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1.
Environ Monit Assess ; 191(1): 9, 2018 12 10.
Artículo en Inglés | MEDLINE | ID: mdl-30535805

RESUMEN

This article [1] has been retracted at the request of the Editor-in-Chief. Significant sections of the article show a similarity with the author's own article published previously [2]. All the authors agree with the retraction.

2.
Int J Syst Evol Microbiol ; 62(Pt 9): 2187-2193, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22058326

RESUMEN

A Gram-positive, non-endospore-forming bacterium, designated strain SK 18(T), was isolated from surface soil of a landfill site by dilution plating on trypticase soy broth agar. Preliminary characterization of strain SK 18(T) via biochemical tests, analysis of fatty acid methyl esters and partial 16S rRNA gene sequencing placed it within the genus Microbacterium. Analysis of the cell wall indicated that the peptidoglycan was of cross-linkage type B, containing the amino acids lysine and ornithine and with muramic acid in the N-glycolyl form. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid and an unidentified glycolipid. The major fatty acids of the cell membrane were anteiso-C(17 : 0), anteiso-C(15 : 0) and iso-C(16 : 0). These data further strengthened placement of the strain within the genus Microbacterium. Strain SK 18(T) shared highest 16S rRNA gene sequence similarity (97.2 %) with Microbacterium ulmi DSM 16931(T). Levels of similarity with the type strains of all other recognized Microbacterium species were less than 97.0 %. DNA-DNA hybridization experiments with strain SK 18(T) and its closest relative, M. ulmi DSM 16931(T), revealed a low reassociation value of 39.0 % (σ = 3.8 %). Moreover, strain SK 18(T) showed a number of differences in phenotypic characteristics (colony colour, catalase activity, hydrolysis of polymers, acid production from sugars and oxidation of various substrates), and its DNA G+C content was also higher than that of M. ulmi DSM 16931(T). These data indicated that strain SK 18(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium immunditiarum sp. nov. is proposed. The type strain is SK 18(T) (= MTCC 7185(T) = JCM 14034(T)). An emended description of the genus Microbacterium is also provided.


Asunto(s)
Actinomycetales/clasificación , Filogenia , Microbiología del Suelo , Actinomycetales/genética , Actinomycetales/aislamiento & purificación , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/análisis , Datos de Secuencia Molecular , Peptidoglicano/análisis , Fosfolípidos/análisis , ARN Ribosómico 16S/genética , Eliminación de Residuos , Análisis de Secuencia de ADN , Suelo/análisis
3.
Environ Monit Assess ; 172(1-4): 249-62, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20151189

RESUMEN

Electronic waste or E-waste comprises of old, end-of-life electronic appliances such as computers, laptops, TVs, DVD players, refrigerators, freezers, mobile phones, MP3 players, etc., which have been disposed of by their original users. E-waste contains many hazardous constituents that may negatively impact the environment and affect human health if not properly managed. Various organizations, bodies, and governments of many countries have adopted and/or developed the environmentally sound options and strategies for E-waste management to tackle the ever growing threat of E-waste to the environment and human health. This paper presents E-waste composition, categorization, Global and Indian E-waste scenarios, prospects of recoverable, recyclable, and hazardous materials found in the E-waste, Best Available Practices, recycling, and recovery processes followed, and their environmental and occupational hazards. Based on the discussion, various challenges for E-waste management particularly in India are delineated, and needed policy interventions were discussed.


Asunto(s)
Residuos Electrónicos , Eliminación de Residuos/métodos , Administración de Residuos/métodos , India
4.
Environ Monit Assess ; 168(1-4): 55-61, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19626446

RESUMEN

Plantation or green belt (GB) grown around the factories and industrial premises improves the condition of land, mitigates air pollution (as the plants serve as a sink for pollutants and check the flow of dust, etc.), and reduces the level of noise pollution. The software developed by NEERI for the determination of the optimal width of GB in and around an industry is based on the pollution attenuation coefficient of selected plant species of deciduous trees existing in the region. The assessment of the impact of these plantations/green belts of 500-m width in and around a petroleum refinery in the west coast of India is evaluated for reducing/managing various waste generated, and it is observed that the overall efficiency is more than 60%.


