Evaluation of the viability of the use of Lactobacillus casei in the removal of organic contaminants in waste from the craft brewing industry

Abstract

Brewers’ spent grains (BSGs) are the most abundant waste generated from the craft brewing process, accounting for approximately 85% of the total byproduct obtained. The need to develop beneficial alternatives for the contribution of the industrial sector and sustainable development has increased interest in the fermentation processes used to produce biomass, using probiotic microorganisms that provide health benefits for those who consume it, obtaining byproducts rich in nutrients. Therefore, this research aimed to evaluate the growth of Lactobacillus casei in Mar, Rogosa and Sharpe broth (MRS) and to evaluate the feasibility of growing L. casei in craft beer residues. To achieve this goal, a 10% v/v inoculum of probiotic bacteria was used in both media. The process consisted of monitoring the biotransformation process at 37°C and 120 rpm for 72 hours and evaluating carbohydrate consumption and cell growth. At the end of 52 h, the carbohydrate concentration in combination with BSG was completely consumed, considering that the initial value was 16.49 g/L. In the case of the MRS medium, a value of 3.42 g/L was obtained at 72 h. Regarding the pH range with the MRS broth and with BSG, the values were 6.89-5.43 and 5-4.41, respectively. Due to the acidity of the synthetic medium, the pH of the synthetic medium was greater than that of BSG. However, L. casei managed to develop in a similar way since quite similar cell growth values were obtained in both media, so it is feasible to use BSG as a culture medium for the development of probiotic species.