• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.973-979
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• 2023

Lycopene is a carotenoid widely used as a food and feed supplement due to its antioxidant, anti-inflammatory, and anti-cancer functions. Various metabolic engineering strategies have been implemented for high lycopene production in Escherichia coli, and for this purpose it was essential to select and develop an E. coli strain with the highest potency. In this study, we evaluated 16 E. coli strains to determine the best lycopene production host by introducing a lycopene biosynthetic pathway (crtE, crtB, and crtI genes cloned from Deinococcus wulumuqiensis R12 and dxs, dxr, ispA, and idi genes cloned from E. coli). The 16 lycopene strain titers diverged from 0 to 0.141 g/l, with MG1655 demonstrating the highest titer (0.141 g/l), while the SURE and W strains expressed the lowest (0 g/l) in an LB medium. When a 2 × YTg medium replaced the MG1655 culture medium, the titer further escalated to 1.595 g/l. These results substantiate that strain selection is vital in metabolic engineering, and further, that MG1655 is a potent host for producing lycopene and other carotenoids with the same lycopene biosynthetic pathway.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.2
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• pp.169-173
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• 2010

This study evaluated the effects of gamma ray irradiation on the safety of dried seafood products. Dried salted squid, Engraulis japonica, Hizikia fusiformis, Mytilus coruscus, and Porphyra tenera were gamma-irradiated at doses of 0, 1, 3, and 5 kGy. The total bacterial populations were then enumerated on total plate count agar, and bacteria isolated from the samples were identified by 16S rDNA sequencing. In addition, the isolated strains were inoculated in the products to determine $D_{10}$ values. The total bacterial populations in the dried seafood products ranged from 3.40 to 6.59 log CFU/g, and those of yeasts and molds ranged from 2.21 to 4.56 log CFU/g. The sequence analysis identified Staphylococcus sp. as the most common species in the dried seafood products, except for dried P. tenera. The $D_{10}$ values of the contaminating bacteria were lower than 0.7 kGy, except for Deinococcus sp., which had a value of 1.39 kGy. This study demonstrated that gamma irradiation could be used to improve the safety of dried seafood products.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.1916-1924
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• 2017

In this study, we synthesized a glycosylated derivative of caffeic acid phenethyl ester (CAPE) using the amylosucrase from Deinococcus geothermalis with sucrose as a substrate and examined its solubility, chemical stability, and anti-inflammatory activity. Nuclear magnetic resonance spectroscopy showed that the resulting glycosylated CAPE (G-CAPE) was the new compound caffeic acid phenethyl ester-4-O-${\alpha}-{\small{D}}$-glucopyranoside. G-CAPE was 770 times more soluble than CAPE and highly stable in Dulbecco's modified Eagle's medium and buffered solutions, as estimated by its half-life. The glycosylation of CAPE did not significantly affect its anti-inflammatory activity, which was assessed by examining lipopolysaccharide-induced nitric oxide production and using a nuclear factor erythroid 2-related factor 2 reporter assay. Furthermore, a cellular uptake experiment using high-performance liquid chromatography analysis of the cell-free extracts of RAW 264.7 cells demonstrated that G-CAPE was gradually converted to CAPE within the cells. These results demonstrate that the glycosylation of CAPE increases its bioavailability by helping to protect this vital molecule from chemical or enzymatic oxidation, indicating that G-CAPE is a promising candidate for prodrug therapy.

• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.562-570
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• 2019

${\beta}$-Glucosylglycerol (${\beta}-GG$) and their derivatives have potential applications in food, cosmetics and the healthcare industry, including antitumor medications. In this study, ${\beta}-GG$ and its unnatural glycosides were synthesized through the transglycosylation of two enzymes, Sulfolobus shibatae ${\beta}$-glycosidase (SSG) and Deinococcus geothermalis amylosucrase (DGAS). SSG catalyzed a transglycosylation reaction with glycerol as an acceptor and cellobiose as a donor to produce 56% of ${\beta}-GGs$ [${\beta}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}1/3$)-$\text\tiny{D}$-glycerol and ${\beta}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}2$)-$\text\tiny{D}$-glycerol]. In the second transglycosylation reaction, ${\beta}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}1/3$)-$\text\tiny{D}$-glycerol was used as acceptor molecules of the DGAS reaction. As a result, 61% of ${\alpha}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}4$)-${\beta}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}1/3$)-$\text\tiny{D}$-glycerol and 28% of ${\alpha}$-$\text\tiny{D}$-maltopyranosyl-($1{\rightarrow}4$)-${\beta}$-$\text\tiny{D}$-glucopyranosyl-($1{\rightarrow}1/3$)-$\text\tiny{D}$-glycerol were synthesized as unnatural glucosylglycerols. In conclusion, the combined enzymatic synthesis of the unnatural glycosides of ${\beta}-GG$ was established. The synthesis of these unnatural glycosides may provide an opportunity to discover new applications in the biotechnological industry.

