Changes in the microbial community during bioremediation of gasoline-contaminated soil

Abstract We aimed to verify the changes in the microbial community during bioremediation of gasoline-contaminated soil. Microbial inoculants were produced from successive additions of gasoline to municipal solid waste compost (MSWC) previously fertilized with nitrogen-phosphorous. To obtain Inoculant A, fertilized MSWC was amended with gasoline every 3 days during 18 days. Inoculant B received the same application, but at every 6 days. Inoculant C included MSWC fertilized with N–P, but no gasoline. The inoculants were applied to gasoline-contaminated soil at 10, 30, or 50 g/kg. Mineralization of gasoline hydrocarbons in soil was evaluated by respirometric analysis. The viability of the inoculants was evaluated after 103 days of storage under refrigeration or room temperature. The relative proportions of microbial groups in the inoculants and soil were evaluated by FAME. The dose of 50 g/kg of inoculants A and B led to the largest CO2 emission from soil. CO2 emissions in treatments with inoculant C were inversely proportional to the dose of inoculant. Heterotrophic bacterial counts were greater in soil treated with inoculants A and B. The application of inoculants decreased the proportion of actinobacteria and increased of Gram-negative bacteria. Decline in the density of heterotrophic bacteria in inoculants occurred after storage. This reduction was bigger in inoculants stored at room temperature. The application of stored inoculants in gasoline-contaminated soil resulted in a CO2 emission twice bigger than that observed in uninoculated soil. We concluded that MSWC is an effective material for the production of microbial inoculants for the bioremediation of gasoline-contaminated soil.

Uso de Leersia hexandra (Poaceae) en la fitorremediación de suelos contaminados con petróleo fresco e intemperizado / Use of Leersia hexandra (Poaceae) for soil phytoremediation in soils contaminated with fresh and weathered oil

ResumenLa industria petrolera ha generado derrames crónicos de petróleo y su acumulación en Gleysoles en zonas anegadas en el estado de Tabasco, en el sureste de México. El anegamiento es un factor que limita el uso de tecnologías de remediación por el alto costo y los bajos niveles de degradación del petróleo, sin embargo, Leersia hexandra Sw. es un pasto que crece en estas zonas contaminadas con petróleo intemperizado. El objetivo del estudio fue evaluar la densidad de bacterias, producción de biomasa vegetal y fitorremediación de L.hexandra en suelo contaminado con petróleos fresco e intemperizado, bajo condiciones experimentales de anegamiento. Se realizaron dos experimentos (E1 y E2) en un túnel de plástico. El E1 se basó en ocho dosis: 6 000, 10 000, 30 000, 60 000, 90 000, 120 000, 150 000 y 180 000 mg kg-1 base seca (b.s.) de hidrocarburos totales de petróleo fresco (HTPF), y en el E2 se evaluaron cinco dosis: 14 173, 28 400, 50 598, 75 492 y 112 142 mg kg-1 b. s. de hidrocarburos totales de petróleo intemperizado (HTPI), con ocho repeticiones en cada experimento, además se utilizó un testigo con 2 607 mg kg-1 b. s. de HTP de origen biogénico. Las variables evaluadas a los tres y seis meses fueron 1) densidad microbiana de las bacterias fijadoras de nitrógeno de vida libre totales (BFN), del grupo Azospirillum (AZP) y Azotobacter (AZT), por cuenta viable en placa seriada; 2) producción de materia seca total (MS), se cuantificó por el peso seco por gravimetría, y 3) el porcentaje de descontaminación de los hidrocarburos (DSC) por extracción en equipo soxhlet. En suelos con HTPF, la población de BFN, AZP y AZT se estimuló hasta cinco veces más que el tratamiento testigo a los tres y seis meses; sin embargo, concentraciones de 150 000 y 180 000 mg kg-1 b. s. inhibieron entre un 70 y 89 % la densidad bacteriana. A su vez, en suelos con PI, la inhibición se registró hasta en un 90 %, a excepción del tratamiento con 14 173 mg kg-1 b. s., el cual estimuló las BNF y AZT en 2 y 0.10 veces más que testigo, respectivamente. La producción de MS fue continua en los experimentos hasta los seis meses, con valores de 63 y 89 g en PF y PI, respectivamente; sin diferencias significativas con el testigo (p ≤ 0.05). El DSC alcanzó valores del 66 % al 87 % en HTPF como HTPI a los seis meses, respectivamente. Estos resultados demuestran la habilidad del L. hexandra para desarrollar una rizósfera con alta densidad de BFN, producir biomasa vegetal y fitorremediar Gleysoles con petróleo fresco e intemperizado en ambientes tropicales inundados.

Abstract:The oil industry has generated chronic oil spills and their accumulation in wetlands of the state of Tabasco, in Southeastern Mexico. Waterlogging is a factor that limits the use of remediation technologies because of its high cost and low levels of oil degradation. However, Leersia hexandra is a grass that grows in these contaminated areas with weathered oil. The aim of the study was to evaluate the bacteria density, plant biomass production and phytoremediation of L. hexandra in contaminated soil. For this, two experiments in plastic tunnel were performed with fresh (E1) and weathered petroleum (E2) under waterlogging experimental conditions. The E1 was based on eight doses: 6 000, 10 000, 30 000, 60 000, 90 000, 120 000, 150 000 and 180 000 mg.kg-1 dry basis (d. b.) of total petroleum hydrocarbons fresh (TPH-F), and the E2, that evaluated five doses: 14 173, 28 400, 50 598, 75 492 and 112 142 mg. kg-1 d. b. of total petroleum hydrocarbons weathered (TPH-W); a control treatment with 2 607 mg.kg-1 d. b. was used. Each experiment, with eight replicates per treatment, evaluated after three and six months: a) microbial density of total free-living nitrogen-fixing bacteria (NFB) of Azospirillum (AZP) and Azotobacter group (AZT), for viable count in serial plate; b) dry matter production (DMP), quantified gravimetrically as dry weight of L. hexandra; and c) the decontamination percentage of hydrocarbons (PDH) by Soxhlet extraction. In soil with TPH-F, the NFB, AZP y AZT populations were stimulated five times more than the control both at the three and six months; however, concentrations of 150 000 and 180 000 mg.kg-1 d. b. inhibited the bacterial density between 70 and 89 %. Likewise, in soil with TPH-W, the FNB, AZP and AZT inhibitions were 90 %, with the exception of the 14 173 mg.kg-1 d. b. treatment, which stimulated the NFB and AZT in 2 and 0.10 times more than the control, respectively. The DMP was continued at the six months in the experiments, with values of 63 and 89 g in fresh and weathered petroleum, respectively; had no significant differences with the control (p≤0.05). The PDH reached values of 66 to 87 % both TPH-F and TPH-W at six months, respectively. These results demonstrated the ability the L. hexandra rhizosphere to stimulate the high NFB density, vegetal biomass production and phytoremediation of contaminated soils (with fresh and weathered petroleum), in a tropical waterlogging environment. Rev. Biol. Trop. 65 (1): 21-30. Epub 2017 March 01.

Chemical composition and antibacterial activity of Laureliopsis philippiana (Looser) essential oil / Composición química y actividad antibacteriana del aceite esencial de Laureliopsis philippiana (Looser)

Laureliopsis philippiana (Looser) is native evergreen specie from Chile and Argentina used in traditional medicine. In this study, chemical composition as well as its in vitro antibacterial activity against Escherichia coli, Enterobacter aerogenes, Staphylococcus epidermidis and Staphylococcus aureus of essential oil from leaves of this species was determinated. Chemical analysis by GC-MS resulted in the identification of 19 compounds representing 98.8 percent onoterpenes; linalool (32.3 percent) and eucalyptol (37.4 percent) were the main constituents. To evaluate the antibacterial activity disc diffusion method and broth dilution method were used. The essential oil exhibited inhibitory activity against Gram (-) and Gram (+) bacteria, whereas similar activity to essential oil was showed for linalool against E. aerogenes and S. epidermidis whereas linalool alone, achieves an inhibitory effect against E. aerogenes and S. epidermidis comparable to the essential oil.

