• KSBB Journal
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• v.31 no.3
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• pp.158-164
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• 2016

Plant growth promoting (PGP) hormones, which are produced in a small quantity by bacteria, affect in plant growth and development. PGPs play an important role on the crop productivity in agricultural field. In this study, a photosynthetic bacterial strain producing the PGP was isolated from paddy soil. Bacterial isolate was gram negative, rod-shaped and motility positive. From the 16s rRNA gene sequence analysis, the isolate was identified as Rhodobacter capsulatus PS-2. The mass cultivation of R. capsulatus PS-2 was optimized by considering of the carbon, nitrogen and inorganic salt sources. Optimal medium composition was determined as Na-succinate 4.5 g, yeast extract 5 g, $K_2HPO_4$ 1 g, $MgSO_4$ 5 g, per liter. From the result of 500 L fermentation for 2 days using the optimal medium, the viable cells were $8.7{\times}10^9cfu/mL$. R. capsulatus PS-2 strain produced the carotenoid and indole-3-acetic acid (IAA). The carotenoid extraction and quantitative analysis were performed by HCl-assisting method. Total carotenoid contents from R. capsulatus PS-2 culture broth were measured as $7.02{\pm}0.04$ and $6.93{\pm}0.05mg/L$ under photoheterotrophic and chemoheterotrophic conditions, respectively. To measure the productivity of IAA, colorimetric method was employed using Salkowski reagent at optical density 535 nm. The results showed that the highest content of IAA was $197.44{\pm}5.92mg/L$ in the optimal medium supplemented with 0.3% tryptophan.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.142-149
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• 1991

Gardenia callus was induced in MS medium containing $10{\;}{\mu}M$ of 2,4 diphenoxy acetic acid (2,4-D), $1{\;}{\mu}M$ kinetin, and 3% sucrose in the dark. $B_5$ medium was identified to be the most adequate medium for cell growth. Indole-3-acetic acid (IAA) was better growth regulator than 2,4-D not only for cell growth but slso for carotenoid production. Ligt also played a critical role on synthesis of carotenoid. Gardenia cells grown in $B_5$ medium could utilize a polysaccharide, soluble starch, as a carbon source. The cell growth was stimulated in $B_5$ medium fortified with 0.2% yeast extract. The optimum pH for cell growth was 5.7. High density cultures can be maintained by increasing inoculum size and medium concentration accordingly. Specific growth rate and mass doubling time were 0.095 $day^{-1}$ and 7.3 days, respectively. The cell immobilized in alginate tends to formulate more enlarged vacuoles containing yellow pigment compared with those of suspended cell. Carotenoid content of immobilized cell was about $264.4{\;}{\mu}g/g$ fresh weight (F.W.) corresponding twice of the content of suspended cell ($112.08{\;}{\mu}g/g$ F.W.). The color of gardenia cell was shifted from yellow to red when carbohydrase-secreting fungus, Trichoderma reesei, was co-cultivated with gardenia cells.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.843-859
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• 2017

The JK-1 isolate which was the best producer of indole-3-acetic acid and carotenoid among the 388 strains isolated from 28 wetlands in Jeju, was identified to be Rhodopseudomonas palustirs belongs to a typical group of non sulfur purple bacteria based on 16S sRNA sequencing. This study investigated the effect of different cultural conditions of pH, temperature, agitation, light and aeration on growth, IAA and carotenoid production of photosynthetic bacterium JK-1 for optimization of IAA and carotenoid production. It was found that growth, IAA, carotenoid, and bacteriochlorophyll production with light (3,000~3,500 Lux) and agitation (100 rpm) showed better results than those with dark/static or dark/agitation (100 rpm) in anaerobic conditions. The optimal pH, temperature and agitation speed for cell growth were 7, $30^{\circ}C$, 150 rpm, for IAA production were 9, $30^{\circ}C$, 150rpm and for carotenoid production were 6, $25^{\circ}C$, 50 rpm, cultured for 72 h under anaerobic light, respectively. The growth and IAA production were high in aerobic culture compared with anaerocic culture, whereas carotenoid and bacteriochlorophyll content were decreased extremely in aerobic condition (0.5~1 vvm). Subsequently, the optimal culture conditions for JK-1 were selected with pH 7, $30^{\circ}C$ and 100 rpm under anaerobic light and the effect on plant growth was tested by pot assay. Inoculation of JK-1 with 3% (v/v) level caused increase in shoot and root dry weigh that varied from 20%~58% to 40%~28% in young radish in camparison to uninoculated treatment at 50 days of growth. The study suggests that the JK-1 isolate may serve as efficient biofertilizer inoculants to promote plant growth.