Effects of peptidic fractions from <i>Saccharomyces cerevisiae</i> culture on growth and metabolism of the ruminal bacteria <i>Megasphaera elsdenii</i>

Abstract

The aim of this study was to evaluate the effects of peptide fractions purified from a Saccharomyces cerevisiae product on the growth of the ruminal bacterium Megasphaera elsdenii. Such compounds have been shown to affect the growth and metabolism of M. elsdenii, the ruminal bacteria which uses lactate the most. A hydrophilic fraction purified by means of HPLC has proven to stimulate cell growth, the production of butyrate (+100%) and valerate (+76.1%) as well as the metabolization of lactate (+ 16.9%). This chromatographic fraction was further characterized and seven positively charged peptides were identified. It was observed that two peptides rich in lysine and histidine were the most effective in stimulating growth (+ 18.5%) and lactate utilization (+ 74.1%) in M. elsdenii. These results show that, in addition to previously studied factors such as the supply of nutrients or oxygen removal, the presence of peptidic fractions is involved in the stimulation of bacterial growth by S. cerevisiae.