Earticle

Lait caille is a traditional fermented milk product in Burkina Faso. The objective of this study was to contribute to consumer acceptance of lait caille . For this purpose, the production practices in rural and urban areas were identified through semi-structured interviews, while the perceived quality of lait caille in urban area was investigated through a survey. Then, microbiological and physico-chemical parameters were analysed on samples from rural and urban sites. Finally, an attempt to improve the hygiene of the traditional processing was proposed by use of Lactococcus lactis and Leuconostoc mesenteroides stains as starter. These were previously isolated from traditional lait caille . The results on the manufacturing processes revealed from the raw milk practices of spontaneous fermentation, backslopping and contact with bacterial biofilms attached to container. The survey on perceived quality indicated that traditional lait caille possessed a niche market which could be enlarged by implementation of good manufacturing practices in the production sites. The microbiota of the end product was characterised by high loads of Enterococcus spp., Enterobacteria and Pichia spp. Fermented milks by starter cultures showed improved hygienic quality and a positive sensory appreciation. However, the use of selected strains might be followed by loss of some features of traditional lait caille , which scientists should work to resolve.

Effect of nitrogen-load condition on hydrogen (H2) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight H2 production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest H2 production was obtained when the C/N ratio was 36, the H2 production yield (mol-H2 / mol-glucose) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the H2 production. The H2 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 H2 production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of H2 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 H2 productivity through the change of bacterial community in anaerobic hydrogen fermentation.

This study was indicated to enhance the anti-inflammation activities by the fermentation of the fruits of Aroniamelanocarpa (Michx.) Elliott. The extracts by 70% ethanol (EE) showed better biological activities than those by hotwater (WE) from campared result of the effect of extraction solvents. Then, the extract from 70% ethanol extraction wasfurther fermented by lactic acid, denoted as FEE. For antioxidant activities, the FEE had showed the highest value as 0.832of reducing powder, in comparison with those of EE and WE. Cytotoxicity of the water extraction (WE) was measured for12.06% in addition of 1.0 ㎎/㎖ of FEE. For anti-inflammation activities, NO production from the macrophage, RAW 264.7was observed as 7.24 μM and 8.52 μM from FEE and EE, respectively. Prostaglandin E2 (PGE2) production from humanfibroblast cell, CCD-986sk, was also estimated for 152 pg/㎖ in addition of 1.0 ㎎/㎖ of the FEE. The lowest production ofboth IL-6 and TNF-α were 3.5 pg/㎖ and 865.5 pg/㎖, respectively in addition of 1.0 ㎎/㎖ of the FEE, whereas 74.5 pg/㎖and 982.4 pg/㎖ in treated with same concenrations of the EE. It was also found that the FEE was higher amounts thanother extracts through HPLC analysis of the anthocyanins. These results strongly indicate that fermentation process of thelactic acid could enhance anti-inflammation activities of extracts by increasing the amounts of the anthocyanins, especiallycyanidin-galactoside. Our results suggest that the application of the fermentation process for other medicinal herbs can beimproved their biological activities.

This study was performed to enhance contents of low molecular ginsenoside using steaming and fermentationprocess in low quality fresh ginseng. For increase in contents of Rg2, Rg3, Rh2 and CK in low quality fresh ginseng, a steamingprocess was applied at 90℃ for 12 hr which was followed by fermentation process at Lactobacillus rhamnosus HK-9incubated at 36℃ for 72 h. The contents of ginsenoside Rg1, Rb1, Rc, Re and Rd were decreased with the steaming associatedwith fermentation process but ginsenoside Rg2, Rg3, Rh2 and CK increased after process. It was found that under thesteaming associated with fermentation process, low molecule ginsenosides such as Rg2, Rg3, Rh2 and CK were increased as3.231 ㎎/g, 2.585 ㎎/g and 1.955 m/g and 2.478 ㎎/g, respectively. In addition, concentration of benzo[α]pyrene in extracts ofthe low quality fresh ginseng treated by the complex process was 0.11 ppm but it was 0.22 ppm when it was treated with thesteaming process. This result could be caused by that the most efficiently breakdown of 1,2-glucoside and 1,4-glucoside linkageto backbone of ginsenosides by steaming associated with fermentation process. This results indicate that steaming processand fermenration process can increase in contents of Rg2, Rg3, Rh2 and CK in low quality fresh ginseng.

