• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.319-327
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• 2022

γ-Aminobutyric acid (GABA) is a multi-functional compound with broad applications for food industry. GABA producing bacteria were isolated from cabbage kimchi. Among them, B737 was the best GABA producer when culture supernatants were analyzed by TLC. B737 was identified as Levilactobacillus brevis by 16S rRNA gene sequencing. Its glutamate decarboxylase (GAD) gene was cloned by PCR and the nucleotide sequence determined. B737 GAD consisting of 485 amino acids is the largest in size among GADs reported from LAB so far. gadB from L. brevis B737 was overexpressed in Escherichia. coli BL21(DE3) using pET26b(+).pET26b(+). The recombinant GAD was purified and its size was 55 kDa by SDS-PAGE. Maximum GAD activity was observed at pH 5 and 40℃ and the activity was dependent on pyridoxal 5'-phosphate. K_m and V_max of recombinant GAD were 6.2 ± 0.06 mM and 0.34 ± 0.002 mM/min, respectively. L. brevis B737 can be used as a starter for fermented foods with high GABA contents.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.775-784
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• 2021

After isolating the DIMO 52 strain with a large inhibition zone diameter for Clostridium perfringens and maximum butyric acid production from the fecal sample of a breastfeeding infant, it was identified as Clostidium butyricum. The maximum growth of the DIMO 52 strain was reached 24 h after inoculation, and the maximum butyric acid concentration was approximately 34.73±4.27 mM. The DIMO 52 strain survived approximately 67.5% of the initial inoculum at pH 2.0, and approximately 64.9% survived in RCM broth supplemented with 0.3% (w/v) oxgall. In addition, DIMO 52 showed antibacterial activity against Escherichia coli KCTC 2441 and Salmonella Typhimurium KCTC 1925. In LPS-stimulated RAW264.7 cells, 1×10³ CFU/mL viable cells of the DIMO 52 strain also exhibited significant NO (nitric oxide) production inhibitory activity (33%, p<0.01). This result suggests that C. butyricum DIMO 52 has anti-inflammatory activity related to NO radical-scavenging activity. In conclusion, C. butyricum DIMO 52 isolated in this study has the potential to be used as a probiotic.

• Journal of Marine Life Science
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• v.5 no.2
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• pp.35-42
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• 2020

17β-estradiol (E₂) is a natural hormone secreted by ovary, and continuously discharged from household and livestock wastewater into aquatic environment. Due to its strong estrogenic activity, it has adverse effects on development and reproduction in crustacean as an endocrine disrupting chemical. Although ecdysteroid signaling pathway play a key role in development in crustacean, little information on transcriptional modulation of ecdysteroid-related genes in response to E₂ is available in small crustacean. Here, we investigated the acute toxicity of E₂ to obtain 24-h LC_x values in the brackish water flea Diaphanosoma celebensis. Time-dependent expression patterns of seven ecdysteroid pathway - related genes (CYP314a1, EcRA, EcRB, USP, ERR, Vtg, VtgR) were further examined using quantitative real time reverse transcriptase polymerase chain reaction (qRT-PCR). As results, 24-h LC₅₀ and LC₁₀ values were 9.581 mg/l and 4.842 mg/l, respectively. The mRNA expression of CYP314a1, EcRA, USP, VtgR was significantly up-regulated at 12 or 24 h after exposure to E₂. These findings indicate that E₂ can affect their molting and reproduction by modulating the expression of ecdysteroid pathway - related in D. celebensis. This study will be useful for better understanding of molecular mode of action of endocrine disrupting chemicals on molting process in small crustacean.

• Journal of Applied Biological Chemistry
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• v.61 no.3
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• pp.245-255
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• 2018

The research was aimed to analyze the functional constituents (GABA and isoflavone), radical (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and hydroxyl) scavenging activities and enzyme (${\alpha}-glucosidase$ and lipase) inhibitory effects of soypowder milk (SPM) and fermented soy-powder milk (FSPM) with varied Lactobacillus brevis. Ten ${\gamma}-aminobutyric$ acid (GABA) producing lactic acid bacteria that showed 96-99% similarity with L. brevis, according to 16S rRNA gene sequence analysis, were isolated from fermented kimchi. The conversion rates of GABA were obtained 66.96-93.51, 63.76-84.58, and 57.05-69.75% in monosodium glutamate, gluten and soy protein, respectively. The levels of pH and glutamic acid of FSPM were found lower than those of SPM, but the acidity and GABA contents were higher. The GABA conversion rate of FSPM with BMK484 strain was attained the highest 69.97%. The contents of isoflavone glycoside ($1290.93{\mu}g/g$) was higher in SPM, but the content of isoflavone aglycone ($287.27-501.9{\mu}g/g$) was higher in FSPM. The levels of isoflavone aglycone such as daidzein, glycitein and genistein, were found as the highest 240.2, 61.24 and $200.45{\mu}g/g$, respectively, when FSPM was made with BMK484 strain. The DPPH, ABTS and hydroxyl radical scavenging and ${\alpha}-glucosidase$ and pancreatic lipase inhibitory activities of FSPM made with BMK484 strain were the relatively higher 60.31, 88.10, 61.25, 52.71, and 39.37%, respectively. Therefore, the L. brevis can be used as a material capable of simultaneously enhanced GABA and isoflavone aglycone in FSPM.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.1
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• pp.17-22
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• 2004

