Caracterização de leveduras de processos de fermentação alcoolica utilizando atributos de composição celular e caracteristicas cineticas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

In the past years, there has been a significant increase in studies seeking to understand the dynamics of the yeast population inhabiting alcoholic fermentation vats. The studies generated have elucidated important issues. Among them, which would be the basic characteristics for a strain to remain in a processo Following this context, this study has had the purpose of enhancing the knowledge on the characteristics of the dominant strains of industrial fermentation processes of Brazilian distilleries. This study has sought to describe the fermentative performance attributes and the cellular makeup of 19 strains, with particular characteristics, isolated from several processes installed in different regions of Brazil. The attributes studied were: fermentative capacity; Numerical Taxonomy; tolerance to ethanol, and contents of trehalose, protein/amino acids, and fatty acids. In order to compare the attributes studied, one strain assigned to the baking industry as well as one isolated from an alcohol production process installed in the Indian territory were evaluated. The results have shown that ali strains have presented good fermentative characteristics in spite of being divided in 17 different groups. As for the numerical taxonomy, 20 out of the 22 strains analyzed have been classified, of which 8 have been classified as Saccharomyces chevalieri, 5 as Saccharomyces coreanus and 7 as Saccharomyces cerevisiae. If the classification according to BARNET (1992) is considered, ali of them are representative of S. cerevisiae. As for ethanol tolerance, there is a variable range between 0.166 and 0.653 11M. The trehalose concentration level in the cellular mass encompasses concentrations varying from 0.47 to 6.3%. With regard to the amount of protein, this sample has shown a 10% variation of the strain presenting the highest amount to the one presenting the lowest. The strains presenting the highest value of specific cellular mass production were also the ones showing the lowest amount of proteinie material. As for the amino-aeid distribution in this protein, the results have shown that ali of them were within the expeeted profile for S. cerevisae strains. Ali strains tested presented the following fatty aeids in their makeup: C-12:0 (laurie acid), C-14:0 (myristie aeid), C-16:0 (palmitie acid), C-16:1 (palmitoleie aCid), C-18:0 (stearic acid), and C-18:1 (oleie aeid). Some strains have also presented the C14:1 (myristoleic aeid) unsaturated fatty acid. The C-16: 1 and C-18: 1 unsaturated fatty aeids are the most plentiful in the fatty material composing the strains tested and, according to some authors, they are linked to the tolerance of the strains to ethanol. Some indications as for relationship between the content of C-16:1 and C­18: 1 fatty acids and the tolerance to ethanol may be notieed, even though an exaet correlation has not been able to be determined. From the compilation of the data obtained in this study, it is possible to state that the strains isolated from several fermentation processes have shown behavioral and cellular makeup variations. However, when the fermentative capacity parameter is evaluated, ali strains are classified as suitable for the alcoholic fermentation processo This fact confirms the hypothesis that, although some strains have similar fermentative eharacteristics, since, otherwise, they could not inhabit a hostile environment such as the one in the fermentation vats, each process selects its own strain, and such strain is probably a natural inhabitant of the raw-material of the unit processing it

ASSUNTO(S)

fermentação aminoacidos trealose acidos graxos leveduras (fungos) - engenharia genetica

ACESSO AO ARTIGO

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