This study was to investigate anti-skin wrinkle effect of Agastache rugosa Kentz extracts by extraction processes. In the comparison of the effect of the solvent extraction, the extracts by 70% ethanol (EE) showed better biological activitiesthat those by hot water. Therefore, further fermented Agastache rugosa was applied to 70% ethanol extraction process(FEE). FEE showed higher DPPH scavenging activity of 62.98% than EE’s 62.71% at 1.0 ㎎/㎖, but there was no significant. Elastase inhibition was measured 23.0% from FEE at 1.0 ㎎/㎖. Cytotoxicity showed the highest 16.26% from FEE, thisvalue is safe in the cell experiment. Collagen production showed 113.1 ng/㎖ from FEE, on the other hand EE was measured77.4 ng/㎖ in adding 1.0 ㎎/㎖. MMP-1 production was observed 1398 pg/㎖ from FEE and EE was measured1632 pg/㎖. These results were found the highest antioxidant and anti-wrinkle effect. As a result, it was also confirmed thatanti-skin wrinkle activities of the Agastache rugosa Kentz extract was correlated with anti-oxidant activities.

This study compared the contents of low molecular ginsenoside according to fermentation process in low grade fresh ginseng. Low grade fresh ginseng was directly inoculated with a 24 h seed culture of Bifidobacterium Longum B6., Lactobacillus casei., and incubated at 36℃ for 72 h. Bifidobacterium Longum B6 was specifically was found to show the best growth on 3,255 × 106CFU/㎖ after 48 h of fermentation. The content of ginsenoside Rb1, Re and Rd were decresed with the fermentation but ginsenoside Rh2 and Rg2 incresed after fermentation process. In the case of low molecular ginsenoside conversion yields were 56.07% of Rh2, 12.03% of Rg3 and 77.11% of Rg2, respectively. In addition, compound-K was irregular conversion yield as long as 72 h of fermentaion. This results indicate that fermentation process could increase the low molecular ginsenoside in low grade fresh ginseng.

Odor management is significantly concerned with sustainable livestock production because odor nuisance is a primary cause for complaint to neighbors. This study was conducted to measure the concentration of odorous compounds, odor intensity, and odor offensiveness at unit process in animal waste treatment facility combined composting and methane fermentation process by an instrumental analysis and direct olfactory method. Ammonia, sulfur-containing compounds, and volatile fatty acid were analyzed at each process units and boundary area in summer and winter, respectively. Higher concentration of odorants occurred in the summer than in the winter due to high ambient temperature. The maximum concentration of odorants was detected in composting pile when mixed manure was being turned followed by inlet, curing, outlet, and screen & packing process. Highest concentration of detected odorous compounds was ammonia ranging from 3.4 to 224.7 ppm. Among the sulfur-containing compounds measured, hydrogen sulfide was a maximum level of 2.3 ppm and most of them exceeded reported odor detection thresholds. Acetic acid was the largest proportion of VFA generated, reaching a maximum of 51 to 89%, followed by propionic and butyric acid at 1.9 to 35% and 1.8 to 15%, respectively. Malodor assessment by a human panel appeared a similar tendency in instrumental analysis data. Odor quotient for predicting major odor-causing compounds was calculated by dividing concentrations measured in process units by odor detection thresholds. In the composting process, hydrogen sulfide, ammonia, dimethyl sulfide, and methyl mercaptan were deeply associated with odor-causing compounds, while the major malodor compounds in the inlet process were methyl mercaptan, hydrogen sulfide, and butyric acid.

This study was performed to compare alcohol fermentation ability and saccharification of potatoes and sweet potatoes. Cooperated with ultrasonification process is not contain pass through cook process, but contain process using ulrasonification instead cook process. In result of sugar contents measurements sweet potato and potato was highest of a family at 6 hours fermentation, and it showed the highest sugar contents as each 11.5 brix, 10.4 brix. In result of alcohol contents measurements of sweet potato and potato, highest of a family in 4 days, and it showed th highest alcohol contents as each 8.2, 6.0%. Finally complex enzymes II process revealed similar activities like cook process.

