by Castiglioni, Gabriel Luis

Abstract (Summary)
Studies related to the biosurfactants production have been gaining interest because of their vast application in the industrial sector. Their obtainance from renewable and lowpriced substracts, as well as their high biodegradability and low toxicity to the environment, is the great potential for the future substitution of the chemical surfactants. Beyond the biosurfactants, the application of lipases has been increasing in the last years, due to recent biotechnological advances, and it presents great industrial importance in respect to the other enzymes. The data obtainance referent to the biosurfactants and lipases production is a determining stage, not only for the collection of information, but also in the implantation and optimization of the processes.The usage of mathematical models that express those results can, considerably, reduce efforts. Having this in mind, this work was divided in four stages: the first onehas as purpose to develop, to optimize and to validate the mathematical models of description of the biosurfactants production; the second stage, has as aim to developoptimization models of lipase production; has as purpose to experimentally optimize the biosurfactants production; the third, has as purpose to experimentally optimize thebiosurfactants production; the fourth stage, is the evaluation of the lipase production during the fermentation process. All the stages had as study the solid-state fermentation stage using Aspergillus fumigatus in different nutritional conditions and air supply. Experiments using soybean oil and diesel oil as extra sources of carbon were used, for later comparison to the experiments without their use. The aerations variedfrom 0 a 200 mLair.gsubstrate -1.h-1 and the fermentations conducted in bioreactors of columns with fixed berth. The conditions of the cultive environment were maintained in30°C, pH 4,5, humidity of 50% and initial concentration of inoculum 4.106 esporos.gsubstrate -1. The mathematical models were obtained using the environment aeration and fermentation time as variants of control. The objective function that represents the increase of the biosurfactant concentration (first stage) and lipase (second stage) was optimized by fixating the aeration and calculating the optimized time in which the maxim biosurfactants concentration and enzyme were obtained considering the fermentation time. The validation of the models of the biosurfactants production was accomplished through the comparison of the experimental results of two Central Compound Projections 22 with the results generated from the model. The Emuslsificant Activities found in the experimental optimization of the biosurfactant production were 11,17 UE.g-1 providing 148 mLair.gsubstrate -1.h-1 in the absence of acarbon extra source, 8,47 UE.g-1 with 119 mLair.gsubstrate-1.h-1 added of soybean oil and 9,99 UE.g-1 using 140 mLair.gsubstrate -1.h-1 with diesel. The use of the carbon extra sources acted as inducer of the "lipase" production, and the greatest Lipase Activity was found in the experiment without the air supply using diesel oil as carbon extrasource (127,22 U.g-1 in 96h). The predicted results, compared to the experimental ones, showed statistically equal tracks (p < 0,05), and the Emulsificant Activities foundin the optimization of the models without carbon and diesel extra sources were, respectively, , 8,03 UE.g-1 in 104h and 7,85 UE.g-1 in 111h and in the numerical optimization of the "Lipase" production were found Lipase Activity 100,31 U.g-1 in 103h, 117,02 U.g-1 in 90h and 124,12 U.g-1 in 119h for the experiments without carbon, soybean oil and diesel oil extra sources, respectively. The manufactured models showthe efficiency of the process of biosurfactants and lipase production, becoming an important tool in solid-state fermentation using Aspergillus fumigatus, significantly contributing to the use of simple technologies and a smaller environmental risk.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Susana Juliano Kalil; Luiz Antonio de Almeida Pinto; Jorge Alberto Vieira Costa; Glaucia Maria Falcão de Aragão; Luiz Alberto Oliveira Rocha

School:Fundação Universidade Federal do Rio Grande

School Location:Brazil

Source Type:Master's Thesis

Keywords:Aspergillus fumigatus biossurfactante lipase biosurfactant solid-state fermentation


Date of Publication:01/31/2006

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