Metatranscriptomic analysis of lactic acid bacterial gene expression during kimchi fermentation

Area of Science:

• Microbiology
• Metagenomics
• Fermentation Science

Background:

• Kimchi fermentation involves a complex microbiome dominated by lactic acid bacteria (LAB).
• Understanding the specific roles and gene expression of dominant LAB is crucial for controlling kimchi fermentation quality.

Purpose of the Study:

• To investigate the metatranscriptomic gene-expression profiles of dominant LAB during kimchi fermentation.
• To identify the key metabolic pathways and bacterial dynamics throughout the fermentation process.

Main Methods:

• 16S rRNA gene pyrosequencing to identify dominant LAB species.
• Metatranscriptomic analysis of kimchi samples at five time points during 29-day fermentation.
• Illumina sequencing and MG-RAST analysis for gene expression profiling.

Main Results:

• Six LAB species, including Leuconostoc mesenteroides and Lactobacillus sakei, dominated the kimchi microbiome.
• Lc. mesenteroides showed high activity in early fermentation, while Lb. sakei and Weissella koreensis were more active later.
• Active expression of carbohydrate metabolism and lactic acid fermentation genes, including mannitol dehydrogenase (mdh) genes in Leuconostoc species.

Conclusions:

• The study provides insights into the dynamic gene expression of LAB during kimchi fermentation.
• Specific LAB species play distinct temporal roles, contributing to the characteristic flavor and preservation of kimchi.
• Identification of mdh genes in Leuconostoc species highlights their potential role in kimchi metabolism.