Metabolic Profiling of Lactococcus lactis Under Different Culture Conditions

Kamalrul Azlan Azizan,Normah Mohd Noor,Syarul Nataqain Baharum

doi:10.3390/molecules17078022

Kamalrul Azlan Azizan, Normah Mohd Noor + Show 1 more

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https://doi.org/10.3390/molecules17078022

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Journal: Molecules	Publication Date: Jul 3, 2012
Citations: 38	License type: CC BY 4.0

Affiliation: National University of Malaysia

Abstract

Gas chromatography mass spectrometry (GC-MS) and headspace gas chromatography mass spectrometry (HS/GC-MS) were used to study metabolites produced by Lactococcus lactis subsp. cremoris MG1363 grown at a temperature of 30 °C with and without agitation at 150 rpm, and at 37 °C without agitation. It was observed that L. lactis produced more organic acids under agitation. Primary alcohols, aldehydes, ketones and polyols were identified as the corresponding trimethylsilyl (TMS) derivatives, whereas amino acids and organic acids, including fatty acids, were detected through methyl chloroformate derivatization. HS analysis indicated that branched-chain methyl aldehydes, including 2-methylbutanal, 3-methylbutanal, and 2-methylpropanal are degdradation products of isoleucine, leucine or valine. Multivariate analysis (MVA) using partial least squares discriminant analysis (PLS-DA) revealed the major differences between treatments were due to changes of amino acids and fermentation products.

Highlights

Lactococcus lactis is a facultative anaerobe widely used for dairy production and food fermentation [1,2]
The relationship between the fermentation end products and changes of amino acids under the influence of temperature and agitation are of great interest because it relates to the central carbon metabolism [10], for better understanding of bacteria adaptation to environmental stress
The first two principal components plots showed that fermentation end products of lactate, ethanol and acetate, followed by several organic acids belonging to the tricarboxylic acid (TCA) cycle are detected

Summary

Introduction

Lactococcus lactis is a facultative anaerobe widely used for dairy production and food fermentation [1,2]. L. lactis is important as the low pH inhibits growth of other microorganism, and contributes to changes in food texture and biochemical conversions that produce flavors and aromas [3]. Coagulation steps by acidification and heating during cheese manufacturing process affects the growth of L. lactis which enhance metabolite changes that influence the texture, taste and smell of the produced cheese [3,4,5,6]. The relationship between the fermentation end products and changes of amino acids under the influence of temperature and agitation are of great interest because it relates to the central carbon metabolism [10], for better understanding of bacteria adaptation to environmental stress

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