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The effect of acid stress on lactate production and growth kinetics in Lactobacillus rhamnosus cultures

Paper ID Volume ID Publish Year Pages File Format Full-Text
35730 45104 2008 6 PDF Available
Title
The effect of acid stress on lactate production and growth kinetics in Lactobacillus rhamnosus cultures
Abstract

The present study describes the inhibitory effect on growth and lactate production by Lactobacillus rhamnosus cells exposed to acidic stress conditions. Cultivations were carried out in presence of an uncoupling agent, hexanoic acid, as a model weak acid, on several initial concentrations and at different incubation temperatures. A statistical experimental design was used showing a more marked influence of temperature than hexanoic acid on both lactate production and biomass concentration. The effect of temperature is more intense on biomass (decrease of about 50% in the production) than on lactate production (decrease of about 35% in the production).Lactate production does not follow a proportional decay to biomass in the presence of the acid, i.e. the decrease is less accentuated. It indicates that the decrease of lactate in acid toxicity conditions is a result of cell drop and not a direct effect on lactate metabolism. The dissociation between lactate production and biomass in cultures under acid stress indicates that the excess of carbon inside the cells due to the diversion of ATP to expel protons expands metabolite production as the metabolic pathways receive the excess carbon acting as a cell dissipation mechanism.

Keywords
Lactic acid; Acid stress; Hexanoic acid; Lactobacillus rhamnosus
First Page Preview
The effect of acid stress on lactate production and growth kinetics in Lactobacillus rhamnosus cultures
Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 43, Issue 4, April 2008, Pages 356–361
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering