Glycerol, a co-product of biodiesel production, was evaluated as carbon source for biosurfactant production. For this reason, seven non-pathogenic biosurfactant-producing Bacillus strains, isolated from the tank of chlorination at the Wastewater Treatment Plant at Federal University of Ceara, were screened. The production of biosurfactant was verified by determining the surface tension value, as well as the emulsifying capacity of the free-cell broth against soy oil, kerosene and N-hexadecane. Best results were achieved when using LAMI005 and LAMI009 strains, whose biosurfactant reduced the surface tension of the broth to 28.8 ± 0.0 and 27.1 ± 0.1 mN m(-1), respectively. Additionally, at 72 h of cultivation, 441.06 and 267.56 mg L(-1) of surfactin were produced by LAMI005 and LAMI009, respectively. The biosurfactants were capable of forming stable emulsions with various hydrocarbons, such as soy oil and kerosene. Analyses carried out with high performance liquid chromatography (HPLC) showed that the biosurfactant produced by Bacillus subtilis LAMI009 and LAMI005 was compatible with the commercially available surfactin standard. The values of minimum surface tension and the CMC of the produced biosurfactant indicated that it is feasible to produce biosurfactants from a residual and renewable and low-cost carbon source, such as glycerol.

-In this study, the phase behaviour of emulsified systems (oil + biosurfactant + water) was analyzed. The biosurfactant was produced in a 4-L batch bioreactor by Bacillus subtilis LAMI005, using residual glycerine from biodiesel production as a carbon source. Fourier Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (NMR), and High Performance Liquid Chromatography (HPLC) analyses demonstrated that the biosurfactant produced by Bacillus subtilis (LAMI005) consists of a lipopeptide similar to surfactin. The influences of temperature and the composition of oil + biosurfactant + water were determined by using phase diagrams. Three types of oil were used, namely: motor oil, hydrogenated naphthenic oil (NH140) and castor bean oil. The emulsified systems were analyzed using optical micrography. The results presented here indicated that the biosurfactant produced in this work presents a potential use as stabilizing agent for oil-in-water emulsions.

In this study, the biosurfactant produced by Pseudomonas aeruginosa was evaluated in view of its ability to be used in Microbial-Enhanced Oil Recovery (MEOR). This microorganism was isolated from a soil artificially contaminated with crude oil and used to produce rhamnolipid using glycerol as the carbon source. The biosurfactant efficiently reduced water surface tension from 72 to 35.26 mN/m at its critical micelle concentration of 127 mg/L and emulsification rate (E 24) of 69% for the crude oil. Furthermore, it was demonstrated that the rhamnolipid can recover oil, even 2 months after its production, which shows that its biodegradability is not a disadvantage to the application in MEOR. The best result, for a biosurfactant concentration of 100% above the Critical Micelle Concentration (CMC) and petroleum with API gravity of 21.90, showed that the total recovery factor was 50.45 ± 0.79%, of which 11.91 ± 0.39% corresponds to MEOR.

Biosurfactants are surfactants biologically produced by microorganisms, presenting several advantages when compared to synthetic surfactants. Pseudomonas aeruginosa is known for producing rhamnolipids, considered one of the most interesting types of biosurfactants due to their high yields, when compared to other types. In this work, the production of rhamnolipid from P. aeruginosa was optimized. At first, the Plackett–Burman design was used to select most significant variables affecting the biosurfactant production yield among nine variables—carbon–nitrogen ratio, carbon concentration, nitrogen source, pH, cultivation time, potassium and magnesium concentrations, agitation, and temperature. Then, using main variables, a central point experimental design aiming to optimize rhamnolipid production was performed. The maximum biosurfactant concentration obtained was 0.877 mg L−1. The rhamnolipid also displayed a great emulsification rate, reaching approximately 67%, and the ability to reduce water surface tension from 72.02 to 35.26 mN m−1 at a critical micelle concentration (CMC) of 127 mg L−1, in addition to presenting a good stability when exposed to wide pH and salinity ranges. The results suggest that rhamnolipids are promising substitutes for synthetic surfactants, especially due to lower impacts on the environment.

Biosurfactants are employed in several industrial applications which require a high purity level. However, the downstream purification processes are responsible for a large portion of the expenses incurred by biosurfactant production plants. The high costs associated with these processes turn their application on a large scale a challenge for companies. This study aimed to evaluate the influence of the purification step on the capacity of the rhamnolipid produced by a Pseudomonas aeruginosa strain to recover oil. Both purified and non-purified biosurfactants were efficient in their ability to recover oil. The best result, for the API gravity oil of 27.67, presented a total Recovery Factor of 47.45±1.78%, in which 10.2±0.85% corresponds to the MEOR. However, the results show that non-purified biosurfactant was more efficient in terms of amount of oil recovered during the MEOR stage. This demonstrates that the purification step may not be necessary, reducing the production costs of the rhamnolipid.

Nova metodologia para determinação do estoque de segurança: um estudo aplicado a um banco de sangue no Rio Grande do Norte New methodology for determining the safety stock: a study applied to a blood bank in Rio Grande do Norte

Este artigo tem o objetivo de investigar a construção do ethos masculino no discurso publicitário a partir dos efeitos discursivos que provocam nos interlocutores. Para realizar nosso estudo, temos como aporte teórico a Análise de Discurso Semiolinguística, teoria que considera o sujeito linguageiro ser feito de discurso e ser social (CHARAUDEAU, 2010a). Para tratar o ethos masculino, partimos de Charaudeau (2013); para caracterizar o discurso publicitário, utilizamos conceitos aportados por Charaudeau (2010b). No que se refere à metodologia, realizamos uma pesquisa indutiva, do tipo analítico-discursiva, para analisar quatro anúncios publicitários de perfume. Para a análise, controlamos as seguintes categorias: os sujeitos da encenação, as identidades social e discursiva, as configurações genéricas, seguindo Charaudeau (2009; 2010a; 2010b). Como resultados, constatamos que o ethos masculino construído em relação com os sujeitos da encenação e as identidades discursiva e social em anúncios publicitários de perfume torna-se aliado ao apelo do consumo, característica própria do discurso publicitário que torna as pessoas reféns da sociedade de consumo

Water contamination by monoaromatic compounds has risen throughout time, which leads to the necessity of developing new water treatment technology, capable of minimizing their negative effect on the environment. In this context, biological processes present themselves as a solution to the processes of extraction. Bioremediation makes use of microbial groups capable of using hydrocarbons as a source of carbon to perform their metabolic functions. This work evaluated the biodegradation efficiency of Pseudomonas aeruginosa strain isolated from contaminated matrices, for the substrates benzene, ethylbenzene and toluene, aiming to determine to which compound the bacteria had better adaptation. For that, bioremediation assays were performed for each of the monoaromatic compounds, in an isolated way, with the goal of obtaining experimental data and from this Monod and Andrews kinetic models were discretized and numerically developed through the Runge-Kutta method. It was possible to observe that Pseudomonas aeruginosa has a bigger affinity for ethylbenzene, while benzene generated a bigger microbian coefficient. Monod´s model was capable of predicting satisfactorily the experimental data.