Biotechnological product from the use of Pediococcus pentosaceus as a biological additive for the natural conservation of silages

Abstract

Ensilage consists of fermentation of free sugars to lactic acid irrespective of forage by epiphytic microorganisms, mainly lactic acid bacteria (LAB), varying in number and composition during fermentation. Silages are used to preserve forages for extended periods of time when fresh forage is limited or seasonally unavailable and its inadequate fermentation and poor feed-out management favor the proliferation of pathogens and contributes to the spoilage of silage. LAB are a group of well-distributed microorganisms in nature having lactic acid as the major metabolite resulting after sugar fermentation. Some LAB belonging to the Pediococcus genus, which are considered as probiotics due to their colonization of the gastrointestinal tract of mammals, produce antimicrobial molecules such as bacteriocins, which have a broad spectrum of action against Gram-positive and Gram-negative bacteria, protozoa, fungi and viruses, thereby being able to behave effectively in the conservation of silage. Preliminary studies, carried out by Dr. Azevedo, demonstrated that a new antimicrobial produced by Pediococcus pentosaceus has antibacterial and antifungal activities against important contaminants and spoilage of silage, showing its potential as a natural silage preservative. Our hypothesis is the improvement of silage preservation using P. pentosaceus and its antimicrobial molecule as silage inoculant to control the growth of others LAB, especially heterofermentative bacteria, fungi and yeasts, aiming to reduce the production of acetic acid, to maintain the production of lactic acid and to produce a silage more stable and nutritive when exposed to air. To reach these goals, this antimicrobial will be characterized by Fourier-Transform Infrared Spectroscopy, it will be tested as antibacterial and antifungal agent by agar diffusion and count colonies assays, and it will be inoculated with P. pentosaceus by manual sprayer as natural additive for grain silage. After treatment, silage ensilability will be determined by assessing its dry mass, organic mass, crude protein and fibers, followed by chemical analysis (concentration of organic acids, ammonia, alcohols and biogenic amines) by HPLC and microbiological analysis (counting of LAB, fungi and yeasts) by the pour plate methodology. The scientific innovation of this proposal concerning the use of the P. pentosaceus and its antimicrobial molecule, in particular the antifungal effect, as natural grain inoculant to preserve silage, a potential bacterium for the application in agriculture as a natural bio-controlling agent and also contributing to preserve the quality of livestock feed. (AU)