خيارات البحث
النتائج 711 - 720 من 2,512
Indole derivatives inhibited the formation of bacterial biofilm and modulated Ca2+ efflux in diatom النص الكامل
2014
Yang, Cuiyun | Yu, Yanan | Sun, Wenjun | Xia, Chuanhai
Marine biofouling is a serious environmental problem worldwide. As an effort to find environmental friendly antifoulants, indole derivatives were determined for their activities to inhibit the growth of bacteria and diatom. The minimum inhibitory concentrations (MICs) of indole derivatives against bacteria were very low, especially for 6-chloroindole. It was proved that 6-chloroindole obviously inhibited the growth of bacteria, interfered with the formation of bacterial biofilm, destroyed bacterial cell morphology and also inhibited the growth of diatom Cylindrotheca sp. as well. By using noninvasive micro-test technique (NMT), 6-chloroindole triggered algal cellular Ca2+ efflux. The highest value was 72.03pmolcm−2s−1, 10.6 times of the control group. The present studies indicated that indole derivatives might have the potential to be new antifouling agents because of their excellent antibacterial and anti-algal activities. At the same time, Ca2+ efflux might be one of the mechanisms that indole derivatives inhibited the growth of diatom.
اظهر المزيد [+] اقل [-]Biodegradation of nitrobenzene in a lysogeny broth medium by a novel halophilic bacterium Bacillus licheniformis النص الكامل
2014
Li, Tian | Deng, Xinping | Wang, Jinjun | Chen, Yucheng | He, Lin | Sun, Yuchuan | Song, Caixia | Zhou, Zhifeng
The Bacillus licheniformis strain YX2, a novel nitrobenzene-degrading halophilic bacterium, was isolated from active sludge obtained from a pesticide factory. Strain YX2 can withstand highly acidic and alkaline conditions and high temperatures. Degradation of nitrobenzene (200mgL−1) by YX2 exceeded 70% after 72h in lysogeny broth medium (pH 4–9). Under optimal degradation conditions (33°C, pH 7 in LB medium) YX2 degraded 50, 100, 200, and 600mgL−1 nitrobenzene within 36, 36, 72, and 156h, respectively. Even in the presence of benzene, phenol or aniline, strain YX2 efficiently degraded nitrobenzene. Furthermore, strain YX2 completely degraded 600mgL−1 nitrobenzene in 7% NaCl (w/w). Thus, our data show that strain YX2 may have promise for removing nitrobenzene from complex wastewaters with high salinity and variable pH.
اظهر المزيد [+] اقل [-]Population dynamics and antimicrobial susceptibility of Aeromonas spp. along a salinity gradient in an urban estuary in Northeastern Brazil النص الكامل
2014
Silva, Camila Magalhães | Evangelista-Barreto, Norma Suely | Vieira, Regine Helena Silva dos Fernandes | Mendonça, Kamila Vieira | Sousa, Oscarina Viana de
The main objective of this study was to quantify population and identify culturable species of Aeromonas in sediment and surface water collected along a salinity gradient in an urban estuary in Northeastern Brazil. Thirty sediment samples and 30 water samples were collected from 3 sampling locations (A, B and C) between October 2007 and April 2008. The Aeromonas count was 10–7050CFU/mL (A), 25–38,500CFU/mL (B) and<10CFU/mL (C) for water samples, and ∼100–37,500CFU/g (A), 1200–43,500CFU/g (B) and<10CFU/g (C) for sediment samples. Five species (Aeromonas caviae, A. sobria, A. trota, A. salmonicida and A. allosaccharophila) were identified among 41 isolates. All strains were sensitive to chloramphenicol and ceftriaxone, whereas 33 (80, 4%) strains were resistant to at least 2 of the 9 antibiotics tested. Resistance to erythromycin was mostly plasmidial. In conclusion, due to pollution, the Cocó River is contaminated by pathogenic strains of Aeromonas spp. with a high incidence of antibacterial resistance, posing a serious risk to human health.
