Analysis of microbial communities in doenjang, a Korean fermented soybean paste, using nested PCR-denaturing gradient gel electrophoresis

• Published in: International journal of food microbiology Vol. 131; no. 2; pp. 265 - 271
• Main Authors: Kim, Tae-Woon, Lee, Jun-Hwa, Kim, Sung-Eon, Park, Min-Hee, Chang, Hae Choon, Kim, Hae-Yeong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.05.2009; [Amsterdam; New York, NY]: Elsevier Science; Elsevier
• Subjects: Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; biodiversity; Biological and medical sciences; denaturing gradient gel electrophoresis; DGGE; DNA Fingerprinting; DNA, Bacterial; DNA, Fungal; Doenjang; Electrophoresis - methods; fermentation; fermented foods; Food industries; Food Microbiology; food paste; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Fungi - classification; Fungi - genetics; Fungi - isolation & purification; gel electrophoresis; Genes, Bacterial; Genes, Fungal; Genes, rRNA; Glycine max - microbiology; isolation; Microbial diversity; microbial load; microorganisms; Polymerase Chain Reaction; RNA, Ribosomal, 16S - genetics; sequence analysis; Soy Foods - microbiology; Soybean paste; soybean products; starter cultures; traditional foods; South Korea; Doenjang; Microbial diversity; Soybean paste; DGGE; Polymerase chain reaction; Grain legume; Gel electrophoresis; Soybean; Molecular biology; Fermented product
• DOI: 10.1016/j.ijfoodmicro.2009.03.001
• ISSN: 0168-1605

Doenjang is a traditional Korean fermented soybean paste that provides a major source of protein. The microbial diversity of 10 samples of doenjang (5 commercially manufactured products and 5 homemade products) was investigated using nested PCR-denaturing gradient gel electrophoresis (DGGE). In the first step, the nearly complete 16S rRNA and 18S rRNA genes were amplified using universal primers. Subsequently, these products were used as a template in a nested PCR to obtain fragments suitable for DGGE. The bacterial DGGE profile targeting the V3 region of the 16S rRNA gene indicated that lactic acid bacteria such as Leuconostoc mesenteroide, Tetragenococcus halophilus, and Enterococcus faecium were the predominant species. However, bands corresponding to Bacillus species, known to be the main organisms in doenjang, were not detected under the conditions described above. When selective PCR was conducted using a primer specific for Bacillus species, Bacillus subtilis and B. licheniformis were detected in several doenjang samples. In analysis of fungi, Mucor plumbeus, Aspergillus oryzae, and Debaryomyces hansenii were the most common species in the doenjang samples. On the basis of DGGE, a few differences in community structure were found for different samples. Also, cluster analysis of the DGGE profile revealed that the microbial diversity did not differ clearly between commercially manufactured and homemade products. The nested PCR-DGGE technique was used for the first time in this study to asses a microbial community in doenjang and proved to be effective in profiling microbial diversity.