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Detailed Mode of Action of Arabinan-Debranching α-ʟ-Arabinofuranosidase GH51 from Bacillus velezensis

  • Oh, Gyo Won;Kang, Yewon;Choi, Chang-Yun;Kang, So-Yeong;Kang, Jung-Hyun;Lee, Min-Jae;Han, Nam Soo;Kim, Tae-Jip
    • Journal of Microbiology and Biotechnology
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    • v.29 no.1
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    • pp.37-43
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    • 2019

  • The gene encoding an ${\alpha}-{\text\tiny{L}}-arabinofuranosidase$ (BvAF) GH51 from Bacillus velezensis FZB42 was cloned and expressed in Escherichia coli. The corresponding open reading frame consists of 1,491 nucleotides which encode 496 amino acids with the molecular mass of 56.9 kDa. BvAF showed the highest activity against sugar beet (branched) arabinan in 50 mM sodium acetate buffer (pH 6.0) at $45^{\circ}C$. However, it could hardly hydrolyze debranched arabinan and arabinoxylans. The time-course hydrolyses of branched arabinan and arabinooligosaccharides (AOS) revealed that BvAF is a unique exo-hydrolase producing exclusively ${\text\tiny{L}}-arabinose$. BvAF could cleave ${\alpha}-(1,2)-$ and/or ${\alpha}-(1,3)-{\text\tiny{L}}-arabinofuranosidic$ linkages of the branched substrates to produce the debranched forms of arabinan and AOS. Although the excessive amount of BvAF could liberate ${\text\tiny{L}}-arabinose$ from linear AOS, it was extremely lower than that on branched AOS. In conclusion, BvAF is the arabinan-specific exo-acting ${\alpha}-{\text\tiny{L}}-arabinofuranosidase$ possessing high debranching activity towards ${\alpha}-(1,2)-$ and/or ${\alpha}-(1,3)-linked$ branches of arabinan, which can facilitate the successive degradation of arabinan by $endo-{\alpha}-(1,5)-{\text\tiny{L}}-arabinanase$.

  • https://doi.org/10.4014/jmb.1807.11035 인용 PDF KSCI

Failure of Ciprofloxacin Therapy in the Treatment of Community-Acquired Acute Pyelonephritis caused by In-Vitro Susceptible Escherichia coli Strain Producing CTX-Type Extended-Spectrum β-Lactamase

  • Seok, Hyeri;Cha, Min Kyeong;Kang, Cheol-In;Cho, Sun Young;Kim, So Hyun;Ha, Young Eun;Chung, Doo Ryeon;Peck, Kyong Ran;Song, Jae-Hoon
    • Infection and chemotherapy
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    • v.50 no.4
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    • pp.357-361
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    • 2018

  • While carbapenems are the drug of choice to treat extended-spectrum-${\beta}$-lactamase (ESBL)-producing strains, some alternative carbapenem-sparing regimens are suggested for antibiotic stewardship. We experienced a case of ciprofloxacin treatment failure for acute pyelonephritis caused by an apparently susceptible Escherichia coli. A 71-year-old woman presented the emergency department with fever for 7 days and bilateral flank pain for 2 days. The laboratory results and abdominopelvic computed tomography finding were compatible with acute pyelonephritis. During 3-day ciprofloxacin therapy, the patient remained febrile with persistent bacteremia. After the change in antibiotics to ertapenem, the patient's clinical course started to improve. ESBL-producing E. coli isolates were identified in all three consecutive blood samples. Pulsed-field gel electrophoresis (PFGE) patterns, serotypes, and sequence types showed the three isolates were derived from the identical strain. The isolates produced CTX-M-14 type ESBL belonging to the ST69 clonal group. Despite in vitro susceptibility, the failure was attributed to a gyrA point mutation encoding Ser83Leu within quinolone resistance-determining regions. This case suggests that ciprofloxacin should be used cautiously in the treatment of serious infections caused by ciprofloxacin-susceptible, ESBL-producing E. coli, even in acute pyelonephritis because in-vitro susceptibility tests could fail to detect certain genetic mutations.

  • https://doi.org/10.3947/ic.2018.50.4.357 인용 KSCI

STUDY ON X-RAYS AND NEUTRONS LEAKED FROM A 45 MeV ELECTRON LINAC FACILITY

  • Sawamura, Sadashi;Kitaichi, Masatoshi;Nojiri, Ichiro;Yamada, Takuma;Kaneko, Junichi;Sawamura, Teruko
    • Journal of Radiation Protection and Research
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    • v.26 no.3
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    • pp.133-137
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    • 2001

  • Spatial and time distributions of x-rays and neutrons from Hokkaido University 45 MeV electron linac facility were measured and compared with the calculation. In the calculation, x-rays in a Pb-target were evaluated using the EGS-code. The x-rays and the neutrons from the target to the facility building boundary and skyshine process outside the facility building were simulated with the EGS and the MCNP respectively.

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