• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.640-651
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• 1997

This study was performed to examine the distribution patterns, ecological characteristics and celluar fatty acid compositions of marine bacteria in Suyeong Bay. During study periods, total cell count (TC) and viable cell count (VC) were $10^7-10^8/m\ell\;and\;10^4-10^6\;cfu/m\ell$, respectively. The temporal variations of TC showed similar patterns between surface and bottom layer, but the VC at bottom decreased gradually from winter to summer. Among the 303 bacterial strains isolated in the study area, which belong to 10 genus types, Pseudomonas spp., $(32.3\%)$, Acinetobader sup. $(19.1\%)$, Vibrio spp. $(11.2\%)$, Flovobacterium spp. $(10.6\%)$ and Bacillus spp. $(7.9\%)$ were dominant. Thirty-one fatty acids were detected from Pseudomonas spp. and Bacillus spp., which were the most predominated among Gram positive and Gram negative bacteria. Celluar fatty acid compositions of Bacillus spp. were relatively simple compared to those of Pseudomonas spp.. Relatively high ratio of monounsaturated forms were detected in Pseudomonas spp. while branched types were dominant in those of Bacillus spp.. Hydroxy and cyclopropane fatty acid were detected only in the cellular fatty acid of Pseudomonas spp.. Cellular fatty acid compositions of Pseudomonas spp. revealed relatively high percentage of $C_{16:1},\;C_{17:1},\;C_{18:1}\;and\;C_{16:0}$, While Bacillus spp. predominated $C_{16:0}\;iso\;C_{16:0}\;anteiso,\;C_{17:0}\;anteiso\;and\;C_{16:1}$.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.355-367
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• 2016

Soil salinization refers to the buildup of salts in soil to a level toxic to plants. The major factors that contribute to soil salinity are the quality, the amount and the type of irrigation water used. The presented review discusses the different sources and causes of soil salinity. The effect of soil salinity on biological processes of plants is also discussed in detail. This is followed by a debate on the influence of salt on the nutrient uptake and growth of plants. Salinity decreases the soil osmotic potential and hinders water uptake by the plants. Soil salinity affects the plants K uptake, which plays a critical role in plant metabolism due to the high concentration of soluble sodium ($Na^+$) ions. Visual symptoms that appear in the plants as a result of salinity include stunted plant growth, marginal leaf necrosis and fruit distortions. Different strategies to ameliorate salt stress globally include breeding of salt tolerant cultivars, irrigation to leach excessive salt to improve soil physical and chemical properties. As part of an ecofriendly means to alleviate salt stress and an increasing considerable attention on this area, the review then focuses on the different plant growth promoting bacteria (PGPB) mediated mechanisms with a special emphasis on ACC deaminase producing bacteria. The various strategies adopted by PGPB to alleviate various stresses in plants include the production of different osmolytes, stress related phytohormones and production of molecules related to stress signaling such as bacterial 1-aminocyclopropane-1-carboxylate (ACC) derivatives. The use of PGPB with ACC deaminase producing trait could be effective in promoting plant growth in agricultural areas affected by different stresses including salt stress. Finally, the review ends with a discussion on the various PGPB activities and the potentiality of facultative halophilic/halotolerant PGPB in alleviating salt stress.

• The Korean Journal of Pharmacology
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• v.25 no.1
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• pp.53-58
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• 1989

For several years, we investigated the pharmacological action of several substances isolated from Buxus microphylla var koreana Nakai, which had been used as folk remedies of malaria and venereal disease. Cyclobuxine $D(C_{25}H_{42}ON_2)$, a steroidal alkaloid, exerted an antiinflammatory action, hypotensive and bradycardic effects in rats. In the present study, we isolated alkaloid from the acetone-insoluble fraction of the strong bases of this plants. This alkaloid $(C_{25}H_{38}ON_2)$ was identified as a steroidal alkaloid contained a cyclopropane ring by physical and chemical methods. It is a derivative of cyclobuxine D and named cyclobuxine E. We examined the effect of cyclobuxine E on the contractile response induced by acetylcholine and two distinct types of potassium-activated calcium channels in an intestinal smooth muscle of the rat. Cyclobuxine E inhibited significantly the Ach-induced contraction. The isolated longitudinal muscle from the rat duodenum was immersed calcium-depleted potassium depolarizing solution. Ten minutes after, 1.8 mM $CaCl_2$ was added to muscle bath and elicited a biphasic increase in muscle tension. Cyclobuxine E produced an appreciable inhibition of both components of the mechanical response. In addition, Cyclobuxine E introduced at a point when the tonic response had reached its maximum level, caused the muscle to exhibit a rapid loss of tension. Based on these experimental results, we proposed the possibility that the inhibitory action of cyclobuxine E on the isolated rat duodenum may be due to inhibiting the transmembrane fluxes of calcium ion in potassium-activated calcium channels.