• 환경생물
• /
• 제21권4호
• /
• pp.358-365
• /
• 2003

A bacterial strain capable of producing a novel bioflocculant was isolated from a biofilm sample and identified as Bacillus megaterium G31. The highest biopolymer yield was achieved when the organism was cultivated in a medium containing acetate as the sole carbon source and ($NH_4)_2HPO_4$as the nitrogen source. In kaolin suspension, the flocculating activity was highest at 170 mg I$^{-1}$ and decreased at the higher bioflocculant concentrations. The crude bioflocculant produced by the organism was purified by ethanol precipitation and gel permeation chromatography. The FTIR spectrum of the purified bioflocculant revealed that the bioflocculant might be a heterogeneous polysaccharide composed of hexosamines and neutral sugars. The analysis of sugar components of the bioflocculant using high performance anion-exchange chromatography showed that the sugar constituents of the bioflocculant were glucosamine, fucose, galactosamine, galactose, glucose, mannose in approximate molar ratio of 4 : 1 : 6 : 3 : 8 : 19. Its flocculating activity was stimulated by various cations. The bioflocculant was thermo-stable and retained 64% of its original activity after heating at $100^{\circ}C$ for 50 min.

• 미생물학회지
• /
• 제36권3호
• /
• pp.167-172
• /
• 2000

제주도의 여섯 지역과 인천 작약도 근해의 해수로부터 내염성 그람양성 세균 25균주를 분리하여 화학 분류학적 특징과 표현형적 특성을 조사하였다. 분리된 균주들은 화학 분류학적 특징에 의거하여 4개의 group으로 구분되었다. Group1은 40.~49.9 mol% 의 G+C함량과 MK-7의 menaquinome type, peptidoglycan의 주요 아미노산으로 meso-A2pm을 함유하며 Bacillus pumilus와 Bacillus licheniformis, Bacillu megaterium, bacillus subtilis로 동정되었으며, Group 2는 63.9~66.4 mol% 의 G+C 함량과 MK-8을 함유하는 Arthrobacter속 세균이었으며 , Group 3은 31.0~37.6 mol%의 G+G 함량과 MK-7을 함유하며 Staphylococcus haemolyticus, Staphylococcus saprophyticyus, Staphylococcus intermedius 로 , Group 4는 72.0 mol% 의 G+C 함량과 MK-8을 주요 quinone으로 함유하는 Micrococcus luteus로 동정되었다. 분리된 세균들 중 Bacillus 속 세균들은 68%로 우세한 분포를 나타내었다.

• Journal of Microbiology and Biotechnology
• /
• 제25권11호
• /
• pp.1810-1818
• /
• 2015

For the synthesis of various pharmaceuticals, chiral alcohols are useful intermediates. Among them, (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB) is an important building block for the synthesis of L-carnitine. (R)-ECHB is produced from ethyl-4-chloro-3-oxobutanoate (ECOB) by a reductase-mediated, enantioselective reduction reaction. The Saccharomyces cerevisiae YOL151W reductase that is expressed in Escherichia coli cells exhibited an enantioselective reduction reaction toward ECOB. By virtue of the C-terminal His-tag, the YOL151W reductase was purified from the cell-free extract using Ni²⁺-NTA column chromatography and immobilized onto Ni²⁺-magnetic microparticles. The physical properties of the immobilized reductase (Imm-Red) were measured using electron microscopy, a magnetic property measurement system, and a zeta potential system; the average size of the particles was approximately 1 μm and the saturated magnetic value was 31.76 emu/g. A neodymium magnet was used to recover the immobilized enzyme within 2 min. The Imm-Red showed an optimum temperature at 45℃ and an optimum pH at 6.0. In addition, Bacillus megaterium glucose dehydrogenase (GDH) was produced in the E. coli cells and was used in the coupling reaction to regenerate the NADPH cofactor. The reduction/oxidation coupling reaction composed of the Imm-Red and GDH converted 20 mM ECOB exclusively into (R)-ECHB with an e.e._p value of 98%.

• Journal of Microbiology
• /
• 제42권4호
• /
• pp.285-291
• /
• 2004

The soil bacterial community and some inoculated bacteria were monitored to assess the microbial responses to prescribed fire in their microcosm. An acridine orange direct count of the bacteria in the unburned control soil were maintained at a relatively stable level $(2.0\~2.7\times10^9\;cells/g^{-1}{\cdot}soil)$ during the 180 day study period. The number of bacteria in the surface soil was decreased by fire, but was restored after 3 months. Inoculation of some bacteria increased the number of inoculated bacteria sev­eral times and these elevated levels lasted several months. The ratios of eubacteria detected by a flu­orescent in situ hybridization (FISH) method to direct bacterial count were in the range of $60\~80\%$ during the study period, with the exception of some lower values at the beginning, but there were no definite differences between the burned and unburned soils or the inoculated and uninoculated soils. In the unburned control soil, the ratios of $\alpha-,\beta-\;and\;\gamma-subgroups$ of the proteobacteria, Cytophaga-Fla­vobacterium and other eubacteria groups to that of the entire eubacteria were 13.7, 31.7, 17.1, 16.8 and $20.8\%,$ respectively, at time 0. The overall change on the patterns of the ratios of the 5 subgroups of eubacteria in the uninoculated burned and inoculated soils were similar to those of the unburned con­trol soil, with the exception of some minor variations during the initial period. The proportions of each group of eubacteria became similar in the different microcosms after 6 months, which may indicate the recovery of the original soil microbial community structure after fire or the inoculation of some bac­teria. The populations of Azotobacter vinelandii, Bacillus megaterium and Pseudomonas fluorescens, which had been inoculated to enhance the microbial activities, and monitored by FISH method, showed similar changes in the microcosms, and maintained high levels for several months.