음폐수(FWL)는 퇴비화와 사료화와 같은 음식물류 자원화 시설로부터 발생된다. 본 연구의 목 적은 벤치규모의 부상분 리 및 상향류 블랭킷 여상(UBF) 연계공정을 이용한 산발효액 특성에 대해 조사 분석을 하였다 . 부상분리 공정에서 고형 물과 지방성분의 높은 제거효율을 보였다. 이는 UBF 반응조의 상부에 스컴과 머드볼의 생성 을 막을 수 있었다. 산발효 액의 휘발성 유기산(VFA)의 농도는 21,610 mg/L이었고, 조성은 acetic acid, butyric acid, propoinic acid와 같은 short chain 유기산이 약 82%를 차지하였다. 또한 산발효조에 총 미생물 중 부착미생물이 차지하는 비율은 61.2%이었다. 산 발 효한 FWL액의 특성은 N·P함량이 낮고 용존 물질이 높다. 따라서 이액은 생물학적 질소 인 제 거시 외부탄소원으로 사용 될 수 있을 것으로 사료된다.

The food waste leachate (FWL) produces from food waste resource plant as a compost and feed. The objective of this study was to investigate the characteristics of acid fermentation liquid from food waste leachate by combined bench scale floating separation and upflow blanket filter (UBF) process. The constituents of solids and fat showed high removal efficiency in floating separation process. These results could prevent the generation of scum and mud balls at the top of the UBF reactor. The volatile fatty acid (VFA) of acid fermentation liquid was 21,610 mg/L, the major components were the short chain fatty acids such as acetic acid, butyric acid, and propoinic acid. These acids were about 82% in composition of VFA. Also, the ratio of attached biomass to total biomass in acid fermentation reactor was 61.2%. The characteristics of fermented FWL have a low N·P content and a high soluble matter. Therefore, this liquid could be used as an external carbon source for the biological N and P removal.

본 연구의 목적은 알칼리 가수분해와 상향류 블랭킷 여상(upflow blanket filter : UBF)의 조합공정을 이용한 음식물류폐기물의 전처리 및 산발효 특성에 대해 조사 분석을 하였다. 음식물류 폐기물의 이상적인 산발효 효율을 얻기 위해,NaOH희석수 0.075 g NaOH/g TS의 주입은 UBF 산발효조의 pH조정을 위해 사용하였다. 생산된 최대 휘발성유기산(VFA)농도와 생산율은 TS농도 기준 2배 희석, 수리학적 체류시간(HRT) 2일에서 19,070 mg/L, 120.6%이었다. 이들 조건들이 UBF 산발효조의 최적운전 조건이었다. COD 제거율과 가용화율(Ps)은 희석비가 낮고 체류시간이 길수록 증가하였다. 단백질, 지방, 탄수화물은 체류시간이 길수록, 유기물부하가 높을수록 제거율이 높았다. 조 내의 총 미생물량 중 부착미생물이 차지하는 비율은 5.8~12.4%이었다. 반응조 상부에는 다량의 머드볼(mudball)이 생성되었으며, 이것은 장치운전에 영향을 미칠 수 있었다.

The objective of this study was to investigate the characteristics of pretreatment and acid fermentation of food wastes by combining alkali hydrolysis and upflow blanket filter (UBF) process. In order to obtain reasonable acid fermentation efficiency of food wastes, the NaOH dilution water of 0.075 g/g TS was injected to adjust the pH in the UBF acid fermentation reactor. The maximum concentration and production rate of volatile fatty acid (VFA) were 19,070 mg/L, 120.6% at the hydraulic retention time (HRT) of 2days and the dilution ratio of 2 times based on initial TS concentration, respectively. These conditions were optimal operating conditions for UBF acid fermentation reactor. The COD removal efficiency and solubilization rate (Ps) were increased with the lower dilution ratio and longer HRT. The removal efficiencies of protein, fatty, carbohydrate in this reactor became higher with the increment of organic loading rate and HRT. The attached biomass of total biomass in the reactor was 5.8~12.4%. Much of the mudball in the upper part of the reactor had been created, it could affect on the device operation.

