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631
Bacterial and fungal community structure of conventional and brown midrib corn hybrids ensiled with or without a combo inoculant at high dry matter concentrations
The objective was to evaluate the effects of a combo inoculant on the microbial community structure of 4 corn hybrids ensiled at high DM. Treatment design was the factorial combination of 4 corn-types (HYB) ensiled with (INO) and without (CON) inoculant. Corn hybrids were TMF2R737, F2F817 (A and B, 44.0 and 38.1% DM, respectively; from Mycogen), P2089YHR, and P1449XR (C and D, 42.0 and 41.3% DM, from Pioneer). B and D were brown midrib mutants. The inoculant added contained Lactobacillus buchneri and Pediococcus pentosaceus (4 × 105 and 1 × 105 cfu/g of fresh corn). Experimental design was a complete randomized design with treatments replicated 6 times (silos). Corn was chopped, treated or not with inoculant, packed into 7.6L bucket silos, and stored for 100 d. At d 0, neither HYB nor INO affected the relative abundances of Enterobacteriaceae (61.4±4.54%), and Brucellaceae (3.8±1.24%) bacterial families. B had more abundance (P ≤ 0.05) of Rhizobiaceae (5.2 vs. 2.41±0.48%) and Pseudomonadaceae (3.3 vs. 1.8±0.17%) families, compared to A and C. For fungi, 45% (±4.17) consisted of unidentified fungal sequences, followed by unidentified sequences of the Tremellales order which were more abundant in C vs. the others (21.4 vs. 9.5; P ≤ 0.05). At d 100, a HYB × inoculation effect was observed for the Lactobacillaceae and Leuconostocaceae bacterial families (P < 0.02). For the former, INO increased its abundance in all HYB (99.1 vs. 58.9±5.3%) but to a larger extent for B (98.3 vs. 34.3%) and for the latter, INO reduced its abundance in all HYB (0.1 vs. 11.3±3.58%), except C (0.06 vs. 6.67), and to a larger extent in B (0.7 vs. 28.7). INO decreased (P < 0.01) the Enterobacteriaceae (0.6 vs. 23.5±1.16%), Streptococcaceae (0.1 vs. 4.6±0.54%), Aeromonadaceae (0.01 vs. 0.55±0.03%), and Brucellaceae (0.01 vs. 0.39±0.05%) families. For fungi, INO had less abundance (P < 0.01) of Pichiaceae (6.5 vs. 47.3±5.19%) but more of the Debaryomycetaceae (63.1 vs. 17.3±4.1%) and Mucoraceae (2.7 vs. 0.8±0.53%) families, when compared to CON. The results indicate that epiphytic microbial composition differ depending on HYB and that after ensiling, INO favors the dominance of the Lactobacillaceae and Debaryomycetaceae families compared to a more diverse microbial community in the CON.
Keywords:
Corn silage
Bacterial and fungal diversity
Combo inoculant