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Produção de carotenoides por leveduras

by Maldonade, Iriani Rodrigues

Abstract (Summary)
Pigmented yeasts were collected from soils, flowers, leaves, fruits from Campinas-SP region and industrialized foods. The samples were put in 50 mL erlenmeyers flasks, containing YM broth, and they were incubated at 30°C for 48 hours. After 48 hours, these samples were inoculated in Petri plates with YM agar, and incubated at 30°C for 120 hours. The yeasts colonies that had color between red and yellow were transferred to tubes, containing YM agar, and incubated at 30°C. These yeasts were reisolated by screening in Petri plates with YM agar (30°C for 72 hours) and then, transferred into tubes containing GYMP agar. After the selection, the pigmented yeasts were identified by a code: L12, was isolated from tomato sauce; L108, from soils of State University of Campinas; L125, from leaves of sugar cane; L135 e L137, from soils of Holambra-SP. The yeasts were identified by their morphology characteristics, reproduction characteristics, physiology and biochemical tests. The yeasts L12, L108, L135 and L137 were identified as Rhodotorula mucUaginosa and L125 as Rhodotorula graminis. The carotenoid composition of yeasts isolated in Brazil was studied. The yeasts were cultured in 200 mL broth yeast malt at 200 rpm in rotary shaker, 25°C for 5 days without illumination. Open column, thin layer chromatography and high performance liquid chromatography were used to separate, identify and determine carotenoid concentrations. The yeast Rhodotorula glutinis had the highest total carotenoid concentration (881 mg/L), followed by Rhodotorula graminis (594 mg/L), Rhodotorula mucUaginosa-137 (590 mg/L) and Rhodotorula mucilaginosa-135 (545 mg/L). Rhodotorula minuta and Sporobolomyces had the lowest carotenoid contents (168 mg/L and 237 mg/L, respectively). The principal pigments found in these yeasts were torulene and b-carotene. b-Carotene predominated in Rhodotorula graminis-125, Rhodotorula glutinis and Sporobolomyces, while torulene was the major carotenoid in Rhodotorula mucilaginosa. In specific carotenoid production (mg/g of dried cells), Rhodotorula glutinis had a total carotenoid concentration of 132 mg/g. Two of these strains were selected to optimize the carotenoid production, Rhodotorula mucilaginosa-137 and Rhodotorula glutinis. The cultures were cultivated into 200 mL broth yeast malt at 200 rpm in rotary shaker, 25°C for 5 days without illumination. Response surface design was used to study the effects of initial pH and concentrations of glucose, yeast extract, magnesium sulfate and potassium phosphate. Two statistical designs were used for each strain. For the strain of Rhodotorula mucilaginosa-137, the yeast extract the most important variable in terms of enhancing carotenoid formation; magnesium sulfate and potassium phosphate had a negative influence. The initial pH had no significant effect on carotenoid formation or on cell production. Analysis of the quadratic surfaces showed that after 5 days of cultivation at 25°C, the maximum carotenoid concentration of 745 mg/L appeared at 15 g/L of yeast extract and 20 g/L of glucose. The maximum concentration of specific carotenoid production was 152 mg/g at 5 g/L of yeast extract and 10 g/L of glucose. The concentrations of yeast extract and glucose were also important on biomass production, which reached maximum value of 8.0 g/L at a range of 15 to 17.1 glL of yeast extract and 15 to 20 g/L of glucose. The variables that had most influence on carotenoid production by Rhodotorula glutinis were initial pH, yeast extract and glucose. Magnesium sulfate and potassium phosphate had no influence. The carotenoid production was described by second order p01ynomial equation. Analysis of the 23 factorial design surfaces showed that after 5 days of cultivation at 25°C, the maximum carotenoid concentration of 1,269 mg/L with initial pH 4, 4 g/L of yeast extract and 17 g/L de glucose. The maximum specific carotenoid production was 337 j..tglg with initial pH 4, 4 g/L of yeast extract and 7 g/L of glucose. Moreover, carotenoid production in mg/g per liter was more sensitive to changes in yeast extract than to changes in glucose concentrations, in the vicinity of the optimum point of carotenoid production. The growth of the microorganism was affected by initial pH and concentration of yeast extract and glucose. However, the model obtained for biomass from the experimental designs had not a good correlation and because of that it should be used only to study the tendency of response
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Adilma Regina Pippa Scamparini; Adilma Regina Pippa Scamparini [Orientador]; Paulo Roberto Nogueira Carvalho; Mieko Kimura; Celia maria de Sylos; Ranulfo Monte Alegre

School:Universidade Estadual de Campinas

School Location:Brazil

Source Type:Master's Thesis

Keywords:Levedos

ISBN:

Date of Publication:03/21/2003

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