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Improvement of Butanol Fermentation by Supplementation of Butyric Acid Produced from a Brown Alga
Jey -R. S. Ventura,장덕진 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.6
This study investigated butanol fermentationusing glucose and culture broth containing butyrate from thebutyrate fermentation of a brown alga, Laminaria japonica. Prior to the use of the biologically-produced butyrate, theinitial glucose in tryptone-yeast extract acetate (TYA)medium was first optimized for butanol fermentation usingClostridium saccharoperbutylacetonicum N1-4 ATCC 27021T. Then, a commercially-acquired (synthetic) butyrate wassupplemented to the TYA medium containing the optimalglucose concentration (around 30 and 60 g/L). Accordingto the experimental results, the highest butanol carbon yield(0.580 C-mol/C-mol) was obtained from the fermentationof 36.65 g/L glucose and 7.29 g/L synthetic butyrate. Fermentation of a similar amount of glucose (32.28 g/L) inthe absence of butyrate gave a butanol carbon yield of0.402 C-mol/C-mol. For the experiment with fermentedbutyrate, a 100 g/L biomass of brown alga was fermentedby Clostridium tyrobutyricum ATCC 25755 and the culturebroth containing butyrate was used to prepare TYA mediumafter removing the bacterial cells. Fermentation using thesynthetic butyrate and the biologically-produced butyrate(4.95 g/L) gave a comparable butanol concentration (13.23 g/L)and butanol carbon yield (0.513 C-mol/C-mol). Overall,this study proved that the addition of fermented butyratefrom brown alga fermentation could be an effective way toimprove butanol production. Furthermore, the reuse ofspent medium and the absence of rigorous purification ofthe broth containing butyrate would lower the productioncost of the fermentation.
Ventura, Jey-R S.,Hu, Hui,Jahng, Deokjin Springer-Verlag 2013 Applied microbiology and biotechnology Vol.97 No.16
<P>This study elucidated the importance of two critical enzymes in the regulation of butanol production in Clostridium acetobutylicum ATCC 824. Overexpression of both the 6-phosphofructokinase (pfkA) and pyruvate kinase (pykA) genes increased intracellular concentrations of ATP and NADH and also resistance to butanol toxicity. Marked increases of butanol and ethanol production, but not acetone, were also observed in batch fermentation. The butanol and ethanol concentrations were 29.4 and 85.5?% higher, respectively, in the fermentation by double-overexpressed C. acetobutylicum ATCC 824/pfkA+pykA than the wild-type strain. Furthermore, when fed-batch fermentation using glucose was carried out, the butanol and total solvent (acetone, butanol, and ethanol) concentrations reached as high as 19.12 and 28.02?g/L, respectively. The reason for improved butanol formation was attributed to the enhanced NADH and ATP concentrations and increased tolerance to butanol in the double-overexpressed strain.</P>
OSA 공정의 세포 내 ATP, NAD(H), NADP(H) 농도
벤추라제이알 ( Jey R Sabado Ventura ),남지현 ( Ji Hyun Nam ),양빈친 ( Benqin Yang ),나리 ( Ri Na ),길혜진 ( Hyejin Kil ),남덕현 ( Deok Hyeon Nam ),강기훈 ( Ki Hoon Kang ),장덕진 ( Deokjin Jahng ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.6
In order to investigate why OSA (oxic-settling-anaerobic) process produces less sludge than CAS (conventional activated sludge) process, sequential cultivation through 1st aerobic-anaerobic-2nd aerobic conditions, were carried out. Then, the intracellular concentrations of adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD and NADH), and nicotinamide adenine dinucleotide phosphate (NADP and NADPH) were monitored for these three stages. Results showed that the concentrations of these energy substances rapidly decreased through time in both aerobic and anaerobic conditions but the anaerobic culture contained the lower energy level than aerobic culture. The 2nd aerobic culture that experienced anaerobic condition showed lower concentration of these energy substances than those of the 1st aerobic culture. Meanwhile, the anaerobic culture corresponding to the sludge holding stage of OSA was subjected to different soluble chemical oxygen demand (SCOD) levels, detention time, and temperature to evaluate the effects of these variations on the energy level difference between the 1st and 2nd aerobic stages. The lower the SCOD concentration, the longer detention time; and the higher temperature in the anaerobic stage tended to further reduce the intracellular level of the 2nd aerobic culture. On the average, the intracellular energy level of the anaerobic and 2nd aerobic stage were 57.73% and 39.12% of the 1st aerobic culture, respectively. These indicated that the insertion of an anaerobic stage between two aerobic stages could lower the intracellular energy levels, hence the lower the sludge in OSA than CAS process. Moreover, manipulation of the operating conditions of the intervening anaerobic stage can change intracellular energy levels thereby controlling sludge production.
( Ji-hyun Nam ),( Jey-r S. Ventura ),( Ick Tae Yeom ),( Yongwoo Lee ),( Deokjin Jahng ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.11
1,4-Dioxane-degrading bacterial consortia were enriched from forest soil (FS) and activated sludge (AS) using a defined medium containing 1,4-dioxane as the sole carbon source. These two enrichments cultures appeared to have inducible tetrahydrofuran/dioxane and propane degradation enzymes. According to qPCR results on the 16S rRNA and soluble di-iron monooxygenase genes, the relative abundances of 1,4-dioxane-degrading bacteria to total bacteria in FS and AS were 29.4% and 57.8%, respectively. For FS, the cell growth yields (Y), maximum specific degradation rate (V<sub>max</sub>), and half-saturation concentration (K<sub>m</sub>) were 0.58 mg-protein/mg-dioxane, 0.037 mg-dioxane/mg-protein·h, and 93.9 mg/l, respectively. For AS, Y, V<sub>max</sub>, and K<sub>m</sub> were 0.34 mg-protein/mg-dioxane, 0.078 mg-dioxane/mg-protein·h, and 181.3 mg/l, respectively. These kinetics data of FS and AS were similar to previously reported values. Based on bacterial community analysis on 16S rRNA gene sequences of the two enrichment cultures, the FS consortium was identified to contain 38.3% of Mycobacterium and 10.6% of Afipia, similar to previously reported literature. Meanwhile, 49.5% of the AS consortium belonged to the candidate division TM7, which has never been reported to be involved in 1,4-dioxane biodegradation. However, recent studies suggested that TM7 bacteria were associated with degradation of non-biodegradable and hazardous materials. Therefore, our results showed that previously unknown 1,4-dioxane-degrading bacteria might play an important role in enriched AS. Although the metabolic capability and ecophysiological significance of the predominant TM7 bacteria in AS enrichment culture remain unclear, our data reveal hidden characteristics of the TM7 phylum and provide a perspective for studying this previously uncultured phylotype.