The Bacterial Community Associated with the Amarillo Zamorano Maize (Zea mays) Landrace Silage Process

Humberto Ramírez-Vega,Victor M Gómez-Rodríguez,José M Ruvalcaba-Gómez,Ramón I Arteaga-Garibay,L X Zelaya-Molina,Raquel Loperena-Martínez,Otoniel Maya-Lucas,Ismael F Chávez-Díaz,Darwin Heredia-Nava

doi:10.3390/microorganisms8101503

Abstract

Maize silage is used in the diet of dairy cows, with suitable results in milk yield. In this study, the composition and diversity of the bacterial communities of the silage process of Amarillo Zamorano (AZ) Mexican maize landrace with relation to the Antilope (A) commercial hybrid are described. From both types of maize, seeds were sown in experimental plots, plants harvested at the reproductive stage, chopped, and packed in laboratory micro-silos. Physicochemical parameters were evaluated, and DNA was extracted from the juice in the micro-silos. The bacterial communities were analyzed by next-generation sequencing (NGS) of seven hypervariable regions of the 16S rRNA gene. The composition of both bacterial communities was dominated by Lactobacillales and Enterobacteriales, Lactobacillales mainly in A silage and Enterobacteriales in AZ silage; as well, the core bacterial community of both silages comprises 212 operational taxonomic units (OTUs). Sugar concentration showed the highest number of significant associations with OTUs of different phyla. The structure of the bacterial communities was different in both silage fermentation processes, showing that AZ silage has a shorter fermentation process than A silage. In addition, NGS demonstrated the effect of the type of maize and local conditions on silage fermentation and contributed to potential strategies to improve the quality of AZ silage.

Highlights

Ensiling is a method used to preserve forage through a rapid decrease in pH by lactic acid fermentation, and it indeterminately maintains an acid pH under anaerobic conditions [1,2]
The microbial communities of silage are primarily driven from the phyllosphere of leaves and lower stems of the forage crops. the composition of the communities can change according to the crop and its varieties selected for the fermentation process [8]
Several bacterial species in the different silage phases have been described through studies with culture and DNA-based profiling techniques, i.e., facultative aerobic microorganisms, such as Erwinia herbicola and Rahnella aquitilis in the aerobic phase; lactic acid bacteria of Enterococcus, Lactococcus, Lactobacillus, Leuconostoc, Paralactobacillus, Pediococcus, Streptococcus, and Weissella genera, as well as different enterobacteria and clostridia in the fermentation and stabilization phases; and acetic acid and aerobic bacteria in the feeding out phase, depending on the quality of the silage [10,11,12,13,14,15,16,17,18,19,20,21,22]

Summary

Introduction

Ensiling is a method used to preserve forage through a rapid decrease in pH by lactic acid fermentation, and it indeterminately maintains an acid pH under anaerobic conditions [1,2]. Forage is preserved for the off-season periods when fresh forage is not available, with a minimum loss of dry matter and nutrients, while maintaining the palatability for livestock and limiting the presence of spoilage microorganisms for cattle [3]. The success of this process depends on various factors, such as crop features during the harvesting period, climatic conditions, silage establishment, intrinsic factors of the process, and silage microbiota, among others [2,4,5,6,7]. There are no NGS studies on the composition, diversity, and succession of the bacterial communities associated with Mexican fodder maize landraces

Objectives

Methods

Results