• Journal of Microbiology
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• v.39 no.3
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• pp.213-218
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• 2001

The treatment of Patients with bacteraemia and septicemia requires accurate and rapid identification of the pathogen so that the physician can be guided regarding the selection of the proper antimicrobial therapy. The usual procedure is to withdraw an aliquot of the positive blood culture sample for gram staining and subculturing on the media for the growth and subsequent identification, and susceptibility determinations. It was noticed that during the process some microbiologists would sniff the effluent gases that are products of metabolism and in some cases guess the identity of the bacterium. That Prompted us to engage in systematic investigation of two gram positive and two gram negative bacteria using an electronic nose that had been proven successful in distinguishing the aroma of coffee beans from different sources. The investigation was successful in illustrating the efficacy of such a device in this clinical setting to distinguish Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. A representative set of patterns obtained with this apparatus is displayed as well. A representative set of patterns obtained with this apparatus is displayed as well. No effort was made to determine an optimal set of sensors for some specific set of bacterial metabolism gaseous products.

• Journal of Plant Biotechnology
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• v.6 no.3
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• pp.157-163
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• 2004

An efficient system for the regeneration of adventitious shoots from in vitro cultured leaf sections of Lycium chinense Miller was developed and silent somaclones from the regenerants detected with RAPD method. Among the eight media tested (B5, SH, N&N, 1/2MS, MS, 3/2MS, GD and WPM), and four cytokinins (BA, kinetin, 2ip and zeatin) with different concentrations (1, 5, 10, 20, 30 and 40 $\mu{M}$), 1/2 MS medium supplemented with 20 and 30 $\mu{M}$ zeatin showed the best regeneration frequency (100% and 93.7%) and higher average number of shoots (9.0 and 9.4). All regenerants easily elongated after subculturing on 1/4MS without growth stimulants and produced spontaneous adventitious roots from their basal parts. With phenotypically normal 40 regenerants, RAPD analysis with 15 different random primers was performed to examine the cryptic somaclonal variants. No substantial differences in banding patterns were found in the amplified polymorphic DNAs implying no DNA changes during dedifferentiation into adventitious shoots. However, one (OPF-4) of the 15 primers detected silent somaclonal variation in one regenerant in which two different polymorphic bands did not appear when compared with the rest regenerants. The results indicate that regenerantion via intervening callus phase can be used to establish true-to-type planting stocks for homogeneous population.

• Korean Journal of Medicinal Crop Science
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• v.10 no.2
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• pp.116-119
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• 2002

A protocol has been developed for differentiation of adventitious shoots directly from leaf segments of Tetragonia tetragonoides O. Kuntze. Murashige and Skoog (MS) medium supplemented with 2 mg/L $N^6-benzyladenine$ (BA) and 0.5 mg/L ${\alpha}-naphthaleneacetic$ acid (NAA) supported the induction of adventitious shoots from leaf explants. Adventitious shoots were multiplied by subculturing on the double strength MS (2MS) medium supplemented with 0.5 mg/L NAA and 2 mg/L BA. Shoots were rooted on MS basal medium without any growth regulators.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.257-263
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• 1995

As a first step for developing Lactobacillus strains capable of fermenting starch directly, the $\alpha$-amylase gene (amyL) from Bacillus licheniformis (Kim et al., 1988. Kor. J. Appl. Microbiol. Bioeng. 16: 369-373) was introduced into Lactobacillus casei strains and the level of $\alpha$-amylase expression in transformants was examined. 3 kb EcoRI fragments encompassing amyL were subcloned into the suitable lactococcal cloning vectors (pSA3, pMG36e, and p1L2530) and then recombinant plasmids were introduced into E. coli and L. casei strains by electroporation. Only one recombinant plasmid, $pIL2530\alpha$ was able to transform few L. casei strains tested at low efficiencies. The transformation efficiencies with the plasmid into L. casei YIT 9018 and L. casei A Tee 4646 were less than $10^2/\mu$ g pIL2530\alpha$. The level of amylase activities in L. casei was five to ten-fold lower than that in E. coli cells. $p1L2530\alpha$ was stably maintained in Lactobacillus strains in the presence of Em (5 $\mu $g/ml) but without antibiotic selection, it was unstable so more than 95$%$ of cells lost plasmids after a week of daily subculturing.