This study was to establish the optimum process conditions to improve the content of low molecular weight ginsenosides in low quality fresh ginseng by steaming pretreatment process associated with fermentation process. To increase the low molecular ginsenoside Rg2 and Rg3 content, the low quality fresh ginseng was extracted at 240 bar for 3 hrs, then fermented by Lactobacillus rhamnosus HK-9 at 36 for 24, 48, 72 hr. At this time, the amount of fermented broth was set to 100, 300, 500L to select the optimal fermentation conditions. Ginsenosides Rg1, Rb1, Rc, Re, Rd content in the low quality fresh ginseng was decreased throughout the steaming pretreatment associated with fermentation process. The low molecular ginsenosides Rg2, Rg3 content was depend on the fermentation time and amount of fermentation broth. When fermented for 72 hours from the fermentation broth of 100L, Rg2 and Rg3 maximum content shows 3.704 mg/g, the 4.609 mg/g, respectively. When fermented for 72 hours still in fermentation broth 300L, the maximum content of Rg2 and Rg3 was 3.411 mg/g, 4.642 mg/g, respectively. In the case of 500L fermentation, when the fermentation time was 48 hours, Rg2, Rg3 maximum content showed up to 3.426 mg/g, 4.736 mg/g, respectively. These results that low molecular ginsenoside content does not appear to change significantly in the bulk of the fermentation process conducted to determine the optimal process conditions, 500L fermentation volume was carried out 48 hours fermentation (inoculum concentration 10% v/v) the highest to the low molecular weight ginsenosides was confirmed that the transition is possible. It was found that high molecule ginsenosides were efficiently converted low molecule ginsenosides through steamed process and Lactobacillus fermentation process that are generated from β-glucosidase enzyme activity due to the promotion of the party in the presence of ginsenosides β-1,2 and β-1,4 bond through hydrolysis. These showed that scale-up fermentaton associated with steaming pretreatment process were increased the low molecule ginsenosides Rg2, Rg3 content from low quality fresh ginseng.

본 연구에서는 광학적 특성이 우수한 GPTMS 졸-겔에 pH와 용존산소를 검출할 수 있는 6-aminofluorescein과 Ru(dpp)32+를 고정화하였다. 제조한 검출막의 광학적 특성을 조사하였고 E.coli JM109와 P.pastoris X-33의 발효 중 pH와 용존산소를 모니터링하는데 사용하여 오프라인으로 측정 된 데이터와 비교, 고찰하였다. 여기파장 480 nm와 방출파장 600 nm에서 최적 형광검출파장을 나타내는 용존산소 검출막에 흑연이 혼합된 절광층을 재코팅한 막이 0%와 100% 용존산소 조건에서 800 [RFU]의 형광세기 차이를 나타냈다. 제조한 용존산소 검출막을 사용하여 E.coli JM109와 P.pastoris X-33의 발효중 배양액내의 용존산소를 모니터링한 결과, 미생물의 성장에 따른 용존산소량의 변화를 잘 모니터링 할 수 있었다. 한편, GPTMS 졸-겔에 6-aminofluorescein을 고정화하여 제조한 pH 검출막은 여기파장 480 nm와 방출파장 520 nm에서 최적 검출파장을 나타내었고 절광막을 재코팅한 검출막이 pH의 변화에 따라 높은 감도를 나타내었다. 제조한 pH 검출막에 E.coli JM109와 P.pastoris X-33을 배양하여 발효시간에 따른 배양액의 pH 변화를 오프라인으로 측정하고 형광세기 변화와 비교하였다. 발효중 미생물의 유기산 생산과 단백질분해로 인한 pH 변화를 pH 검출막이 잘 모니터링 함을 볼 수 있었다. 따라서 본 연구에서 제조한 pH와 용존산소 검출막은 높은 감도등 우수한 광학적 특성을 보여줄 뿐만 아니라 미생물 발효 중 pH와 용존산소를 온라인 모니터링 할 수 있음을 알 수 있다.

