• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.615-621
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• 2010

The viability of low-temperature sulfate reduction with hydrogen as electron donor was studied with a bench-scale gas-lift bioreactor (GLB) operated at $9^{\circ}C$. Prior to the GLB experiment, the temperature range of sulfate reduction of the inoculum was assayed. The results of the temperature gradient assay indicated that the inoculum was a psychrotolerant mesophilic enrichment culture that had an optimal temperature for sulfate reduction of $31^{\circ}C$, and minimum and maximum temperatures of $7^{\circ}C$ and $41^{\circ}C$, respectively. In the GLB experiment at $9^{\circ}C$, a sulfate reduction rate of 500-600 mg $l^{-1}d^{-1}$, corresponding to a specific activity of 173 mg ${SO_4}^{2-}g\;VSS^{-1}d^{-1}$, was obtained. The electron flow from the consumed $H_2$-gas to sulfate reduction varied between 27% and 52%, whereas the electron flow to acetate production decreased steadily from 15% to 5%. No methane was produced. Acetate was produced from $CO_2$ and $H_2$ by homoacetogenic bacteria. Acetate supported the growth of some heterotrophic sulfate-reducing bacteria. The sulfate reduction rate in the GLB was limited by the slow biomass growth rate at $9^{\circ}C$ and low biomass retention in the reactor. Nevertheless, this study demonstrated the potential sulfate reduction rate of psychrotolerant sulfate-reducing mesophiles at suboptimal temperature.

• The Plant Pathology Journal
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• 제31권2호
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• pp.132-139
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• 2015

Bt-cotton germplasm, consisting of 75 genotypes was evaluated against cotton leaf curl disease (CLCuD) under high inoculum pressure in the field and using graft inoculation in glasshouse by visual symptom scoring assessments. None of the tested genotype was found disease free under both evaluation tests. Under field conditions in 2011, 3 genotypes were found resistant, 4 moderately resistant, 3 tolerant, 2 moderately susceptible and one susceptible; in 2012, 3 genotypes were tolerant, 7 moderately susceptible, 5 susceptible and 38 highly susceptible; in 2013, one was moderately susceptible and 51 were highly susceptible with varying degree of percent disease index (PDI) and severity index (SI). However, through graft evaluation in glasshouse, none of the graft inoculated plant was symptomless. All tested genotypes showed disease symptoms with SI values ranging between 5.0 and 6.0, and latent period between 12 and 14 days. Of the 75 genotypes evaluated using graft inoculation, 11 were found susceptible with SI values of 5.0 to 5.4 while remaining 64 were highly susceptible with SI values of 5.5 to 6.0. Inoculated plants of all tested genotypes exhibited severe disease symptoms within 10 days after the appearance of initial symptoms. No reduction in SI value was observed until the end of the experiment i.e., 90 days after grafting. Information generated under the present study clearly demonstrates that no sources of resistance to CLCuD are available among the tested Bt-cotton genotypes. So, a breeding programme is needed to introgress the CLCuD-resistance from other resistant sources to agronomically suitable Bt-cotton genotypes.

• 식물병연구
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• 제17권1호
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• pp.82-85
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• 2011

2009년 전남 해남 지역의 논에서 벼 키다리병과 유사한 병징을 나타내는 피를 채집하여 병원균을 분리하였다. 이병 식물체는 줄기가 고사하여 하얗게 말라 죽고, 줄기 표면에 흰가루 모양의 포자가 형성되었다. 분리균은 균학적 특성과 분자생물학적 특성에 따라 Fusarium fujikuroi로 동정되었다. Translation elongation factor 1-alpha 유전자의 염기서열 분석 결과, GenBank에 등록된 F. fujikuroi와 상동성을 나타내었다. 벼와 피를 대상으로 침지접종에 의해 병원성을 확인하였으며, 이는 피가 벼 키다리병의 전염원으로서의 역할을 할 수 있음을 의미한다. 따라서 벼 키다리병의 방제와 건전종자의 채종을 위해서는 논에 발생한 이병식물체뿐 아니라 전염원으로 작용할 수 있는 피를 제거해야 할 것으로 생각된다.

