• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.355-364
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• 2016

This study was initiated to evaluate the antioxidant and antimicrobial activities of methanol extract (ME) and hot water extract (HWE) obtained from the fruiting bodies of medicinal mushroom, Phellinus gilvus. The free radical scavenging activity of ME from P. gilvus on 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 93.65% at 2 mg/mL, which was comparable with the positive control, butylated hydroxytoluene (BHT, 96.97%) at the same concentration. The ferrous ion-chelating ability of ME and HWE was significantly higher than that of BHT at all concentration levels. The antimicrobial assay of ME was performed against six bacteria and one species of fungus. ME exhibited antibacterial activity against 5 out of 6 bacteria: Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa; whereas, ME did not show antimicrobial activity against gram-negative bacterium Vibrio vulnificus and fungal species Candida albicans. The minimum inhibitory concentration (MIC) of ME against 5 strains of bacteria, such as S. aureus, S. mutans, B. subtilis, E. coli, and P. aeruginosa, was 100, 100, 50, 100, 200 mg/mL, respectively. The results suggest that good antioxidant and microbial activities of P. gilvus fruiting bodies might be used for natural antioxidant and antimicrobial agents.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.39-43
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• 2014

The antimicrobial activity of Orixa japonica Thunb. leaf extract towards 13 microorganism strains was evaluated. Both methanol (MEex) and 70% ethanol extracts showed antimicrobial activity towards Streptococcus mutans, Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. MEex showed a higher antimicrobial activity than the 70% ethanol extract. In addition, the dichloromethane fraction (DCMfr) of the MEex also had an antimicrobial effect against the microorganisms examined. The minimum inhibitory concentrations (MICs) towards S. mutans, B. cereus, S. aureus, and P. aeruginosa were 49.22, 24.61, 49.22, and 49.22 mg/mL, respectively. In contrast, the MICs of the DCMfr tpwards S. mutans, B. cereus, S. aureus, and P. aeruginosa were 3.31, 0.21, 1.7, and 1.7 mg/mL, respectively. The MEex antimicrobial activity was not affected by a 3 h exposures to pH in the range of 3-11 or by temperatures were maintained between $80^{\circ}C-100^{\circ}C$ for 6 h. However, the MEex antimicrobial activity decreased at a heat treatment of $121^{\circ}C$ 1 h.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1269-1275
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• 2006

The selection of multienzyme complex-producing bacteria under aerobic condition was conducted for improving the degradation of lignocellulosic substances. The criteria for selection were cellulase and xylanase enzyme production, the presence of cellulose-binding domains and/or xylan-binding domains in enzymes to bind to insoluble substances, the adhesion of bacterial cells to insoluble substances, and the production of multiple cellulases and xylanases in a form of a high molecular weight complex. Among the six Bacillus strains, isolated from various sources and deposited in our laboratory, Paenibacillus curdlanolyticus B-6 strain was the best producer of cellulase and xylanase enzymes, which have both cellulose-binding factors (CBFs) and xylan-binding factors (XBFs). Moreover, multiple carboxymethyl cellulases (CMCases) and xylanases were produced by the strain B-6. The zymograms analysis showed at least 9 types of xylanases and 6 types of CMCases associated in a protein band of xylanase and cellulase with high molecular weight. These cells also enabled to adhere to both avicel and insoluble xylan, which were analyzed by scanning electron microscopy. The results indicated that the strain B-6 produced the multienzyme complex, which may be cellulosome or xylanosome. Thus, P. curdlanolyticus B-6 was selected to study the role and interaction between the enzymes and their substrates and the cooperation of multiple enzymes to enhance the hydrolysis due to the complex structure for efficient cellulases and xylanases degradation of insoluble polysaccharides.

• Food Science and Preservation
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• v.12 no.5
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• pp.470-475
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• 2005

Antimicrobial activities of pyroligneous liquor were investigated by determining Minimal Inhibitory Concentration (MIC). The solvent extracts of pyroligneous liquor, which were extracted by using solvents with different polarities such as hexane, ethylacetate, or butanol. The activities were examined by disc diffusion method using MIC against 7 food poisoning microbe type strains. Antimicrobial activities were shown in hexane, ethylacetate, butanol, and aqueous fractions of pyroligneous liquor. Among the four fractions, ethylacetate fraction showed the highest inhibitory effect on the microorganism such as Shigella sonnei, and Yersinia enterocolitica at the concentration of 2.0 mg/disc. The purified P-1 and P-2 fractions isolated by silica gel column chromatography from ethylacetate fraction of pyroligneous liquor had the highest antimicrobial activity. The total phenolic compounds content in ethylacetate, hexane, butanol, and aqueous fraction was 488.3 mg/g, 403.8 mg/g, 83.6mg/g, and 74.5 mg/g, respectively. Taken together, these results suggest that the ethyl acetate fraction could be suitable for the development of isolation and identification of antimicrobial compound from pyroligneous liquor, resulting from the above antimicrobial activity.

