Inoculação de Bacillus subtilis e seus metabólitos em silagem de milho

Abstract

Corn silage is the world most widely used preserved crop because of high crop productivity, nutrient value and energy concentration. However, both plant silage and wet corn grains are rich in soluble carbohydrates and lactic acid, which makes them susceptible to aerobic deterioration in post-opening silos. In order to reduce silage losses, optimize the fermentation process, reduce aerobic deterioration and maintain nutritional value, we have studied the use of microbial inoculants in silage, with or without enzymes such as cellulase, hemicellulase and amylase as additives . And to reduce the costs of producing enzymes, agroindustrial residues such as rice and wheat straw, wheat bran, maize and sugarcane bagasse are used as an alternative and inexpensive substrate for fermentation, in addition to reducing environmental problems caused by Inadequate disposal in the environment. In this context, the objective of the work was the production of β-glucosidase enzyme and evaluation of the effects of bacterial and bacterial enzymatic inoculants on the chemical-bromatological, microbiological and aerobic stability of corn silages after 30 and 60 days of silage. The production of β-glucosidase was carried out by Bacillus subtilis in submerged fermentation using coffee pulp as carbon source and enzyme inducer. The treatments inoculated in the silos were: silage without inoculant (SC), silage with B. subtilis 1.0 x 108 CFU / g forage (SB1), silage with B. subtilis 1.0 x 109 CFU / g forage (SB2) and Silage with B. subtilis 7.0 x 109 CFU / g forage + β-glucosidase enzyme (SBE). A completely randomized experimental design was used, with four treatments, two opening times and three replications. The specific activity value for β-glycosidase found in the crude extract was 1.3170 IU mL-1. Regardless of the type of treatment used, all evaluated silages were well preserved, as they presented pH below 4.2, showing good fermentation quality for corn silage. In the 60-day period, the levels of soluble carbohydrates in the silage improved significantly: SB1 (0.96%), SB2 (0.96%) and SBE (0.88%) when compared to SC (0.63%). For lactic acid bacteria, the highest populations were found in SB1 (6.86 log CFU / ml) and SBE (6.84 CFU / ml) treatments, followed by SC and SB1, which showed no differences between them (6.22 CFU / ml). The SB2 treatment significantly improved the aerobic stability (247.75 hours) and the time for the peak temperature to be reached (297.50 hours), and SC and SB1 presented intermediate values and SBE presented the lowest values.