• Journal of Microbiology and Biotechnology
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• 제18권6호
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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).

• Journal of Microbiology and Biotechnology
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• 제10권5호
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• pp.667-667
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• 2000

Pseudomonas sp. BK7, an alkalophile, displayed the highest growth and protease activity when grown in a fermenter which was controlled at a pH level of 9.0, and the enzyme production was significantly enganced by the increase of agitation speed. Two formas of alkaline proteases (BK7-1 and BK7-2) were fractionated and purified to near homogeneity. Protease BK7-1 was purified through CM-Sepharose CL-6B and Sephadex G-75 column chromatographies, and Protease BK7-2 was purified through CM-Sepharose CL-6B and Sephadex G-75 column chromatographies, and Protease BK7-2 was purified through CM-Sepharose CL-6B, DEAE-Sepharose, and Sephadex G-75 column chromatographies. The molecular weights of proteases BK7-1 and BK7-2 determined by gel filtration chromatography were 20,700 and 40,800, respectively. The $K_m$ value, isoelectric point, and optimum pH of protease BK7-1 were 2.55 mg/ml, 11.0 and 11.0, respectively, whereas those of protease BK7-2 were 1.57 mg/ml, 7.2, and 10.0, respectively. Both protease were practically stable in the pH range of 5-11. The optimum temperatures for the activities of both protease BK7-1 and BK7-2 were 50℃ and 45℃, respectively. About 56% of the original protease BK7-2 activity remained after being treated at 50℃ for 30 min but protease BK7-1 was rapidly inactivated at above 25℃. Both proteases were completely inhibited by phenylmethane sulfonyl fluoride, a serine protease inhibitor. Protease BK7-2 was stable against EDTA, EGTA, STP, and detergents such as SDS and LAS, whereas protease BK7-1 was found to be unstable.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.500-506
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• 2017

To investigate the potential applications of bacterial heme, aminolevulinic acid synthase (HemA) was expressed in a Corynebacterium glutamicum HA strain that had been adaptively evolved against oxidative stress. The red pigment from the constructed strain was extracted and it exhibited the typical heme absorbance at 408 nm from the spectrum. To investigate the potential of this strain as an iron additive for swine, a prototype feed additive was manufactured in pilot scale by culturing the strain in a 5 ton fermenter followed by spray-drying the biomass with flour as an excipient (biomass: flour = 1:10 (w/w)). The 10% prototype additive along with regular feed was supplied to a pig, resulting in a 1.1 kg greater increase in weight gain with no diarrhea in 3 weeks as compared with that in a control pig that was fed an additive containing only flour. To verify if C. glutamicum-synthesized heme is a potential electron carrier, lactic acid bacteria were cultured under aerobic conditions with the extracted heme. The biomasses of the aerobically grown Lactococcus lactis, Lactobacillus rhamosus, and Lactobacillus casei were 97%, 15%, and 4% greater, respectively, than those under fermentative growth conditions. As a potential preservative, cultures of the four strains of lactic acid bacteria were stored at $4^{\circ}C$ with the extracted heme and living lactic acid bacterial cells were counted. There were more L. lactis and L. plantarum live cells when stored with heme, whereas L. rhamosus and L. casei showed no significant differences in live-cell numbers. The potential uses of the heme from C. glutamicum are further discussed.

• Asian-Australasian Journal of Animal Sciences
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• 제25권2호
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• pp.234-239
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• 2012

The objective of this study was to evaluate the effects of forage level and oil supplement on selected strains of rumen bacteria believed to be involved in biohydrogenation (BH). A continuous culture system consisting of four fermenters was used in a $4{\times}4$ Latin square design with a factorial arrangement of treatments, with four 10 d consecutive periods. Treatment diets were: i) high forage diet (70:30 forage to concentrate (dry matter basis); HFC), ii) high forage plus oil supplement (HFO), iii) low forage diet (30:70 forage to concentrate; LFC), and iv) low forage plus oil supplement (LFO). The oil supplement was a blend of fish oil and soybean oil added at 1 and 2 g/100 g dry matter, respectively. Treatment diets were fed for 10 days and samples were collected from each fermenter on the last day of each period 3 h post morning feeding. The concentrations of vaccenic acid (t11C18:1; VA) and c9t11 conjugated linoleic acid (CLA) were greater with the high forage diet while the concentrations of t10 C18:1 and t10c12 CLA were greater with the low forage diet and addition of oil supplement increased their concentrations at both forage levels. The DNA abundance of Anaerovibrio lipolytica, and Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) were lower with the low forage diets but not affected by oil supplement. The DNA abundance of Butyrivibrio fibrisolvens stearic acid producer subgroup (Butyrivibrio SA) was not affected by forage level or oil supplement. In conclusion, oil supplement had no effects on the tested rumen bacteria and forage level affected Anaerovibrio lipolytica and Butyrivibrio VA.

