Comparative genome analysis of the candidate functional starter culture strains Lactobacillus fermentum 222 and Lactobacillus plantarum 80 for controlled cocoa bean fermentation processes.

Luc De Vuyst,Stefan Weckx,Koen Illeghems

doi:10.1186/s12864-015-1927-0

Luc De Vuyst, Stefan Weckx + Show 1 more

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https://doi.org/10.1186/s12864-015-1927-0

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Journal: BMC genomics	Publication Date: Oct 12, 2015
Citations: 146	License type: cc-by

Affiliation: Vrije Universiteit Brussel

Abstract

BackgroundLactobacillus fermentum 222 and Lactobacillus plantarum 80, isolates from a spontaneous Ghanaian cocoa bean fermentation process, proved to be interesting functional starter culture strains for cocoa bean fermentations. Lactobacillus fermentum 222 is a thermotolerant strain, able to dominate the fermentation process, thereby converting citrate and producing mannitol. Lactobacillus plantarum 80 is an acid-tolerant and facultative heterofermentative strain that is competitive during cocoa bean fermentation processes. In this study, whole-genome sequencing and comparative genome analysis was used to investigate the mechanisms of these strains to dominate the cocoa bean fermentation process.ResultsThrough functional annotation and analysis of the high-coverage contigs obtained through 454 pyrosequencing, plantaricin production was predicted for L. plantarum 80. For L. fermentum 222, genes encoding a complete arginine deiminase pathway were attributed. Further, in-depth functional analysis revealed the capacities of these strains associated with carbohydrate and amino acid metabolism, such as the ability to use alternative external electron acceptors, the presence of an extended pyruvate metabolism, and the occurrence of several amino acid conversion pathways. A comparative genome sequence analysis using publicly available genome sequences of strains of the species L. plantarum and L. fermentum revealed unique features of both strains studied. Indeed, L. fermentum 222 possessed genes encoding additional citrate transporters and enzymes involved in amino acid conversions, whereas L. plantarum 80 is the only member of this species that harboured a gene cluster involved in uptake and consumption of fructose and/or sorbose.ConclusionsIn-depth genome sequence analysis of the candidate functional starter culture strains L. fermentum 222 and L. plantarum 80 revealed their metabolic capacities, niche adaptations and functionalities that enable them to dominate the cocoa bean fermentation process. Further, these results offered insights into the cocoa bean fermentation ecosystem as a whole and will facilitate the selection of appropriate starter culture strains for controlled cocoa bean fermentation processes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1927-0) contains supplementary material, which is available to authorized users.

Highlights

Lactobacillus fermentum 222 and Lactobacillus plantarum 80, isolates from a spontaneous Ghanaian cocoa bean fermentation process, proved to be interesting functional starter culture strains for cocoa bean fermentations
In-depth genome sequence analysis of the candidate functional starter culture strains L. fermentum 222 and L. plantarum 80 revealed their metabolic capacities, niche adaptations and functionalities that enable them to dominate the cocoa bean fermentation process. These results offered insights into the cocoa bean fermentation ecosystem as a whole and will facilitate the selection of appropriate starter culture strains for controlled cocoa bean fermentation processes
The reads obtained from the genomic DNA of L. fermentum 222 were assembled into 73 contigs (>500 bp) with a 104-fold depth of coverage, whereas the reads obtained from the genomic DNA of L. plantarum 80 were assembled into 67 contigs (>500 bp) with a 65-fold depth of coverage

Summary

Introduction

Lactobacillus fermentum 222 and Lactobacillus plantarum 80, isolates from a spontaneous Ghanaian cocoa bean fermentation process, proved to be interesting functional starter culture strains for cocoa bean fermentations. It has been proposed that L. plantarum is the dominant member at the onset of the cocoa bean fermentation process, while L. fermentum dominates in later stages [7, 8, 18, 21]. This is in accordance with the cocoa-specific functional roles that have been associated with these two species [24,25,26]

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