High-Throughput Metabolic Fingerprinting of Legume Silage Fermentations via Fourier Transform Infrared Spectroscopy and Chemometrics

Abstract

Silage quality is typically assessed by the measurement of several individual parameters, including pH, lactic acid, acetic acid, bacterial numbers, and protein content. The objective of this study was to use a holistic metabolic fingerprinting approach, combining a high-throughput microtiter plate-based fermentation system with Fourier transform infrared (FT-IR) spectroscopy, to obtain a snapshot of the sample metabolome (typically low-molecular-weight compounds) at a given time. The aim was to study the dynamics of red clover or grass silage fermentations in response to various inoculants incorporating lactic acid bacteria (LAB). The hyperspectral multivariate datasets generated by FT-IR spectroscopy are difficult to interpret visually, so chemometrics methods were used to deconvolute the data. Two-phase principal component-discriminant function analysis allowed discrimination between herbage types and different LAB inoculants and modeling of fermentation dynamics over time. Further analysis of FT-IR spectra by the use of genetic algorithms to identify the underlying biochemical differences between treatments revealed that the amide I and amide II regions (wavenumbers of 1,550 to 1,750 cm ؊1 ) of the spectra were most frequently selected (reflecting changes in proteins and free amino acids) in comparisons between control and inoculant-treated fermentations. This corresponds to the known importance of rapid fermentation for the efficient conservation of forage proteins.

Rice Metabolomics

“…Among the various pulse sequence programs, 1 H-NMR has been routinely employed for high-throughput metabolomic studies due to its relatively short acquisition time per analysis. Alternatively, several conventional as well as innovative analytical instruments, such as Fourier transform infrared spectrometry [51], direct-infusion time-of-flight (TOF) MS [24,77], ion mobility MS [25], and LC-FT-ICR MS [48,91], have recently been applied to metabolomic studies.…”

Technical problems and practical operations in plant metabolomics

“…Some examples with their advantages and limitations are listed in Table 1. The system 1 using Fourier transform infrared spectroscopy (FT-IR) 13,21,22) or nuclear magnetic resonance (NMR) 14,23,24) is a high throughput system for metabolic fingerprinting that does not contain a separation process. This approach can cause difficulty in metabolite identification.…”

Metabolic Control Analysis of Complex Biological Systems

“…The newly-developed high-throughput devices have contributed to the recent growing interests in dynamic modelling and analysis of the living systems (Johnson et al, 2004;Villas-Boas et al, 2005), which provide invaluable information for biological research. The main purpose of dynamic analysis is to predict the changes in system behaviours upon given perturbations.…”