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A novel perchlorate- and nitrate-reducing bacterium, Azospira sp. PMJ
Nam, Ji-Hyun,Ventura, Jey-R S.,Yeom, Ick Tae,Lee, Yongwoo,Jahng, Deokjin Springer-Verlag 2016 Applied microbiology and biotechnology Vol.100 No.13
<P>A novel perchlorate-reducing bacterium (PCRB), PMJ, was isolated from the mixed liquor suspended solids in the aerobic tank of a wastewater treatment plant. The 16S ribosomal RNA (rRNA), perchlorate reductase, and chlorite dismutase gene sequences revealed that PMJ belonged to the genus Azospira. PMJ was removed high-strength (700 mg/L) perchlorate and also removed low-strength (a parts per thousand currency sign50 mg/L) perchlorate below the detection limit (2 mu g/L) when acetate was used as a sole and carbon source. The maximum specific perchlorate utilization rate, q (max,) was 0.96 mg ClO4 (-)/mg dry cell weight day, and the half-saturation constant, K (S) , was lower than 0.002 mg ClO4 (-)/L. PMJ also utilized inorganic electron donors [(H-2, S-0, and Fe(II)] with perchlorate as an electron acceptor. Perchlorate reduction by PMJ was completely inhibited by oxygen and chlorate but was not inhibited by nitrate. In the presence of similar concentrations (100 similar to 140 mg/L) of nitrate and perchlorate, PMJ simultaneously removed both electron acceptors. Therefore, it was concluded that the strains PMJ might possess separate pathways for perchlorate and nitrate reduction. These results indicated that Azospira sp. PMJ could be efficiently used for treating perchlorate-contaminated groundwater and wastewater because many of these water bodies are known to contain both perchlorate and nitrate. In addition, low K (S) value and autotrophic perchlorate reduction of PMJ might be useful to design the biological treatment systems.</P>
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>
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.
Butyric Acid Production from Brown Algae Using Clostridium tyrobutyricum ATCC 25755
Ji-Hee Song,Jey -R. S. Ventura,이창희,장덕진 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1
Butyric acid fermentation by Clostridium tyrobutyricum ATCC 25755 using glucose or brown algae as a carbon source was carried out. Initially, different fermentation modes (batch, fed-batch, and semi-continuous)at pH 6 and 37oC were compared using a model medium containing glucose as a carbon source. By feeding the whole medium containing 40 ~ 50 and 30 g/L of glucose into the fed-batch and semi-continuous fermentations,very similar butyrate yields (0.274 and 0.252 g butyrate/g glucose, respectively) and productivities (0.362and 0.355 g/L/h, respectively) were achieved. The highest butyrate concentration was about 50 g/L, which was observed in the fed-batch fermentation with whole medium feeding. However, semi-continuous fermentation sustained a longer fermentation cycle than the fed-batch fermentation due to end-product and metabolic waste inhibition. The established conditions were then applied to the fermentation using brown algae, Laminaria japonica and Undaria pinnatifida, as substrates for butyric acid fermentation. To hydrolyze brown algae, 7.5 ~ 10% (w/v) dried brown algae powder was suspended in 1% (w/v) NaOH or 0.5 ~ 2.5%(w/v) H2SO4 and then autoclaved at 121oC for 30 ~ 90 min. The resulting butyrate concentration was about 11 g/L,which was produced from 100 g/L of L. japonica autoclaved for 60 min in 1.5% H2SO4 acid solution.
( 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.