Myung-Ki Lee

Pyrosequencing analysis of microbiota reveals that lactic acid bacteria are dominant in Korean flat fish fermented food, gajami-sikhae

The gajami-sikhae, traditional Korean cuisine fermented with flat fish, samples were collected from eight different manufacturers (GS1–GS8). We employed pyrosequencing method to analyze the bacterial communities of the gajami-sikhae samples. Family- and genus-level analyses indicated that the bacterial community compositions of GS3 and GS6 were distinct from those of the rest. The species-level structures of bacterial communities of the gajami-sikhae samples except for GS3 and GS6 featured Lactobacillus sakei as the most abundant species. Leuconostoc mesenteroides was revealed as the most dominant species among the bacterial community of GS6 and the bacterial community of GS3 was composed of various lactic acid bacteria. We employed a culture-based method to isolate beneficial strains from the gajami-sikhae samples. However, most of the 47 selected colonies were identified as Bacillus subtilis and Bacillus amyloliquefaciens. This study indicated that gajami-sikhae was mainly composed of many beneficial lactic acid bacteria. Graphical Abstract Pyrosequencing was employed to analyze the bacterial communities of Korean fermented food (gajami-sikhae) samples

Pyrosequencing-based analysis of the bacterial community during fermentation of Alaska pollock sikhae: traditional Korean seafood

We analyzed the bacterial community of Alaska pollock sikhae, a traditional Korean food made by natural fermentation with Alaska pollock, utilizing pyrosequencing. We fermented the Alaska pollock sikhae at two different temperatures (10°C and 20°C). Before fermentations, the bacterial community was varied. After fermentations, however, Lactobacillus sakei became dominant. The Alaska pollock sikhae sample before fermentations contained only 2% L. sakei, but the sample on day 6 of fermentation at 10°C comprised 74% L. sakei (90% at 20°C). In addition, we observed a reduction in the composition of unpreferred bacterial species for foods after fermentation. The composition of unpreferred bacterial species was more than 30% of total reads in samples before fermentation and decreased to less than 0.2% after fermentation. This result suggested that the fermentation of Alaska pollock sikhae can be beneficial for food safety. Alaska pollock sikhae might be a favorable habitat for L. sakei. Our study is the first report illustrating the alteration of the bacterial community of Alaska pollock sikhae during fermentation utilizing pyrosequencing analysis.

Characterization and use of microbial communities in Doenjang to control the unpleasant odor of Ginkgo epicarp

The Ginkgo epicarp is usually discarded due to contained butyric acid causing an unpleasant odor. Control of butyric acid in the Ginkgo epicarp was achieved by fermenting with doenjang under different fermentation conditions. The contents of butyric acid decreased 3.2× when Ginkgo epicarp was fermented at 30°C for 6 months. Microbes in doenjang were probably responsible for the reduction in the butyric acid content. Microbial communities were analyzed during fermentation. Communities were isolated using selective media and analyzed using metagenomic pyrosequencing based on 16S rRNA sequences. Changes in the microbial communities were confirmed at the species level. Staphylococcus gallinarum was the dominant species and maintained a constant level during fermentation. The possibility of a new fermented food with Ginkgo epicarp is suggested.