• Journal of Plant Biology
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• v.36 no.1
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• pp.113-120
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• 1993

Effects of various NaCl concentrations on salt-tolerant callus of tobacco were investigated. Selection of NaCl-tolerant (S) callus was conducted by subculturing Nicotiana tabacum cv. BY 4 callus in 200 mM NaCl-containing MS medium for more than 18 months. In spite of the long subculture period, characteristics of salt tolerance were maintained very stably. Significant differences were found in ion contents of each callus which was subcultured with treatment of various NaCl concentrations: Na+ and Cl- became higher but Mg2+, Ca2+ and K+ became lower with the increasing external salt contents. Therefore, the ratios of Na+/Ca2+ and Na+/K+ also increased resulting close to those of halophytic property. The contents of chlorophylls and carotenoids in S callus were estimated to 3.1 and 2.9 times more, respectively. than those of non-selected (NS) callus (control). The higher content of external NaCl tended to increase the amount of water soluble proteins and to decrease the amounts of the total sugars, reducing sugars and free amino acids. The activity of peroxidase was increased with higher contents of external NaCl in S callus, but it was maintained at a higher level than S callus at lower NaCl, followed by a subsequent decrease above 80 mM NaCl in NS callus. These results suggest that S callus may have a biological system converting energy source to efficient growth leading to reduction of the growth inhibition under stress environment.

• YAKHAK HOEJI
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• v.52 no.3
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• pp.219-224
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• 2008

Clinically isolated methicillin-resistant Staphylococcus aureus strains were exposed to subinhibitory concentration of DW286, DW-224a, gemifloxacin, trovafloxacin, sparfloxacin and ciprofloxacin during 26- to 39-days period. Subculturing led to resistance development, and most of the selected mutants were above susceptible breakpoints. Selected mutants had broad cross resistance to other quinolone antibiotics and only one mutant was completely susceptible to all fluoroquinolones. Twenty five among 42 mutants revealed mutations on DNA gyrase and topoisomerase IV by sequencing. Also 16 mutants had fluoroquinolones MICs that were 4-32 times lower in the presence of reserpine. In conclusion, alterations in DNA gyrase or topoisomerase IV and action of efflux pumping out system are the resistance mechanisms of DW-224a.

• Journal of Marine Bioscience and Biotechnology
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• v.14 no.2
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• pp.112-123
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• 2022

Photosynthetic bacteria (PSB) play an important role in water purification, and their application is beneficial for sustainable aquaculture. However, maintaining the microbial stability of PSB from subculturing to preservation is a challenging task. Since improvement in the microbial stability of PSB is a crucial parameter, optimized conditions for cell immobilization and lyophilization were investigated. In PSB immobilization, 0.1-M CaCl₂ was found to be the most effective divalent metal ion solution in terms of cost-effectiveness, resulting in beads with a 4-mm diameter and high loading (1.91×10⁹ CFU/mL) of viable cells. Maintenance of cell viability, external appearance, and color of PSB beads was best in 3.5% NaCl during storage. In lyophilization, the addition of skim milk (9%) and dextrose (2%) as cryoprotective additives allowed the highest cell viability. Over an 18-week shrimp breeding period, when optimally manufactured beads and lyophilized powder of PSB were applied to shrimp aquaculture water, NH⁴⁺, NO₃^-, and NO₂^- were more effectively removed by 55%, 100%, and 100%, respectively, compared to controls. Thus, microbial stability of PSB through optimized cell immobilization and lyophilization was successfully enhanced, enabling a wide application.

• Journal of Plant Biotechnology
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• v.7 no.4
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• pp.247-257
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• 2005