اظهر المزيد [+] اقل [-]Human health risks in national capital territory of Delhi due to air pollution النص الكامل
2014
Nagpure, Ajay Singh | Gurjar, Bhola Ram | Martel, Jc
This study evaluates the human health risks in Indian National Capital Territory of Delhi (NCT Delhi) in terms of mortality and morbidity due to air pollution. The spreadsheet model, Risk of Mortality/Morbidity due to Air Pollution (Ri–MAP) was used to evaluate the direct health impacts of various criteria air pollutants present in various districts of NCT Delhi during the period 1991 to 2010. By adopting the World Health Organization (WHO) guideline concentrations for the air pollutants SO2, NO2 and total suspended particles (TSP), concentration–response relationships and a population attributable–risk proportion concept were employed. About 11 394, 3 912, 1 697 and 16 253 excess number of cases of total mortality, cardiovascular mortality, respiratory mortality and hospital admission of COPD respectively were observed for entire NCT Delhi in year 2000. However, within a one decade, in year 2010 these figures became 18 229, 6 374, 2 701 and 26 525. District–wise analysis shows that North West district is having the highest number of mortality and morbidity cases continuously after 2002, moreover least excess number of cases was observed for New Delhi district.
اظهر المزيد [+] اقل [-]Petroleum hydrocarbons in water from a Brazilian tropical estuary facing industrial and port development النص الكامل
2014
Lemos, Rafael Thompson de Oliveira | Carvalho, Paulo Sérgio Martins de | Zanardi-Lamardo, Eliete
A fast paced industrial and port development has occurred at Suape Estuary, Northeast Brazil, but no information about hydrocarbon concentrations in water is available to this area. Considering that, the contamination level of Suape was determined by UV-Fluorescence in terms of dissolved and/or dispersed petroleum hydrocarbons (DDPHs), during wet and dry seasons. DDPHs ranged between 0.05 and 4.59μgL−1 Carmópolis oil equivalents and 0.01–1.39μgL−1 chrysene equivalents, indicating DDPHs close to a baseline contamination level. Some relatively high concentrations (>1μgL−1) were probably associated with shipyard operations (hull paintings and ship docking), pollutants remobilization by dredging operations, occasional industrial discharges and oil derivatives released by vessels. DDPHs concentrations were lower in the wet season suggesting that the increased dilution rates caused by rainfall dominated upon the wet deposition of atmospheric combustion-derived PAHs process. Results in this study may be used as baseline to further studies in this area.
اظهر المزيد [+] اقل [-]Functional and molecular characterization of a lipopeptide surfactant from the marine sponge-associated eubacteria Bacillus licheniformis NIOT-AMKV06 of Andaman and Nicobar Islands, India النص الكامل
2014
Lawrance, Anburajan | Balakrishnan, Meena | Joseph, Toms Cheriath | Palaiya Sukumaran, Dheenan | Nambali Valsalan, Vinithkumar | Gopal, Dharani | Ramalingam, Kirubagaran
The production of a lipopeptide surfactant from the sponge-associated eubacteria Bacillus licheniformis NIOT-AMKV06 from the Andaman and Nicobar Islands was investigated. The highest production was attained with glucose and yeast extracts as the carbon and nitrogen sources (1.789mgmL−1), respectively. The surfactant was highly stable over a pH range of 5.0–10 and a temperature range of 20–70°C with high NaCl concentrations. Excellent emulsification activity was exhibited by the purified surfactant with crude oil, kerosene, and diesel. A two-fold increase in surfactant production (3.0mgmL−1) was observed using the newly formulated medium in this study. The surfactant biosynthesis gene cluster (sfp, sfpO, and srfA) from B. licheniformis NIOT-AMKV06 was heterologously expressed in Escherichia coli, and the production was increased three-fold (11.78gL−1) over the original strain. The results confirm the potential of the surfactant for use in bioremediation of hydrocarbons in a marine environment and for enhanced oil recovery. To our knowledge, this is the first report on the ability of a hydrocarbon to degrade B. licheniformis from marine sponges for the biosynthesis of a potent lipopeptide surfactant possessing characteristics of maximum stability, outstanding surfactant activity, and exceptional emulsifying capability.
