Sonmat, a citizen-science enabled Kimjang kimchi case study on associations between hand and kimchi microbiotaOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This citizen-science study asked whether the microbes on a maker's hands seed kimchi, and how the traditional group Kimjang practice shapes the ferment. Researchers ran two workshops at a Belgian festival, one where people made kimchi individually and one traditional group batch. They swabbed participants' hands before preparation. They tracked pH and gas after fermentation. Hand and kimchi communities were profiled by RNA-based V4 16S rRNA sequencing to capture the active bacteria, resolved to genus and amplicon sequence variant level.
Who was studied?
The samples were fermented cabbage kimchi and human hand skin swabs, not clinical subjects. Twenty-five people joined the individual-kimchi workshop and 20 joined the group Kimjang workshop in Belgium. Each individual maker gave one hand swab matched to their own kimchi jar. Ingredients, chopping, and storage were standardized across both workshops. Fermentations ran 48 hours at room temperature, then 24 hours refrigerated, and were sampled on day 3.
What were the most important findings?
Group Kimjang kimchi was more uniform and safer, reaching pH 4.29 plus or minus 0.09 versus 4.61 plus or minus 0.28 for individual batches. Gas appeared in 71% of group jars but only 36% of individual jars. Seven of eight group ferments were dominated (over 75%) by Leuconostoc, a heterofermentative lactic acid bacterium. Individual ferments were led by Latilactobacillus and Leuconostoc. Hands were dominated by Staphylococcus. Skin and kimchi communities differed sharply, with at most 6 shared ASVs per person. Hand Staphylococcus abundance correlated with kimchi diversity and negatively with Latilactobacillus and Leuconostoc.
What are the greatest implications of this study?
The findings suggest raw vegetables, not hands, supply most kimchi bacteria, since skin taxa rarely colonized the ferment. Fermentation conditions like salt and acid likely block most skin microbes. Still, hand Staphylococcus was associated with the lactic acid bacteria that dominate early fermentation, hinting at an indirect influence on flavor. Group Kimjang preparation produced a more consistent, safer product. The authors caution that genus-level 16S data cannot confirm strain transfer, and hand disinfection was a limitation.