Alexandre Soares Dos Santos

Production of biosurfactants from Pseudomonas aeruginosa PA 1 isolated in oil environments

The potential production of rhamnolipid-type biosurfactants is assessed based on the development of a fermentative process with a strain of Pseudomonas aeruginosa PA1, which was isolated from oil production wastewater in the Northeast of Brazil. These production of molecules using different carbon (n-hexadecane, paraffinic oil, glycerol and babassu oil) and nitrogen sources (NaNO3, (NH4)2SO4 and CH4N2O) was studied. The best results were obtained when using glycerol as substrate. A C/N ratio of 60/1 and use of sodium nitrate as nitrogen source resulted in higher production of the rhamnolipid, expressed by rhamnose (3.16 g/L) and by the yield in relation to biomass (Yp/x = 0.70 g/g). Additionally, physical-chemical characteristics of the spent broth with and without cells were studied, providing a low critical micelle concentration of 19 mg/L and toxicity values of 13 and 13.8 mg/L using two test organisms, the micro crustacean Daphnia similis and the bacterium Vibrio fisheri (Microtox), respectively.

Evaluation of Different Carbon and Nitrogen Sources in Production of Rhamnolipids by a Strain of Pseudomonas aeruginosa

Culture conditions involving variations in carbon and nitrogen sources and different C:N ratios were examined with the aim of increasing productivity in the process of rhamnolipid synthesis by Pseudomonas aeruginosa. In addition to the differences in productivity, the use of different carbon sources resulted in several proportions related to the types of rhamnolipids synthesized (monorhamnolipids and dirhamnolipids). Furthermore, the variation in nutrients, mainly the nitrogen source, resulted in different amounts of virulence factors, as phenazines and extracellular proteins. The data point out a new concern in the choice of substrate to be used for rhamnolipid production by P. aeruginosa: toxic byproducts.

Biosurfactant Production by Rhodococcus erythropolis Grown on Glycerol As Sole Carbon Source

The production of biosurfactant by Rhodococcus erythropolis during the growth on glycerol was investigated. The process was carried out at 28°C in a 1.5-L bioreactor using glycerol as carbon source. The bioprocess was monitored through measurements of biosurfactant concentration and glycerol consumption. After 51 h of cultivation, 1.7 g/L of biosurfactant, surface, and interfacial tensions values (with n-hexadecane) of 43 and 15 mN/m, respectively, 67% of Emulsifying Index (E24), and 94% of oil removal were obtained. The use of glycerol rather than what happens with hydrophobic carbon source allowed the release of the biosurfactant, originally associated to the cell wall.

Acid and enzymatic hydrolysis of the residue from Castor Bean (Ricinus communis L.) oil extraction for ethanol production: detoxification and biodiesel process integration

The starch hydrolysis process of Castor Bean Cake by (CBC) acid or enzymatic combination of alpha-amylase, glucoamylase and pullulanase was evaluated and followed by fermentation. The chemical hydrolysis resulted in 27.3 g L-1 of sugars with 33.4% of hydrolysis efficiency. The generated hydrolyzate was fermented yielding 11 g L-1 of ethanol (YP/S=0.48 g g-1). The best enzymatic hydrolysis condition was as follows (per gram of CBC): 200 µL of a-amylase, at 90 oC; 200 µL of glucoamylase and 100 µL of pullulanase, both at 60 °C, which yielded 75 g L-1 of total reducing sugars corresponding to 91.4 % of hydrolysis efficiency. These sugars were subsequently converted to 34.5 g L-1 of ethanol. The acid hydrolysis process was also capable to allow the detoxification of the Castor Bean Cake.

PEQUI CAKE COMPOSITION, HYDROLYSIS AND FERMENTATION TO BIOETHANOL

Pequizeiro (Caryocar brasiliense Camb) fruits have been evaluated as a potential raw material for the newly established biodiesel industry. This scenario demands applications using the solid co-product derived from the extraction of pequi oil, called cake or meal. This study analyses the acid hydrolysis of carbohydrates present in the pequi meal in order to obtain fermentable sugars and evaluates their conversion to bioethanol. There was 27% starch in the pequi meal. The use of a CCRD experimental design type to study the acid saccharification of pequi meal results in 61.6% conversion of its starch content to reducing sugars. Positive and significant linear effects were observed for H2SO4 concentration and temperature factors, while the quadratic effect of H2SO4 concentration and the linear effect of solid-liquid ratio were negative. Even, with non-optimized fermentative condition using 1% of dried bakers yeast in conical flasks, it was possible to obtain a value equivalent to 53 L of ethanol per ton of hydrolyzed pequi meal.

