• Ocean and Polar Research
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• 제30권4호
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• pp.509-518
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• 2008

Distribution of bacterial abundance and production was investigated in seawater around Saemangeum dike 7 times during March, $2007{\sim}July$, 2008. In the inner area of the dike, salinity variation was great due to river runoff from Mangyung and Dongjin Rivers and high chlorophyll a (chl a) concentrations up to $124.3{\mu}g\;l^{-1}$ was found. In the outer area of the dike, salinity was higher than in the inner area of the dike, and chl a was lower up to 10 times than in the inner area of the dike. Thus, the area of Saemangeum showed meso- to hypereutrophic conditions. Bacterial abundance and production ranged from 0.3 to $4.3{\times}10^9\;cells\;l^{-1}$ and from 5.2 to $570 pmol\;l^{-1}h^{-1}$ in outer area of the dike, respectively, while in the inner area of the dike bacterial abundance and production was 3 to 4 times higher ($0.4{\sim}12.7{\times}10^9\;cells\;l^{-1}$ and $12.3{\sim}1309\;pmol\;l^{-1}h^{-1}$, respectively) than those in the outer area. In both areas, bacterial abudance and production was highest in summer and lowest in winter. However, the variations of bacterial parameters was very large in each season. These large variations seemed to be related with the supply of organic matter. Bacterial abundance and production showed significant negative correlations with salinity in the inner area, suggesting that allochthonous organic matter input by river runoff could be an important factor in regulating the distribution of bacterial abundance and production. In addition, bacterial production also correlated positively with chl a in the inner area, suggesting that autochthonous substrate might be another regulating factor of bacterial growth in the area. These results suggest that the supply of both allochthonous organic substrates introduced by river runoff and autochthonous substrates produced by phytoplankon could be important in regulating bacterial growth and utilization of organic matter in the area. Thus, to manage water quality in the inner area of dike, it seems to be important to lower the load of both organic and inorganic nutrients from adjacent rivers.

• 한국식품영양과학회지
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• 제31권4호
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• pp.572-577
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• 2002

Gluconacetobacter persimmonus KJ145를 사용하여 bacterial cellulose 생산에 최적 배지와 배양조건을 설정하였다. Bacterial cellulose를 생성하기 위한 최적배지로는 HS배지보다는 천연사과과즙이 더 우수한 경향을 나타내었으며, 사과과즙에 각종 탄소원을 보강한 결과 탄소원으로 pyruvate가 적합하였다. 탄소원의 농도를 조사한 결과, 1%가 적합하였으며, 각종 질소원의 영향을 조사한 결과 CSL이 가장 우수한 결과를 나타내었다. CSL의 농도에 따른 bacterial cellulose의 생산성을 조사한 결과, 10% 농도에서 가장 좋았다. Bacterial cellulose의 생성에 미치는 배지의 초기 pH의 영향을 조사한 결과 pH 6.0에서 최적이었으며,배양온도별 영향을 조사한 결과 35$^{\circ}C$에서 하는 것이 최적이었다. 최적 배양조건에서 배양시간별로 생성되는bacterial cellulose의 양을 조사한 결과 16일간 배양하는 것이 가장 좋았으며, 이 때 생성되는 bacterial cellulose의 생산량은 8.96 g/L으로 비교적 높았다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권5호
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• pp.643-647
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• 2004

An in vitro experiment was carried out to investigate effects of solid associated (SAB) and liquid associated bacteria (LAB) and the type of incubation substrate on ruminal fermentation and gas production profiles. Bacterial fraction did not influence total numbers of bacteria. Gas production degradation parameters were significantly influenced by bacterial fraction and type of substrate (p<0.05). There was significant interaction between bacterial fraction and type of substrate in gas production (p<0.01). Total VFA concentration and acetic and propionic acid ratio were also influenced by bacterial fraction and type of substrate with little differences in individual VFA concentration.