Laureliopsis philippiana (Looser) es una especie siempre verde nativa de Chile y Argentina usado en medicina tradicional. En este estudio se determinó tanto la composición química del aceite esencial obtenido a partir de hojas de esta especie, así como su actividad antibacterial in vitro contra Escherichia coli, Enterobacter aerogenes, Staphylococcus epidermidis and Staphylococcus aureus. El análisis químico por GC-MS permitió la identificación de 19 compuestos, representando el 98,8 por ciento de la composición del aceite. Monoterpenos oxigenados, eucaliptol y linalol fueron los mayores constituyentes del aceite con un 37,4 por ciento y 32,3 por ciento respectivamente. Para evaluar la actividad antibacteriana se utilizaron los métodos de difusión en agar y dilución en caldo. El aceite esencial muestra actividad inhibitoria contra las bacterias Gram (-) y Gram (+) evaluadas, mientras que linalol por si solo logra un efecto inhibitorio comparable con el aceite esencial contra E. aerogenes y S. epidermidis mientras que el linalol por si solo, logra un efecto inhibitorio contra E. aerogenes y S. epidermidis comparable al del aceite esencial.

Toxicological evaluation of vegetable oils and biodiesel in soil during the biodegradation process

Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida. are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa and lettuce (Lactuca sativa. to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

Biodegradation of petroleum hydrocarbons in hypersaline environments

Literature on hydrocarbon degradation in extreme hypersaline media presents studies that point to a negative effect of salinity increase on hydrocarbonoclastic activity, while several others report an opposite tendency. Based on information available in the literature, we present a discussion on the reasons that justify these contrary results. Despite the fact that microbial ability to metabolize hydrocarbons is found in extreme hypersaline media, indeed some factors are critical for the occurrence of hydrocarbon degradation in such environments. How these factors affect hydrocarbon degradation and their implications for the assessment of hydrocarbon biodegradation in hypersaline environments are presented in this review.

Biosurfactants production by yeasts using soybean oil and glycerol as low cost substrate

Biosurfactants are bioactive agents that can be produced by many different microorganisms. Among those, special attention is given to yeasts, since they can produce many types of biosurfactants in large scale, using several kinds of substrates, justifying its use for industrial production of those products. For this production to be economically viable, the use of residual carbon sources is recommended. The present study isolated yeasts from soil contaminated with petroleum oil hydrocarbons and assessed their capacity for producing biosurfactants in low cost substrates. From a microbial consortium enriched, seven yeasts were isolated, all showing potential for producing biosurfactants in soybean oil. The isolate LBPF 3, characterized as Candida antarctica, obtained the highest levels of production - with a final production of 13.86 g/L. The isolate LBPF 9, using glycerol carbon source, obtained the highest reduction in surface tension in the growth medium: approximately 43% of reduction after 24 hours of incubation. The products obtained by the isolates presented surfactant activity, which reduced water surface tension to values that varied from 34 mN/m, obtained from the product of isolates LBPF 3 and 16 LBPF 7 (respectively characterized as Candida antarctica and Candida albicans) to 43 mN/m from the isolate LPPF 9, using glycerol as substrate. The assessed isolates all showed potential for the production of biosurfactants in conventional sources of carbon as well as in agroindustrial residue, especially in glycerol.

