Nei Pereira Junior

Biosurfactant production by Rhodococcus erythropolis and its application to oil removal

The influence of different nutrients on biosurfactant production by Rhodococcus erythropolis was investigated. Increasing the concentration of phosphate buffer from 30 up through 150 mmol/L stimulated an increase in biosurfactant production, which reached a maximum concentration of 285 mg/L in shaken flasks. Statistical analysis showed that glycerol, NaNO3, MgSO4 and yeast extract had significant effects on production. The results were confirmed in a batchwise bioreactor, and semi-growth-associated production was detected. Reduction in the surface tension, which indicates the presence of biosurfactant, reached a value of 38 mN/m at the end of 35 hours. Use of the produced biosurfactant for washing crude oil-contaminated soil showed that 2 and 4 times the critical micellar concentration (CMC) were able to remove 97 and 99% of the oil, respectively, after 1 month of impregnation.

Influence of some sugars on xylanase production by Aspergillus awamori in solid state fermentation

Aspergillus awamori showed high extracellular endoxylanase (100 U/ml) and b-xylosidase activities (3.5 U/ml) when grown on milled sugar cane bagasse as the principal carbon source without treatment. Partial characterization of xylanases showed that the apparent values of Km were 3.12 ± 0.05 mg/ml for endoxylanase (in birchwood xylan) and 0.45 ± 0.05 mM for b-xylosidase (in p -nitrophenyl b-D-xylanopiranoside). Corresponding values of Vmax were 6.63 ± 0.02 and 0.078 ± 0.02 mmol/min. Gradual repression of endoxylanase activity was observed when increasing concentrations of glucose and xylose (1, 2, 4, 6 and 8 g of carbohydrate / 4 g of sugar cane bagasse) were added to production media. In contrast, b-xylosidase activity was stimulated using low levels of carbohydrates (1 g xylose or glucose/ 4 g of sugar cane bagasse).

Technology Prospecting on Enzymes for the Pulp and Paper Industry

The use of enzymes in the pulp and paper industry was introduced in the 1986. However, their use has been relatively minor. This prospective study aims at enhancing the understanding of the most important advances regarding the use of enzymes in this industry and to identify the future trends of this technology. Information gathered from the Web of Science shows a growing number of papers published on this topic indicating an increased interest in this issue. A study on patents also displayed a high number documents related to this technology. Cellulase, xylanase, laccase and lipase are the most important enzymes that can be used in the pulp and paper processes. Furthermore, the key objectives of enzymes development have been in the bleaching boosting with xylanases and fiber modification with cellulases. The current and future trends on the development of enzymes are focused on increasing their thermostability and their alkalinity strength.

A chemically defined medium for production of actinomycin D by Streptomyces parvulus

A chemically defined medium consisting of D(+)fructose, L(-)threonine, K2HPO4, MgSO4.7H2O, ZnSO4.7H2O, CaCl2.2H2O, FeSO4.7H2O and deionized water, was developed to maximize the synthesis of actinomycin D by the Streptomyces parvulus DAUFPE 3124 strain. This medium resulted in the maximum antibiotic concentration of 133mg/L while using the original medium the production of actinomycin D was poor not surpassing 43mg/L.

Avaliação do consumidor sobre sorvetes com xilitol

The aim of this study was to evaluate, firstly, consumer preference for ice cream formulations (cream, strawberry and chocolate) sweetened with sucrose against formulations with xylitol, through paired comparison tests with consumers. The acceptability of the ice creams formulated with xylitol was also evaluated, considering the following attributes: overall aspect, colour, consistency, sweetness and flavour, in addition to observing consumer habits with respect to ice cream consumption and their purchase intention. The ice creams sweetened with sucrose were prefered when compared to those sweetened with xylitol, with the chocolate ice creams presenting the lowest sensory difference, followed by strawberry and cream ice creams. The acceptability of the ice creams containing xylitol was considered high, with results for overall aspect of 91% for the strawberry ice creams, 88% for the chocolate ice creams and 67% for the cream ice creams, which can be considered between good and excellent. These results reflected on the purchase intention results, where consumers were quite receptive to take home any of the ice cream flavours evaluated, especially the chocolate flavour, which was preferred amongst the consumers consulted. The results confirm the commercialization potential of ice creams sweetened with xylitol, as an option for individuals with diabetes and obesity.

