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Glycerol assimilation and production of 1,3-propanediol by Citrobacter amalonaticus Y19
Ainala, Satish Kumar,Ashok, Somasundar,Ko, Yeounjoo,Park, Sunghoon Springer-Verlag 2013 Applied microbiology and biotechnology Vol.97 No.11
<P>Citrobacter amalonaticus Y19 (Y19) was isolated because of its ability for carbon monoxide-dependent hydrogen production (water-gas shift reaction). This paper reports the assimilation of glycerol and the production of 1,3-propanediol (1,3-PDO) by Y19. Genome sequencing revealed that Y19 contained the genes for the utilization of glycerol and 1,2-propanediol (pdu operon) along with those for the synthesis of coenzyme B12 (cob operon). On the other hand, it did not possess the genes for the fermentative metabolism of glycerol of Klebsiella pneumoniae, which consists of both the oxidative (dhaD and dhaK) and reductive (dhaB and dhaT) pathways. In shake-flask cultivation under aerobic conditions, Y19 could grow well with glycerol as the sole carbon source and produced 1,3-PDO. The level of 1,3-PDO production was improved when vitamin B12 was added to the culture medium under aerobic conditions. Under anaerobic conditions, cell growth and 1,3-PDO production on glycerol was also possible, but only when an exogenous electron acceptor, such as nitrate or fumarate, was added. This is the first report of the glycerol metabolism and 1,3-PDO production by C. amalonaticus Y19.</P>
Metabolic Flux Change in Klebsiella pneumoniae L17 by Anaerobic Respiration in Microbial Fuel Cell
김창만,Satish Kumar Ainala,오유관,전병훈,박성훈,김중래 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.2
The metabolic flux in microbial fuel cells (MFCs) is significantly different from conventional fermentation because the electrode in MFCs acts as a terminal electron acceptor. In this study, the difference in the carbon metabolism of Klebsiella pnuemoniae L17 (Kp L17) during growth in MFCs and conventional bioreactors was studied using glucose as the sole carbon and energy source. For metabolic flux analysis (MFA), the in silico metabolic flux model of Kp L17 was also constructed. The MFC bioreactor operated in oxidative mode, where electrons are removed by the anode electrode, generated a smaller quantity of reductive metabolites (e.g., lactate, 2,3-butanediol and ethanol) compared to the conventional fermentative bioreactor (non-MFC). Stoichiometric analysis indicated that the cellular metabolism in MFC had partially (or significantly) shifted to anaerobic respiration from fermentation, the former of which was similar to that often observed under micro-aerobic conditions. Electron balance analysis suggested that 30% of the electrons generated from glucose oxidation were extracted from the microbe and transferred to the electrode. These results highlight the potential use of MFCs in regulating the carbon metabolic flux in a bioprocess.
설은희,( Sundara Sekar Balaji ),( Satish Kumar Ainala ),박성훈 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
To address low H<sub>2</sub> production yield by dark fermentation, co-production of H<sub>2</sub> and ethanol by E. coli from glucose, was suggested in this study. Moreover, ethanol is one of the attractive biofuel producible through the fermentation. In order to increase the cofactor availability for ethanol production, operation of Pentose-Phosphate (PP) pathway was tried by deleting pgi in the base strain (E. coli BW25113 ΔhycA ΔhyaAB ΔhybBC ΔldhA ΔfrdAB). Additional over-expression of G6PHD and 6PGDH recovered the cell growth of Δpgi mutant as well as increased co-production yield by decreasing acetate formation. Resulting strain increased co-production yield (1.65 for H<sub>2</sub> and 1.38 mol/mol for ethanol) which corresponds to ~85% energy recovery from glucose showing the possibility of operating PP pathway under anaerobic condition.