• 방사성폐기물학회지
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• 제4권2호
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• pp.153-159
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• 2006

우라늄 변환시설 가동 중 발생하여 라군(lagoon)에 저장중인 방사성 슬러지 폐기물에 대한 처리는 시설 해체과정에서 매우 중요한 업무 중 하나이다. 슬러지 구성성분 중 다량을 차지하는 질산암모늄의 폭발 위험성 등으로 인해 미생물을 이용한 질산염의 분해는 질산염을 안정적으로 처리할 수 있는 효과적인 방법이라 할 수 있다. 본 연구에서는 라군 슬러지의 약 60 wt%를 차지하는 질산염을 혐기성 균주의 하나인 Pseudomonas halodenidificans를 이용하여 탈질하기위한 공정 변수에 대한 영향을 평가하였다. 온도, 질산염 농도, 전자공여체의 영향, C/N 비율, 초기 접종하는 균주의 비율, pH등의 공정변수에 대하여 실험한 이번 결과는 향후 연속식 공정 설계를 위한 기초 자료로 사용될 것이다.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.358-365
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• 2015

ε-Poly-L-lysine (ε-PL) is a homopolymer of L-lysine molecules connected between the epsilon amino and alpha carboxyl groups. This polymer is currently used as a natural preservative in food. Insufficient biomass is a major problem in ε-PL fermentation. Here, to improve cell growth and ε-PL productivity, various nitrogen-rich nutrients were supplemented into flask cultures after 16 h cultivation, marking the onset of ε-PL biosynthesis. Yeast extract, soybean powder, corn powder, and beef extract significantly improved cell growth. In terms of ε-PL productivity, yeast extract at 0.5% (w/v) gave the maximum yield (2.24 g/l), 115.4% higher than the control (1.04 g/l), followed by soybean powder (1.86 g/l) at 1% (w/v) and corn powder (1.72 g/l) at 1% (w/v). However, supplementation with beef extract inhibited ε-PL production. The optimal time for supplementation for all nutrients examined was at 16 h cultivation. The kinetics of yeast-extract-supplemented cultures showed enhanced cell growth and production duration. Thus, the most commonly used two-stage pH control fed-batch fermentation method was modified by omitting the pH 5.0-controlled period, and coupling the procedure with nutrient feeding in the pH 3.9-controlled phase. Using this process, by continuously feeding 0.5 g/h of yeast extract, soybean powder, or corn powder into cultures in a 30 L fermenter, the final ε-PL titer reached 28.2 g/l, 23.7 g/l, and 21.4 g/l, respectively, 91.8%, 61.2%, and 45.6% higher than that of the control (14.7 g/l). This describes a promising option for the mass production of ε-PL.

• 상하수도학회지
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• 제20권3호
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• pp.397-402
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• 2006

The treatment characteristics of leachate produced from pretreatment facilities like composting and feeding were investigated in a mesophilic anaerobic treatment. Experiments were performed in two phase which were acidification and methane fermentation. The acidification step was optimized for OLR from 1 to $4.5kg\;COD/kg\;VS{\cdot}day$ without adding NaOH. As experiment dates became longer, the solubilization ratio of particles increased up to 30% over 70 days. TVA was generated up to maximum 9,970mg HAc/L at OLR of $2kg\;COD/kg\;VS{\cdot}day$. But TVA was generated to minimum 6,519mg HAc/L at OLR of $4.5kg\;COD/kg\;VS{\cdot}day$. The acidification ratio was analyzed from 10.9% to 3.8% at OLR of $2kg\;COD/kg\;VS{\cdot}day$ and $4.5kg\;COD/kg\;VS{\cdot}day$ respectively. After 55 days, salt contents in the acid fermenter were accumulated and stabilized at the concentration of 3,150mg/L. Sodium ion($Na^+$) concentration was stabilized at 1,300mg/L. At methane fermentation step, biogas was generated up to 750ml and 937.5ml at the feeding volume of 20ml and 25ml respectively for acid fermented liquid during 25 days. About 80% of total biogas was generated during early 15 days and 95% were generated during 18 days respectively. After 25 days of the BMP test, acetic acid was removed approximately 97% and 98%, in case of those two experimental conditions.

