Bacterial Distribution, Biogenic Amine Contents, and Functionalities of Traditionally Made Doenjang, a Long-Term Fermented Soybean Food, from Different Areas of Korea

Abstract

Since doenjang quality depends on the bacterial composition, which ambient bacteria in the environment and production conditions influence, a complete understanding of the bacteria community in traditionally madetraditionally made doenjang (TMD) from different regions is needed. We aimed to investigate the bacteria composition and quality of TMD in the following areas: Chonbuk (CB), Chonnam (CN), Kyungsang (KS), Kangwon (KW), Chungchung (CC) provinces, and Jeju island (JJ) of Korea. Twenty-nine TMD samples from different regions were used to assess biogenic amine contents, bacteria composition using next-generation methods, and metabolic functions of the bacteria using Picrust2. Bacillus spp. were isolated, and their antioxidant and fibrinolytic activities were determined. Most TMD contained high amounts of beneficial bacteria (Bacillus, Lactobacillus, Pediococcus and Weissella). However, some KS samples contained harmful bacteria (Cronobacter, Proteus and Acinetobacter) and less beneficial B. velezensis bacteria. There was no similarity among the regional groups, and each TMD showed a different bacteria composition. Shannon index, α-diversity index, was lower in TMD from JJ and CB than the other areas, but there was no β-diversity among TMD from the six area groups. Picrust2 analysis revealed that the functional potential for arachidonic acid metabolism was lowest in JJ and CN, that for supporting insulin action was highest in KS and JJ, and that for carbohydrate digestion and absorption was lowest in CB and JJ among all groups (p < 0.05) according to the Kyoto Encyclopedia of Genes and Genomes Orthology. Histamine contents were lower in CN and CC, and tyramine contents did not differ significantly. B. velezensis, B. subtilis, B. licheniformis, B. siamensis, and B. amyloliquefaciens were isolated from TMD. None of the isolated Bacillus spp. contained the B. cereus gene. B. subtilis from CN had the highest fibrinolytic activity, and B. velezensis from CB had the highest antioxidant activity. In conclusion, TMD mainly contained various Bacillus spp., and the predominant one was B. velezensis, which had antioxidant and fibrinolytic activity regardless of the regional origin.

Bacterial Community and Anti-Cerebrovascular Disease-Related Bacillus Species Isolated from Traditionally Made Kochujang from Different Provinces of Korea

“…Although the dominant bacteria, Bacillus spp., were similar in TMK and doenjang, TMK contained more diverse bacterial communities than doenjang because of the digested rice powder and lower salt contents in TMK than doenjang [5]. TMK from different areas in Korea may have different bacterial distributions and temperatures.…”

“…Libraries of the DNA PCR products were prepared according to the GS FLX plus library prep guide. The DNA was amplified with 16S universal primers in the FastStart High Fidelity PCR System (Roche, Basel, Switzerland) described elsewhere [5]. Bacterial DNA sequences in the TMK samples were measured using the Illumina MiSeq standard operating procedure on a Genome Sequencer FLX plus (454 Life Sciences, Branford, CT, USA) in the Microbial Institute for Fermentation Industry (Soon Chang, Korea).…”

“…The PCR products were identified by running electrophoresis in 2% agarose gel. The DNA bands for CytK, nheA, ent FM, bceT, hblC, CER, hdc, and tdc expression were detected [5].…”

“…Each isolated Bacillus colony from the TMK samples was individually cultured in LB liquid media at 30 • C for 24 h, and the culture media was separated after centrifuging at 13,000 rpm for 10 min. The antioxidant activity was estimated by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH, Sigma-Aldrich, St. Louis, MO, USA) activity and superoxide dismutase (SOD)-like activity [5,24]. The culture media supernatants were mixed to 100 µM DPPH in ethanol (10:1) and incubated in a dark room for 30 min.…”

“…The isolated Bacillus spp. may have different characteristics in different types of Jang because their fermentation condition and ingredient compositions are different [5]. Functionalities of the Jang depend on the bacteria compositions and their metabolites.…”