• 미생물과산업
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• 제19권4호
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• pp.2-13
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• 1993

Some microorganisms, including actinomycetes, cyanobacteria, and other bacteria, algae, fungi, and yeast, can accumulate and retain relatively high quantities of heavy metals and radionuclides from their external environments (1-4). Both living and dead cells can be used for biosorptive metal/radionuclide removal from solution. Thus microorganisms and products excreted by or derived from microbial cells (2) may provide an alternative or adjunct to conventional techniuqes of metal removal and recovery. Recent approaches have separated the microbial growth and metal removal process to manipulate production of metal-adsorptive capacity of bacteria and metal removal process. If pre-grown cells are immobilized and used for metal removal, mathematical modeling can be applied to predict immobilized cell reactor behavior under specific process conditions. Waste and microbial adsorbent could be separated from the treated flow in one step. Once treated, the metal waste is concentrated in a small volume of sorbed form for easy metal disposal or recovery.

• 한국식품영양과학회지
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• 제19권5호
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• pp.395-402
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• 1990

The semicontinuous production of blue pigment from gardenia fruit by immobilized cells of Bacillus subtilis KS-380 which excreted $\beta$-glucosidase was investigated in comparison with free cells, . The blue pigment produced higher productivity under the conditions of aeration of 0.2m$\ell$/min and 2mm diameter of gel beads by using 3.5% sodium alginate. Semicontinuous production by immobilized cell showed the highest productivity with replacement of fresh production medium in every 24hr for fourth fermentation cycle following the conditions of blue pigment productivity.

• KSBB Journal
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• 제6권4호
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• pp.351-361
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• 1991

This study is on the investigation of hydrogen production and substrate removal by photosynthetic bacteria. After using of Rhodospillum rubrum KS-301 and IFO 3986, which are photosynthetic bacteria as strains, R. rubrum KS-301 was turned out a better strain. And result of experiment in which glucose and sodium lactate, components of wastewater, were used limiting substrates, showed that the productivity of hydrogen was indifferent with the kind of substrates. In batch experiments using free cells and immobilized whole cells, the decrease in hydrogen productivity was observed in the latter case. From the results of these experiments, specific growth rate of cells, specific utilization rate of glucose, and specific production rate of hydrogen were calculated. And each rate was expressed in the form of Monod equation of which parameters were estimated. Also the optimum condition of hydrogen production for free cells was $30^{\circ}C$, pH 7, and 12,000 Lux, and the optimum immobilized condition was as follows: initial immobilized cell concentration 1.0g/L, sodium alginate concentration 2% and light intensity 12,000 Lux.

• 한국식품과학회지
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• 제11권4호
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• pp.249-257
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• 1979

전보에서 저자들을 물리적 견고성이 우수한 포도당 이성화 효소를 세포 고정화 시킨 제품을 얻었다.(한국 식품 과학 회지, 11(No. 3), 192(1979). 이 효소 제품을 사용하여 실험실 조건에서 회분식 반응조와 충진식 반응조를 운영하여 효소의 반응 특성과 생산성, 활성 감소 현상을 비교 하였다. 본 고정화 효소의 비활성 역가는 회분식 반응조와 충진식 반응조에서 1 g당 각각 48 및 114 units였으며 연속적인 공정에서 더 높은 생산성과 이성화율을 보였다. 효소의 생산성은 체장 시간, 기질의 농도, 효소 부하율(附荷率) 및 반응조의 외형에 영향을 받았으며 충진 밀도가 450 g/l일 때 실제 공간율은 0.36이었으며 비교적 좋은 충진 현상을 보였다. 연속 공정중 효소의 활성 감퇴 현상을 고찰하기 위하여 2.5 M 포도당 용액을 체장 시간이 5.3시간이 되도록 약 220시간 동안 반응시켜 본 결과, 효소 활성 감퇴 곡선은 일차 반응을 따르며 활성 반감기는 115일로 연속 공정에 이용 가능함을 알았다. 이 고정화 효소 제품은 물리적 안정성이 높은 반면 물질 전달 계수가 반응 속도에 큰 영향을 미치는 것으로 나타났다.

