SC096 strain. 相似文献
46.
生物膜反应器在污水处理工艺中是与活性污泥法并行的一种生物污水处理方法,广泛应用于工业废水和城市污水处理的二级处理中,也是污水处理的关键环节。对生物膜反应器在污水处理中的应用进展进行了综述。 相似文献
47.
Flagella-mediated motility is required for biofilm formation by Erwinia carotovora subsp. carotovora
To elucidate the role of flagella in biofilm formation by Erwinia carotovora subsp. carotovora EC1, we used a nonflagellate, nonmotile mutant (ΔfliC) and a flagellate, nonmotile mutant (ΔmotA). A biofilm-inducing medium, which contains the yeast peptone (YP) medium plus the salts of M-63 minimal medium, supported
biofilm formation to a greater extent than either the YP or Luria Bertani (LB) medium alone. We demonstrated that both the
ΔfliC and ΔmotA mutants greatly reduced their ability to form a biofilm on the surface of the wells of polyvinyl chloride (PVC) microtiter
plates. The inability of both mutants to form biofilm on the PVC surface was further confirmed with phase-contrast microscopy.
Both aflagellate (ΔfliC) and flagellate (ΔmotA) nonmotile mutants were equally defective in attachment to the PVC surface. The treatment of bacteria with the protonophore
carbonyl cyanide m-chlorophenylhydrazone (CCCP), which inhibits the motility of this organism, reduced greatly the biofilm formation. Based
on these results, flagella-mediated motility may play an important role in biofilm formation of E. carotovora subsp. carotovora EC1. 相似文献
48.
This study evaluated the influence of different quantities of artificial substrate on water quality and the performance of Litopenaeus vannamei in an integrated biofilm-biofloc culture system. Thus, three treatments were performed: the control, the treatment without the addition of artificial substrate; T200, the treatment with a 200 % increase in the lateral area of the tanks using artificial substrates; and T400, the treatment with a 400 % increase in the lateral area of the tanks using artificial substrates. The study was conducted in nine 800 L tanks over 60 days. The animals were stocked at an initial density of 300 shrimp.m−2 (equivalent to 500 shrimp m-3), with an initial weight of 1.27 g (± 0.48). Ammonia concentrations did not differ significantly between treatments (p > 0.05). Increasing the amount of substrate from 200 % to 400 % did not cause significant differences in the nitrite concentrations between these treatments. However, in the control treatment, nitrite remained high (above 20 mg.L-1) for a long period, negatively affecting shrimp performance. Nitrate was lower in T400, indicating a more dynamic process in the nitrogen cycle when the quantity of artificial substrate increased. Weekly growth rates, final weight, survival, and productivity were higher in the treatments integrating biofilm and biofloc substrates and did not show significant differences between T200 and T400. The results demonstrate the importance of artificial substrates in enhancing the water quality in biofloc culture systems over the long term, mostly in terms of maintaining nitrite concentrations below levels toxic to L. vannamei. The performance of the shrimp and the improved water quality at the end of the study reflected the advantages provided by incorporating artificial substrates in shrimp biofloc culture. 相似文献
49.
粪肠球菌生物被膜的研究进展 总被引：1，自引：1，他引：0
生物被膜是粪肠球菌致病机制的一个重要原因,临床上许多生物医学材料相关感染和某些慢性顽固性感染性疾病都与其密切相关。在生物膜中的细菌不仅耐抗生素,还可耐抗体的杀菌作用,严重危害动物以及人类的健康。对粪肠球菌生物被膜的历史、生物膜特性及作用进行了综述。 相似文献
50.
Peracetic acid (PAA) products are being introduced to aquaculture as sustainable disinfectants. Two strategies are used to apply PAA: high dose pulse applications, or low dose continuous application. In the present study, their impacts on fish health and water quality were investigated in triplicate flow-through tanks stocked with rainbow trout. The gentler and shorter water cortisol increase measured along twice-per-week pulse applications of 1 mg L−1 PAA indicated a progressive adaptation of fish. In contrast, the continuous application of 0.2 mg L−1 PAA caused no stress to fish. Meanwhile, no mortality and no impact on growth or innate cellular immunity were observed. The pulse applications restricted biofilm formation, and partially inhibited nitrification. Additionally, the highest oxygen concentration and stable pH were observed. In contrast, the continuous application promoted biofilm formation, and caused a pH increase and intermediate oxygen concentration. The contrast was probably due to different susceptibility of microbes to PAA-induced oxidative stress. To summarize, pulse PAA applications cause minor stress in fish, but have advantages over continuous application by ensuring better water quality. 相似文献