Hye Jung Choi

Isolation and characterization of BTEX tolerant and degrading Pseudomonas putida BCNU 106

Bacterial strains growing in river sediments were screened to identify an organic solvent-tolerant strain of Pseudomonas. Using this screen, Pseudomonas sp. BCNU 106 was isolated on the basis of its ability to grow on benzene, toluene, ethylbenzene, and three xylene isomers, o-, m- and p-xylene, as its sole carbon source. BCNU 106 was identified as a gram-negative, rod-shaped aerobic and mesophilic bacterium, which grew in liquid media containing high concentrations of organic solvents. 16S rDNA analysis classified BCNU 106 as a new member of the genus Pseudomonas. BCNU 106 was distinguishable from other Pseudomonas strains that are tolerant to organic solvents in that the isolate had the ability to utilize all three xylene isomers as well as benzene, toluene and ethylbenzene. The unique properties of the isolate such as solvent-tolerance and the ability to degrade xylene isomers may have important implications for the efficient treatment of solvent wastes.

Probiotic Potential of Lactobacillus Isolates

The purpose of this study was to investigate the probiotic properties of lactic acid bacterial strains isolated from animal feces. BCNU 9041 and BCNU 9042 isolates were assigned to Lactobacillus brevis on the basis of their physiological properties and 16S ribosomal DNA sequences analysis. They were confirmed as safe bioresources because of their non-hemolytic activities and non-production of harmful -glucosidase, -glucuronidase, tryptophanase, or urease. These isolates were also highly resistant to acid (at pH 2.5) and bile acids (at concentration of 0.3%, 0.6%, and 1% oxgall). In addition, they exhibited good antibacterial activity against food-borne bacteria, especially Bacillus cereus, Listeria monocytogenes, and Shigella sonnei. Furthermore, it was demonstrated that they have the highest levels of hydrophobicity and that they showed bile salt hydrolytic and cholesterol assimilation activity. These results suggest that BCNU 9041 and 9042 have good potential for application in functional foods and health-related products.

Antimicrobial and Anti-oral Malodor Efficacy of Schizandra chinensis Extracts against Oral Pathogens

This study was conducted to investigate the antimicrobial and anti-oral malodor effect of Schizandra chinensis extracts against oral pathogens. S. chinensis methanol (MeOH) extract showed better antimicrobial activities against oral pathogens than the S. chinensis hot water extract did. In particular, ethylacetate (EA) fraction of S. chinensis MeOH extract had the greatest effects against Streptococcus mutans, S. sanguinis, S. salivaris subsp. thermophols and Porphyromons gingivalis. The anti-malodor effect of S. chinensis against the generation of volatile sulfur compounds (VSC), such as hydrogen sulfide, methyl mercaptan, and dimethyl sulfide, was estimated using oral chroma in a practical study. The results showed that 2% MeOH extract of S. chinensis against the production of hydrogen sulfide, methyl mercaptan, and dimethyl sulfide had inhibitions of 91.15, 78.72 and 71.58%, respectively. These results showed that Schizandra chinensis extract had antimicrobial activity against several oral pathogens and exhibited significant effects on the inhibition of VSCs. Thus, Schizandra chinensis extract could be an alternative to available synthetic chemicals and oral hygiene products.against Oral Pathogens Nam Suk Heo, Hye Jung Choi, Su Mi Hwang, Young Whan Choi, Young Geun Lee and Woo Hong Joo* Department of Dental Hygiene, Masan University, Changwon 630-729, Korea Department of Biology and Interdisciplinary Program for Biotechnology, Changwon National University, Changwon 641-773, Korea Department of Clinical Pathology, Masan University, Changwon 630-729, Korea Department of Horticultural Bioscience, Pusan National University, Miryang 627-706, Korea Department of Food Science and Technology, Pusan National University, Miryang 627-706, Korea

Broad-spectrum In vitro antimicrobial activities of Streptomyces sp. strain BCNU 1001

Streptomyces sp. strain BCNU 1001 was isolated from forest soil samples. Cultural, morphological, and physiological characteristics as well as 16S rDNA analysis revealed that the isolate, BCNU 1001, belonged to the genus Streptomyces. The antimicrobial activity of the ethyl acetate extract was confirmed using the broth microdilution technique. The minimum inhibitory concentration (MIC) of the BCNU 1001 ethyl acetate extract was 0.25 mg/mL for Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, and 0.125 mg/mL for Micrococcus luteus, Staphylococcus aureus, and Pseudomonas fluorescens. The MIC of the BCNU 1001 ethyl acetate extract for Aspergillus niger, Candida albicans, and Saccharomyces cerevisiae was 0.5, 0.125, and 0.25 mg/mL, respectively. BCNU 1001 was also active against dermatophytic fungi such as Trichophyton mentagrophytes and T. rubrum. Furthermore, BCNU 1001 was also found to be effective against Methicillin-resistant Staphylococcus aureus (MRSA), and its ethyl acetate extract showed MIC = 0.5 mg/mL against MRSA. The most abundant antimicrobial compound was identified as a 2-hydroxybenzyl alcohol through analysis utilizing a nuclear magnetic resonance spectroscopy. This compound was seen to be very effective against some kinds of bacteria and fungi.