Asunto(s)
Contaminantes Atmosféricos/toxicidad , Ambiente , Monitoreo del Ambiente , Petróleo/toxicidad , Plantas/efectos de los fármacos , Contaminantes Atmosféricos/metabolismo , Contaminación del Aire/prevención & control , Contaminación del Aire/estadística & datos numéricos , Biodegradación Ambiental , Industria Procesadora y de Extracción , Modelos Químicos , Petróleo/metabolismo , Plantas/metabolismo
5.
Environ Monit Assess ; 160(1-4): 457-64, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19130274

RESUMEN

Carbon emission is supposed to be the strongest factor for global warming. Removing atmospheric carbon and storing it in the terrestrial biosphere is one of the cost-effective options, to compensate greenhouse gas emission. Millions of acres of abandoned mine land throughout the world, if restored and converted into vegetative land, would solve two major problems of global warming and generation of degraded wasteland. In this study, a manganese spoil dump at Gumgaon, Nagpur in India was reclaimed, using an integrated biotechnological approach (IBA). The physicochemical and microbiological status of the mine land improved after reclamation. Soil organic carbon (SOC) pool increased from 0.104% to 0.69% after 20 years of reclamation in 0-15 cm spoil depth. Soil organic carbon level of reclaimed site was also compared with a native forestland and agricultural land. Forest soil showed highest SOC level of 1.11% followed by reclaimed land and agriculture land of 0.70% and 0.40%, respectively. Soil profile studies of all three sites showed that SOC pool decreased from 0-15, 15-30, and 30-45 cm depths. Although reclaimed land showed less carbon than forestland, it showed better SOC accumulation rate. Reclamation of mine lands by using IBA is an effective method for mitigating CO2 emissions.


Asunto(s)
Carbono/análisis , Manganeso , Minería , Suelo/análisis , Dióxido de Carbono/análisis , Conservación de los Recursos Naturales/métodos , Monitoreo del Ambiente , Calentamiento Global , India
7.
Environ Monit Assess ; 157(1-4): 471-81, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18850289

RESUMEN

An important goal of ecological rehabilitation is to accelerate natural successional processes to increase biological productivity, soil fertility and biotic control over biogeochemical fluxes within the recovering ecosystems. A new approach called Microbe Assisted Green Technology (MAGT) is an integrated biotechnological approach developed at National Environmental Engineering Research Institute (NEERI) through exhaustive laboratory as well as field studies and serve as a model for land reclamation and development of lush green vegetation on mine overburdens. One year old seedlings of native tree species were planted on 6.3 ha area of manganese mine overburden at Gumgaon under Manganese Ore India Ltd., Maharashtra, India. Continuous efforts resulted in nutrient rich soil with high N, P, K and organic carbon; well developed biodiversity, including bacteria, fungi, higher plants (more than 350 species) and different classes of animals. Planted trees accumulated 698 t ha( - 1) above ground biomass and 143 t ha( - 1) below ground mass. This was achieved in 18 years by MAGT, which otherwise takes hundreds of years.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Residuos Industriales/análisis , Minería , Microbiología del Suelo , Suelo , Bacterias/crecimiento & desarrollo , Biodegradación Ambiental , Carbono/análisis , Hongos/crecimiento & desarrollo , Cinética , Nitrógeno/análisis , Fósforo/análisis , Evaluación de Programas y Proyectos de Salud , Plantones/crecimiento & desarrollo , Suelo/análisis , Contaminantes del Suelo/análisis , Árboles/crecimiento & desarrollo
8.
Bull Environ Contam Toxicol ; 82(2): 255-9, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18784898

RESUMEN

Emission load of particulate matter from 42 sponge iron industrial units located in clusters in the Indian State of Chhattisgarh was estimated to be 1,361 TPD. US EPA air pollution dispersion model ISCST-3 applied to predict the impact of the sponge iron industry emissions on ambient air quality showed contribution up to 546 microg/m(3) to the surrounding air basin causing the air quality exceeding the national ambient air quality standards. Electrostatic precipitator (ESP) has been suggested to all the above industrial units that would bring down the contribution to as low as 27 microg/m(3).


