• Journal of Life Science
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• v.22 no.10
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• pp.1295-1306
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• 2012

A microorganism producing carboxymethylcellulase (CMCase) was isolated from seawater and identified as Bacillus atrophaeus. This species was designated as B. atrophaeus LBH-18 based on its evolutionary distance and the phylogenetic tree resulting from 16S rDNA sequencing and the neighbor-joining method. The optimal conditions for rice bran (68.1 g/l), peptone (9.1 g/l), and initial pH (7.0) of the medium for cell growth was determined by Design Expert Software based on the response surface method; conditions for production of CMCase were 55.2 g/l, 6.6 g/l, and 7.1, respectively. The optimal temperature for cell growth and the production of CMCase by B. atrophaeus LBH-18 was $30^{\circ}C$. The optimal conditions of agitation speed and aeration rate for cell growth in a 7-l bioreactor were 324 rpm and 0.9 vvm, respectively, whereas those for production of CMCase were 343 rpm and 0.6 vvm, respectively. The optimal inner pressure for cell growth and production of CMCase in a 100-l bioreactor was 0.06 MPa. Maximal production of CMCase under optimal conditions in a 100-l bioreactor was 127.5 U/ml, which was 1.32 times higher than that without an inner pressure. In this study, rice bran was developed as a carbon source for industrial scale production of CMCase by B. atrophaeus LBH-18. Reduced time for the production of CMCase from 7 to 10 days to 3 days by using a bacterial strain with submerged fermentation also resulted in increased productivity of CMCase and a decrease in its production cost.

• Journal of the Mineralogical Society of Korea
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• v.4 no.1
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• pp.22-31
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• 1991

Three crystal structures of dehydrated $Ag^+$-and $Ca^{2+}$- exchanged zeolite $A(Ag_4Ca_4-A,\;Ag_^Ca_3-A,\;and\;Ag_8Ca_2-A)$ treated at 250${\circ}C$ with 0.1 Torr of Rb vapor have been determined by single-crystal x-ray diffraction techniques in the cubic space group Pm3m at 21(1)${\circ}C$ (a=12,271(1)${\AA}$, 12.255(1)${\AA}$, and 12.339(1)${\AA}$, respectively). Their structures were refined to the final error indices. R(weighted) of 0.072 with 130 reflections, 0.050 with 110 reflections, and 0.083 with 86 reflections, respectively, for which $I>3{\rho}(I)$. In each structure, Rb species are found at three different crystallographic sites:3$Rb^+$+ions per unit cell are located at 8-ring centers, ca. 5.6 to 6.4 $Rb^+$ ions are found opposite 6-rings on threefold axes in the large cavity, and ca. 2.5 to 3.0 $Rb^+$ ions are found on threefold axes in the sodalite unit. Also, Ag species are found at two different crystallographic stites: ca. 0.7 to 2.1 $Ag^+$ lie opposite 4-rings and ca. 2.2 to 4.8 Ag atoms are located near the center of the large cavity. In these structures, the numbers of Ag atoms per unit cell are 2.2, 2.4, and 4.8, respectively, and these may form hexasilver clusters at the centers of the large cavities. The $Rb^+$ ions, by blocking 8-rings, may have prevented silver from migrating out of the structure. Each hexasilver cluster is stabilized by coordination to up to 13 $Rb^+$ions. An excess absorption of about 0.8 Rb atom per unit cell indicates that the presence of a triangular symmetric $(Rb_3)2^{+}$ cation in sodalite cavity. At least one large-cavity six-ring $Rb^+$ ion must necessarily approach this cluster and may be viewed as a member of it to give $(Rb)_4^{3+}$, $(Rb)_5^{4+}$ or $(Rb)_6^{5+}$.