• Microbiology and Biotechnology Letters
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• v.10 no.1
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• pp.27-32
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• 1982

Many microorganisms capable of hydrogen photoproduction were isolated from samples of mud fiats of paddy field collected in Seongnam area near Seoul. Among the 63 isolants, a strain K-13 was selected for the capability of hydrogen evolution. As the results of examinations in physiological, morphological and cultural characteristics, the strain K-13 was identified as Rhodopseudomonas gelatinosa.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.733-737
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• 1996

The formation of microbial films(biofilm) by a non-sulfur phototrophic bacteria, Rhodopseudomonas capsulata, on inorganic media was studied. Porous ceramic beads(PCB) were superior to other immobilizing media for the biofilm formation in a packed-bed reactor. It was found that the formation of microbial films favored a lower hydraulic retention time, showing a higher ratio of cells attatched to the media to those suspended in the solution. The cell concentration in the biofilm reactor was as high as 11,400mg/l, which is 8-folds of the cell concentration in an ordinary suspended treatment. It was observed that the formation of micribial film by R. capsulata followed a general serial process of cell attachment, microcolony formation, and biofilm formation. The microbial films thus formed was very stable even for an extremely high volumetric BOD loading rate of 15gBOD/l day. The scanning electron micrographs of the microbial films showed that the cells were attached to both the surface and pores of the media.

• Korean Journal of Organic Agriculture
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• v.5 no.2
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• pp.105-115
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• 1997

This experiment was conducted to clarify the plant growth promoting effect of compost supplemented with cultured solution of photosynthetic bacteria(Rhodopseudomonas capsulatus) before sowing on the early growth of plug seedling of tomato and to evaluate the optimum concentration of bacterialization. Bacterializing concentrations(v/w) to the compost were 2%, 3.3%, 10%, 20% and 50%, respectively. Plant growth in terms of plant height, stem diameter, leaf area, total fresh and dry weight were promoted by the bacterialization of photosynthetic bacteria. Especially, in the plots supplemented with 10 to 20% the early growth was promoted markedly over 2 times. Compositions of photosynthetic bacteria consisted of crude protein 60.7%, soluble carbohydrates 20.1%, crude fat 7.6%, crude fiber 3.2% and crude ash 4.8, respectively.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.265-268
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• 1992

In this study, we want to detect bacteriocin production in purple nonsulfur bacteria. As a results, it was showed that bacteriocin produced between some strains of Rhodobacter capsulatus, Rhodobacter sphaeroides and Rhodocyclus gelatinosus. In particular, it was appeared that cell membrane-bound bacteriocin was also produced by Rhodobacter capsulatus ATCC 17016.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.179-185
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• 1991

We examined optimum culture conditions of Rhodopseudomonas sphaeroides B5 for effective utilization of substrate and sunlight for hydrogen production. The optimum concentration range of DL-lactate as electron donor for hydrogen production by resting cells was from 5 to 50mM, and optimun CN ratio (lactate/glutamat) for maintenence of hydrogen production activity by growing cultures was from 5 to 6. Hydrogen production by the cultures of low cell density (0.36mg/ml dry cells) was saturated with 10 Klux light intensity. Under constant illumination of 50Klux which was set up as the average medium value of annual variation of sunlight intensity, hydrogen production with various cell densities in the culture resulted in highest production rate (132${\mu}$l/hr/mg dry cells) up to 0.64mg/ml dry cells. However, the amount of total hydrogen production was saturated with cell density of 2.1mg/ml dry cells. In addition to these, the optimum inner thickness pervious to light of the culture vessel for hydrogen production which was measured under sunlight was 5 cm.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1136-1140
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• 2008

The Rhodopseudomonas palustris KUGB306 hemA gene codes for 5-aminolevulinic acid (ALA) synthase. This enzyme catalyzes the condensation of glycine and succinyl-CoA to yield ALA in the presence of the cofactor pyridoxal 5'-phosphate. The R. palustris KUGB306 hemA gene in the pGEX-KG vector system was transformed into Escherichia coli BL21. The effects of physiological factors on the extracellular production of ALA by the recombinant E. coli were studied. Terrific Broth (TB) medium resulted in significantly higher cell growth and ALA production than did Luria-Bertani (LB) medium. ALA production was significantly enhanced by the addition of succinate together with glycine in the medium. Maximal ALA production (2.5 g/l) was observed upon the addition of D-glucose as an ALA dehydratase inhibitor in the late-log culture phase. Based on the results obtained from the shake-flask cultures, fermentation was carried out using the recombinant E. coli in TB medium, with the initial addition of 90 mM glycine and 120 mM succinate, and the addition of 45 mM D-glucose in the late-log phase. The extracellular production of ALA was also influenced by the pH of the culture broth. We maintained a pH of 6.5 in the fermenter throughout the culture process, achieving the maximal levels of extracellular ALA production (5.15 g/l, 39.3 mM).

