J_Environmetal Microbiology and Engineering

Thermodynamic and Kinetic Analyses of the Binding of a Bacterial
Expansin (BsEXLX1) to Plant Cell Wall Components
Injung KIM 2 , Hyeok-Jin KO 2 , In-Geol CHOI 2 , Douglas S. CLARK 3 ,
Tae-Wan KIM 3 and Kyoung Heon KIM* 1
1
School of Life Sciences and Biotechnology, Korea University, Seoul 136-713,
Korea. 2 Biotechnology, Korea University, Seoul 136-713, Korea. 3 J-16
Energy
Biosciences Institute, Department of Chemical &Biomolecular Engineering,
University of California, Berkeley, CA, 94720, USA.
*Corresponding author: khekim@korea.ac.kr
BsEXLX1 is a protein belonging to expansin family, found in a soil
bacterium, Bacillus subtilis, and was previously shown to possess the
synergistic activity with cellulase on the cellulose hydrolysis. In this study,
binding characteristics of BsEXLX1 to plant cell wall components were
thermodynamically and kinetically investigated. At 4°C, the values of
binding constants, such as Ka and [No], obtained from Langmuir isotherm
were 6.73´10 6 M -1 and 54 nmol/g cellulose, respectively. Also, the binding
of BsEXLX1 to cellulose was found to be an endothermic but spontaneous
reaction (∆Gº=-36.2 kJmol -1 and ∆Hº=57 kJmol -1 ). Generally, the
BsEXLX1 exhibited an enhanced binding efficiency under acidic
conditions. Also, the amount of bound protein increased in the presence
of NaCl. Against cellopentaose and cellohexaose, the binding activity of
BsEXLX1 was negligible in the isothermal titration calorimetry. Against
the pretreated lignocellulosic biomass with different compositions of
cellulose, hemicelluloses and lignin, the preferential binding of BsEXLX1
to lignin was observed. This finding could be applicable in cellulose-based
pulp and textile industries or biofuel production for using the bacterial
expansin as a non-blocking agent to enhance the accessibility of cellulose
to enzymes.
Keywords: Bacterial expansin, Cellulose, Lignocellulose
Screening of an Esterase/lipase-Producing Bacteria from
Gastropods
Jung-Hee WOO* 1 , Sun Mee HONG 1 , Jun-Tae KIM 1 , Tae-Hyung KWON 1 ,
Hyun-Soo RHO 2 , Jong-Shik KIM 1 , Nyun-Ho PARK 1 and
Choong-Gon KIM 1
1
1Gyeongbuk Institute for Marine Bio-Industry (GIMB), Uljin 767-813,
Gyeongbuk, Korea. 2 J-17
2East Sea Research Institute, Korea Ocean Research
&Development Institute (KORDI), Uljin 767-813, Gyeongbuk, Korea.
*Corresponding author: jhwoo@gimb.or.kr
Esterases and lipases are enzymes that catalyze the hydrolysis of
carboxyl esters and are found in various organisms including animals,
plants, fungi and bacteria. These enzymes have increased the
biotechnological interest for a number of industrially significant
biotransformations, either as hydrolytic or as synthetic catalysts.
Previously we reported that bacteria isolated 127 strains from six
gastropods F. oregonensis, N. cumingi, N. constricta, C. fulmen, V.
emphaticus, JG in June to December 2010 were studied to find out the
bacterial assemblages associated with local gastropod collected in Uljin,
the East Sea, Korea. Esterase/lipase-producing bacteria were isolated from
gastropods. To screen for lipolytic activity, various agar medium
supplemented with 1% tributyrin (TBN) and tricaprylin (TCN) were used.
We found that 56 isolates showed lipolytic activity on TBN agar plate
and 22 isolates showed lipolytic activity on TCN agar plate
(esterase-producing strains= 34, lipase-producing strains= 22). This study
presents a first example which discovered esterases/lipases from
gastropods successfully. [This work was supported by the Marine and
Extreme Genome Research Center Program, Ministry of Land, Transport
and Maritime Affairs, Republic of Korea.]
400 www.kormb.or.kr
J-18
Survival of Escherichia coli O157:H7 and Listeria in Manure
Compost in Korea
Sook Young JANG, Sunggi HEU, Eunjung ROH, Dong Hwan LEE,
Yang Kyun KIM, Mukesh KUMAR, Shweta MALHOTRA, Jong Chul YUN
and Kyu Seok JUNG*
Microbial Safety Division, National Academy of Agricultural Science, RDA,
Suwon, 441-707, Korea.
*Corresponding author: win258@korea.kr
On-farm contaminations through contaminated manure were considered
likely sources of the pathogen for several outbreak. Of particular concern
are bacteria causing human food-borne illness such as Salmonella species
and E. coli O157:H7. The objective of this study was to quantify the
level of environmental impact of temperature on E. coli O157:H7 and
Listeria survival in manure compost. Commercial manure compost
(manure 60%, sawdust 40%) was inoculated with E. coli O157:H7 and
Listeria. Composts were incubated at four different temperature (10, 25,
35, and 55℃) and consistent moisture content (55%). Samples had been
collected during 49 days depending on the given conditions. E. coli
O157:H7 and Listeria persisted for up to 1 day in compost at 55℃ and
49 days at three different temperature (10, 25 and 35℃). It is noted that
as the temperature increased, the number of E. coli O157:H7 and Listeria
gradually decreased over time. The results indicate that E. coli O157:H7
and Listeria persisted longer under low temperature condition. This study
will provide useful and practical guidelines to applicators of soil in
deciding appropriate handling and time frames for land application for
sustainable agriculture.
Keywords: E. coli O157:H7, Listeria, survival
Microbiological Safety of Gamma-Irradiated Porcine Skin for
the Development of Dressing Material
Jong-Il CHOI 1 , Eu-Ri JO 1 , Pil-Mun JUNG 1 , Jae-Hun KIM 1 ,
Beom-Suk SONG 1 , Jae-Kyung KIM 1 , Jong-Heum PARK 1 , Tae-Woon KIM 2
and Ju-Woon LEE* 1
J-19
1
Team for Radiation Food Science and Biotechnology,Advanced Radiation
Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185.
2
Rion-Biotechnology Co.,wanju-gun 565-902, Korea.
*Corresponding author: sjwlee@kaeri.re.kr
In this study, sensitivities of bacteria and virus in porcine skin by gamma
irradiation were evaluated to develope the optimum sterilization condition
for the development of dressing material. Escherichiacoli (E.coli) and
Bacillus substilis (B. substilis) were used as model pathogens and
inoculated 106-107log CFU/g. As model virus from porcine, porcine
parvovirus (PPV), bovine viral diarrhoea virus (BVDV) and poliovirus
were inoculated 105-106TCID50/g into porcine skin. The D10 value of
E.coli was determined as 0.25±0.1 kGy. B. substilis showed lower
radiation sensitivity as D10 was 3.88±0.3 kGy. The D10 values of PPV,
BVDV and poliovirus were determined as 1.73±0.2, 3.81±0.2 and 6.88±0.3
kGy, respectively. These results suggest that gamma irradiation can reduce
the risk of contamination and offer the basic information to inactivate
the pathogens as microbiologically safe dressing material of porcine skin.
Keywords: radiation sensitivity, bacteria and virus, porcine skin