BIOFUEL PRODUCTION IN ARGENTINA. OPPORTUNITIES AND CHALLENGES

SIÑERIZ F.; MENDEZ, BS

Dalian, China

Conferencia; XIII International Biotechnology Symposium; 2008

Biofuels are considered as a viable alternative to liquid fuels, especially for transportation. Recent legislation passed in Argentina indicates that biofuels should replace 5% of the liquid fuels by year 2010. This would mean the production of about 400.000 m3 of ethanol to mix with gasoline and about 800.000 m3 of biodiesel. This goal, though modest, has stirred an open debate on the rationality of the approaches employed to reach this production. Ethanol from sugar cane is the most efficient way to produce biofuels from plant material at the present time, due to the fact that sugar cane is planted once every 6-8 years, that very little labouring is needed and that bagasse is burnt in the boilers to produce energy to run the whole process. (1 unit of fuel used produces 8 units of energy as ethanol). The diminution of Green house gases due to the actual production of 200.000 m3 is 430.000 Tm CO2 eq per year [1]. One of the main drawbacks detected is related to the production of  waste products like stillage in the case of alcohol distilleries or by products like glycerol in the case of biodiesel production. Glycerol, which constitutes about 10% of the product of the biodiesel synthesis, could be a suitable substrate for fermentations conducting to reduced bioproducts as ethanol using Escherichia coli. ArcA is a global regulator that switches on the expression of fermentation genes and represses the aerobic pathways when E. coli enters low oxygen growth conditions[2]. CreBC is a two-component signal transduction pair, where CreB is the regulator and CreC the sensor kinase The cre regulon includes ack/pta, talA, trgB and malE, involved in carbon metabolism. These genes are activated upon transfer of E.coli to minimal medium, with the exception of malE, that is repressed[3]. The metabolic profile of E. coli CT1062 (¦¤arcA) and CT1061 (arcA::IS10 creCc) grown for 48 h in microaerobiosis with glycerol as carbon source were determined and compared with E. coli K1060, the arcA+ parent. The ethanol/acetate ratio was 0.87 for the parent strain, 2.01 for CT1062 and 12.51 for CT1061. Accordingly, the NADH/NAD+ ratios were 0.18, 0.63 and 0.97 respectively[4]. This method could result in an increased production of ethanol as by product of biodiesel production. References [1] Macedo, I. De C., Lima, M. R., Ramos da Silva, J., Azevedo, E. , 2004. Assesment of greenhouse gas emissions in the production and use of fuel ethanol in Brazil. Governo do Estado de Sao Paulo.  [2] Lynch, A. S., and E. C. C. Lin. 1996. Responses to molecular oxygen, p. 1526-1538. In F. C. Neidhardt, R.Curtiss, J. L. Ingraham, E. C. C. Lin, K. B. Low, B. Magasanik, W. S. Reznikoff, M. Riley, M. Schaechter, and H. E. Umbarger (ed.), Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 1. ASM Press, Washington D.C. [3] Avison, M. B., R. E. Horton, T. R. Walsh, and P. M. Bennett. 2001. Escherichia coli CreBC is a global regulator of gene expression that responds to growth in minimal media. J. Biol. Chem. 276:26955-26961 [4] Nikel. P.I., Pettinari, M.J., Ram¨ªrez, C., Galvagno, M. A.  and M¨¦ndez, B. S. Escherichia coli arcA mutants: metabolic profile characterization of microaerobic cultures using glycerol as a carbon source. J. Molec. Microbiol. Biotechnol. 15: 48-54 .2008