Asunto(s)
Contaminantes Atmosféricos/análisis , Industria Química , India
9.
Arch Toxicol ; 82(12): 965-71, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19002669

RESUMEN

Many surface waters in Europe, Asia and South America have been reported to be contaminated with genotoxic substances. Therefore, it is important to establish strategies for identification of the most critical sources. In this study, we used a battery of four genotoxicity assays namely chromosomal aberration, DNA strand break, DNA laddering and P53 accumulation tests in mononuclear blood cells. Before cleaning of wastewater high levels of genotoxic contamination could be observed. For instance, we observed an increase in chromosomal aberrations from 2.6 +/- 1.1 (aberrant cells in %; control), to 33.6 +/- 6.6 in a petrochemical plant, 29.4 +/- 3.3 in a petroleum refinery and 14.4 +/- 1.8 in a coke plant of steel industry. A good correlation between the four assays was found. The most sensitive and reproducible results were obtained with the chromosomal aberration assay. Interestingly, clear differences in the efficiency of wastewater cleaning in three different treatment plants were observed. The first and second treatment plants in petrochemical industry and coke plant of steel industry completely eliminated genotoxicity of the wastewater. However, the third plant in petroleum refinery could achieve a reduction in genotoxicity but significant genotoxic contaminations were still present. In conclusion, our battery of genotoxicity tests allows the identification of critical sources contributing to contamination of surface waters.


Asunto(s)
Pruebas de Mutagenicidad , Mutágenos/toxicidad , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/toxicidad , Aberraciones Cromosómicas/inducido químicamente , Coque/efectos adversos , Daño del ADN , Residuos Industriales/efectos adversos , Industrias , Hidrocarburos Policíclicos Aromáticos/toxicidad , Purificación del Agua/métodos
10.
Bioresour Technol ; 99(14): 6512-9, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18155903

RESUMEN

An investigation was carried out in the laboratory to find out the microbial dynamics and enzyme activities during rapid composting of municipal solid waste (MSW). Various treatments such as aeration (A), addition of chemical agents (glucose (G) and acetic acid (AA) and application of cellulolytic microbial (M) inoculum (Phanerochaete chrysosporium and Trichoderma reesei) were used to facilitate the decomposition of MSW. The result of the present investigation revealed that the degradation of organic substrates were quick (within 9-12 days) in case of rapid composting as indicated by the reduction (below 20) in C/N ratio. Whereas, normal composting took more than 20 days to attain C/N ratio of below 20. Estimation of selected enzymes (amylase, protease, phosphatase and cellulase) provided information on the substrate specific degradation profiles of various labile substrates contained in organic waste.


Asunto(s)
Eliminación de Residuos/métodos , Suelo , Amilasas/metabolismo , Biomasa , Péptido Hidrolasas/metabolismo , Monoéster Fosfórico Hidrolasas/metabolismo
11.
Tsitol Genet ; 42(5): 16-31, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-19140437