• KSBB Journal
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• v.27 no.2
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• pp.75-85
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• 2012

Although, microbial arsenic mobilization by dissimilatory arsenate-reducing bacteria (DARB) and the practical use to the removal technology of arsenic from contaminated soil are expected, most previous research mainly has been focused on the geochemical circulation of arsenic. Therefore, in this review we summarized the previously reported DARB to grasp the characteristic for bioremediation of arsenic. Evidence of microbial growth on arsenate is presented based on isolate analyses, after which a summary of the physiology of the following arsenate-respiring bacteria is provided: Chrysiogenes arsenatis strain BAL-$1^T$, Sulfurospirillum barnesii, Desulfotomaculum strain Ben-RB, Desulfotomaculum auripigmentum strains OREX-4, GFAJ-1, Bacillus sp., Desulfitobacterium hafniense DCB-$2^T$, strain SES-3, Citrobacter sp. (TSA-1 and NC-1), Sulfurospirillum arsenophilum sp. nov., Shewanella sp., Chrysiogenes arsenatis BAL-$1^T$, Deferribacter desulfuricans. Among the DARB, Citrobacter sp. NC-1 is superior to other dissimilatory arsenate-reducing bacteria with respect to arsenate reduction, particularly at high concentrations as high as 60 mM. A gram-negative anaerobic bacterium, Citrobacter sp. NC-1, which was isolated from arsenic contaminated soil, can grow on glucose as an electron donor and arsenate as an electron acceptor. Strain NC-1 rapidly reduced arsenate at 5 mM to arsenite with concomitant cell growth, indicating that arsenate can act as the terminal electron acceptor for anaerobic respiration (dissimilatory arsenate reduction). To characterize the reductase systems in strain NC-1, arsenate and nitrate reduction activities were investigated with washed-cell suspensions and crude cell extracts from cells grown on arsenate or nitrate. These reductase activities were induced individually by the two electron acceptors. Tungstate, which is a typical inhibitory antagonist of molybdenum containing dissimilatory reductases, strongly inhibited the reduction of arsenate and nitrate in anaerobic growth cultures. These results suggest that strain NC-1 catalyzes the reduction of arsenate and nitrate by distinct terminal reductases containing a molybdenum cofactor. This may be advantageous during bioremediation processes where both contaminants are present. Moreover, a brief explanation of arsenic extraction from a model soil artificially contaminated with As (V) using a novel DARB (Citrobacter sp. NC-1) is given in this article. We conclude with a discussion of the importance of microbial arsenate reduction in the environment. The successful application and use of DARB should facilitate the effective bioremediation of arsenic contaminated sites.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.492-500
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• 2015

Our previous report demonstrated successful isolation of soil-borne bacteria that suppressed the potential of Rhizoctonia solani AG2-2 (IV) causing turfgrass large patch disease when applied to Korean lawngrass (Zoysia japonica). The current study aimed to uncover the mechanisms of this antagonism of Rhizoctonia solani and to define culture conditions for the isolated microbes. We found that two Bacillus isolates, I-009 and FRIN-001-1 strains, produced cellulase and siderophore, but not chitinase, while the Pseudomonas YPIN-022 strain was found to release only siderophore, implying that three antagonistic bacteria commonly interrupt Fe uptake by the large patch pathogen. The I-009 and FRIN-001-1 isolates grew best at 35 and $30^{\circ}C$ in growth medium of pH 5 to 8 for 32 and 28 h, respectively, while optimum growth for the YPIN-022 strain was found at $35^{\circ}C$ at pH 5 to 9 for 24 h. Good growth of I-009 and YPIN-022 over 24 h was obtained in M9 minimal medium supplemented with 1% sucrose, 0.5% yeast extract and 0.1% potassium chloride. FRIN-001-1 grew well in M9 medium with 1% mannitol, 0.5% yeast extract and 0.1% potassium phosphate dibasic.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2159-2170
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• 2016