• Journal of Species Research
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• v.8 no.2
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• pp.176-190
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• 2019

A total of 38 bacterial strains within the classes Bacilli and Deinococci were isolated from various sources in Korea. Samples were collected from animal intestine, urine, soil, tidal flat mud, and kimchi. In the sequence comparison and phylogenetic analysis of 16S rRNA sequences, the 38 isolates were assigned to the classes Bacilli and Deinococci with sequence similarities more than 98.7%. Twenty-four strains and 13 strains were classified the order Bacillales and Lactobacillales in the class Bacilli, respectively. In the order Bacillales, there were nine species in the genus Bacillus, seven species in the genus Paenibacillus, and the remaining eight species in the genera Domibacillus, Halobacillus, Virgibacillus, Lysinibacillus, Paenisporosarcina, Planococcus, Savagea, and Staphylococcus. In the order Lactobacillales, there were four species in the genus Lactobacillus, three species in the genus Leuconostoc, three species in the genus Lactococcus, and the remaining three species in the genera Aerococcus, Enterococcus, and Streptococcus. One species was related to the genus Deinococcus of the order Deinococcales. Most of the isolated strains were Gram-stain-positive, but some were Gram-stain-variable or Gram-stain-negative. Cells were rod or cocci-shaped. Based on the results of 16S rRNA analysis, we report 38 strains as previously unrecorded species to Korea, and the basic characteristics of strains are described herein.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.43-50
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• 2021

A newly cloned 4-α-glucanotransferase (αGT) from Deinococcus geothermalis and two typical bacterial αGTs from Thermus scotoductus and Escherichia coli (MalQ) were investigated. Among 4 types of catalysis, the cyclization activity of αGTs that produces cycloamylose (CA), a valuable carbohydrate making inclusion complexes, was intensively studied. The new αGT, DgαGT, showed close protein sequence to the αGT from T. scotoductus (TsαGT). MalQ was clearly separated from the other two αGTs in the phylogenetic and the conserved regions analyses. The reaction velocities of disproportionation, cyclization, coupling, and hydrolysis of three αGTs were determined. Intriguingly, MalQ exhibited more than 100-fold lower cyclization activity than the others. To lesser extent, the disproportionation activity of MalQ was relatively low. DgαGT and TsαGT showed similar kinetics results, but TsαGT had nearly 10-fold lower hydrolysis activity than DgαGT. Due to the very low cyclizing activity of MalQ, DgαGT and TsαGT were selected for further analyses. When amylose was treated with DgαGT or TsαGT, CA with a broad DP range was generated immediately. The DP distribution of CA had a bimodal shape (DP 7 and 27 as peaks) for the both enzymes, but larger DPs of CA quickly decreased in the DgαGT. Cyclomaltopentaose, a rare cyclic sugar, was produced at early reaction stage and accumulated as the reactions went on in the both enzymes, but the increase was more profound in the TsαGT. Taken together, we clearly demonstrated the catalytic differences between αGT groups from thermophilic and pathogenic bacteria that and showed that αGTs play different roles depending on their lifestyle.

• Food Science and Preservation
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• v.23 no.1
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• pp.139-143
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• 2016

This study investigated the effect of electron beam (EB) treatment on the microbial reduction of dried laver (Porphyra tenera) and identified EB-resistant bacteria from the treated dried laver. After EB treatments of 4 kGy and 7 kGy, the numbers of total bacteria and EB-resistant bacteria were measured using tryptic soy agar and mannitol salt agar, respectively. The morphological and biochemical characteristics of each isolated EB-resistant bacteria were investigated and these bacteria were identified. Compared to the control ($1.5{\pm}0.2){\times}10^6CFU/g$, the total bacterial number was significantly decreased to ($5.4{\pm}0.5){\times}10^4CFU/g$ and ($1.1{\pm}0.6){\times}10^4CFU/g$ after EB treatments of 4 kGy and 7 kGy, respectively. With a higher EB dosage, the number of red colonies was almost same, whereas the number of yellow colonies was significantly decreased to ($3.3{\pm}1.2){\times}10^3CFU/g$ and 0 CFU/g for 4 kGy and 7 kGy, respectively. All red and yellow colonies were gram-positive cocci, catalase-positive, and resistant to 3% and 5% NaCl media. From the 16S rDNA sequence analysis, yellow and red colonies were identified as either Micrococcus flavus or M. luteus, with 99% similarity for the yellow colonies, and Deinococcus proteolyticus and D. piscis, with 99% and 97% similarity for the red colonies, respectively.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.207-216
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• 2021

Supplement of high-protein food plays an important role in improving the symptoms of malnutrition and the immune capacity of the body, but the association of high-protein diet and gut microbiota remained unaddressed. Here, we systematically analyzed the internal organs and gut microbiota in C57(WT) or PD-1H-depleted (KO) mice (T cells were activated) fed with pupae or feed for six weeks. We observed that the body weight gain in the mice fed with pupae increased less significantly than that of the feed group, while the villi and small intestine lengths in the pupa group were reduced compared with that of mice given feed. However, the average body weight of the KO mice increased compared with that of the WT mice fed with pupae or feed. Pupae increased the concentration of blood glucose in WT, but not in KO mice. Moreover, in the feed group, there was no difference in the weight of the internal organs between the WT and KO mice, but in the pupae-fed group, liver weight was decreased and spleen weight was increased compared with that of KO mice. The amounts/plural/amounts of Melainabacteria, Chloroflexi, and Armatimonadetes were specifically upregulated by pupae, and this upregulation was weakened or eliminated by PD-1H depletion. Some bacteria with high abundance in the feed-fed KO mice, such as Deferribacteres, Melainabacteria, Acidobacteria, Bacteroidetes, Spirochaetes and Verrucomicrobia, were decreased in pupae-fed KO mice, and Proteobacteria and Deinococcus were specifically enriched in pupae-fed KO mice. Bacteroidetes, Firmicutes and Akkermansia were associated with weight loss in the pupae-fed group while Lachnospiraceae and Anaerobiospirillum were related glucose metabolism and energy consumption. Based on high-throughput sequencing, we discovered that some gut bacteria specifically regulated the metabolism of a high-protein diet, and PD-1H deficiency improved life quality and sustained blood glucose. Moreover, PD-1H responses to high-protein diet through modulating the type and quantity of gut bacteria. These findings provide evidence about the association among gut microbiota, T cell activation (for PD-1H depletion) and high-protein diet metabolism, have important theoretical significance for nutrition and health research.