• 약학회지
• /
• 제37권2호
• /
• pp.187-192
• /
• 1993

Approximately 1% of intestinal bacteria of human and rats was alkalotolerant. Among these bacteria of human, bacteria producing $\beta$-glucosidase, $\beta$-glucuronidase and sulfotransferase were 40%, 4% and 0%, respectively. Among alkalotolerant intestinal bacteria of rats, bacteria producing, these enzymes were 70%, 8% and 0%, respectively. $\beta$-Glucosidase and $\beta$-glucuronidase of alkalotolerant intestinal bacteria of human and rat were induced by the medium of high pH: these enzymes activities were increased by elevating pH of the medium, but the growths were not changed. The enzyme activities at the medium of pH 7 were about ten-fold higher than those at the medium of pH 6.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권4호
• /
• pp.367-371
• /
• 2005

About 3,000 bacterial colonies with esterase activities were isolated from soil samples by enrichment culture and halo-size on Luria broth-tributyrin (LT) plates. The colonies were assayed for esterase activity in microtiter plates using enantiomerically pure (R)- and (S)-2-phenylbutyric acid resorufin ester (2PB-O-res) as substrates. Two enantioselective strains (JH2 and JH13) were selected by the ratio of initial rate of hydrolysis of enantiomerically pure (R)- and (S)-2-PB-O-res. When cell pellets were used, both strains showed high apparent enantioselectivity ($E_{app}>100$) for (R)-2PB-O-res and were identified as Exiguobacterium acetylicum. The JH13 strain showed high esterase activity on p-nitrophenyl acetate (pNPA), but showed low lipase activity on p-nitrophenyl palmitate (pNPP). The esterase was located in the soluble fraction of the cell extract. The crude intracellular enzyme preparation was stable at a pH range from 6.0 to 11.0.

• 한국미생물·생명공학회지
• /
• 제23권3호
• /
• pp.304-310
• /
• 1995

A thermophilic bacterium producing the extracellular cellulase-free xylanase was isolated from soil and has been identified as Bacillus sp. The optimal growth temperature was 50$\circ$C and the optimal pH, 7.0. Under the optimal growth condition, maximal xylanase production was 2.2 units/ml in the flask culture. The enzyme production was induced by xylan and xylose, but was repressed by sucrose or trehalose. The partially purified xylanase was most active at 70$\circ$C. It was found that the enzyme was stable at 65$\circ$C for 10 hours with over 75% of the activity. The enzyme was most active at pH 7.0 and retained 90% of its maximum activity between pH 5.0 and pH 9.0 though Bacillus sp. was not grown on alkaline conditions (>pH 8.0). In addition, the activity of xylanase was over 60% at pH 10.0. At the ambient temperature, the enzyme was stable over a pH range of 5.0 to 9.0 for 10 h, indicating that the enzyme is thermostable and alkalotolerant. The activity of xylanase was completely inhibited by metal ions including Hg$^{2+}$ and Fe$^{2+}$, while EDTA, phenylmethylsulfonyl fluoride (PMSF), $\beta$-mercaptoethanol and SDS didn't affect its activity. The enzyme was also identified to exert no activity on carboxymethylcellulose, laminarin, galactomannan, and soluble starch.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제17권1호
• /
• pp.47-54
• /
• 2012

When quicklime is added into soil for various purposes, abrupt changes in soil chemistry may affect essential ecological functions played by indigenous bacterial communities in soil. The magnitude of influence was estimated by observing changes in abundance and diversity of soil bacteria after quicklime treatment. When several soil samples were treated up to 20% (w/w) quicklime, plate count of viable cells ranged $10^2{\sim}10^3$ CFU $g^{-1}$, showing a reduction of more than $10^4$ times from viable counts of the untreated sample. Diversity of the bacterial isolates that survived after quicklime treatment was analyzed by conducting $GTG_5$ rep-PCR fingerprinting. There were only two types of fingerprints common to both 5% and 20% quicklime samples, implying that bacteria surviving at different strength of quicklime treatment differed depending on their tolerance to quicklime-treated condition. Isolates surviving the quicklime treatments were further characterized by Gram staining and endospore staining. All isolates were found to be Gram positive bacteria, and 85.4% of them displayed endospores state. In conclusion, most bacteria surviving quicklime treatment appear to be endospores. This finding suggests that most of ecological functions of bacteria in soil are lost with quicklime treatment.

• 자연과학논문집
• /
• 제16권1호
• /
• pp.15-29
• /
• 2005

내열성의 cyclomaltodextrin glucanotransferase (CGTase)를 이용하여 열에 안정한 싸이클린 텍스트린 (CD)을 생산하기 위하여 매우 높은 CGTase 활성을 보이는 고열성이며 호알카리성인 B-13세균을 분리하여 형태적, 생리학적 특성과 16S 리보솜 RNA 서열분석 등을 통하여 Bacillus cereus B-13으로 동정하였다. Bacillus cereus B-13 2% 가용성 전분, 1% 효모 추출물, 1% $Na_2CO_3$ 등을 함유하는 SYC 배지 (pH 8.5)에 접종하여 $50^{\circ}C$에서 24시간 배양하였을 때 최고의 CGTase 활성(130 U/ml)을 보였다. 또한 부분 정제된 CGTase의 작용 최적 온도와 pH는 각각 $60^{\circ}C$, pH 8.5-9.0 이었고 $80^{\circ}C$이하와 pH5.0-10.0에서 안정하였다. 1% 가용성 전분을 부분 정제한 CGTase와 작용시켰을 때 49%의 CD 수율을 보였다.