An efficient, rapid and large-scale in vitro clonal propagation of agronomically important Indian cereal crop genotypes (NSH27 & K5) of Sorghum bicolor (L.) Moench. by enhanced shoot proliferation in shoot tip segments was designed. MS medium fortified with plant growth regulators and coconut water markedly influenced in vitro propagation of Sorghum bicolor. In vitro plantlet production system has been investigated on Murashige and Skoog (MS) medium with the synergistic combination of 6-benzyladenine ($22.2\;{\mu}M$), kinetin ($4.6\;{\mu}M$), adenine sulphate ($2.8\;{\mu}M$), 5% coconut water and 3% sucrose which promoted the maximum number of shoots as well as beneficial shoot length. Subculturing of shoot tip segments on a similar medium enabled continuous production of more than 100 healthy shoots with similar frequency. When the healthy shoot clumps were cultured on MS medium fortified with 6-benzyladenine ($22.2\;{\mu}M$), kinetin ($4.6\;{\mu}M$), adenine sulphate ($2.8\;{\mu}M$), ${\alpha}$-naphthaleneacetic acid ($2.7\;{\mu}M$), ascorbic acid ($30.0\;{\mu}M$) and 5% coconut water, a rapid production of axillary and adventitious buds was developed after 8 wk culture. More than 300 shoots were produced 10 wk after culture. Rooting was highest (100%) on half strength MS medium containing 22.8 mM IAA. Micropropagated plants established in garden soil, farmyard soil and sand (2:1:1) were uniform and identical to the donor plant with respect to growth characteristics. These plants grew normally without showing any traits.

• Plant Biotechnology Reports
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• v.5 no.2
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• pp.147-156
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• 2011

Efficient Agrobacterium-mediated genetic transformation of Scoparia dulcis L. was developed using Agrobacterium tumefaciens strain LBA4404 harboring the binary vector pCAMBIA1301 with ${\beta}$-glucuronidase (GUS) (uidA) and hygromycin phosphotransferase (hpt) genes. Two-day precultured leaf segments of in vitro shoot culture were found to be suitable for cocultivation with the Agrobacterium strain, and acetosyringone was able to promote the transformation process. After selection on shoot organogenesis medium with appropriate concentrations of hygromycin and carbenicillin, adventitious shoots were developed on elongation medium by twice subculturing under the same selection scheme. The elongated hygromycin-resistant shoots were subsequently rooted on the MS medium supplemented with $1mg\;l^{-1}$ indole-3-butyric acid and $15mg\;l^{-1}$ hygromycin. Successful transformation was confirmed by PCR analysis using uidA- and hpt-specific primers and monitored by histochemical assay for ${\beta}$-GUS activity during shoot organogenesis. Integration of hpt gene into the genome of transgenic plants was also verified by Southern blot analysis. High transformation efficiency at a rate of 54.6% with an average of $3.9{\pm}0.39$ transgenic plantlets per explant was achieved in the present transformation system. It took only 2-3 months from seed germination to positive transformants transplanted to soil. Therefore, an efficient and fast genetic transformation system was developed for S. dulcis using an Agrobacterium-mediated approach and plant regeneration via shoot organogenesis, which provides a useful platform for future genetic engineering studies in this medicinally important plant.

• Plant Biotechnology Reports
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• v.5 no.2
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• pp.187-195
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• 2011

The gesneriaceous perennial plant Titanotrichum oldhamii has beautiful foliage and attractive bright yellow flowers. However, breeding of T. oldhamii by conventional sexual hybridization may be difficult because sexual reproduction of this species is very rare. In the present study, plant regeneration systems via both direct and indirect formation of adventitious shoots from leaf explants were established as the first step toward breeding T. oldhamii by using biotechnological techniques. Adventitious shoots were formed efficiently on medium containing $0.1mg\;l^{-1}$ benzyladenine. Histological observation showed that shoot formation on this medium occurred directly from leaf epidermal cells without callus formation. On the other hand, leaf explants formed calluses on medium containing $0.1mg\;l^{-1}$ 2,4-dichlorophenoxyacetic acid. The calluses could be maintained by monthly subculturing to fresh medium of the same composition. When the calluses were transferred to plant growth regulator-free medium, they formed adventitious shoots. Directly and indirectly formed shoots rooted well on medium containing $0.1mg\;l^{-1}$ indole-3-butyric acid. Plantlets thus obtained were successfully acclimatized and grew vigorously in the greenhouse. Flow cytometry analysis indicated that no variation in the ploidy level was observed in plants regenerated via direct shoot formation, whereas chromosome doubling occurred in several plants regenerated via indirect shoot formation. Regenerated plants with the same ploidy level as the mother plants showed almost the same phenotype as the mother plants, whereas chromosome-doubled plants showed apparent morphological alterations: they had small and crispate flowers, and round and deep green leaves.