• 한국식품조리과학회지
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• 제29권5호
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• pp.599-603
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• 2013

Tarak is our own traditional fermented milk made through lactic acid fermentation by using makgeolli as inoculum for milk or using already made tarak as inoculum but it is hardly known to people as its related studies are also insufficient. Accordingly, the purpose of this study was to manufacture jelly by using tarak and analyze its quality characteristics for the diversification of consumption promotion and demand of traditional fermented milk tarak. Tarak jelly that was made according to the percentage of adding tarak showed a tendency that the content of crue protein, crude fat and crude ash except for moisture water meaningfully increased as the amount of tarak added increased (P<0.05). In the case of pH, it declines as the amount of tarak added was high. The chromaticity measurement result of tarak jelly was 54.32 in the case of control group for L, and it increased as the amount of tarak added increased. In the case of a, it decreased as tarak was added, whereas b meaningfully increased. There was meaningful difference between samples in the case of chewiness, fracturability and adhesiveness (p<0.05). The sensory test result showed that there was meaningful difference between samples in their appearance and taste but there was no meaningful difference in the case of overall preference, scent and texture.

• The Plant Pathology Journal
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• 제16권6호
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• pp.312-317
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• 2000

The selected five plant growth-promoting rhizobacteria (PGPR) strains, WR8-3 (Pseudomonas fluorescens), WR8-6 (P. putida), WR9-9 (P. fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (P. putida) isolated in the rhizosphere of watermelon plants were tested on their growth promotion and control effect against gummy stem rot of watermelon. Strains, WR8-3 and WR9-16 significantly increased stem length of watermelon, and there was a little increase in leaf area, fresh weight and root length when strains, WR8-3, WR9-9 and WR9-16 were treated. Generally, seed treatment was better for plant growth promotion than the soil drench, but there was no significant difference. Seed treatment and soil drench of each bacterial strain also significantly reduced the mean lesion area (MLA) by gummy stem rot, but there was no significant difference between the two treatments. At initial inoculum densities of each strain ranging from 10$^6\;to\;10^{15}$ cfu/g seed, approximately the same level of disease resistance was induced. But resistance induction was not induced at the initial inoculum density of 10$^3$ cfu/g seed. Resistance was induced by treating the strains, WR9-9, WR9-11 and WR9-16, on all of four watermelon varieties tested, and there was no significant difference in the decrease of gummy stem rot among varieties. Populations of the strains treated initially at log 9-10 cfu/g seed, followed with a rapid decrease from planting day to 1 week after planting, but the population density was maintained above log 5.0 cfu/g soil until 4 weeks after planting. Generally no or very weak in vitro antagonism was observed at the strains treated excepting WR9-11. Rifampicin-resistant bacteria which had been inoculated were not detected in the stems or leaves, which suggesting that the bacterium and the pathogens remained spatially separated during the experiment. This is the first report of rsistance induction in watermelon to gummy stem rot by PGPR strains.

• 미생물학회지
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• 제35권1호
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• pp.53-60
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• 1999

난분해성 다핵방향족 탄화수소인 pyrene의 생분해를 해수와 해사로 구성된 microcosm에서 조사하였다. 농도 100~1,000 ppm pyrene의 5주동안 자연분해도는 5~$20^{\circ}C$에서 1~11% 이고 이때 전환율은 310~2,200 ng/g(ml).day 이었다. 생분해에 미치는 분해균주 접종량, pyrene 농도, 온도와 계면활성제 첨가의 영향등을 영양염류가 투여된 시료에서 조사하였다. 혼합 분해균주접종시 해수보다는 해사에서 전환율이 전체적으로 높았으며 $10^{7}$cells/ml 접종시 pyrene 200 ppm 농도의 해사에서 대조구보다 분해도가 7.8배 높았다. 가장 높은 전환율 4,860 ng/g/day는 1,000 ppm pyrene이 첨가된 해사에 복합균주를 접종한 시료에서 측정되었다. Glucose 첨가시 해사에서는 배양초기에만 분해도의 증가가 나타났으며, 해수에서는 분해도가 8~10% 증가하였다. 계면활성제와 mineral oil 의 첨가는 오히려 pyrene 분해도를 대부분 감소시켰는데 CMC가 생분해에 큰 영향을 미치는 것으로 판단된다.

• 한국작물학회지
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• 제32권4호
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• pp.462-465
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• 1987

서광벼/밀양5004, HR 1619-6-2-1-2-2 /밀양5004 및 55061/IR 19735-5-2-3-2-1등 3개 조합의 F$_1$ 잡종과 이들 양친품종들의 혼묘를 각각 도열병 race IA-61, IB-47, IC-13 및 IH-1 등의 단독 race와 IC-13과 IA-61, IC-13과 IB-47 및 IC-13과 IH-1 등 2 race씩의 혼합 inoculum으로 접종시켜 이들의 잎도열병 발병반을을 검토하였다. 3개 조합의 양친품종들은 단독 race에 대해서 서로 다른 반응을 보여 각각 서로 다른 저항성 유전자의 지배를 받는 것으로 나타났다. 이들 서로 다른 정항성 유진자를 가진 양친품종들은 반응이 다른 2 race 씩의 혼합 inoculum에 대해서 모두 이병성이었으나 이들간의 F$_1$ 잡종은 모두 저항성이었다. 저항성 유전자가 서로 다른 양친품종간의 F$_1$ 잡종은 저항성 유전자의 집적효과로 인해 양친보다 광범한한 저항성을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제4권4호
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• pp.316-321
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• 1994