• 공업화학
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• 제8권4호
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• pp.660-666
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• 1997

본 연구에서는 Streptomyces peucetius subsp. caesius 돌연변이주에 의한 doxorubicin의 생산에 있어서 배양조건 및 배지의 성분을 확립하여 doxorubicind의 생산을 높이는데 목적이 있다. Doxorubicin 생산을 위한 최적 배지조성은 4% maltose, 0.5% HEPES, 0.02% $K_2HPO_4$, 0.01% $MgSO_4$로 나타났고, 가장 적합한 종균 접종량과 시기는 10% (v/v), 72시간이었다. Doxorubicin생산에 적합한 소포제를 찾기위해 여러 종류의 소포제를 배지에 첨가한 결과 가장 적합한 소포제는 KG(10% K+10% G)이었으며 최적농도는 0.01%이었다. 교반식반응기에서 배양할 경우 적합한 통기량은 1.5v/v min으로 최대 29mg/l의 doxorubicin을 생산하였고, 1.0v/v min의 경우에도 플라스크 배양보다 15% 증가된 23mg/l의 doxorubicin을 생산하였다.

• KSBB Journal
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• 제18권2호
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• pp.155-160
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• 2003

Streptoverticillium morbaraene로부터 미생물 유래 transglutaminase 생산을 위하여 최적의 용존산소 농도를 구명하였다. 용존산소는 용존산소 농도 자동 조절 시스템에 의해 조절되었다. 발효 중 용존산소 농도 조절을 위하여 통기속도는 0.3-3.9 L/min, 교반속도는 260-360 rpm으로 각각 범위를 설정하였다. 용존산소 농도를 조절한 다양한 회분식 배양에서 용존산소가 20%일 때 최대 미생물유래 transgiutaminase 생산이 가능하였다. 최분배양에서 용존산소 농도를 20%로 조절한 경우 미생물유래 transglutaminase 생산은 2.12 U/mL이었고, 용존산소를 조절하지 않은 회분식 배양의 미생물유래 transglutaminase 생산보다 1.1배 향상되었다. 역시 가장 높은 미생물유래 transglutaminase 생산은 용존산소를 20%로 조절한 유가식 배양에서 가능하였으며, 용존산소를 조절하지 않은 회분식 배양의 미생물유래 transglutaminase 생산에 비교해서 1.3배 증가하였다. 최대 건조균체량과 미생물유래 transglutaminase 생산은 각각 13.2 g/L와 2.6 U/mL이었다. 용존산소를 20%로 용존산소 농도 자동 조절 시스템에 의해 조절한 유가식 배양은 미생물유래 transgiutaminase 생산에 적절하였으며 다른 미생물 배양에도 적용할 수 있을 것으로 판단된다.

• 한국식품영양학회지
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• 제29권6호
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• pp.962-970
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• 2016

Commercialized production of onion vinegar, which has biological activities formed through alcohol and acetic acid fermentation, requires standardization. The objective of this study was to determine optimal conditions of sugar contents ($11{\sim}15^{\circ}Brix$) and agitation rate (100~300 rpm) of fermenter in the alcohol-acetic fermentation for producing onion vinegar. The alcohol and total acidity contents increased, whereas contents of total sugars decreased during alcohol fermentation. Contents of alcohol of 13 and $15^{\circ}Brix$ reactants were about 8% in 36 hr and total acidities of all samples were below 0.2% in 60 hr. During acetic fermentation, total acidity increased with highest value at 9 days (3.2% in 100 rpm), 10 days (4.1% in 200 rpm) and 8 days (4.3% in 300 rpm), respectively. From these results, sugar contents ($13^{\circ}Brix$) were measured for alcohol fermentation and agitation rate (300 rpm) for fast fermentation method of vinegar. The contents of total phenols, flavonoids and quercetin in onion vinegar were 33.3 mg/100 g, 3.0 mg/100 g and 2.0 mg/100 g, respectively. Onion vinegar showed an antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Escherichia coli and Enterobacter aerogenes. Antioxidant effect of onion vinegar was 26.23% in DPPH radical inhibition and 58.58% in superoxide dismutase like activity, respectively. Fibrinolytic activity was 1.51 plasmin unit/mL in onion vinegar. In conclusion, onion vinegar processed by alcohol and acetic fermentation had nutritional values and potential biological activities.