Avaliação de parametros que afetam a floculação de leveduras e bacterias isoladas de processos industriais de fermentação alcoolica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The bacterial contamination in the alcoholic fermentation is one of the problems in the process of alcohol production. Yeast flocculation is one of the consequences of this contamination that strains of actobacillus fermentum are the first one microorganism quoted as responsible by this fenomen. Many factors may influence the yeast flocculation such as, genetic coumponds, proteins, temperature, pH, fermentation products like ethanol and necessity of metalicions, especifically calcium. This research was carried out to examine the conditions of yeast flocculation ccurency caused by some bacterial species which contaminate the process of alcohol production, evaluating the effect of the population of contamlnant bacteria needed to occur the flocculation process, effect of alcohol amount and temperature in the flocculency capacity of these bacterias. Moreover,this research tried to contribute to the flocculation mecanisms elucidation of industrial yeasts provoked by strains and cepa of contaminant bacteria of alcohol fermentation process, throught the chemistIy modification effect evaluation of proteins and carbohidrates from the wall of cell and the enzimic treatment on the flocculant capacity of these microorganisms. The resulties obteined indicated that L fermentum, L. plantarum, L. fructtvorans, L. fructosus and L. buchneri can be responsablesby the S cerevisiae flocculation,but it is necessary a ratio of yeast:bacteria for flocculation to occur flocculation, and this ratio is different for some species of Lactobacillus. The ethanol amount (O to 10%) and the temperature (25°C to 65°C) affected significantly the bacterial flocculence capacity on the studied yeasts. Proteic compounds in the cell wall of L. plantarum, L. fermentum and L. buchneri may participate in the flocculation process, because chemical changers which react with fenol and indol funcional groups in the lateral chain of aminoacids (maleic anidride and acetic anidride) inhibited the bacterial flocculency capacity, suggesting that these groups are responsible for the flocculation processo For L. fructivorans and L. fructosus species the treatment with these chemical changers did not afIect the flocculation process. Cells of S. cerevisiae submited to carbohidrate chemical changers treatment (NaIO4 0,01M) showed some inhibitions in their flocculant capacity promoted by bacteria, that indicates that carbohidrates are essential for flocculation process. According of these results, it suggest that S. cerevisiae flocculation caused by Lactobacillus bacteria genus may show up a intercelular mechanisms at cell wall of these microorganisms.This process involves proteic compounds of the celular stnÍace of L.plantarum, L. fermentum and L. buchneri and carbohidrates of the cell wall of the yeasts. On the other hand for L. fructivorans and L. fructosus strains, others compounds of the cell wall may also be envolved in the flocculation process

ASSUNTO(S)

floculação bacterias fermentação

ACESSO AO ARTIGO

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