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.211-216
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• 1983

Rhodopseudomonas sphaeroides K-7 evolves large quantities of molecular hydrogen under anaerobic and light illuminated conditions in the presence of utilizable organic compounds as electron donors. Photoevolution of molecular hydrogen was strictly dependent on light as the activity of nitrogenase in this organism. Both of these were inhibited to the nearly same extent at varying concentrations of ammonium ion which also depressed nitrogenase synthesis. In the reaction mixtures devoid of molybdenum ion which is known as the component of nitrogenase, hydrogen evolution also decreased similarly like nitrogenase activity. Photoevolution of molecular hydrogen appeared to have no relationship with hydrogenase activity and bacteriocholophyll content and it was markedly inhibited under the atmosphere of $C_2$H$_2$, $N_2$ or $O_2$. The results strongly indicate that hydrogen evolution by R. sphaeroides K-7 might be catalyzed by nitrogenase. Both hydrogen evolution and nitrogenase activity were largely influenced by the nutritional history of the resting cells. From which we propose that glutamate might play an important role in the regulation of nigrogenase activity in vivo.

• Journal of Life Science
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• v.9 no.3
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• pp.268-275
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• 1999

Rhodopseudomonas sp. was immobilized in three supports(agar, k-carrageenan, and PVA) in order to remove nitrate in wastewater coming from fish farm. Among them 3% agar was the most suitable support when denitrification rate and bead durability were tested. Optimum bead size was 4mm-diameter when the substrate transfer into the bead and shear stress for bead were considered, and optimum cell loading was 25mg dry $cells/cm^2$gel gel. Ethanol was the best as a carbon source, and optimum C:N ratio, temperature and pH were 1.5:1, $31^{\circ}C$,, and 6, respectively. Under these conditions the maximum denitrification rate in synthetic wastewater was $$345{\MU}{\ell};N_2/Cm^3 gel{\cdot}hr;and that in modified MYC medium was 450{\MU}{\ell}};N_2/Cm^3 gel{\cdot}hr $$.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.176-182
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• 2009

Hydrogen producing bacterium, strain MeL 6-2 was isolated from the sludge of the factory areas in Anyang through the acclimation in basal salt medium (BSM) supplemented with 10 g/L of sucrose. Isolated strain MeL 6-2 was a facultative anaerobe which could grow in both aerobic and anaerobic environments. An aerobically grown pure culture isolated from enriched culture was analyzed by 16S rDNA sequencing and identified as Rhodopseudomonas sp. MeL 6-2. Effects of the concentrations of glucose and sucrose on the hydrogen production rate and the hydrogen production yield were investigated. When glucose in the range of 1~12 g/L was supplemented to the BSM, strain MeL 6-2 could grow without lag phase. An increased glucose concentration increased the specific hydrogen production rate linearly to $4.2\;mmol-H_2{\cdot}L^{-1}{\cdot}h^{-1}$ at 10 g/L, and $60\;mmol-H_2{\cdot}mg-DCW^{-1}{\cdot}h^{-1}$, but decreased slightly as the concentration increased to 12 g/L. The hydrogen production yield was maintained over a range from 2.6 to $3.1\;mol-H_2{\cdot}mol-glucose^{-1}$. When sucrose in the range of 1~12 g/L was supplemented to the BSM, strain MeL 6-2 could grow after ten hours. An increased sucrose concentration increased the specific hydrogen production rate and the hydrogen production yield to $163\;mmol-H_2{\cdot}mg-DCW^{-1}{\cdot}h^{-1}$ and to $4.5\;mol-H_2{\cdot}mol-sucrose^{-1}$, respectively.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.89-95
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• 1998

Rhodopseudomonas sphaeroides K7 and E15-1 produced hydrogen from glucose rapidly for the first 24 hrs of culture under the anaerobic and photosynthetic conditions and then ceased the hydrogen production because of the accumulation of organic acids such as acetic acid and formic acid in the culture broth, decreasing the pH to 4.2-4.5. Only 43% and 73% of glucose in the culture were consumed even after 6 days of incubation by R. sphaeroides K7 and E15-1, respectively. The hydrogen production and glucose consumption, however, were substantially increased when the pH of the culture was adjusted to 6.8-7.0: Hydrogen production continues even after 10 days of culture and glucose was consumed completely after 2.5 and 4.5 days by R. sphaeroides K7 and E15-1, respectively, Furthermore, the bacteriochlorophyll contents in R. sphaeroides K7 and E15-1 were increased by 44 and 9 folds and the cell concentrations by 10 and 2.5 folds, respectively, after 7 days of culture. R. sphaeroides K7 and E15-1 also produced hydrogen from acetic, lactic, butyric and malic acids under the anaerobic and photosynthetic conditions even though the amounts of hydrogen produced were lower than that from glucose. The results of this experiment indicate that under the anaerobic and synthetic conditions R. sphaeroides K7 and E15-1 might use the NADH oxidation mediated by ferredoxin and hydrogenase to evolve hydrogen from glucose for the first 24 hrs and then the organic acids produced were used as electron donners for the production of hydrogen in the nitrogen-limited condition.