In this study, the sensing membranes for detection of pH and dissolved oxygen(DO) were prepared by immobilizing 6-aminofluorescein or ruthenium complex onto the sol-gel matrixes of GPTMS, MTMS, and TEOS and then recoated with the mixture of hydrophobic sol-gel and graphite for light insulation. The pH and DO sensing membranes recoated with the light insulation layer showed a higher sensitivity than those without light insulation layer. The sensing membranes were immobilized on the wells of 24-well microplate and used to monitor the fluorescence intensity for pH and DO in E.coli JM109 and P.pastoris X-33 fermentation processes. The change of the fluorescence intensity in the DO sensing membrane agreed with the growth patterns of microorganisms, that the membranes are valuable to monitor the DO in fermentation processes. In the case of pH monitoring, the fluorescence intensity has showed good correlation to the off-line pH data, that the pH membranes are valuable to monitor pH values in fermentations.

본 연구에서는 고가의 TreH를 형질전환한 대장균으로부터 생산하고 부분적으로 정제한 후, 에폭시에 고정화하고 트레할로스-FIA 시스템에 이용하였다. 산소 전극을 이용한 트레할로스 검출 방법과 분광학적 방법을 이용한 트레할로스 검출 방법을 비교하고, 공정에서의 온라인 모니터링의 가능성을 검토하였다. 산소 전극을 이용한 분석의 경우 다른 대사 물질로 인한 간섭현상이 상대적으로 적고 검출 가능한 농도가 0.1~1.0 g/L로 많은 량의 트레할로스를 생산 하는 공정을 모니터링할 경우 적합한 시스템임을 알 수 있었다. 반면 분광학적 방법으로 트레할로스를 검출한 실험의 경우 TreH와 GOD/HRP를 고정하여 실험한 경우와 TreH만 고정하고 GOD와 HRP를 직접 주입하는 방식을 비교했을 때 검출 가능한 농도는 0.01~0.2 g/L로 낮은 농도의 트레할로스를 모니터링할 경우에 적합하다. 그러나 ABTS나 GOD, HRP의 주입량 등 경제성과 운전이 편이성 등을 고려할 경우 GOD와 HRP를 직접 주입하는 시스템이 가장 효과적임을 알 수 있었다. 이 시스템을 이용하여 소형 생물반응기 내 트레할로스의 농도를 온라인 모니터링한 결과는 오프라인 값과 매우 잘 일치함을 보였다. 생물공정에서 트레할로스의 온라인 모니터링이 FIA 기술에 의해 가능함을 확인하였다.

Trehalose is non-reducing disaccharide which is found in bacteria, fungi, plants and insects. Trehalose has been determined by several analysis methods. To monitor the concentrations of trehalose in a process, enzymatic methods have more advantage over others, e.g. more specific. In this work, trehalase was immobilized on VA-epoxy polymer and applied to FIA systems. The behaviours of these FIA systems were characterized and used to monitor the trehalose concentrations. Use optical detection technique was chosen for trehalose-FIA system. On-line monitoring data and off-line data were measured HPLC.

본 연구에서는 2차원 형광스펙트럼의 PCA분석을 통하여 발효 공정을 모니터링하고 PCR과 PLS과 같은 다변량 분석 기법을 이용하여 공정을 모델링하였다. 재조합 대장균 E. coli와 효모 S.cerevisiae의 발효 공정 중에 얻어진 많은 양의 2차원 형광스펙트럼 자료는 우선 PCA를 통해 축소된다. 그리고 PCA에서 주성분점수와 적재 산점도는 발효 공정의 정성적 경향을 묘사하기 위해 사용되었다. 또한, PCR과 PLS는 2차원 형광스펙트럼의 분석을 위해 사용되었으며 PLS모델이 보정과 예측 능력에서 PCR모델보다 조금 더 우수한 성능을 나타냈다. 따라서 2차원 형광스펙트럼 자료를 이용하여 생물공정을 모델링 하고자 할 때는 PCR 방법보다는 PLS 방법을 사용하는 것이 유리할 것이다.

spectrofluorometer produces many spectral data during fermentation processes. The fluorescence spectra are analyzed using chemometric methods such as principal component analysis (PCA), principal component regression (PCR) and partial least square regression (PLS). Analysis of the spectral data by PCA results in scores and loadings that are visualized in score-loading plots and used to monitor a few fermentation processes by S. cerevisae and recombinant E. coli. Two chemometric models were established to analyze the correlation between fluorescence spectra and process variables using PCR and PLS, and PLS was found to show slightly better calibration and prediction performance than PCR.

