Growth and antimicrobial activity of lactic acid bacteria from rumen fluid according to energy or nitrogen source

Viviane Aparecida Carli Costa,Daiany Iris Gomes,Hilário Cuquetto Mantovani,Edenio Detmann,Mário Fonseca Paulino,Isabela Pena Carvalho De Carvalho,Sebastião De Campos Valadares Filho

doi:10.1590/s1516-35982011000600014

Abstract

The objective of this study was to evaluate the effects of supplementation with different sources of energy and nitrogenous compounds on the in vitro growth and production of bacteriocin of lactic acid bacteria. Incubations were performed by using ruminal fluid from a rumen-fistulated Holstein-Zebu steer. The animal was kept on a Brachiaria decumbens pasture receiving 200 g/day of supplemental crude protein. Substrates and inoculum were placed in glass flasks considering eight treatments: cellulose, cellulose and casein, cellulose and soy peptone, cellulose and urea, starch, starch and casein, starch and soy peptone and starch and urea. Successive incubations were conducted to select microorganisms according to the energy sources and nitrogenous compounds. Starch favoured growth of lactic acid bacteria when compared to cellulose. Supplementation with true protein (soy peptone and casein) stimulated the growth of these bacteria when compared to the control (without supplementation with nitrogenous compounds). The addition of urea did not stimulate the growth of lactic acid bacteria. No antimicrobial activity was detected from colonies of isolated lactic acid bacteria. Sources of true protein increase the competition between non-structural and structural carbohydrates fermenting bacteria.

Highlights

Recent studies conducted under tropical conditions showed increases in animal production when supplemental sources of non-protein nitrogen were added to the diet (Paulino et al, 2005; Porto, 2005; Paulino et al, 2008; Costa, 2009).On the other hand, despite the beneficial effects of nitrogen on ruminal fibrolytic activity when low-qualityThe negative effect of true protein supplementation was called “protein effect” (Costa et al, 2009)
In some studies conducted under tropical conditions, it has been speculated that negative effects of the addition of protein should be attributed to the occurrence of antagonistic interactions between microbial species, such as growth inhibition mediated by bacteriocins (Paez-Bernal, 2007; Costa et al, 2009; Zorzi et al, 2009)
lactic acid bacteria (LAB) growth was favoured (P

Summary

Introduction

Recent studies conducted under tropical conditions showed increases in animal production when supplemental sources of non-protein nitrogen were added to the diet (Paulino et al, 2005; Porto, 2005; Paulino et al, 2008; Costa, 2009).On the other hand, despite the beneficial effects of nitrogen on ruminal fibrolytic activity when low-qualityThe negative effect of true protein supplementation was called “protein effect” (Costa et al, 2009). In some studies conducted under tropical conditions, it has been speculated that negative effects of the addition of protein should be attributed to the occurrence of antagonistic interactions between microbial species, such as growth inhibition mediated by bacteriocins (Paez-Bernal, 2007; Costa et al, 2009; Zorzi et al, 2009). The production of these inhibitory compounds may be enhanced by increasing the supply of amino acids, which favours the growth of bacteriocin-producing microbial species (De Vuyst & Vandamme, 1993; Kim et al, 1997; Parente & Ricciardi, 1999; Aasen et al, 2000). Bacteriocins may reduce the cellulolytic activity in the rumen (Wolin et al, 1997)

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Methods

Results