Anionic surfactant based reverse micellar extraction of l-asparaginase synthesized by Azotobacter vinelandii

Application of experimental designs and response surface methods in screening and optimization of reverse micellar extraction

Reverse micellar extraction (RME) has emerged as a versatile and efficient tool for downstream processing (DSP) of various biomolecules, including structural proteins and enzymes, due to the substantial advantages over conventional DSP methods. However, the RME system is a complex dependency of several parameters that influences the overall selectivity and performance of the RME system, hence this justifies the need for optimization to obtain higher possible extraction results. For the last two decades, many experimental design strategies for screening and optimization of RME have been described in literature. The objective of this article is to review the use of different experimental designs and response surface methodologies that are currently used to screen and optimize the RME system for various types of biomolecules. Overall, this review provides the rationale for the selection of appropriate screening or optimization techniques for the parameters associated with both forward and backward extraction during the RME of biomolecules.

Cationic reverse micellar based purification of recombinant glutaminase free L-asparaginase II of Bacillus subtilis WB800N from fermentation media

Reverse micellar extraction (RME), a liquid-liquid based separation is a versatile tool for protein purification. A statistical approach was employed for the purification of recombinant glutaminase free anti-cancerous enzyme viz., l-asparaginase II to evaluate the effects of RME in current study. The cationic system (CTAB/iso-octane/hexanol/butanol) was used in RME to optimize both forward and backward protein extraction efficiency. By adapting Taguchi's orthogonal array (OA), maximum forward extraction efficiency (FEE) of 86.98% with 84.82% enzyme activity recovery and 1.04 times purification fold achieved with the optimized parameters. Under the optimal levels, the back extraction efficiency (BEE) was observed to be 96.97% with 93.07% enzyme activity recovery and 1.38 times purification fold. Further, mass transfer kinetic studies of RME indicated the mass transfer coefficients of forward and backward extraction to be 0.049 min^-1 and 0.036 min^-1 respectively.

Azotobacter vinelandii: the source of 100 years of discoveries and many more to come

Azotobacter vinelandii has been studied for over 100 years since its discovery as an aerobic nitrogen-fixing organism. This species has proved useful for the study of many different biological systems, including enzyme kinetics and the genetic code. It has been especially useful in working out the structures and mechanisms of different nitrogenase enzymes, how they can function in oxic environments and the interactions of nitrogen fixation with other aspects of metabolism. Interest in studying A. vinelandii has waned in recent decades, but this bacterium still possesses great potential for new discoveries in many fields and commercial applications. The species is of interest for research because of its genetic pliability and natural competence. Its features of particular interest to industry are its ability to produce multiple valuable polymers - bioplastic and alginate in particular; its nitrogen-fixing prowess, which could reduce the need for synthetic fertilizer in agriculture and industrial fermentations, via coculture; its production of potentially useful enzymes and metabolic pathways; and even its biofuel production abilities. This review summarizes the history and potential for future research using this versatile microbe.