RESUMEN

An ecotype of brake fern (Pteris vittata) was assessed for arsenic tolerance and accumulation in its biomass under in vivo and in vitro condition; using soil, and agar-gelled Murashige and Skoog (MS) medium supplemented with different concentrations of arsenic. The plants were raised in soil amended with 100-1000 mg arsenic kg(-1) soil, and MS medium was supplemented with 10-300 mg arsenic L(-1) medium using Na2HAsO4 x x 7H2O. The spores and haploid gametophytic-prothalli were raised in vitro on MS medium supplemented with arsenic. The field plants showed normal growth and biomass formation in arsenic amended soil, and accumulated 1908-4700 mg arsenic kg(-1) dry aerial biomass after 10 weeks of growth. Arsenic toxicity was observed above > 200 mg arsenic kg(-1) soil. The concentrations of arsenic accumulated in the plant biomass were statistically significant (p < 0.05). Normal plants were developed from spores and gametophyte prothalli on the MS media supplemented with 50-200 mg arsenic L(-1) medium. The in vitro raised plants were tolerant to 300 mg arsenic kg(-1) of soil and accumulated up to 3232 mg arsenic kg(-1) dry aerial biomass that showed better growth performance, biomass generation and arsenic accumulation in comparison to the field plants.


Asunto(s)
Adaptación Fisiológica , Arsénico/análisis , Contaminantes Ambientales/análisis , Pteris/crecimiento & desarrollo , Biodegradación Ambiental , Biomasa , Pteris/metabolismo , Pteris/fisiología
12.
Biomed Environ Sci ; 20(3): 226-34, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17672214

RESUMEN

OBJECTIVE: To study the modulatory effect of distillate of Ocimum sanctum (traditionally known as Tulsi) leaf extract (DTLE) on genotoxicants. METHODS: In the present investigation, we studied the antigenotoxic and anticlastogenic effect of distillate of Tulsi leaf extract on (i) human polymorphonuclear leukocytes by evaluating the DNA strand break without metabolic activation against mitomycin C (MMC) and hexavalent chromium (Cr+6) and (ii) human peripheral lymphocytes (in vitro) with or without metabolic activation against mitomycin C (MMC), hexavalent chromium (Cr+6) and B[a]P by evaluating chromosomal aberration (CA) and micronucleus assay (MN). Three different doses of DTLE, 50 microL/mL, 100 microL/mL, and 200 microL/mL were selected on the basis of cytotoxicity assay and used for studying DNA strand break, chromosomal aberration and micronucleus emergence. The following positive controls were used for inducing genotoxicity and clastogenicity: MMC (0.29 micromol/L) for DNA strand break, chromosomal aberration and 0.51 micromol/L for micronucleus assay; Potassium dichromate (Cr+6) 600 micromol/L for DNA strand break and 5 micromol/L for chromosomal aberration and micronucleus assay; Benzo[a]pyrene (30 micromol/L) for chromosomal aberration and 40 micromol/L for micronucleus assay. The active ingredients present in the distillate of Tulsi leaf extract were identified by HPLC and LC-MS. RESULTS: Mitomycin C (MMC) and hexavalent chromium (Cr+6) induced statistically significant DNA strand break of respectively 69% and 71% (P<0.001) as revealed by fluorometric analysis of DNA unwinding. Furthermore, the damage could be protected with DTLE (50 microL/mL, 100 microL/mL, and 200 microL/mL) on simultaneous treatment. Chromosomal aberration and micronucleus formation induced by MMC, Cr+6 and B[a]P were significantly protected (P<0.001) by DTLE with and without metabolic activation. CONCLUSION: Distillate of Tulsi leaf extract possesses antioxidants contributed mainly by eugenol, luteolin and apigenin as identified by LC-MS. These active ingredients may have the protective effect against genotoxicants.