Presence of 3-(pentadec-10-enyl)-catechol allergen in the epicuticular components of Lithrea caustica (Anacardiaceae) / Presencia del alérgeno 3-(pentadec-10-enil)-catecol en los componentes epicuticulares de Lithrea caustica (Anacardiaceae)

Epicuticular components were obtained using methylene chloride extraction of fresh leaves from two populations of Lithrea caustica. The methylene chloride extracts were analyzed using GC and GC-MS. The extracts from both sampled populations showed a mixture of a hydrocarbon fraction of n-alkanes from C-21 to C-33 as their main components and small amounts of monoterpene hydrocarbons. The allergen 3-(pentadec-10-enyl)-catechol was also identified in the epicuticular sample in very different proportions in both extracts. A second extract obtained after the epicuticle had been removed from the sample revealed oxygenated monoterpenes, sesquiterpene hydrocarbons and an increased amount of the allergen 3-(Pentadec-10-enyl)-catechol. These results demonstrate that the cuticle hydrocarbons of the leaves function as a lipophylic barrier that controls allergen release.

Los componentes epicuticulares se obtuvieron mediante la extracción con cloruro de metileno de hojas frescas de dos poblaciones de Lithrea caustica. Los extractos de cloruro de metileno fueron analizados mediante CG y CG-EM. Los extractos de ambas poblaciones mostraron una mezcla de una fracción de hidrocarburos n-alcanos de C-21 a C-33 como sus componentes principales y pequeñas cantidades de hidrocarburos monoterpenicos. El alérgeno 3 - (pentadec-10-enil)-catecol también fue identificado en epicuticula en proporciones muy diferentes en ambos extractos. Un segundo extracto obtenido después que la epicutícula había sido eliminada de la muestra mostró monoterpenos oxigenados, hidrocarburos sesquiterpenos y una mayor cantidad del alérgeno 3 - (Pentadec-10-enil)-catecol. Estos resultados demuestran que los hidrocarburos de la cutícula de las hojas funcionan como una barrera lipofílica que controla la liberación del alérgeno.

Multiple responses of gram-positive and gram-negative bacteria to mixture of hydrocarbons

Most of our knowledge about pollutants and the way they are biodegraded in the environment has previously been shaped by laboratory studies using hydrocarbon-degrading bacterial strains isolated from polluted sites. In present study Gram-positive (Mycobacterium sp. IBB Po1, Oerskovia sp. IBB Po2, Corynebacterium sp. IBB Po3) and Gram-negative (Chryseomonas sp. IBB Po7, Pseudomonas sp. IBB Po10, Burkholderia sp. IBB Po12) bacteria, isolated from oily sludge, were found to be able to tolerate pure and mixture of saturated hydrocarbons, as well as pure and mixture of monoaromatic and polyaromatic hydrocarbons. Isolated Gram-negative bacteria were more tolerant to mixture of saturated (n-hexane, n-hexadecane, cyclohexane), monoaromatic (benzene, toluene, ethylbenzene) and polyaromatic (naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons than Gram-positive bacteria. There were observed cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria. These modifications differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate.

Selection of biosurfactan/bioemulsifier-producing bacteria from hydrocarbon-contaminated soil

Petroleum-derived hydrocarbons are among the most persistent soil contaminants, and some hydrocarbon-degrading microorganisms can produce biosurfactants to increase bioavailability and degradation. The aim of this work was to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated sites, and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with a layer of combustoleo were used for screening, and positive strains were grown in liquid medium, and surface tension and emulsification index were determined in cell-free supernantant and cell suspension. A total of 324 bacterial strains were tested, and 17 were positive for the drop-collapse and hydrocarbon-layer agar methods. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus, Rhodococcus). Surface tension was similar in cell-free and cell suspension measurements, with values in the range of 58 to 26 (mN/m), and all formed stable emulsions with motor oil (76-93 percent E24). Considering the variety of molecular structures among microbial biosurfactants, they have different chemical properties that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.

