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목차

ABBREVIATIONS 13

제1장 총설 (Introduction and Review) 15

1-1. 생분해성 고분자(Biopolymer)의 개요 16

1-2. 미생물에서 PHA granule의 발견 21

1-3. 세포내 저장물질로서의 PHAs 23

1-4. PHAs의 종류 25

1-5. PHAs 생산을 위한 후보 미생물 28

1-6. 식물체에서의 PHA 생산 46

1-7. 미생물로부터 PHAs의 분리 및 회수 49

1-8. PHAs의 응용분야 및 용도 52

1-9. PHAs의 고분자적 물성 55

1-10. PHAs의 생분해도 61

1-11. 본 연구의 목적 65

제2장 Ralstonia eutropha KHB 8862의 유가배양 조건탐색과 Pilot scale fermentor에서의 PHB 대량생산 (Kinetics and Optimization for PHB Mass Production in Pilot Scale Fermentor) 70

1. 서론 71

2. 재료 및 방법 77

2-1. 미생물과 탄소원 77

2-2. 균체성장 및 PHB 축적조건 최적화 77

2-3. P(3HB-co-3HV)의 축적조건 탐색 79

2-4. Jar fermentor에서의 유가배양 조건탐색 81

2-5. Pilot scale fermentor로의 scale-up 83

2-6. Pilot fermentor에서의 PHB 대량생산 조건검토 83

2-7. 분석방법 84

3. 결과 및 고찰 89

3-1. R. eutropha KHB 8862의 특성 89

3-2. 균체성장 및 PHB 축적에 관한 kinetics 93

3-3. 균체성장과 3HV 생합성에 미치는 sodium propionate의 영향 101

3-4. Jar fermentor에서의 PHB 대량생산 103

3-5. Jar fermentor와 pilot fermentor의 dimension 비교 및 scale-up 104

3-6. Pilot fermentor를 이용한 PHB 대량생산 106

제3장 발효생산에 의한 PHB의 경제성 분석(Fermentation Economics of PHB) 110

1. 서론 111

2. 재료 및 방법 117

2-1. 20 ㎥ 발효조에서의 PHB 생산 cost simulation 117

2-2. PHB 생산 cost와 배양학적 parameter의 상관성 118

2-3. 범용 plastic(PET)과의 경제성 비교 118

3. 결과 및 고찰 119

3-1. 20 ㎥ 발효조에서 항목별 PHB cost 산정 119

3-2. PHB 생산 cost down과 배양학적 parameters 122

3-3. 범용수지로서의 PHB 경제성 128

제4장 PHB를 축적한 Biomass로부터 Native PHB Microsphere의 제조 및 생체적합 소재로서의 활용을 위한 특성분석 131

1. 서론 132

2. 재료 및 방법 134

2-1. Microsphere의 제조 134

2-2. Spray drying 134

2-3. 정제 단계별 분자량 변화조사 135

2-4. Microsphere의 형태학적 분석 135

2-5. Microsphere의 입도분석 136

2-6. Mercury porosimetry 분석 137

2-7. 자외선 투과효율 비교측정 138

2-8. 약물이 흡수된 PHB microsphere의 제조 138

2-9. 약물 방출효과 비교측정 139

3. 결과 및 고찰 141

3-1. PHB microsphere를 축적한 R. eutropha의 배양 141

3-2. Microsphere 제조 단계별 분자량 변화 141

3-3. PHB microsphere의 분체로서의 특성 143

3-4. PHB microspheres의 약물흡수 및 방출효과 150

제5장 결론(Conclusions) 155

5-1. R. eutropha KHB 8862의 유가배양을 통한 PHB 대량생산 156

5-2. 미생물 발효생산에 의한 PHB의 경제성 분석 157

5-3. PHB의 새로운 응용분야 탐색과 PHB microsphere 161

참고문헌(References) 164

ABSTRACT 186

Table 1-1. Potential world market size of biodegradable plastics 17

Table 1-2. Restrictions of non-degradable plastic usage in various country. 17

Table 1-3. Recent trends of research and development for biodegradable plastics. 19

Table 1-4. Chemical structure of the major polyhydroxyalkanoates (PHAs) produced in bacteria. 29

Table 1-5. The accumulation of PHAs in a various microorganisms known to from intracellular storage products. 30

Table 1-6. List of limiting compounds leading to PHA formation. 32

Table 1-7. Various PHB purification methods 53

Table 1-8. Possible application fields and usage of PHAs 56

Table 1-9. Physical and thermal properties of various PHAs, PP and PET. 58

Table 1-10. Biodegradation of PHB in various environments 62

Table 2-1. Summary of fed-batch fermentation results for PHB production by various bacteria. 72

Table 2-2. Composition of fructose syrup (HFS-55) 78

Table 2-3. (a) The medium compositions for R. eutropha KHB 8862 (b) The composition of the trace element solution 80