• 한국식품영양과학회지
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• 제32권2호
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• pp.181-184
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• 2003

G. persimonensis-KJ145를 차용하여 BC 생산과 식초생산에 미치는 에탄올의 영향을 조사하였다. 그 결과 사과쥬스배지에 에탄올을 2%(v/v) 첨가하였을 때 BC의 생산성이 가장 좋았으며, 7%(v/v)를 첨가하였을 때 총산의 함량이 가장 높았다. BC와 식초를 동시 생산하기 위해서는 에탄올을 5%(v/v) 첨가하는 것이 가장 좋을 것으로 생각되며 발효과정 중의 식초 품질 변화에 대한 보다 자세한 연구가 요구되었다. BC와 식초 생산에 가장 효과적인 질소원은 CSL인 것으로 조사되었고 최적 농도는 15%(w/v)이었다. 배양시간의 영향을 조사한 결과 14일간 배양하는 것이 가장 많은 양의 BC를 생산하였으며, 최적조건에서 생산되는 BC 생산량은 7.55 g/L이었다.

• 한국해양학회지
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• 제27권2호
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• pp.154-163
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• 1992

박테리아의 개체수와 생산량의 분포률, 그리고 하구 혼합 (estuarine mixing)이 이들 분포에 미치는 영향을 조사하기 위해, 1990년 10월부터 1991년 8월까지 만경강 및 동진강 하구의 유광대에서 박테리아의 개체수, 생산량, 수온 및 염분도를 3번 조사 하였다. 제한된 조사에도 불구하고 조사기간에 나타난 박테리아의 개체수와 생산량은 넓은 범위의 값을 보였다. 각각 0.4-5.8$\times$10/SUP 9/ 1/SUP -1/와 0.1-22.2 ug C /SUP -1/ d/SUP -1/이었다. 이는 박테리아의 성장이, 하구에서 매우 유동적임을 나타냈다. 흥미롭게도 박테리아의 개체수는 대부분의 수임이 얕은 정점의 표면 아래에서 증가하 였으나, 박테리아의 생산량은 뚜렷이 감소하였다. 이러한 현상은 하구 혼합에 의해서 설명될 수 있을 것으로 판단되며, mixing diagrams의 분석은 하구 혼합이 박테리아 개 체수와 생산량을 conservative하게 혼합하기도 하나, 박테리아 개체수를 증가시키며, 생산량을 감소시키는 작용을 하였으며를 보여주었다. 이것은 하구 혼합의 역할이 박테 리아의 개체수와 생산량의 분포에 따라서 하구에서의 생지화학적 순환에 있어서 중요 함을 제시하였다.

• 한국습지학회지
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• 제9권1호
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• pp.123-131
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• 2007

Effect of nitrogen-load condition on hydrogen ($H_2$) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight $H_2$ production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest $H_2$ production was obtained when the C/N ratio was 36, the $H_2$ production yield ($mol-H_2/mol-glucose$) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the $H_2$ production. The $H_2$ production was decreased on both the lower (C/N: 72) and higher (C/N: 18) nitrogen-load conditions. The excess nitrogen-load was not always suitable for the hydrogen production. The fluctuation of $H_2$ production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of $H_2$ productivity was possible by a control of nitrogen-load condition through the bacterial community change. When the nitrogen-load condition was not suitable for hydrogen production, the lactic acid concentration was increased and also lactic acid bacteria were definitely detected, which suggested that the competition between hydrogen fermentator and lactic acid producer was occurred. These results demonstrated that the nitrogen-load condition affect on the $H_2$ productivity through the change of bacterial community in anaerobic hydrogen fermentation.

• Journal of the korean society of oceanography
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• 제33권4호
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• pp.205-211
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• 1998

Participating in a multi-disciplinary oceanography program in July 1997 in the vicinity of Tokdo, we studied the distributions of bacterial abundance and production along with those of phytoplankton and heterotrophic nanoflagellates. In the euphotic zone, chlorophyll a (chl a) concentrations ranged from 0.14 to 0.52 ${\mu}$g 1$^{-1}$. Bacterial abundance in the euphotic zone (0.12-0.21 ${\times}$ 10$^9$ cells 1$^{-1}$) in the study area was quite lower than that expected from the observed chi a concentration in the marine environment. The low bacterial abundance seemed to be due to active grazing pressure on bacteria. The fraction of primary production utilized by bacteria was also low(8-12%). Interestingly, surface water temperatures were love. at stations near islands compared to an offshore station located between Ulleungdo and Tokdo and the highest values of bacterial production and chi a were found at stations near islands, strongly indicating island mass effects.