اظهر المزيد [+] اقل [-]Heavy metals in particulate and colloidal matter from atmospheric deposition of urban Guangzhou, South China النص الكامل
2014
Huang, Wen | Duan, Dandan | Zhang, Yulong | Cheng, Hefa | Ran, Yong
Suspended particulate matter (SPM) and colloidal matter (COM) in annual dry and wet deposition samples in urban Guangzhou were for the first time collected, and their trace metals were investigated by using inductively coupled plasma mass spectrometry (ICP-MS). The deposition flux of SPM and of metal elements varied largely among the investigated seasons, and reached the maximum in spring. The correlation analysis indicated that significant correlations existed among some of the metal elements in the deposition samples. The enrichment factors (EF) of metals in COM in the deposition ranging from 79.66 to 130,000 were much higher than those of SPM ranging from 1.65 to 286.48, indicating the important role of COM. The factor analysis showed that emissions from street dust, non-ferrous metal production, and heavy fuel oil were major sources of the trace metals. Positive matrix factorization (PMF) model was used to quantitatively estimate anthropogenic source.
اظهر المزيد [+] اقل [-]Acetylcholinesterase activity in the host–parasite system of the cod Gadus morhua and acanthocephalan Echinorhynchus gadi from the southern Baltic Sea النص الكامل
2014
Podolska, M. | Nadolna, K. | Szostakowska, B.
Acetylcholinesterase (AChE) activity measurement is widely used as a specific biomarker of neurotoxic effects. The aim of this study was to evaluate AChE activity in a host fish (the cod) and its acanthocephalan parasite Echinorhynchus gadi from the southern Baltic. AChE activity in hosts and parasites was inversely related: the highest cod AChE activity corresponded to the lowest E. gadi enzymatic activity and vice versa (“mirror effect”). This is the first report on the simultaneous application of this biomarker in cod and its acanthocephalan parasites. Results obtained for the host–parasite system are complementary and provide comprehensive information about the response of this biomarker. Analysis of the system allows for detection of a greater number of factors influencing AChE activity in the marine environment than separate analysis of the host and parasites. Thus, AChE activity measurement in a host–parasite system may be considered to be a promising tool for biomonitoring.
اظهر المزيد [+] اقل [-]Disturbance influences the invasion of a seagrass into an existing meadow النص الكامل
2014
McKenzie, Len J. | Yoshida, Rudi L. | Unsworth, Richard K.F.
Future impacts from climate change and human activities may increase the likelihood of invasions of native marine species into existing habitats as a result of range shifts. To provide an understanding of the invasion of a native seagrass species (Syringodiumisoetifolium) into a tropical multi-species meadow, detailed field assessments were conducted over a six year period. After establishing in a discrete patch, the extent and standing crop of S.isoetifolium increased 800 and 7000 fold, respectively, between 1988 and 2003 (∼300–260,000 m2 and<1kgDW to 7596±555kgDW). The expansion of S.isoetifolium was confined to subtidal areas and appears primarily from clonal growth. The observed expansion of this species into a new locality was found to be clearly influenced by cumulative impacts and chronic small-scale physical disturbances. This study has immediate relevance to managing impacts which influence the spread of invasive species.
اظهر المزيد [+] اقل [-]Inshore capture-based tuna aquaculture impact on Posidonia oceanica meadows in the eastern part of the Adriatic Sea النص الكامل
2014
Kružić, Petar | Vojvodić, Vjeročka | Bura-Nakić, Elvira
Mapping and monitoring of the seagrass Posidonia oceanica in the eastern (Croatian) part of the Adriatic Sea since 2004 indicates a significant decline in meadow density in an area impacted by inshore capture-based tuna aquaculture. The density and overall condition of P. oceanica meadows impacted by tuna farms near Fulija Islet was compared to two reference sites (Iž Island and Mrtovnjak Islet). The factors with the most significant influence on P. oceanica meadows were found to be the input of organic matter originating from the cages, as well as high epiphyte biomass caused by nutrient enrichment. Significant differences in nutrient concentrations were found between the sites impacted by tuna farms (Fulija Islet) and the control stations. Shoot density of the P. oceanica meadows decreased at the stations in close vicinity to the tuna farm, which suggests that the tuna farm activity strongly affected the surrounding meadows.
اظهر المزيد [+] اقل [-]