Journal of Microbiology

In-Koo Rhee

6 Articles

Gibberellins-Producing Rhizobacteria Increase Endogenous Gibberellins Content and Promote Growth of Red Peppers: Gil-Jae Joo , Young-Mog Kim , Jung-Tae Kim , In-Koo Rhee , Jin-Ho Kim , In-Jung Lee; J. Microbiol. 2005;43(6):510-515.; DOI: https://doi.org/2297 [pii]

Abstract PDF: The growth of red pepper plants was enhanced by treatment with the rhizobacterium, Bacillus cereus MJ-1. Red pepper shoots showed a 1.38-fold increase in fresh weight (fw) and roots showed a 1.28-fold fw gain. This plant growth-promoting rhizobacterium (PGPR) has been reported to produce gibberellins (GAs). Other GAs-producing rhizobacteria, Bacillus macroides CJ-29 and Bacillus pumilus CJ-69, also enhanced the fw of the plants. They were less effective than B. cereus MJ-1, though. The endogenous GAs content of pepper shoots inoculated with MJ-1 was also higher than in shoots inoculated with CJ-29 or CJ-69. When inoculated with MJ-1, bacterial colonization rate of the roots was higher than that of roots inoculated with CJ-29 or CJ-69. These results support the idea that the plant growth-promoting effect of the bacteria also positively related with the efficiency of root colonization by the bacteria. In addition, we identified the major endogenous GAs of the red pepper as originating from both the early C-13 hydroxylation and the early non C-13 hydroxylation pathways, with the latter being the predominant pathway of GA biosynthesis in red pepper shoots.

Molecular Cloning and Expression of a Thermostable Xylose (Glucose) Isomerase Gene, xylA, from Streptomyces chibaensis J-59: Gil-Jae Joo , Jae-Ho Shin , Gun-Young Heo , Young-Mog Kim , In-Koo Rhee; J. Microbiol. 2005;43(1):34-37.; DOI: https://doi.org/2141 [pii]

Abstract PDF: In the present study, the xylA gene encoding a thermostable xylose (glucose) isomerase was cloned from Streptomyces chibaensis J-59. The open reading frame of xylA (1167 bp) encoded a protein of 388 amino acids with a calculated molecular mass of about 43 kDa. The XylA showed high sequence homology (92% identity) with that of S. olivochromogenes. The xylose (glucose) isomerase was expressed in Escherichia coli and purified. The purified recombinant XylA had an apparent molecular mass of 45 kDa, which corresponds to the molecular mass calculated from the deduced amino acid and that of the purified wild-type enzyme. The N-terminal sequences (14 amino acid residues) of the purified protein revealed that the sequences were identical to that deduced from the DNA sequence of the xylA gene. The optimum temperature of the purified enzyme was 85oC and the enzyme exhibited a high level of heat stability.

Chlorothalonil-Biotransformation by Glutathione S-Transferase of Escherichia coli: Young-Mog Kim , Kunbawui Park , Soon-Hyun Jung , Jun-Ho Choi , Won-Chan Kim , Gil-Jae Joo , In-Koo Rhee; J. Microbiol. 2004;42(1):42-46.; DOI: https://doi.org/2002 [pii]

Abstract PDF: It has recently been reported that one of the most important factors of yeast resistance to the fungicide chlorothalonil is the glutathione contents and the catalytic efficiency of glutathione S-transferase (GST) (Shin et al., 2003). GST is known to catalyze the conjugation of glutathione to a wide variety of xenobiotics, resulting in detoxification. In an attempt to elucidate the relation between chlorothalonil detoxification and GST, the GST of Escherichia coli was expressed and purified. The drug hypersensitive E. coli KAM3 cells harboring a plasmid for the overexpression of the GST gene can grow in the presence of chlorothalonil. The purified GST showed chlorothalonil-biotransformation activity in the presence of glutathione. Thus, chlorothalonil is detoxified by the mechanism of glutathione conjugation catalyzed by GST.

Degradation of Cholesterol by Bacillus subtilis SFF34 in Flatfish during Fermentation: Kwan-Pil Kim , In-Koo Rhee , Heui-Dong Park; J. Microbiol. 2003;41(4):284-288.

Abstract PDF: Bacillus subtilis SFF34 degrading cholesterol was applied to reduce residual cholesterol content in fermented flatfish. When the bacterial cells were inoculated as a start culture, a maximal level (1.7 U/g) of cholesterol oxidase was obtained after 10 days, which was two times higher than that (0.8 U/g) without inoculation. Residual cholesterol contents with and without inoculation of the cells were 0.5 mg/g and 0.8 mg/g after 12 days of fermentation, respectively. Cholesterol derivatives including cholesterol- 5?, 6?-epoxide, 4-cholesten-3-one and 7?-hydroxycholesterol were detected in raw flatfish as well as fermented flatfish. Campesterol and 25-hydroxycholesterol were detected only after fermentation. However, no significant differences in their contents were observed regardless of inoculation.

Resistance of Saccharomyces cerevisiae to Fungicide Chlorothalonil: Jae-Ho Shin , Young-Mog Kim , Jong-Woo Park , Jang-Eok Kim , In-Koo Rhee; J. Microbiol. 2003;41(3):219-223.

Abstract PDF: The toxicity of chlorothalonil on the growth of yeasts was investigated using several yeast strains. An alcohol tolerant yeast, Saccharomyces cerevisiae F38-1, was the most chlorothalonil-tolerant. The glutathione content and the glutathione S-transferase activity were related to the chlorothalonil-tolerant phenotype. Several thiol compounds affect the dissipation of chlorothalonil. However, there was no significant difference on the effects of chlorothalonil dissipation among the thiol compounds tested. The growth of yeast cells was arrested by chlorothalonil. It took about 13 h to dissipate 1 mg/l of chlorothalonil, and the growth was restored as the chlorothalonil content decreased. The glutathione content and glutathione S-transferase are suggested to be among the most important factors of yeast resistance to chlorothalonil.

Characteristics of Na^+ -dependent Serine Transport in Haemophilus Influenzae Rd: Young-Mog Kim , In-Koo Rhee , Mi-Yeon Park , Dong-Suck Chang , Tomofusa Tsuchiya; J. Microbiol. 2003;41(2):78-82.

Abstract PDF: We identified two proteins in Haemophilus influenzae Rd that exhibited high similarity to two major serine transporters of Escherichia coli (SstT and SdaC). Then, we investigated serine transport in H. influenzae Rd and detected Na + -stimulated L-serine transport activity. The optimum NaCl concentration for this stimulation was about 20 mM. The uptake of Na^+ by H. influenzae Rd was found to be elicited by L-serine influx, which supports the idea that L-serine is transported by a mechanism of Na^+ / serine symport. No uptake of H + elicited by L-serine influx was detected. Na^+ /serine symport activity was not inhibited by other amino acids such as L-threonine or D-serine. Two distinct Km values were obtained from the kinetic analysis of serine transport. Thus, two serine transport pathways may exist in H. influenzae Rd, and it appears that both systems are stimulated by Na^+ .

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