Optimization of lactic acid production using the sugarcane bagasse by Lactobacillus coryniformis

The lignocellulosic materials such as sugarcane bagasse, consisting of cellulose, hemicellulose and lignin, represent one of the most abundant renewable resources that can be used as raw material for the production of organics acids by fermentation processes. In this context, the lactic acid has applications in the food industries, pharmaceutical, chemical, cosmetics and the highlighted is being driven by the production of biodegradable polymers such as polylactide (PLA). Thus, the aim of this study was to evaluate the fermentation utilizing strains of Lactobacillus coryniformis by simultaneous saccharification and fermentation (SSF) process in different conditions. Statistical experimental design was used to optimize the SSF conditions, evaluating the solid content, enzymatic load and cell concentration by submerged fermentation. Initially, to make easier the accessibility of cellulases to the cellulose microfibrils, the bagasse had to be submitted to a pretreatment with diluted acid to fractionate it and extract the hemicellulose component from the solid residue termed cellulignin. This solid residue was pretreated using NaOH (4%) aiming at its partial delignification. Thereafter, the pretreated cellulignin underwent the action of a commercial celulolytic preparation, allowing the conversion of cellulose to glucose. The Lactobacillus strain reached 20 g/L of lactic acid, employing orbital agitation of 120 rpm and 37°C of temperature. The results were very interesting and pointed out for future developments.