Determination of Sildenafil Citrate (Viagra ® ) in Various Pharmaceutical Formulations by Flow Injection Analysis with Multiple Pulse Amperometric Detection

O presente trabalho apresenta uma metodologia simples, rapida e de baixo custo para a determinacao de citrato de sildenafila (SC) em formulacoes farmaceuticas de referencia (Viagra®) e em produtos similares, genericos e manipulados, por amperometria de multiplos pulsos em sistema FIA (analise por injecao em fluxo). O metodo consiste na aplicacao de tres pulsos de potencial (sequenciais) em funcao do tempo sobre um eletrodo de trabalho de diamante dopado com boro. SC foi detectado em 1,6 e 1,9 V por meio de dois diferentes processos irreversiveis de oxidacao. Um terceiro pulso de potencial (1,0 V) foi aplicado para regeneracao da superficie do eletrodo. Foram obtidos limites de deteccao na ordem de 10 nmol L-1 e desvio padrao relativo menor que 0,2% (n = 10) para SC 4,5 X 10-5 mol L-1, permitindo 86 injecoes por hora. Estudos de adicao e recuperacao nas amostras ficaram proximos de 100% e os resultados foram validados por cromatografia.

Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1.

Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies for increasing the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of P. aeruginosa spent culture medium and the use of a fed-batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of synthesized mono- and dirhamnolipids. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. The recycling of 20% of the spent culture medium in where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed-batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (2.9 g L−1–10.9 g L−1). These results offer promising pathways for the optimization of processes for the production of rhamnolipids.

Ethanol production from castor bean cake (Ricinus communis L.) and evaluation of the lethality of the cake for mice

The castor bean cake is rich in starch (48 ± 0.53%) and bears a problem linked to the occurrence of a toxic protein (ricin). The chemical hydrolysis (ratio solid:liquid = 1:6; H2SO4= 0.1 mol L-1; 120 °C; 40 min) generated a medium with 27 g L-1 of reducing sugars (hydrolysis efficiency= 32%). The hydrolyzed product was fermented and produced 11 g L-1 of ethanol (volumetric productivity=1.38 g L-1 h-1 and ethanol yield on substrate consumed=0.45 g g-1). In vivo experiments (DL50) revealed a reduction of roughly 240 times in the CBC toxicity (2.11 µg g-1).

Caracterização física e físico-química de frutos de duas variedades de tamarilho oriundas do Norte de Minas Gerais

The tamarillo (Solanum betaceum) is a subtropical species exploited as a fruit for exportation in countries such as Colombia and New Zealand. In Brazil, this fruit is exotic and their nutritional characteristics and technology are little known. This study aimed to characterize the fruits of two varieties of tamarillo, the yellow and the red, found in the Vale do Jequitinhonha region in the state of Minas Gerais. It was discussed the physical, physicochemical and proximate composition. The results of proximate composition and physicochemical characterization showed that there is a great similarity between the two varieties, presenting only major difference in the percentage of ash (0.152 ± 0.046 and 1.054 ± 0339) and reducing sugars (5.283 ± 0.463 and 2.979 ± 0.090). The yield of tamarillo pulp was more than 67%, the average value of total soluble solids was in order of 12.5%, and the average of the quotient from TSS / TAc was above 7.0. These characteristics of the tamarillo allow considering it for consumption in natura and possible raw material for the food industry.

Microalgae and Biofuels: Integration of Productive Chains

Os biocombustiveis de microalgas sao considerados uma alternativa tecnicamente possivel para atender as demandas do setor automotivo, de aviacao e energetico. Entretanto, os custos associados aos processos de cultivo e transformacao ainda restringem o ganho de escala da producao da biomassa e sua conversao em biocombustiveis. Um dos gargalos associados ao cultivo de microalgas e o custo dos nutrientes usados nos processos heterotroficos e mixotroficos. Nesta revisao sobre o tema foram descritas e analisadas iniciativas de aproveitamento de efluentes ou coprodutos provenientes das cadeias de producao de biocombustiveis convencionais, biodiesel e bioetanol, para uso como fontes de nutrientes para o cultivo de microalgas. Com a perspectiva de reduzir custos e integrar cadeias agroindustriais convergentes, foi aqui abordado o uso da vinhaca das usinas de bioetanol de primeira geracao, do hidrolisado hemicelulosico proveniente do pre-tratamento acido do bagaco de cana de acucar, da glicerina bruta derivada do processo de transesterificacao de oleos e gorduras e da agua de lavagem do biodiesel para a producao de biomassa algal.