Use of palmae wax hydrocarbon fractions as chemotaxonomical markers in Butia and Syagrus / Uso de frações de hidrocarbonetos de palmeiras como marcadores quimiotaxonômicos em Butia e Syagrus

The wax hydrocarbon fractions of native Butia and Syagrus species collected from Palms in different regions of the of Rio Grande do Sul state (Brazil) and in Rocha (Uruguay) were analyzed to evaluate their potential as chemotaxonomic markers. The wax was extracted with chloroform and the resulting wax was fractionated by preparative TLC. The hydrocarbon fractions were analyzed by GC-MS. Statistical analyses were completed with the Statistica 5.0 program. The total crude wax yields averaged 0.31% w.w–1 dried leaves for Butia samples and 0.28% for Syagrus samples. The linear hydrocarbons represented on average 15% of the total waxes in the case of Butia samples and 13.7% in Syagrus samples. Hentriacontane and triacontane were the main components of all samples. The comparison of the means showed significant differences among Butia and Syagrus samples, and amongst Butia samples collected in different localities. In the case of the Syagrus collections no consistent groupings could be made. In the case of Butia samples the formation of three groupings could be observed, which were consistent with the species described for their geographical distribution. These results are discussed in the paper.

Frações de hidrocarbonetos das ceras de espécies nativas de Butia e Syagrus coletadas de palmeiras em diferentes regiões do Rio Grande do Sul (Brasil) e em Rocha (Uruguai) foram analisadas para avaliar o seu potencial como marcadores quiomiotaxonômicos. As ceras foram extraídas com clorofórmio e fracionadas por TLC preparativo. As frações de hidrocarbonetos foram analisadas por CG-EM. As análises estatísticas foram realizadas com auxílio do programa Statistica 5.0. O rendimento total de cera das folhas secas foi de 0,31% g.g–1 para as amostras de Butia e de 0,28% para Syagrus. Os hidrocarbonetos lineares representaram em média 15 e 13% do total das ceras para Butia e Syagrus, respectivamente. Hentriacontano e triacontano foram os compostos majoritários em todas as amostras. A comparação de médias mostrou diferenças significativas entre as amostras de Butia e Syagrus e entre as amostras de Butia coletadas em diferentes localidades. As amostras de Syagrus não formaram agrupamentos relacionados com os locais de coleta. Já no caso de Butia, três agrupamentos puderam ser observados e são consistentes com a distribuição geográfica desta espécie. Estes resultados são discutidos no trabalho.

Purification, partial characterization and role in lipid transport to developing oocytes of a novel lipophorin from the cowpea weevil, Callosobruchus maculatus

Lipid transport in arthropods is achieved by highly specialized lipoproteins, which resemble those described in vertebrate blood. Here we describe purification and characterization of the lipid-apolipoprotein complex, lipophorin (Lp), from adults and larvae of the cowpea weevil Callosobruchus maculatus. We also describe the Lp-mediated lipid transfer to developing oocytes. Lps were isolated from homogenates of C. maculatus larvae and adults by potassio bromide gradient and characterized with respect to physicochemical properties and lipid content. The weevil Lp (465 kDa) and larval Lp (585 kDa), with hydrated densities of 1.22 and 1.14 g/mL, contained 34 and 56 percent lipids and 9 and 7 percent carbohydrates, respectively. In both Lps, mannose was the predominant monosaccharide detected by paper chromatography. SDS-PAGE revealed two apolipoproteins in each Lp with molecular masses of 225 kDa (apolipoprotein-I) and 79 kDa (apolipoprotein-II). The lipids were extracted and analyzed by thin-layer chromatography. The major phospholipids found were phosphatidylserine, phosphatidylcholine and phosphatidylethanolamine in adult Lp, and phosphatidylcholine, phosphatidylethanolamine and sphingomyelin in larval Lp. Hydrocarbons, fatty acids and triacylglycerol were the major neutral lipids found in both Lps. Lps labeled in the protein moiety with radioactive iodine (125I-iodine) or in the lipid moiety with fluorescent lipids revealed direct evidence of endocytic uptake of Lps in live oocytes of C. maculatus.

Intra- and interspecific variation of cuticular hydrocarbon composition in two Ectatomma species (Hymenoptera: Formicidae) based on Fourier transform infrared photoacoustic spectroscopy

We have been able to discriminate different castes and sexes of ants in the same colony by measuring cuticular hydrocarbon levels with Fourier transform infrared photoacoustic spectroscopy, compared by canonical discriminant function analysis. We have now applied this methodology to various colonies of two species of ants of the genus Ectatomma in the Brazilian Cerrado. There were clear interspecific differences in cuticular hydrocarbons of these ants, with a small intraspecific variation. The differences between colonies were greater in E. brunneum than in E. vizottoi. Genetic differences among the colonies and species were well estimated by Fourier transform infrared photoacoustic spectroscopy and statistical analyses.

