Succession of Bacterial Community During the Initial Aerobic, Intense Fermentation, and Stable Phases of Whole-Plant Corn Silages Treated With Lactic Acid Bacteria Suspensions Prepared From Other Silages

Abstract

The present study was aimed at investigating the bacterial community in lactic acid bacteria (LAB) suspensions prepared from whole-plant corn silage (LAB suspension-CS) and <i>Elymus sibiricus</i> silage (LAB suspension-ES) and the bacterial community succession of whole-plant corn silages inoculated with LAB suspension-CS or LAB suspension-ES during initial aerobic phase, intense fermentation phase, and stable phase. The LAB suspensions were cultured in sterile Man, Rogosa, Sharpe broth at 37°C for 24 h and used as inoculants for ensiling. The chopped whole-plant corn was treated with distilled water (CK), LAB suspension-CS (CSL), or LAB suspension-ES (ESL) and then ensiled in vacuum-sealed plastic bags containing 500 g of fresh forage. Silages were sampled at 0 h, anaerobic state (A), 3 h, 5 h, 10 h, 24 h, 2 days, 3 days, 10 days, 30 days, and 60 days of ensiling with four replicates for each treatment. The results showed that <i>Lactobacillus</i>, <i>Weissella</i>, and <i>Lachnoclostridium</i>_5 dominated the bacterial community in LAB suspension-CS; <i>Lactobacillus</i> was the most predominant bacterial genus in LAB suspension-ES. During the initial aerobic phase (from 0 h to A) of whole-plant corn silage, the pH and the abundances of <i>Pantoea</i>, <i>Klebsiella</i>, <i>Rahnella</i>, <i>Erwinia</i>, and <i>Serratia</i> increased. During the intense fermentation phase (from A to 3 days), the pH decreased rapidly, and the microbial counts increased exponentially; the most predominant bacterial genus shifted from <i>Pantoea</i> to <i>Weissella</i>, and then to <i>Lactobacillus</i>; inoculating LAB suspensions promoted the bacterial succession and the fermentation process, and LAB suspension-CS was more effective than LAB suspension-ES. During the stable phase (from 3 to 60 days), the pH and the microbial counts decreased, and <i>Lactobacillus</i> dominated the bacterial community with a little decrease. The results also confirmed the existence of LAB fermentation relay during fermentation process, which was reflected by <i>Weissella</i>, <i>Lactococcus</i>, and <i>Leuconostoc</i> in the first 5 h; <i>Weissella</i>, <i>Lactococcus</i>, <i>Leuconostoc</i>, <i>Lactobacillus</i>, and <i>Pediococcus</i> between 5 and 24 h; and <i>Lactobacillus</i> from 24 h to 60 days.