Asunto(s)
Linfocitos/efectos de los fármacos , Mutágenos/toxicidad , Ocimum/química , Hojas de la Planta/química , Adulto , Benzopirenos/toxicidad , Supervivencia Celular/efectos de los fármacos , Cromo/toxicidad , Aberraciones Cromosómicas/efectos de los fármacos , ADN/metabolismo , Daño del ADN/efectos de los fármacos , Humanos , Espectrometría de Masas , Mitomicina/toxicidad , Extractos Vegetales/farmacología
13.
Toxicol Mech Methods ; 17(1): 1-12, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-20020982

RESUMEN

ABSTRACT In this research work we developed in vitro tests utilizing mammalian cell cultures, which can rapidly assess effect of exposure of oily sludge-derived chemicals on human and ecological health. Many of these are hazardous to health and environment due to their toxicity and/or accumulation potential in sediments as well as in organisms. Petroleum refinery and petrochemical industry-derived oily sludges contain toxic polycyclic aromatic hydrocarbons (PAHs), some of which are lipophilic in nature. Risk assessment of environmental samples suffers from inadequate availability of toxicity data, lack of knowledge about behavior of genotoxic substances in complex matrices, paucity of information on synergistic and antagonistic interactions of mixture of components, etc.; the literature describing the behavior of genotoxic substances in complex mixtures is sparse and sometimes contradictory. The present study aims at assessing the genotoxic potential of oily sludges collected from an integrated petroleum refinery and petrochemical industry located in the southwestern part of India and a petrochemical industry located in the western part of India using a battery of genotoxicity assays such as DNA damage/strand break, chromosomal aberration, p(53) protein induction, and apoptosis in CHO-K1 cell culture system. Exposure with different dose levels of sludge extracts (25, 50, 100 muL) in CHO-K1 cells could cause statistically significant level of (P < 0.001) DNA damage, chromosomal aberration, p(53) protein induction, and apoptosis in comparison to negative control treatment groups, and the genotoxicity was attributed to PAHs present in the sludge as identified by GC-MS. This implies that the sludges are genotoxic in nature in mammalian cells tested, and the exposure to these may pose a potential genotoxic risk to human beings.

14.
Bioresour Technol ; 97(6): 824-30, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15936943

RESUMEN

Biodegradability of technical grade hexachlorocyclohexane (tech-HCH) was studied in an upflow anaerobic sludge blanket reactor (UASB) under continuous mode of operation in concentration range of 100-200 mg/l and constant HRT of 48 h. At steady state operation more than 85% removal of tech-HCH (upto 175 mg/l concentration) and complete disappearance of beta-HCH was observed. Kinetic constants in terms of maximum specific tech-HCH utilization rate (k) and half saturation velocity constant (K(L)) were found to be 11.88 mg/g/day and 8.11 mg/g/day, respectively. The tech-HCH degrading seed preparation, UASB reactor startup and degradation in continuous mode of operation of the reactor is presented in this paper.


Asunto(s)
Reactores Biológicos , Biotecnología/métodos , Hexaclorociclohexano/metabolismo , Aguas del Alcantarillado , Anaerobiosis , Bacterias Anaerobias/metabolismo , Biodegradación Ambiental , Biotecnología/instrumentación , Cinética
15.
Bioresour Technol ; 97(3): 407-13, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15936944

RESUMEN

The present study deals with the decolorisation, biodegradation and detoxification of Direct Black-38, a benzidine based azo dye, by a mixed microbial culture isolated from an aerobic bioreactor treating textile wastewater. The studies revealed a biotransformation of Direct Black-38 into benzidine and 4-aminobiphenyl followed by complete decolorisation and biodegradation of these toxic intermediates. From cytotoxicity studies, it was concluded that detoxification of the dye took place after degradation of the toxic intermediates by the culture.