Distribution and abundance of zooplankton in relation to petroleum hydrocarbon content along the coast of Kollam (Quilon), south west coast of India.

In the present study we examine status, impact and trends in prevailing situation of coastal ecosystem of Chavara, Neendakara, Tangasseri and Paravur zones of Kollam coast in terms of zooplankton density and petroleum hydrocarbon content (PHC). Zooplankton samples and water samples were collected during the period May 2003 to June 2004. The numerical count of zooplankton made and PHC content estimated. Paravur offshore recorded the maximum zooplankton count (1390 no./m3) and Tangasseri nearshore the lowest (700.5 no/m3). The petroleum hydrocarbon content was highest at Tangasseri nearshore (21.95 microg/l) and lowest at Paravur offshore (9.40 microg/l). We also observe statistically significant negative correlation between zooplankton density and PHC for a few organisms. The overall impact appears minor, yet, coastal ocean monitoring imperative for sustainable development.

Studies on exhaust emissions of catalytic coated spark ignition engine with adulterated gasoline.

Adulteration of automotive fuels, especially, gasoline with cheaper fuels is widespread throughout south Asia. Some adulterants decrease the performance and life of the engine and increase the emission of harmful pollutants causing environmental and health problems. The present investigation is carried out to study the exhaust emissions from a single cylinder spark ignition (SI) engine with kerosene blended gasoline with different versions of the engine, such as conventional engine and catalytic coated engine with different proportions of the kerosene ranging from 0% to 40% by volume in steps of 10% in the kerosene-gasoline blend. The catalytic coated engine used in the study has copper coating of thickness 400 microns on piston and inner surface of the cylinder head. The pollutants in the exhaust, carbon monoxide (CO) and unburnt hydrocarbons (UBHC) are measured with Netel Chromatograph CO and HC analyzer at peak load operation of the engine. The engine is provided with catalytic converter with sponge iron as a catalyst to control the pollutants from the exhaust of the engine. An air injection is also provided to the catalytic converter to further reduce the pollutants. The pollutants found to increase drastically with adulterated gasoline. Copper-coated engine with catalytic converter significantly reduced pollutants, when compared to conventional engine.

Comparative study of the cuticular hydrocarbon composition of Melipona bicolor Lepeletier, 1836 (Hymenoptera, Meliponini) workers and queens

In social insects, cuticular hydrocarbons are involved in species, kin, caste and nestmate recognition. Gas chromatography and mass spectrometry were used to compare the cuticular hydrocarbon composition of workers, males and queens of Melipona bicolor. The cuticular hydrocarbon composition of this species was found to consist mainly of C23, C25:1, C25, C27:1, C27, C29:1 and C29, which are already present in imagoes that have not yet abandoned the brood cell. This composition varied quantitatively and qualitatively between and within the castes and sexes. The newly emerged workers and young queens (virgins) had similar cuticular hydrocarbon profiles, which were different from those of the males. When the females start executing their tasks in the colony, the cuticular hydrocarbon profile differences appear. The workers have less variety, while the queens conserve or increase the number of cuticular hydrocarbon compounds. The queens have more abdominal tegumentary glands than the workers, which apparently are the source of the new cuticular compounds

La contaminación de las aguas por hidrocarburos: un enfoque para abordar su estudio / The contamination of water by hydrocarbons: an approach for its study

Se presenta una metodología para estudiar las aguas, ésta, con eficiencia de recursos materiales y humanos permite identificar los hidrocarburos contaminantes, cuantificarlos, determinar su fuente y hacerles su seguimiento después de la intervención. Para ello se combinan como técnicas de análisis las determinaciones de hidrocarburos por el número de olor incipiente y por el método ultravioleta. La simplificación que realiza el método para abordar este tipo de contaminación permite su empleo en laboratorios químicos que cuenten con escasos recursos materiales, lo que hace posible su generalización a centros que cuenten con el equipamiento básico de laboratorio