• The Plant Pathology Journal
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• 제39권5호
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• pp.417-429
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• 2023

Ralstonia solanacearum species complex (RSSC) is a soil borne plant pathogen causing bacterial wilt on various important crops, including Solanaceae plants. The bacterial pathogens within the RSSC produce exopolysaccharide (EPS), a highly complicated nitrogencontaining heteropolymeric polysaccharide, as a major virulence factor. However, the biosynthetic pathway of the EPS in the RSSC has not been fully characterized. To identify genes in EPS production beyond the EPS biosynthetic gene operon, we selected the EPS-defective mutants of R. pseudosolanacearum strain SL341 from Tn5-inserted mutant pool. Among several EPSdefective mutants, we identified a mutant, SL341P4, with a Tn5-insertion in a gene encoding a putative NDP-sugar epimerase, a putative membrane protein with sugar-modifying moiety, in a reverse orientation to EPS biosynthesis gene cluster. This protein showed similar to other NDP-sugar epimerases involved in EPS biosynthesis in many phytopathogens. Mutation of the NDP-sugar epimerase gene reduced EPS production and biofilm formation in R. pseudosolanacearum. Additionally, the SL341P4 mutant exhibited reduced disease severity and incidence of bacterial wilt in tomato plants compared to the wild-type SL341 without alteration of bacterial multiplication. These results indicate that the NDP-sugar epimerase gene is required for EPS production and bacterial virulence in R. pseudosolanacearum.

• Journal of Ginseng Research
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• 제46권1호
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• pp.1-10
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• 2022

Ginseng has been well-known as a medicinal plant for thousands of years. Bacterial endophytes ubiquitously colonize the inside tissues of ginseng without any disease symptoms. The identification of bacterial endophytes is conducted through either the internal transcribed spacer region combined with ribosomal sequences or metagenomics. Bacterial endophyte communities differ in their diversity and composition profile, depending on the geographical location, cultivation condition, and tissue, age, and species of ginseng. Bacterial endophytes have a significant effect on the growth of ginseng through indole-3-acetic acid (IAA) and siderophore production, phosphate solubilization, and nitrogen fixation. Moreover, bacterial endophytes can protect ginseng by acting as biocontrol agents. Interestingly, bacterial endophytes isolated from Panax species have the potential to produce ginsenosides and bioactive metabolites, which can be used in the production of food and medicine. The ability of bacterial endophytes to transform major ginsenosides into minor ginsenosides using β-glucosidase is gaining increasing attention as a promising biotechnology. Recently, metabolic engineering has accelerated the possibilities for potential applications of bacterial endophytes in producing beneficial secondary metabolites.

• 한국해양학회지
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• 제26권3호
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• pp.255-261
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• 1991

중앙 북부 태평양의 두 개의 해산(Horizon guyot와 Magellan rise) 상의 수층에서 박테리아의 생체량과 생산력이 1987년 3월에 조사되었다. 이 기간에 관찰된 표층수의 박테 리아 개체수는 (0.9-2.3$\times$10/SUP 8/l/SUP -1/) 빈영양 해역에서 보고 된 박테리아의 개체수에 비해 낮은 값은 나타냈다. 또한 mesopelagic zone 의 박테리아 개체수도 (대 개 < 5$\times$10/SUP 7/l/SUP -1/) 다른 아열대 지역에서 보고 된 것보다 훨씬 낮았다. 표층수에서의 박테리아 생산력(20-466 ng C l/SUP -1/ d/SUP -1/)또한 다른 빈영양 해 역과 비교시 낮았다. 그러나 표층수의 박테리아 생산력을 이 지역에서 발표된 일차 생 산력과 비교한 경우, 유기물의 이용에 있어서 박테리아의 역할이 중요한 것으로 추정 되었다. 이 연구에서 보고 된 박테리아 생산력의 공간적 분포에 대한 자료는 충분하진 않으나, 매우 빈영양인 수서 환경에서 소규모 그리고 대규모적 공간상의 박테리아 생 산력 분포에 대한 연구의 필요성을 제시하고 있다.