We investigated the possibility of industrial application and economit process of high temperature fermentation by thermotolerant alcohol producing yeasts as previously reported. From the 20% glucose media, the RA-74-2 produced 11.8% (v/v) ethanol at $32^{\circ}C$ (0.5% inoculum) and 10.6% (v/v) ethanol at $40^{\circ}C$ (3% inoculum), respectively. Also, 11.3% (v/v) ethanol was produced for 96 hours in the temperature-gradient fermentation. These results suggest that the RA-74-2 could isuccessfully be applied to save the cooling water and energy in industrial scale without re-investment or modification of established fermentation systems. When potato starch was used as the substrate for the RA-74-2, high temperature fermentation above $40^{\circ}C$ was more appropriate for industrial utilization because organic nitrogen was not necessary to economical fermentation. As the naked barley media just prior to industrial inoculation, taken from the Poongkuk alcohol industry Co., were used, 9.6% (v/v) ethanol was produced at $40^{\circ}C$ for 48 hours in jar-fermentor scale (actually, 9.5-9.8% (v/v) ethanol was produced at 30~$32^{\circ}C$ for 100 hours in industrial scale). The ethanol productivity was increased by the high glucoamylase activity as well as the high metabolic ratio at $40^{\circ}C$ Therefore, if the thermotolerant yeast RA-74-2 would be used in industrial scale, we could obtain a high productivity and saving of the cooling water and energy. Meanwhile, the RA-912 produced 6%(v/v) ethanol in 10% glucose media at $45^{\circ}C$ and showed the less ethanol-tolerance compared with industrial strains. As the produced alcohol was recovered by the vacuum evaporator at $45^{\circ}C$ in 15% glucose media, the final fermentation ratio was enhanced (76% of theoretical yields). This suggest that a hyperproductive process could be achieved by a continuous input of the substrate and continuous recovery of the product under vacuum in high cell-density culture.

• 생명과학회지
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• 제6권2호
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• pp.135-141
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• 1996

양식을 위한 먹이사료로서 가능성 있는 효모균주를 연구하였다. Kluyveromyces fragilis효모와 Candida utilis 효모의 최대 비증식 속도와 바이오매스 효율은 Saccharomyces cervisiae 효모에 비하여 굉장히 높은 값을 나타내었다. 따라서, 이 연구는 대량생산을 위하여, 플라스크 배양을 통한 이들 두 효모균들의 성장특성에 그 초점을 맞추었다. 5% 접종량을 가지고 실험한 결과, 가장 좋은 $\mu$$_{max}$ 와 OD$_{max}$ 값들은 K, fragilis는 2.5% fructose 배지에서, C. utilis는 2% YE배지에서 각각 얻었으며, 이 때의 이 값들은 K. fragilis는 0.73 hr$^{-1}$1 와 3.00을 C. uitilis는 0.59 hr$^{-1}$ 와 2.80으로 밝혀졌다. 또한, 아연과 염의 초기종도가 증가할수록 균성장에 있어서의 우도기는 증가하였으며, 접종량이 증가할수록 유도가는 감소하였다. 두 효모균은 3.5% 염농도에서 비교적 잘 자랄 수 있었으며, C. utilis 효모균만이 아연을 이용할 수 있었다.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.74-79
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• 2017

본 연구에서는 Chlorella saccharophila의 배양을 통하여 바이오에너지 자원을 대량으로 확보하고자 배지 최적화 실험을 진행하였다. 최적화 인자로는 배양 형태, 초기 접종량, 탄소원 종류 및 농도, 질소원 종류 및 농도, 배양시간이다. 실험 결과, 배양 형태는 광원과 외부탄소원을 모두 공급하는 mixotrophic 배양이 적절하였다. 초기 접종량은 3% (v/v), 탄소원은 glucose 30 g/L, 질소원은 $NaNO_3$ 0.95 g/L를 첨가하는 것이 우수하였다. 최적 배지 조건으로 배양한 결과, oil의 함량은 12일에서 가장 높았으나, 회수되는 C. saccharophila의 biomass양과 chlorophyll의 양은 10일에서 가장 높았다. 위의 결과는 미세조류의 배지 최적화를 통하여 대량배양을 위한 기초자료로 사용될 수 있으리라 판단된다.