Effects of aromatic amino acids, phenylacetate and phenylpropionate on fermentation of xylan by the rumen anaerobic fungi,Neocallimastix frontalisandPiromyces communis

Abstract

Aims: Anaerobic fungi are important members of the fibrolytic community of the rumen. The aim of this study was to study their requirement for aromatic amino acids (AA) and related phenyl acids (phenylpropionic and phenylacetic acids) for optimal xylan fermentation. Methods and Results: Neocallimastix frontalis RE1 and Piromyces communis P were grown in a defined medium containing oat spelts xylan as the sole energy source, plus one of the following N sources: ammonia; ammonia plus a complete mixture of 20 AA commonly found in protein; ammonia plus complete AA mixture minus aromatic AA; ammonia plus phenyl acids; ammonia plus complete AA mixture without aromatic AA plus phenyl acids. Both species grew in all the media, indicating no absolute requirement for AA. The complete AA mixture increased (P < 0AE05) acetate concentration by 18% and 15%, sugar utilization by 33% and 22% and microbial yield by about 22% and 15% in N. frontalis and P. communis, respectively, in comparison with the treatments that had ammonia as the only N source. Neither the supply of aromatic AA or phenol acids, nor their deletion from the complete AA mixture, affected the fermentation rate, products or yield of either species. Conclusions: AA were not essential for N. frontalis and P. communis, but their growth on xylan was stimulated. The effects could not be explained in terms of aromatic AA alone. Significance and Impact of the Study: Ruminant diets should contain sufficient protein to sustain optimal fibre digestion by ruminal fungi. Aromatic AA or phenyl acids alone cannot replace the complete AA mixture.

Dynamic changes in the yak rumen eukaryotic community and metabolome characteristics in response to feed type

“…It is also an essential amino acid preferentially used by protozoa in the rumen ( 49 ). In addition, L-phenylalanine, L-tyrosine, and L-tryptophan are important glucogenic and ketogenic amino acids, and low levels may limit the growth and fermentation rate of rumen microorganisms ( 50 ). These Observation may have been the results of amino acids playing important roles in the growth and proliferation of microbe.…”

Effects of aromatic amino acids, phenylacetate and phenylpropionate on fermentation of xylan by species of rumen anaerobic bacteria

“…E-mail: guliye@egerton.ac.ke. Tel: +254-723800242. mixture of 18 AA (Onoda et al, 1996), and achieved maximum growth when a complete mixture were supplied (Orpin and Greenwood, 1986;Onoda et al, 1996;Guliye and Wallace, 2007).…”