Microbial Community and Fermentation Dynamics of Corn Silage Prepared with Heat-Resistant Lactic Acid Bacteria in a Hot Environment

To develop a silage fermentation technique to adapt to global climate changes, the microbiome and fermentation dynamics of corn silage inoculated with heat-resistant lactic acid bacteria (LAB) under high-temperature conditions were studied. Corn was ensiled in laboratory silo, with and without two selected strains, Lactobacillus salivarius LS358 and L. rhamnosus LR753, two type strains L. salivarius ATCC 11741(T) and L. rhamnosus ATCC 7469(T). The ensiling temperatures were designed at 30 °C and 45 °C, and the sampling took place after 0, 3, 7, 14, and 60 days of fermentation. The higher pH and dry matter losses were observed in the silages stored at 45 °C compared to those stored at 30 °C. Silages inoculated with strains LS358 and LR753 at 30 °C had a lower ratio of lactic acid/acetic acid. The dominant bacterial genera gradually changed from Pediococcus and Lactobacillus to Lactobacillus in silages during ensiling at 30 °C, while the bacterial community became more complex and fragmented after 7 d of ensiling at 45 °C. The high temperatures significantly led to a transformation of the LAB population from homo-fermentation to hetero-fermentation. This study is the first to describe microbial population dynamics response to high temperature during corn ensiling, and the results indicate that L. rhamnosus 753 shows potential ability to improve silage fermentation in tropics and subtropics.