Effects of chemical additives and ensiling time on whole plant wheat silage microbial profiles inferred by phenotypic and 16S ribosomal DNA analyses


Bal E. B. B., Bal M. A.

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY, vol.28, no.2, pp.767-776, 2012 (SCI-Expanded) identifier identifier identifier

Abstract

The objectives of this study were to test the effects of various chemical additives, and ensiling time periods on microbial profiles of whole plant wheat silage (WPWS). WPWS was harvested at dough maturation stage, and ensiled with sodium chloride (T), sodium bicarbonate (N), sucrose (S), or urea (U) at 1% dry matter (DM) (w/w). Each WPWS treatment (i.e. T, N, S, and U) was ensiled in 1 dm(3) duplicate anaerobic jars for 7, 14, 28, 35, 42, 49, and 56 days. The highest lactic acid concentration was detected for U (5.9% DM) compared to the control (0.5% DM) at day 56. Similarly, the highest ammonia concentration was observed for U (9.3% DM) compared to the control; T, N, and S treatments averaged 2.4% DM. A higher lactic acid bacteria (LAB) count was observed between days 14 and 56 for all treatments relative to control WPWS, which averaged 6.7 and 5.6 c.f.u./g of fresh material, respectively. The highest quality silage was observed for N and U treated WPWS, with an absence of yeasts and molds from days 7 to 49. Identification of bacterial isolates at days 7 and 56 from each individual silage treatment was performed based on phenotypic (biochemical tests), and molecular (16S rDNA partial gene sequence) methods. 16S rDNA sequence results identified U7 and N56 isolates as Enterococcus faecium, and demonstrated positive galactose, ribose, lactose, maltose, mannitol, mannose, sucrose, and trehalose fermenting characteristics. In addition, most isolates exhibited growth potential in 6.5% NaCl. Overall sequence alignment results supported phenotypic identification, and indicated that U and N treated WPWS were LAB (Enterococcus) dominant compared to the control (non-LAB).