Utilização do vinhoto como substrato para geração de biomassa microbiana

Abstract

Vinasse is the pasty and smelly remnant of the fractional distillation of fermented sugar cane juice to obtain fuel ethanol and cachaça. It has an abundance of organic matter, high corrosivity due to its low pH and high biochemical oxygen demand, making it highly harmful to both fauna and flora in fresh and marine waters. Despite the disadvantages, vinhoto is very nutritious for the cultivation of microorganisms, for the production of microbial biomass, with different agro-industrial applications, one of which is the enrichment of the nutritional value of animal feed. The objective of this work was to quantify the microbial biomass formed using the vinasse as substrate. Two yeast isolates belonging to the collection of starter cultures of the Fermentation Research Group (GEFER) of the Faculty of Biological and Environmental Sciences (FCBA) of the Federal University of Grande Dourados (UFGD) were previously selected. They are an isolate of Lodderomyces elongisporus and an isolate of Rhodotorula mucilaginosa. The isolates were previously characterized as secretors of cellulases, pectinases and extracellular amylases. The vinhoto used was generated at the Biochemistry Laboratory of FCBA/UFGD during the production of sugarcane cachaça. The experimental design was based on the model proposed by Plackett and Burman. The tested variables were concentration in the medium of yeast extract, glucose, peptone and potassium phosphate, amount of vinasse added, pH of the medium and incubation temperature. The population count (UFC.mL -1 ) in the cultures was determined every 24 h by the method of surface spreading in YPD medium (Yeast, Peptone, Dextrose), the plates being incubated at 30 ° C for 48 h. The biomass produced after 168 h was measured using the drying method in an oven at 105 ° C until constant weight. For R. mucilaginosa yeast the largest amount of biomass produced was for treatment 3 (1.002 g. L -1 ), in this treatment the highest concentrations of yeast extract and peptone, the lowest concentration of vinasse (10 % v/v), pH 5 and incubation temperature of 28 ° C. The yeast L. elongisporus expressed statistically significant results, with treatment 8 (51.416 g. L -1 of biomass) being the most advantageous, as it contains the largest amount of vinasse (50 % v/v) and is not statistically different of treatment 10 (10 % v/v of vinasse), second best treatment, and yielding only 22.32 % lower than the best treatment. The variables vinasse, glucose and pH showed significant effects for the production of biomass with the yeast L. elongispor.