수소를 생산하는 미생물은 크게 광합성 세균 (photosynthetic bacteria), 혐기성세균 (non-photosynthetic anaerobic bacteria), 조류 (algae) 등으로 구분되고, 이들의 수소 생성 기작, 사용가능 기질 및 수소 발생량은 상당한 차이가 있다. 광합성세균은 Rhodospirillaceae, Chromatiaceae 및 Chlorobiaceae로 구분되며, 이는 각각 홍색비유황세균 (purple non-sulfur bacteria), 홍색유 황세균 (purple sulfur bacteria), 녹색유황세균 (green sulfur bacteria)으로 통칭된다. 혐기성 세균은 절대 또는 통성혐기세균중 일부가 수소생산에 관여하며, 조류는 녹조류 (green algae)와 남조류 (blue-green algae, cyanobacteria)가 알려져있다. 생물학적 수소생산 기술은 ① 녹조류 (green algae)가 광합성 메카니즘에 의해 수소를 생산하는 직접 물 분해 수소생산(direct bio-photolysis) ② 광합성 작용에 의해 물을 분해하여 산소를 발생하고, 동시에 공기 중 이산화탄소를 고정하여 고분자 저장물질로 균체 내에 저장한 후 혐기 발효 또는 광합성 발효에 의해 수소를 발생하는 간접 물 분해 수소생산(indirect bio-photolysis or two stage photolysis) ③ 빛이 존재하는 혐기상태 배양 조건에서 홍색 세균에 의한 광합성 발효(photo-fermentation) 또는 ④ 광이 존재하지 않는 조건에서 혐기 미생물에 의해 수소와 유기산을 내는 혐기 발효 (dark anaerobic fermentation) ⑤ 균체 외 (in vitro) 수소 발생 ⑥ 일산화탄소 가스 전환 반응 (microbial gas shift reaction)에 의한 수소 생산 기술로 구분할 수 있다. 물로부터 생물학적 기술에 의한 수소생산은 공기 중의 이산화탄소를 고정하고, 수소와 산소를 발생하는 원천기술로써 오래 전부터 미국, 유럽에서 태양에너지를 이용하는 광합성 미생물의 분리, 개선 및 반응기에 관한 연구가 축적되어 왔으며, 유기물 즉 바이오매스로부터 혐기 및 광합성 발효를 연속적으로 적용하는 기술은 비교적 최근에 일본을 비롯한 유기성 폐기물이 많은 국가에서 수소에너지생산과 유기성 폐기물 처리라는 두 가지 목적에 부합하는 연구로써 활발히 진행되고 있다. 유기성 폐기물이나 폐수와 같은 수분함량이 높은 바이오매스는 대부분이 매립처리 되는 실정이지만 높은 수분함량 때문에 매립 시 발생하는 침출수는 환경오염의 주범으로 가까운 장래에는 매립도 금지될 전망이다. 이와 같은 수소에너지 생산기술과 이용시스템 개발은 화석연료 사용을 최소화 할 수 있으며, 국내에서 다량 발생하는 유기성 폐기물을 이용한 에너지 생산으로 자원 강대국 입지에 설수 있다. 미생물에 의한 수소생산 기술은 청정에너지 생산과 아울러, 동시에 산소 발생, 공기 중 이산화탄소 고정, 식품공장 폐수 및 음식쓰레기와 같은 유기성 폐기물 처리 등 환경에 이로운 방향으로 진행될 뿐만 아니라, 미생물 자체가 갖는 생물 산업성도 높아서 비타민류, 천연색소, 피부암 치료제등의 고부가가치 의약품 생산도 활성화할 수 있다.