Asunto(s)
Compuestos Azo/química , Compuestos Azo/metabolismo , Bencidinas/química , Bencidinas/metabolismo , Colorantes/metabolismo , Adsorción , Amoníaco/metabolismo , Compuestos Azo/farmacología , Bencidinas/farmacología , Biodegradación Ambiental , Biomasa , Reactores Biológicos/microbiología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cromatografía Líquida de Alta Presión , Colorantes/farmacología , Relación Dosis-Respuesta a Droga , Cromatografía de Gases y Espectrometría de Masas , Humanos , Leucocitos Mononucleares/metabolismo , Estructura Molecular , Espectrofotometría Ultravioleta
16.
Biomed Environ Sci ; 19(6): 427-31, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17319266

RESUMEN

OBJECTIVE: To determine the DNA damaging potential and the genotoxicity of individual compounds in pesticide contaminated soil. METHODS: In the present study, DNA damaging potential of pesticide-contaminated soil and the genotoxicity of individual compounds present in the soil were assessed using fluorimetric analysis of DNA unwinding assay. RESULTS: The contaminated soil sample showed 79% (P < 0.001) of DNA strand break, whereas technical grade of major carbaryl and alpha-naphthol constituents of the contaminated soil showed 64% (P < 0.01) and 60% (P < 0.02) damage respectively. CONCLUSION: Our results indicate that the toxicity caused by contaminated soil is mainly due to carbaryl and alpha-napthol, which are the major constituents of the soil sample analyzed by GC-MS.


Asunto(s)
Daño del ADN , Plaguicidas/toxicidad , Contaminantes del Suelo/toxicidad , Pruebas Inmunológicas de Citotoxicidad , ADN/efectos de los fármacos , Fluorometría , Cromatografía de Gases y Espectrometría de Masas , Humanos , Leucocitos/efectos de los fármacos , Pruebas de Mutagenicidad , Suelo
17.
Biomed Environ Sci ; 19(6): 487-94, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17319276

RESUMEN

OBJECTIVE: To study the anticlastogenic effect of redistilled cow's urine distillate (RCUD) in human peripheral lymphocytes (HLC) challenged with manganese dioxide and hexavalent chromium. METHODS: The anticlastogenic activity of redistilled cow's urine distillate was studied in human polymorphonuclear leukocytes (HPNLs) and human peripheral lymphocytes in vitro challenged with manganese dioxide and hexavalent chromium as established genotoxicants and clastogens which could cause induction of DNA strand break, chromosomal aberration and micronucleus. Three different levels of RCUD: 1 microL/mL, 50 microL/mL and 100 microL/mL, were used in the study. RESULTS: Manganese dioxide and hexavalent chromium caused statistically significant DNA strand break, chromosomal aberration and micronucleus formation, which could be protected by redistilled cow's urine distillate. CONCLUSION: The redistilled cow's urine distillate posseses strong antigenotoxic and anticlastogenic properties against HPNLs and HLC treated with Cr+6 and MnO2. This property is mainly due to the antioxidants present in RCUD.


Asunto(s)
Antimutagênicos/farmacología , Bovinos/orina , Cromo/antagonistas & inhibidores , Compuestos de Manganeso/antagonistas & inhibidores , Óxidos/antagonistas & inhibidores , Animales , Antioxidantes/farmacología , Células Cultivadas , Cromo/toxicidad , Daño del ADN , Humanos , Concentración de Iones de Hidrógeno , Linfocitos/efectos de los fármacos , Pruebas de Mutagenicidad , Mutágenos/toxicidad , Óxidos/toxicidad , Orina/química
18.
Biomed Environ Sci ; 19(6): 414-21, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17319264

RESUMEN

OBJECTIVE: To investigate the impact of various levels of sublethal temperature (26 degrees C, 31 degrees C, 33 degrees C, 36 degrees C, and 39 degrees C) on growth and heat shock protein (hsp) expression in freshwater green alga Scenedesmus quadricauda. METHODS: Impact of selected levels of temperature on growth rate (based on optical density), population count, chlorophyll-a and biomass of the alga was evaluated in artificial growth medium for 19 days. To determine the induction of hsp in the alga, it was exposed to selected temperature levels for 3 h and further kept for 6 h at culturing condition at 26 degrees C. Induction of hsp was confirmed by immuno-detection followed by SDS-polyacrylamide gel electrophoresis. RESULTS: The selected growth parameters such as growth rate, population count, chlorophyll-a and biomass were reduced significantly (P < 0.001) at 39 degrees C. However, hsp 70 expression was observed only at 39 degrees C. CONCLUSION: Temperature up to 36 degrees C may be considered as the limit of safe exposure for thermal stress for the alga Scenedesmus quadricauda.


