J_Environmetal Microbiology and Engineering

Characterization of Phosphate-Solubilizing Bacteria Isolated from
Soil
Ah Ra CHO 1 , Jae Gon KANG 2 , Hoon Seok KANG 2 and Dae Ook KANG* 1
1
Department of Biochemistry and Health Science, Changwon National University,
Changwon 641-773, Korea. 2 J-8
Korea Biochemical Inc., Igok-ri, Munsan-eup, Jinju
660-841, Korea.
*Corresponding author: biochem1@changwon.ac.kr
Bacteria capable of forming halos on Pikovskaya's agar medium were
isolated from soil as an effort to develop microbial agent for the amendment
of inorganic phosphate-accumulated soil. Five bacterial isolates were
finally selected and identified using biochemical and molecular taxonomy.
Four isolates were identified as Acinetobacter calcoaceticus and the one
Pantoea sp. Phosphate-solubization activity gradually increased for 7-day
growth, which was verified by reciprocal decrease in elctronic conductance.
The optimal temperature and initial pH were 30 o C and 5.0 - 6.0,
respectively. The addition of 3% of NaCl had no effect on cell growth.
We selected optimal C-, N-source and inorganic salts. The Pantoea sp.
showed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. We
examined 2D protein expression profies of three isolates between normal
and salt stressed (4% NaCl) culture condition.
Keywords: ACC deaminase, electronic conductance, optimal temperature,
pH, phosphate-solubilizing bacteria,
Laboratory Evaluation of Entomopathogenic Fungi for Control
of Green Peach Aphid Myzus persicae
Van Hanh VU* 1 , Thi Thuy Duong LE 2 , Dinh Thi QUYEN 2 and Keun KIM 3
1
Institute of Biotechnology, Vietnam Academy of Science and Technology, Hanoi
10600, Vietnam/ Department of Bioscience and Biotechnology, The University of
Suwon, Hwaseong-si 445-743, Korea. 2 Institute of Biotechnology, Vietnam
Academy of Science and Technology, Hanoi 10600, Vietnam. 3 J-9
Department of
Bioscience and Biotechnology, The University of Suwon, Hwaseong-si 445-743,
Korea.
*Corresponding author: vvhanh@ibt.ac.vn
Twenty seven entomopathogenic fungal strains were isolated from
various infected aphids. One fungus exhibited the highest virulence
towards green peach aphids, Myzus persicae. The isolate conformed most
closely to Lecanicillium sp. based on the sequence of internal transcribed
spacer region of its 28S rDNA, and thus was designated as Lecanicillium
sp. Le85. The laboratory bioassay for the aerial conidia of Le85 was
performed for the control of M. persicae. After six days of application
with 1×10 8 aerial conidia/ml, at 20~25 o C and relative humidity of 75~85%,
the mortality of aphid by Le85 was about 97% with LT50 of 3.2 days.
Meanwhile, at 26~31 o C and relative humidity of 60~70%, the evaluations
of Le85 on potted cabbages showed an aphid mortality ranging from 82
to 95%. Significant conidiation was observed on the aphid cadavers
infected with Le85. Undoubtedly, the results suggest that Le85 can be
used as a biocontrol agent for aphid M. persicae on cabbages in
greenhouses.
Keywords: Myzus persicae, entomopathogenic fungi, Lecanicillium sp.,
398 www.kormb.or.kr
Glucose Utilization and Electricity Generation Using Genetically
Modified Shewanella Strains
DongGeon CHOI 1 , Sae Bom LEE 1 , In Geol CHOI 2 and In Seop CHANG* 1
1
School of Environmental Science and Engineering, Gwangju Institute of Science
and Technology(GIST), 261 Cheomdan gwagi-ro, Buk-gu, Gwangju 500-712,
Korea. 2 J-10
College of Life Science and Biotechnology, Korea University, Anam-dong,
Sungbuk-gu, Seoul 136-701, Korea.
*Corresponding author: ischang@gist.ac.kr
Genomic sequence analyses of Shewanella strains have been studied
for carbon metabolism as well as their physiological characteristics. Even
though Shewanella strains seem to have glycolysis pathways and enzymes
as central carbon metabolism, several key enzymes are missing.
Shewanella strains also have only one set of phosphotransferase system
to uptake simple sugar like glucose through the membrane. So, it is unclear
that Shewanella strains can utilize six-carbon carbohydrates (e.g. glucose)
as carbon and energy source. In this study, Shewanella oneidensis MR-1
was metabolically engineered to have the ability of glucose uptake and
utilization as carbon and energy source. Glucokinase (glk) and
glucose-facilitated diffusion protein (glf) of Zymomonas mobilis were
cloned into a broad host range plasmid and introduced to S. oneidensis
MR-1 to help glucose uptake and utilization. This recombinant Shewanella
strain was used for single cell based MFC system in order to confirm
the glucose utilization and concomitant with current production. The
results indicated that cloned genes (glf and glk) were functional for glucose
utilization in S. oneidensis MR-1 wild type. We also found that this
modification was effective to two Shewanella strains, S. putrefaciens
CN-32 and S. loihica PV-4.
Keywords: Shewanella, Glucose, Electricity
Investigation of Candidate Strains for Application of Microbial
Electrosynthesis
Saebom LEE 1 , Dong Geon CHOI 1 , In Geol CHOI 2 and In Seop CHANG* 1
1
School of Environmental Science and Engineering, Gwangju Institute of Science
and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712,
Korea. 2 J-11
College of Life Sciences and Biotechnology, Korea University,
Anam-dong, Sungbuk-ku, Seoul 136-701, Korea.
*Corresponding author: ischang@gist.ac.kr
Reducing power which is obtained from microbial metabolism is used
to produce several valuable chemicals such as ethanol, butanol, and acetate.
Microbial electrosynthesis is a system that produces chemicals using
electron. In microbial electrosynthesis, electrons supplied from electrode
are accumulated to inner cell and are used to produce the reducing power.
The accumulated reducing power can be used to produce chemicals.
Geobacter and Shewanella strains, which are well known as metal reducing
bacteria, can deliver electrons to outer metal ions through the arrangement
of cytochrome C protein in the cell membrane. Recently, as reverse
electron flow of Shewanella strain was revealed, it was known to move
outer electrons to inside through cytochrome C protein. Based on this
point, we selected candidate strains which have cytochrome C protein
in the cell membrane and can produce valuable chemicals though microbial
reaction. We finally selected Carboxydothermus hydrogenoformans strain
Z-2901 and Dethiobacter alkaliphilus AHT 1 which have cytochrome C
protein in extracellular and are able to produce valuable chemicals. Two
candidate strains will be used for microbial electrosynthesis.
Keywords: Microbial electrosynthesis; Reverse electron flow