Manual de toxicologia do refino de petróleo / Toxicology of petroleum refining handbook

A indústria do petróleo caracteriza-se pela multiplicidade de exposiçöes potenciais a agentes tóxicos e, por causa disso, encontra-se em desenvolvimento o Programa de Toxicologia Industrial, previsto na Política de Saúde Ocupacional da PETROBRAS. Deste manual, que muito contribuirá para o desenvolvimento de açöes de proteçäo da saúde contra os riscos químicos nas refinarias, constam os conceitos básicos de Toxicologia necessários à compreensäo do assunto e a aplicaçäo prática das informaçöes sobre extensa relaçäo de substâncias relacionadas ao refino de petroleo

Bioquímica del ciclo evolutivo del Triatoma infestans: IX. composición de los hidrocarburos cuticulares comparada con otros triatominos / Biochemistry of the evolutive cycle of Triatoma infestans: IX. Composition of cuticular hydrocarbons compared to other Triatominae

Se compara la composición de los hidrocarburos epicuticulares de varias especies de la tribu Triatomini: T. infestans, T. delpontei, T. rubrovaria, T. sordida, T. guasayana, T. vitticeps (subgrupo infestans) y T. pallidipennis (subgrupo rubrofasciata). Todas estas especies tienen una misma composión cualitativa donde los hidrocarburos mayoritarios son nC29, nC31, 12+14+15+18 metil C38, 15,19+14,18 dimetil C39, 12+14+17+19 metil C36 y 4 metil C34. Sin embargo, las proporciones en que ciertos hidrocarburos se encuentran en cada especie difieren significativamente entre sí y podrían ser utilizadas como criterio de taxonomía química para especies congenéricas bastante cercanas. Para ello podrían emplearse ya sea las curvas cromatográficas o los cocientes de las cantidades en que se presentan ciertos hidrocarburos

Bioquimica del ciclo evolutivo del triatoma infestans: VII. Composición de los lipidos de la superficie de la cuticula extraibles con hexano / Biochemistry of the developmental cycle of Triatoma infestans: VII. Lipid composition of the cuticle surface extracted with hexane

Los lípidos epicuticulares del insecto Triatoma infestans (vinchuca) fueron extraídos con hexano y fraccionados por cromatografía. Se detectaron alcocholes grasos hidrocarburos, ceras, triacilgliceroles, diacilgliceroles, ácidos grasos libres, colesterol, ésteres de colesterol y monoacilgliroles. Los alcoholes superiores e hidrocarburos constituín los componentes amyoritarios. La composición de los ácidos grasos, hidrocarburos y alcoholes fue estudiada por cromatografía gaseosa y espectrografía de masa. Los hidrocarburos fueron separados en lineales y ramificados. Ambos componentes estaban en proporciones similares y comprendían principalmente cadenas de número impar de carbonos de hasta 41 unidades. En los hidrocarburos lineales predominaron los de 27 a 33 carbonos. Se identificaron hidrocarburos monometil ramificados con la ramificación en posición iso, antelso e interna y dimetil-ramificados. Los alcoholes grasos fraccionados e identificados estaban constituidos por cadenas lineales de 16 a 34 carbonos, predominando los de 28 a 34 carbonos. Los ácidos grasos reconocidos y analizados en las diversas fracciones demostraron la presencia por un lado de un grupo principalmente constituido por ácidos de 16 y 18 carbonos, saturados y no saturados, y un grupo de ácidos saturados pares de m ayor longitud de cadena de 24 a 32 carbonos. La presencia de alcoholes, hidrocarburos y ceras constituidos por componentes principalmente saturados y alta longitud de cadena le conflere a la epicutícula una alta resistencia a los agentes químicos y físicos externos