Avaliação sensorial de sorvetes à base de xilitol

The aim of this study was to compare the sweetening power of xylitol and sucrose solutions, verifying differences in sweetness among cream, strawberry and chocolate flavoured ice creams sweetened with these two sweeteners, and also determining the sensory quality of the products with respect to appearance, colour, aroma, consistency and flavour. There were significant differences (p < 0.05) among all the formulations except between the strawberry formulations made with 100% sucrose and 50% xylitol. With respect to quality, the cream flavoured ice creams presented the greatest differences in quality among the three concentrations of sweeteners, since of the five attributes evaluated, significant differences (p < 0.05) were obtained for four of them (appearance, colour, consistency and flavour). The strawberry ice creams were the most uniform with respect to quality, only presenting significant differences (p < 0.05) for consistency. The chocolate ice creams were intermediate, presenting significant differences (p < 0.05) for consistency and flavour.

Fibras de carbono a partir de lignina: uma revisão da literatura

Os precursores mais empregados para obtencao da fibra de carbono sao a poliacrilonitrila, o piche e o rayon. Com o aumento da demanda de materiais compositos leves e de alta resistencia, a producao da fibra de carbono tem aumentado exponencialmente e novos precursores tem sido requisitados. A lignina, um material orgânico natural, tem sido estudada como possivel candidata para a producao das fibras. Alem de ser rejeito industrial e de biorrefinarias, as fibras de carbono obtidas com a lignina podem ter um custo mais vantajoso quando comparado com os demais precursores comerciais. Em decorrencia da biodiversidade de vegetais na natureza, a lignina pode apresentar diferentes estruturas. O metodo de recuperacao tambem e parâmetro que influencia diretamente na sua composicao. Como as propriedades termicas para extrusao sao fortemente dependentes dessas e de muitas outras variaveis, muitas pesquisas tem sido reportadas utilizando lignina pura de diversas fontes, lignina modificada e com adicao de plastificantes. As etapas de pre-tratamento, termoestabilizacao e carbonizacao/grafitizacao tambem tem sido avaliadas para conferir melhores propriedades mecânicas ao produto final. Nao obstante serem muitas as condicoes para a producao da fibra de carbono a partir da lignina, resultados bastante promissores tem sido alcancados. As aplicacoes em diversas areas estao diretamente relacionadas com o conjunto de propriedades mecânicas inerentes a ela. A fibra de carbono proveniente da lignina vem contribuir com inumeros empregos no mercado, de maneira a baratear sua producao, minimizar a dependencia de materiais fosseis e tornar sua manufatura ecologicamente sustentavel.

Use of Patent Applications as a Tool for Technology Development Investigations on Ethanol Production from Lignocellulosic Biomass in Brazil

The growing concerns regarding the future of global energy supplies have encouraged R&D in alternative sources to complement the global energy matrix. Brazil has earned notoriety as one of the largest producers of ethanol and biomass. This has aroused other countries’ interest in Brazil’s capabilities. However, the technologies for converting biomass into ethanol are not sufficiently mature, and have been developed in a decentralized manner. The lignocellulosic ethanol technologies can be divided into the following three groups: pretreatment, enzymes and ethanol production. One of the most efficient methods for mapping such technologies is through patent applications because the applications provide important information on trends in long-term technological development. Among all the patent applications deposited in the Brazilian database, pretreatment technologies were the most exploited followed by enzymes and ethanol production. The large number of documents from USA and European countries efforts the importance of Brazil in this technological scenario.

The influence of centrifugation on Zymomonas mobilis aggregation

Flocculent Zymomonas mobilis breaks down in smaller flocs and individual cells when centrifuged. The main consequence of it is an increase in the dispersion of the sample, suggesting that the influence of the centrifugal force on the aggregation of cells is worth to study. The experiments showed that the degree of dispersion varied between 30% and 100% when the centrifugal acceleration changed from 25 g to 2500 g. Observation under the electronic microscope showed that a slimy material covered the cells recovered by gentle gravitational settling and, that the centrifuged cells presented a bare cell wall.