Hydrogen (H2) as a clean, and renewable energy carrier will be served an important role in the future energy economy. Several biological H2 production processes are known and currently under development, ranging from direct bio-photolysis of water by green algae, indirect bio-photolysis by cyanobacteria including the separated two stage photolysis using the combination of green algae and photosynthetic microorganisms or green algae alone, dark anaerobic fermentation by fermentative bacteria, photo-fermentation by purple bacteria, and water gas shift reaction by photosynthetic or fermentative bacteria. In this paper, biological H2 production processes, that are being explored in fundamental and applied research, are reviewed.

Polyhydroxyalkanoates (PHAs) are biological polyesters that are produced by a wide variety of bacteria as an intracellular storage material of carbon and energy. PHAs have attracted industrial attention because of their potential use as practical biodegradable thermoplastics. Xylose is the most abundant sugar in the hemicelluloses of hardwoods and crop residues, and the efficient production of PHA from xylose reduces production cost. Certain bacteria can produce PHA from xylose; however, high production rate and yield of PHA from xylose have not been achieved. Some lactic acid bacteria are capable of efficiently fermenting xylose into lactic acid and acetic acid at high production rate. These organic acids produced from xylose can be used as carbon sources for R.eutropha, the most famous PHA producer, and able to convert into PHA. We investigated the feeding strategy of the mixture of lactic acid and acetic acid for fed-batch culture of R. eutropha to efficiently produce PHA from xylose by way of such organic acids. Vegetable oils are also desirable feedstock for PHA production. Since vegetable oils compose a much higher number of carbon atoms per weight than glucose and sucrose, the yield coefficients of PHA production from vegetable oils are as high as over 0.7 g-PHA per g-vegetable oils (sugars are in the range of 0.2-0.4 g-PHA per g-substrate). To produce PHA from soybean oil as a model substrate, recombinant R. eutropha was generated and cultured in 10-l laboratory scale fermentor. As a result, high dry cell weight (138 g/l) and high PHA content (74% w/w) were achieved after 96 h of cultivation, with high production yield ranging from 0.72 to 0.74 g-PHA per g-soybean oil. Furthermore, we evaluated whether PHA production form vegetable oils is environmentally friendly bioprocess by life cycle assessment-based approach.

The bioethanol for use as a liquid fuel by fermentation of renewable biomass as an alternative to petroleum is important from the viewpoint of global environmental protection. Recently, many scientists have attempted to increase the productivity of bioethanol process by developing specific microorganism as well as optimizing the process conditions. In the present study, which is based on our previous investigation on the pretreatment process, the productivity of bioethanol obtained from simultaneous saccharification and fermentation (SSF) process was compared between various domestic materials including barley, brown rice, corn and sweet potato. Additionally, Solid- glucoamylase (SGA; developed in Changhae Co.), from modified strain with UV, was used. The result was compared to commercial glucoamylase. It was observed that the fermentation rate was increased together with the yield which can be derived from the final ethanol concentration. Especially, in the case of brown rice, compared to the experimental results using previous saccharification enzyme, the final ethanol concentration was 1.25 times higher and 12.82% of the yield was increased. Also, the time required for reaching 95% of the maximum ethanol concentration is significantly reduced, which is approximately 36 hours, compared to 88 hours using commercial glucoamylase.

Ethanol production processes using crops have been well established; however, utilization of a cheaper substrate such as lignocellulose could make bioethanol more competitive with fossil fuel, without the ethical concerns associated with the use of potential food resources. This study, in this sense, dealt with the diluted acid pretreatment of cassava stem as lignocellulosic biomass, following by enzymatic saccharification and fermentation to form ethanol by S. cerevisiae. Pretreatment conditions were optimized using response surface methodology (RSM) allowing the study on influence of the different variables (temperature, time, acid concentration). As a result, the optimal conditions were established for the pretreatment process with temperature at 177°C, 10 min of reaction time and acid concentration of 0.14M. In case of saccharification, enzymatic digestibility was fixed at approximately 70% with cellulase 20 FPU/g cellulose considering economic feasibility. Also, ethanol concentration and yield were attained at 7.55 g/L in 24 h and 89.6%, respectively. This study presented not only the overall process but also an efficient bioethanol production from lignocellulosic materials.