Isolation and Identification of Lactic Acid Bacteria That Colonize Tropical Whole-Plant Corn Silage during Fermentation Process

Abstract: The goals of the present study were to isolate and identify the lactic acid bacteria (LAB) that colonize tropical whole-plant corn silage during fermentation process. The experiments were conducted and crops grown at the Department of Animal Science of the Federal University of Vicosa, Minas Gerais, Brazil. Corn (Zea mays) plants were harvested when kernels reached the hard dough stage. The mini-silos were stored at room temperature and opened after 0, 1, 3, 7, 14, 28 and 56 d of storage. The isolates were purified by streaking individual colonies. Pre-selected cells grown in 5 ml of MRS broth at 37°C for 18h were used for 16S rRNA gene sequence. The 16S rRNA gene sequences that show similarity greater than 97% were considered as belonging to the same Operational Taxonomic Unit. One hundred and fifty-one LAB strains were isolated. In the first three days of storage the LAB species Pediococcus pentosaceus, Lactobacillus plantarum, and Weissella cibaria were the most identified. The L. plantarum was the predominant specie until the 28th day of storage. At day 56 of storage the predominant species were L. buchneri followed by Streptococcus salivarius and L. casei. The predominant species of tropical corn silage, considering isolates in MRS agar for all the days of ensiling were Lactobacillus plantarum 53.0%, Pediococcus pentosaceus 11.9%, L. buchneri 9.9%, L. pentosus 5.3%, Weissella cibaria 4.6%, and L. brevis 4.0%. The appearance of L. buchneri occurs naturally in the 56th d of ensiling corn under tropical conditions.

 Supported by Fapemig, CNPq CAPES, and INCT-CA