A bacterial strain WJ-98 found to produce active extracellular keratinase was isolated from the soil of a poultry factory. It was identified as Paracoccus sp. based on its 16S rRNA sequence analysis, morphological and physiological characteristics. The optimal culture conditions for the production of keratinase by Paracoccus sp. WJ-98 were investigated. The optimal medium composition for keratinase production was determined to be 1.0% keratin, 0.05% urea and NaCl, 0.03% K$_2$HPO$_4$, 0.04% KH$_2$PO$_4$, and 0.01% MgCl$_2$$.$6H$_2$O. Optimal initial pH and temperature for the production of keratinase were 7.5 and 37$^{\circ}C$, respectively. The maximum keratinase production of 90 U/mL was reached after 84 h of cultivation under the optimal culturing conditions. The keratinase from Paracoccus sp. WJ-98 was partially purified from a culture broth by using ammonium sulfate precipitation, ion-exchange chromatography on DEAE-cellulose, followed by gel filtration chromatography on Sephadex G-75. Optimum pH and temperature for the enzyme reaction were pH 6.8 and 50$^{\circ}C$, respectively and the enzymes were stable in the pH range from 6.0 to 8.0 and below 50$^{\circ}C$. The enzyme activity was significantly inhibited by EDTA, Zn$\^$2+/ and Hg$\^$2+/. Inquiry into the characteristics of keratinase production from these bacteria may yield useful agricultural feed processing applications.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1011-1015
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• 2008

A Gram-negative, strictly aerobic, motile bacterial strain, designated Gsoil $124^T$, was isolated from a soil sample taken from a ginseng field in Pocheon Province (South Korea). The isolate contained Q-10 as the predominant lipoquinone, plus $C_{18:1}\;{\omega}7c$ and summed feature 4 ($C_{16:1}\;{\omega}6c$ and/or iso-$C_{15:0}$ 2-OH) as the major fatty acids. The G+C content of the genomic DNA was 68.1 mol%, and the major polar lipids consisted of sphingoglycolipid, phosphatidylglycerol, phosphatidylcholine, and phosphatidylethanolamine. A comparative 16S rRNA gene sequence analysis showed that strain Gsoil $124^T$ was most closely related to Sphingopyxis chilensis (98.7%), Sphingopyxis alaskensis (98.2%), Sphingopyxis witflariensis (98.2%), Sphingopyxis taejonensis (98.0%), and Sphingopyxis macrogoltabida (97.6%). However, the DNA-DNA relatedness between strain Gsoil $124^T$ and its phylogenetically closest neighbors was less than 22%. Thus, on the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil $124^T$ should be classified as representing a novel species in the genus Sphingopyxis, for which the name Sphingopyxis panaciterrae sp. nov. is proposed. The type strain is Gsoil $124^T$ (=KCTC $12580^T$=LMG $24003^T$).

• Food Science of Animal Resources
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• v.40 no.3
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• pp.362-376
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• 2020

Rabbit meat bekasam is a traditional fermentation product from Indonesia. This study aimed to determine the chemical and microbiological characteristics of rabbit meat bekasam during the fermentation process in order to isolate, characterize (in vitro and in vivo), and identify lactic acid bacteria (LAB) as the probiotic candidate. The chemical contents of bekasam on 7-day fermentation were investigated in explorative and experimental methods in a completely randomized design. A proximate analysis reported a decrease in the moisture content, fat and carbohydrate content, and an increase in protein content. Also, lactic acid content was increased from 0.48% to 1.12%, and pH was decreased from 5.3 to 4.3. Other properties indicated different values, such as bacteria (2.75×10⁶ to 4.45×10⁷ CFU/g), total LAB (3.82×10⁶ to 4.67×10⁸ CFU/g), total yeast (9.89×10⁶ to 3.82×10⁸ CFU/g) and total mould (4.34×10¹ to 4.86×10³ CFU/g). The experiment produced nine LAB isolates, including two probiotics subjected to further 16S rRNA gene analysis, which indicated that Lactobacillus buchneri was the potential probiotic isolate. After being tested on BALB/c mice, L. buchneri could improve the immune system by inhibiting the growth of Coliform and Salmonella.

• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.167-178
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• 2023

Large amounts of waste and wastewater from aquaculture have negatively impacted ecosystems. Among them, shrimp aquaculture wastewater contains large amounts of nitrogen contaminants derived from feed residues in an aerobic environment. This study isolated candidate strains from adult rockworms to treat shrimp aquaculture wastewater (SAW) in an aerobic environment. Among 87 strains isolated, 25 grew well at the same temperature as the shrimp aquaculture with excellent polymer degradation ability (>0.5 cm clear zone). Six isolates (strains AL1, AL4, AL5, AL6, LA10, and PR15) were finally selected after combining strains with excellent polymer degradation ability without antagonism. 16S rRNA sequencing analysis revealed that strains AL1, AL4, AL5, AL6, LA10, and PR15 were closely related to Bacillus paramycoides, Bacillus pumilus, Stenotrophomonas rhizophila, Bacillus paranthracis, Bacillus paranthracis, and Micrococcus luteus, respectively. When these six isolates were applied to SAW, they reached a maximum cell viability of 2.06×10⁵ CFU mL^-1. Their chemical oxygen demand (COD_Cr) and total nitrogen(TN) removal rates for 12h were 51.0% and 44.6%, respectively, when the COD_Cr/TN ratio was approximately 10.0. Considering these removal rates achieved in this study under batch conditions, these six isolates could be used for aerobic denitrification. Consequently, these six isolates from rockworms are good candidates that can be applied to the field of aquaculture wastewater treatment.

• Microbiology and Biotechnology Letters
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• v.52 no.2
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• pp.135-140
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• 2024

This study reports the isolation of a bacterium capable of degrading agar and the characterization of its agarase. An agar-degrading marine bacterium JS-1 was isolated using Marine agar 2216 media from seawater collected from the seashore of Angolpo, Changwon, Gyeongnam Province, Republic of Korea. An agar-degrading bacterium was named as Tenacibaculum sp. JS-1 by phylogenetic analysis based on 16S rRNA gene sequence. The extracellular crude agarase was prepared from the culture media of Tenacibaculum sp. JS-1 and used for characterization. Relative activities at 20, 30, 40, 50, and 60℃ were 39, 73, 100, 74, and 53%, respectively. Relative activities at pH 5, 6, 7, and 8 were 46%, 67%, 100%, and 49%, respectively. Its extracellular agarase showed maximum activity (164 U/l) at pH 7.0 and 40℃ in a 20 mM GTA buffer. The residual activities after heat treatment at 20, 30, and 50℃ for 30 min were 84, 73, and 26% or more, respectively. After 2 h heat treatment at 20, 30, 40, and 50℃, the residual activities were 80, 64, 52 and 21%, respectively. Thin layer chromatography analysis suggested that Tenacibaculum sp. JS-1 produces extracellular β-agarases that hydrolyze agarose to produce neoagarooligosaccharides, including neoagarohexaose (12.3%), neoagarotetraose (65.1%), and neoagarobiose (22.6%) at 6 h. Tenacibaculum sp. JS-1 and its β-agarase could be valuable for producing neoagarooligosaccharides with a variety of functional properties. These properties include inhibiting bacterial growth, slowing down starch degradation, and whitening, which are of interest for pharmaceuticals, food, cosmeceuticals, and nutraceuticals.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.313-320
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• 2013

Biofilm formed on stainless and copper in water treatment plant was investigated for sixteen weeks. Biofilm reactor was specially designed for this study. It was similar to that of a real distribution pipe. Raw water, coagulated, settled, filtered and treated water were used in this study. The average number of heterotrophic bacteria counts was $1.6{\times}10^4CFU/ml$, $5.8{\times}10^3CFU/ml$, $1.8{\times}10^3CFU/ml$, $1.3{\times}10^2CFU/ml$, 1 CFU/ml, respectively. Density of biofilm bacteria formed on stainless and copper pipes in raw, coagulated and settled water increased above $2.9{\times}10^3CFU/cm^2$ within second weeks while more biofilm bacteria counts were found on the stainless pipe than on the copper pipe. In case of filtered water (free residue chlorine 0.44 mg/L), there was no significant difference in the number of biofilm bacteria on both pipes and biofilm bacteria below $18CFU/cm^2$ were detected on both pipe materials after fifth weeks. Biofilm bacteria were not detected on both pipe materials in treated water (free residue chlorine 0.88 mg/L). According to the results of DGGE analysis, Sphingomonadacae was a dominant species of biofilm bacteria formed on the stainless pipe while the copper pipe had Bradyrhizobiaceae and Sphingomonadaceae as dominant bands. In case of filtered water, a few bands (similar to Propionibacterium sp., Sphingomonas sp., Escherichia sp., and etc.) that have 16S rRNA sequences were detected in biofilm bacteria formed on both pipes after fifth weeks. Stainless pipe had higher species richness and diversity than the copper pipe.