Production of l-aspartic acid by biotransformation and recovery using reverse micelle and gas hydrate methods

Author： Aydoğan Özlem Bayraktar Emine Parlaktuna Mahmut Mehmetoğlu Tanju Mehmetoğlu Ülkü

ISSN： 1024-2422

Source： Biocatalysis and Biotransformation, Vol.25, Iss.5, 2007-09, pp. : 365-372

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Abstract

l-Aspartic acid (l-Asp) was produced using Escherichia coli (ATCC 11303), and its recovery from the reaction mixture was studied using reverse micelle and gas hydrate methods. The effect of initial substrate concentration on l-Asp production was also investigated, and inhibition was shown to occur above 0.75 mol L-1. The values of the kinetic constants were determined as rmax=2.33×10-4 mol L-1 min-1, KM=0.19 mol L-1, and Kss=3.98 mol L-1. The reverse micelle phase used for extraction contained Aliquat-336, 1-decanol and isooctane, and a micro-injection technique was used for extraction of l-Asp. The reverse micelle system is a useful technique for obtaining small particle sizes, which can be used for the synthesis of nanoparticle biomolecules. Recovery of l-Asp from reverse micelles using CO2 hydrates was carried out, giving a recovery of 55%. The formation of CO2 hydrate from the reverse micelle solution breaks the micelle by reducing the amount of water in the micelle structure, thus precipitating the l-Asp.