Hyoun-Young Kim

Degradation of 2,4,6-trinitrotoluene by Klebsiella sp. isolated from activated sludge

Klebsiella sp. strain C1 isolated from activated sludge metabolized 2,4,6-trinitrotoluene (TNT) by two different pathways. The typical metabolites in the nitro group reduction pathway of TNT, such as hydroxylamino-dinitrotoluenes and amino-dinitrotoluenes, were detected. Dinitrotoluenes and nitrite were also detected, possibly produced by a denitration pathway. After incubation of [U-14C]TNT for 28 and 77 d, 2.4 and 6.24%, respectively, were released as 14CO2. This mineralization rate was higher than those reported by any other TNT degrading bacteria and might be due to the dual pathways of degradation in this bacterium.

Comparison of 2,4,6-trinitrotoluene degradation by seven strains of white rot fungi.

The degradation of 2,4,6-trinitrotoluene (TNT) by seven strains of white rot fungi was examined in two different media containing 50 mg L−1 of TNT. When TNT was added into a nutrient-rich YMG medium at the beginning of the incubation, four of the fungal strains completely removed TNT during several days of incubation and showed higher removal rates than those of Phanerochaete chrysosporium. TNT added into YMG medium after a 5-day preincubation period completely disappeared within 12 hours, and the removal rates were higher than those in N-limited minimal medium. Isomers of hydroxylamino-dinitrotoluene were identified as the first detectable metabolites of TNT. These were transformed to amino-dinitrotoluenes, which also disappeared during further incubation from cultures of Irpex lacteus. During the initial phase of TNT degradation by I. lacteus, dinitrotoluenes were also detected after the transient formation of a hydride-Meisenheimer complex, indicating that I. lacteus used two different pathways of TNT degradation simultaneously.

Gene Structure and Function of fkhE, a Forkhead Gene in a Filamentous Fungus Aspergillus nidulans

Department of Pharmaceutical Engineering, Woosuk University, Wanju, 565-701, Republic of Korea (Received December 13, 2010. Accepted December 21, 2010)ABSTRACT: A homothallic filamentous fungus Aspergillus nidulans has been used as the a model organism forstudying growth and development for eukaryotic system. Various studies about specific transcription factors havebeen performed for elucidating the molecular mechanisms of growth, asexual and sexual developmental processes.Among them, the fkhE gene (AN2025.3) is located in chromosome VII and contains an ORF encoding 718 aminoacid polypeptide intervening with two short introns. The cDNA sequencing revealed that at least four types of alter-native splicing events were occurred when the fkhE gene was transcribed. The putative FkhE polypeptide containsa conserved forkhead domain and a bipartite nuclear localization signal at its N-terminus and C-terminus, respec-tively. Deletion of fkhE resulted in impaired conidiophore formation in a solid medium. However, the sexual devel-opmental process or cleistothecia formation was normal. Furthermore, fkhE deletion mutant produced conidiophoresand conidia under the submerged culture, indicating that the fkhE gene is involved in asexual developmental processsimilar to the fkhF gene.KEYWORDS :

Expression and Cloning of Microbial Transglutaminase in S. cerevisiae

A microbial transglutaminase (mTGase) from the actinomycete Streptomyces mobaraensis IFO13819 is a useful enzyme in the food industry. It is consists 406 amino acid residues, which comprised leader and pro region of 75 amino acid residues and the structure region of 331 amino acid residues. Pro and structure gene of TGase were cloned into the yeast shuttle vector pYAEG-TER and then used to transform Saccharomyces cerevisiae 2805. Expression of mTGase in recombinant was confirmed with Northern hybridization and the maximal activity of TGase was shown 26 mU/ml.