Identification and evaluation of contaminating bacteria in the fermentative process of a fuel alcohol plant in the Valle del Cauca, Colombia (Atena Editora)

Abstract

The addition of various nutrients such as vinasse, honey and water in the fermentative process for the production of fuel alcohol can favor the growth of organic acid-producing microorganisms that generate stress for the yeast: Saccharomyces cerevisiae and therefore the reduction of performance in terms of alcohol production. For this reason, this work aimed to identify and evaluate contaminating bacteria in the fermentation process of a fuel alcohol production plant located in the department of Valle del Cuaca, managing to identify 5 bacterial species molecularly through PCR: Lactobacillus hilgardii and Acetobacter tropicalis with a frequency of 33.3%, followed by Lactobacillus plantarum, Acetobacter pasteurianus and Leuconostoc mesenteroides;

with a frequency each of 11.1 % of the total isolated strains, finding that of these the one that generates the most losses in production is L. hilgardii producing 1060 p.p.m ±335 of lactic acidity and 1338 p.p.m ±1059.2 of volatile acidity consuming the 2% ±0.6 of the sugars present in the medium. Therefore, we continued to evaluate the effect of three antibiotics about L. hilgardi using the spectrophotometry technique, showing that the antibiotic with active principle  Hop acid was the one that managed to obtain better control over the growth of this bacterium, followed by the antibiotic with Clindamycin and finally the antibiotic with Monensin sodium. Therefore it can be concluded that L. hilgardii is the cause of decreased productivity Saccharomyces cerevisiae in the fermentative process due to its high production of organic acids that are detrimental to the enzymatic activity of the yeast, but by using antimicrobial substances, especially of vegetable origin, such as hop acid, it is possible to reduce and control the presence of this bacterium and thus improve the efficiency of the company.