• 한국미생물·생명공학회지
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• 제16권6호
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• pp.510-516
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• 1988

본 연구는 균주로 Rhodospirillum rubrum KS-301, 증식 제한 기질로 글루코오스, 고정화 담체로 Ca alginate를 사용한 고정화 생물 반응기를 조작할 때 담체에 의해 형성되는 물질전달 저항에 대한 도입 기질의 농도, 희석속도의 영향을 고찰하였다. 또한 효율인자를 평가하기 위해 속도식 변수를 구하였다. 충전층 반응기의 경우 외부 액막 물질전달 저항보다는 내부 물질전달 저항이 우세함을 알 수 있었고 총괄 효율인자는 희석속도의 증가에 따라 감소하였다. 연속 교반 탱크 반응기의 경우 외부 액막 물질전달 저항은 무시할 수 있으며 총괄 효율인자는 희석속도에 영향을 받지 않았다. 희석속도 0.2/h, 비드 반경 0.15cm, 초기 글루코오스 농도 1.0g/L의 실험조건에서 총괄 효율인자는 충전층 반응기와 연속 교반 반응기에서 각각 0.70과 0.77이었다.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.373-380
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• 1993

When the cells of yeast K35 were immobilized in Ca-alginate gel, cell concentration and viability decreased as alginate concentration increased. Considering the results, 2% (w/v) Ca-alginate concentration would be suitable. Among various concentrations of additives and cross-lin-king agent, the addition of 1.67% (w/v) of bentonite together with 0.33% (v/v) of glutaraldehyde (ABG bead) resulted in the highest ethanol production of 1.8%(w/v), using YPD medium containing 2% glucose. ABG bead seemed to be more resistant to phosphate ion than Ca-alginate bead. 0.33%(w/v) of phosphate was a proper concentration for the ethanol production by ABG bead. Scanning electron microscopic observation depicted that the immobilized cells on the bead surface were coated by alginate gel and that the cells in the internal bead were cross-linked with alginate matrix. When repeated-batch culture was performed with ABG bead for 40 days in a packed-bed reactor, ethanol concentration of about 90~110 g/l-gel was maintained. Cell viability was maintained around 70%, and outgrowing cell concentration was below 6.3% of total cell concentration. Consequently, the results showed that ABG head was a potential carrier for continuous production of ethanol compared to conventional Ca-alginate bead.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.329-331
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• 2000

A marine bacterium, Pseudomonas aeruginosa BYK-2 KCTC 18012P was immobilized in modified polyvinyl alcohol for the continuous production of rhamnolipids. The stability of rhamnolipids production, the mechanical strength of beads and the scanning electron microscope of immobilized cell were determined in a repeated batch culture. The rhamnolipids production was maintained $80{\sim}90%$ stability of initial production, and the mechanical strength also was stable during the repeated batch culture more than 14 cycles. In the case of SEM studies, the internal distribution pattern of the cell entrapped in modified PVA beads was observed. On the basis of optimal conditions, the continuous culture was investigated in 1.8L air lift bioreactor. The result suggested 0.1g/h rhamnolipids was obtained from 1%(v/v) fish oil continuously in conditions of 1.2L working volume, 0.5vvm and 20ml/h flow rate.

• 한국환경농학회지
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• 제29권2호
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• pp.176-183
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• 2010

Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.

• 한국미생물·생명공학회지
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• 제13권2호
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• pp.115-118
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• 1985

리파마이신 B 산화효소의 활성을 갖고 있는 Humicola spp. (ATCC 20620)를 아세톤 처리 한 후 cellulose acetate로 고정화하여 그 특성을 조사하였다. 고정화 효소에 있어서 pH는 7.2온도는 50-55%에서 최대 활성을 보였으며, 비고정화 효소에 비하여 pH와 온도변화에 덜 민감하였다. 외경 3mm bead size에서 20%의 활성회수율을 보였으며, storage stability는 4$0^{\circ}C$ 이하에서는 아주 좋았으며 5$0^{\circ}C$ 이상에서는 급격히 활성이 감소하였다. 고정화 담체로서 cellulose acetate는 물리적으로 견고하여 삼상반응기의 packing material로써 적당하였다.

• Mycobiology
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• 제48권2호
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.