Table 2-4. Biolog test result of R. eutropha KHB 8862 90

Table 2-5. Comparisonal dimensions of jar fermentor and pilot fermentor. 107

Table 2-6. Summary of experimental results of lab scale and pilot scale fermentation. 108

Table 3-1. Production costs breakdown expressed as percentages of total cost 112

Table 3-2. Theoretical yield (Yp/c) of PHB from various carbon sources base on biochemical stoichiometry and their market prices. 115

Table 3-3. Overall process data for estimation of PHB production cost in commercial scale (20 ㎥) fermentor. 120

Table 3-4. Raw materials cost summary 121

Table 3-5. Estimation of PHB production cost in 20 ㎥ fermentor. 124

Table 3-6. Comparison of economic evaluation between PHB and polyester (PET) 129

Table 4-1. Porosimetry results of PHB microsphere 149

Figure 1-1. Biodegradable protects made of PHAs: (a) safety razors made of PHB homopolymer by molding process, (b) bottles made of... 20

Figure 1-2. Transmission electron microscopic (TEM) view of the bacteria showing accumulation of electron-lucent PHA inclusions. 24

Figure 1-3. Classification of various PHAs 27

Figure 1-4. Pathway of PHB and P(3HB-co-3HV) synthesis in Ralstonia eutropha. 34

Figure 1-5. Expression of the PHB biosynthetic pathway in the cytoplasm (a) and plastid (b) of transgenic Arabidopsis cells. 47

Figure 1-6. Sequence of operations for pilot-scale production of PHB/PHAs from microbial biomass using propylene carbonate for extraction after partial... 51

Figure 1-7. Physical properties of P(3HB-co-3HV) : Effects of 3HV composition on (a)melting point, (b)heat of fusion, and (c)mechanical... 59

Figure 1-8. Biodegradability of P(3HB-co-3HV) film and bottle in soil. 66

Figure 1-9. Biodegradability comparison of HDPE, P(3HB-co-3HV), and starch-added film in soil. 67

Figure 1-10. Biodegraded PHB molded product (safety razor) and P(3HB-co-3HV) film in soil. 68

Figure 2-1. Simplified layout of fed-batch system for PHB production 86

Figure 2-2. Pilot scale fermentor and separation system for PHB production. 87

Figure 2-3. CO₂-O₂, gas analyzer system for on-line monitoring of fermentation. (VIA-300 infrared CO₂ analyzer & PMA-200 magnetic... 88

Figure 2-4. Colony morphology of Ralstonia eutropha KHB 8862 on (a) glucose (small yellowish colony) and (b) fructose syrup (large... 91

Figure 2-5. Morphological comparison of (a) normal growth cell and (b) irregular PHB accumulating cell. 92

Figure 2-6. Effect of (a) temperature and (b) pH on cell growth rate. 94

Figure 2-7. Effect of (a) fructose syrup (HFS) and (b) NH4+ concentration on growth rate and PHB production rate : ●, specific growth rate ; ○,...[이미지참조] 95

Figure 2-8. Effect of (a) NH₄OH(28%) and (b) PO4-3 on cell growth and PHA accumulation : ●, specific growth rate; ○, final pH; □, dry cell... 96

Figure 2-9. Effect of (a) MgSO₄ and (b) mineral solution on cell growth: ●, dry cell weight; ○, final pH. 98

Figure 2-10. (a) Effect of C/N ratio of feeding media on cell growth and PHB content in constant feeding (initial DCW＝8.5g/L, PHB content... 99

Figure 2-11. Effect of sodium propionate concentration and proportions in carbon source on cell growth rate, final pH, and 3HV content : ●, dry... 102

Figure 2-12. Experimental results for mass production of PHB by fed-batch culture: (a) ●, dry cell weight; ▲, PHB amount; ○, PHB content... 105

Figure 3-1. The composition of PHB production cost: (a) total cost, (b) raw material cost 123

Figure 3-2. The effect of yield and productivity on PHB production cost : (a) ●, productivity＝1.24; □, 2.0; ▲, 3.0; ○, 4.0; ■, 5.0,... 126

Figure 4-1. Spray dryer for manufacturing PHB microsphere. 140

Figure 4-2. Molecular weight (Mw) distribution according to purification process: ―, chloroform extracted intact PHB; ……,... 142

Figure 4-3. Electron microscopy of spray dried native PHB microsphere; (a)SEM(x 10,000), (b)TEM(x 100,000). 145

Figure 4-4. Cumulative and differential mass distribution of spray dried native PHB microsphere (a) disc centrifuge method, (b) laser diffraction... 146

Figure 4-5. Cumulative and incremental mercury intrusion curve of spray dried native PHB microsphere: (a) inter-microsphere... 148

Figure 4-6. UV transmittance spectra of PHB microsphere (----) and TiO₂(―). 151

Figure 4-7. Cumulative in vitro release profile of ISDN from PHB microspheres: □, free ISDN (20 ㎎ of standard drug); ○, ISDN in PHB microspheres (3%,... 153