Asunto(s)
Proteínas Algáceas/metabolismo , Agua Dulce , Proteínas HSP70 de Choque Térmico/metabolismo , Scenedesmus/crecimiento & desarrollo , Temperatura , Biomasa , Scenedesmus/metabolismo
19.
Genetics ; 81(2): 223-41, 1975 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1325

RESUMEN

The sanguis and pneumoniae species of Streptococcus were used as recipients in transformations from str+ to str-r and from thy- to thy+. The str-r mutations in the two species had been previously shown to be allelic. Homology of the thy- mutations in the two species was demonstrated in the similar phenotypic properties they conferred (death in the absence of thymidine, lack of thymidylate synthetase). The str and thy loci are unlinked in each species.--- When the two species are transformed by both homospecific and heterospecific DNA, the efficiency is always lower in the heterospecific cross. The efficiency of heterospecific transformation is considerably lower at the thy than at the str locus. DNA was extracted from recipients that had integrated markers of heterospecific origin. When such hybrid DNA is tested on the original recipient species, the heterospecific markers are usually as efficient as homospecific markers. When tested on the original donor species, however, the hybrid DNA is usually more efficient than heterospecific DNA. This is true for both thy and str transformation. -- -- Forty independent thy+ hybrids were obtained in the cross of sanguis thy- recipients with pneumoniae thy+ DNA. These hybrids fall into a number of classes based upon the relative efficiency with which their extracted DNA's are able to transfer the thy+ marker into pneumoniae thy- cells. The most efficient of these DNA's exhibits about 20% of the efficiency of homospecific pneumoniae thy+ DNA and three orders of magnitude greater efficiency than heterospecific sanguis thy+ DNA. Thus, very little of the inefficiency of heterospecific transformation of the thy locus is ascribable to a classic restriction mechanism. Rather, the wild-type thy+ loci in the two species appear to differ at multiple sites, and independent heterospecific transfers result in differential extents of integration of these sites. On this basis, the thy+ loci of the two species differ at a greater number of sites than do the respective str+ loci.


Asunto(s)
ADN Bacteriano/metabolismo , Hibridación de Ácido Nucleico , Streptococcus pneumoniae/metabolismo , Streptococcus sanguis/metabolismo , Transformación Genética , Alelos , Genes , Fenotipo , Timidilato Sintasa/deficiencia
20.
Environ Technol ; 26(5): 545-52, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15974272

RESUMEN

Increased utilization of synthetic plastics caused severe environmental pollution due to their non-biodegradable nature. In the search for environmentally friendly materials to substitute for conventional plastics, different biodegradable plastics have been developed by microbial fermentations. However, limitations of these materials still exist due to high cost. This study aims at minimization of cost for the production of biodegradable plastics P(3HB) and minimization of environmental pollution. The waste biological sludge generated at wastewater treatment plants is used for the production of P(3HB) and wastewater is used as carbon source. Activated sludge was induced by controlling the carbon: nitrogen ratio to accumulate storage polymer. Initially polymer accumulation was studied by using different carbon and nitrogen sources. Maximum accumulation of polymer was observed with carbon source acetic acid and diammonium hydrogen phosphate (DAHP) as nitrogen source. Further studies were carried out to optimize the carbon: nitrogen ratios using acetic acid and DAHP. A maximum of 65.84% (w/w) P(3HB) production was obtained at C/N ratio of 50 within 96 hours of incubation.


Asunto(s)
Conservación de los Recursos Naturales , Plásticos , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos/métodos , Biodegradación Ambiental , Conservación de los Recursos Naturales/economía , Control de Costos , Ensayo de Materiales
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