Production of Indigoid Pigments by Persolvent Fermentation with Pseudomonas putida BCNU 106

Pseudomonas sp. BCNU 106 isolated from industrial wastewater was able to produce indigo from indole by utilizing various organic solvents. BCNU 106 produced indigo effectively when grown in the presence of a large volume of p-xylene, propylbenzene, and mesitylene and a high level of indole. The present study demonstrated that the maximal yield was achieved with 20% (v/w) p-xylene and 4 g/l indole. Under these conditions, the indigo yield and the transformation efficiency of indole were 315.5 mg/l and 97%, respectively. The results suggest that Pseudomonas sp. BCNU 106 might be a potential candidate for industrially important indigo production.

Involvement of antioxidant defense system in solvent tolerance of Pseudomonas putida BCNU 106

The highly solvent‐tolerant bacterium Pseudomonas sp. BCNU 106 was investigated to elucidate the solvent tolerance under specific culture conditions with the presence of solvents and its adaptive mechanisms to those conditions with reference to the antioxidant system. When exposed to 10% toluene, Pseudomonas sp. BCNU 106 increased the generation of reactive oxygen species assessed by monitoring the oxidation of 2′,7′‐dichlorofluorescein. Typical antioxidant enzymes (viz. catalase, superoxide dismutase, and glutathione reductase) showed increased activity with prolonged incubation in 10% toluene. In addition, the levels of these antioxidant proteins were higher during exposure to 10% toluene than in toluene‐free condition. The present study indicates that antioxidant defense activity is one of the adaptive and protective mechanisms developed to avoid the deleterious damage of organic solvents, especially toluene.

Organic Solvent-tolerant Lipase from Pseudomonas sp. BCNU 154

An organic solvent-tolerant lipase of Pseudomonas sp. BCNU 154 that was isolated from wastewater in the industrial complex region had optimal activity at and pH 8. This crude extracellular lipase from BCNU 154 exhibited maximum stability in toluene, retaining about 6.01 U/ml (117.53%) activity for 2 h. , , , and ions and triton X-100 activated the enzymes, whereas , , and ions inhibited their activity. Pseudomonas sp. BCNU 154 lipase revealed stable activity comparable to that of the commercial immobilized Novozym 435. Thus, this organic solvent-tolerant lipase could have potential as a whole cell biocatalyst in industrial chemical processes without the use of immobilization.

Probiotic Potential of Indigenous Bacillus sp. BCNU 9028 Isolated from Meju

Spore-forming bacteria are being used as probiotic supplements for human and animal use, due to their low pH stability and ability to survive the gastric barrier. In this study, the BCNU 9028 strain was screened from meju, a Korean fermented soybean food starter. Biochemical and physiological characteristics, as well as 16S rDNA sequence analyses, indicate that this strain belongs to the genus Bacillus. Bacillus sp. BCNU 9028 showed a 92% survivability at pH 2.5 and could also withstand 0.3% ox bile. Furthermore, it was postulated that Bacillus sp. BCNU 9028 could prevent biofilm formation and adherence of food-borne pathogens such as Listeria monocytogenes, S. aureus and E. coli on the basis of its autoaggregation and coaggregation capacity with food-borne pathogens. It was shown that BCNU 9028 has good abilities to adhere to the intestinal tract from its hydrophobic character (63.3%). The Bacillus sp. BCNU 9028 strain especially elicited antibacterial activity against both Gram-positive and -negative pathogens. These findings suggested that the Bacillus sp. BCNU 9028 strain could be used as a potential probiotic.

Characterization of Pseudomonas sp. BCNU 171 tolerant to organic solvents.

An organic solvent‐tolerant bacterium, designated as Pseudomonas sp. BCNU 171, was isolated from industrial wastewater in Korea, on the basis of its ability to survive in the presence of benzene, toluene, propylbenzene and xylenes. Its tolerance limits were 8 mM in phenol, 20 mM in benzene and 60 M in toluene. The log P value of phenol was approximately 1.5, which indicates that Pseudomonas sp. BCNU 171 exhibits the highest tolerance to organic solvents. Pseudomonas sp. BCNU 171, a relative of P. putida, P. mosselii and P. moteillii based on phylogenetic analyses using 16S rRNA sequences, was designated as a new sp. that is tolerant to a wide spectrum of organic solvents, especially xylene isomers. These findings may facilitate the understanding of organic solvent tolerance in bacterial cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Improvement in solvent tolerance by exogenous glycerol in Pseudomonas sp. BCNU 106.

Solvent hypertolerant Pseudomonas sp. BCNU 106 still has some underlying growth limitation in solvents. Therefore, efficient mass cultivation methods are needed to pursue its applications in biotechnology. Pseudomonas sp. BCNU 106 was cultured in a medium supplemented with 0·05 mol l−1 glycerol and cell survival was monitored during its cultivation in the presence of 1% (v/v) toluene. Exogenously supplemented glycerol provided more protection against damage caused by toluene stress and conferred higher solvent tolerance of Pseudomonas sp. BCNU 106 to toluene compared to control Pseudomonas sp. BCNU 106 without the supplementation of glycerol. This low‐cost mass cultivation method can be used to efficiently apply solvent‐tolerant bacteria in biotransformation and biodegradation.