Many plant-pathogenic bacteria are dependent on quorum sensing (QS) to evoke disease. In this study, the population of QS and quorum quenching (QQ) bacteria was analyzed in a consecutive monoculture system of Pseudostellaria heterophylla. The isolated QS strains were identified as Serratia marcescens with SwrIR-type QS system and exhibited a significant increase over the years of monoculture. Only one QQ strain was isolated from newly planted soil sample and was identified as Bacillus thuringiensis, which secreted lactonase to degrade QS signal molecules. Inoculation of S. marcescens to P. heterophylla root could rapidly cause wilt disease, which was alleviated by B. thuringiensis. Furthermore, the expression of lactonase encoded by the aiiA gene in S. marcescens resulted in reduction of its pathogenicity, implying that the toxic effect of S. marcescens on the seedlings was QS-regulated. Meanwhile, excess lactonase in S. marcescens led to reduction in antibacterial substances, exoenzymes, and swarming motility, which might contribute to pathogensis on the seedlings. Root exudates and root tuber extracts of P. heterophylla significantly promoted the growth of S. marcescens, whereas a slight increase of B. thuringiensis was observed in both samples. These results demonstrated that QS-regulated behaviors in S. marcescens mediated by root exudates played an important role in replanting diseases of P. heterophylla.

• Korean journal of food and cookery science
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• v.27 no.4
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• pp.17-26
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• 2011

This study was performed to analyze the antibacterial activity against food hazardous microorganisms and antimutagenic effects of Sanguisorba officinalis L. ethanol extracts on Salmonella Typhimurium TA100. The antibacterial activity was evaluated by paper disc diffusion assay, minimum inhibition concentration (MIC), and optical density of the culture with the ethanol extract for 24 hr. Antibacterial activity was tested with seven microorganisms including Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. The paper disc diffusion assay showed distinct clear inhibition zones around the discs treated with the extract for five microorganisms, except Escherichia coli and Escherichia coli O157:H7. MIC values were 0.625-2.5 mg/mL for these five strains that showed clear zones. The time-kill assay was consistent with the results from the paper disc diffusion assay and MIC test. Additionally, antimutagenicity of the extract was determined using the Ames test. The ethanol extract at 5 mg/plate inhibited 72.42% and 89.85% of mutagenicity induced by 4-nitroquinoline 1-oxide and sodium azide, respectively. These results demonstrate that the ethanol extract from S. officinalis L. has remarkable antibacterial activity and antimutagenicity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.211-215
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• 1983

The changes of microflora during fermentation of low salted sardine were observed. The viable cell count in the low salt fermented sardine with $8\%\;or\;10\%$ salt showed lower than that of control ($20\%$ salt) during the fermentation period and it was considered that the microbial growth was controlled by adding ethanol, sorbitol and lactic acid. Among 48 strains isolated, 7 genus of bacteria and 1 genus of yeast were identified during the fermentation of sardine. The changes of microflora also occurred during fermentation depending on the salt levels in the product. Brevibacterium, Pseudomonas, Flavobacterium and Baciilus were detected at early stage of fermentation and they disappeared after 50 days fermentation from the product with $20\%$ salt and Halobacterium, Micrococcus, Pediococcus and Torulopsis were isolated, whereas Brevibacterium, Micrococcus and Pediococcus were isolated from the product with $8\%\;or\;10\%$ salt.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1151-1157
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• 2017

This study examined the immune response of Philippines eel (Anguilla bicolor) to the oral administration of fermented Sparassis crispa stipe extract for 6 weeks. The S. crispa extract fermented with Lactobacillus plantarum showed a higher total phenol content (301.68 ppm) and DPPH radical scavenging activity (63.9%) than those fermented with other strains. Therefore, L. plantarum was selected as a suitable starter culture for the fermentation of S. crispa stipe. The eels were fed a commercial diet supplemented with 1% of fermented S. crispa stipe extract for 6 weeks. The mortality rate of the eels fed the supplemented diet was significantly lower than those of the control after 6 weeks. The lysozyme activity of the serum was increased significantly (12.33 ${\rightarrow}$ 54.66 units) after 6 weeks in the eel fed supplemented diets of fermented S. crispa stipe. The serum of the eel fed the supplemented diet of the S. crispa stipe extract showed higher bactericidal activity. These results suggest that both the S. crispa stipe extract and fermented S. crispa stipe have strong potential to activate the innate immune response of the Philippines eel.