Soybean is one of the plant species with potential to be used as seed-based bioreactor. As part of the downstream processing (DSP) of this technology, extraction is a key step, since it defines the composition of the solution from which the recombinant product will be purified. In the present work, the characteristics of soybean seeds used as a bioreactor were evaluated from a process engineering standpoint through analysis of the influence of pH and ionic strength on the extraction of recombinant beta-glucuronidase (rGUS). Concentrations of recombinant protein and native soybean compounds were analyzed and compared with similar data from extraction studies using transgenic corn seeds as bioreactor. Efficient rGUS extraction was obtained at pH of around 5.5 with no addition of salt. Soybean seed extracts had lower levels of co-extracted native compounds, than corn seed extracts, and should be considered as a potential plant bioreactor in terms of DSP.

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Electrocoagulation is a technique basically applied in water and wastewater treatment, but which has a number of potential applications in polymer, protein, drug, and vaccine delivery. In this work, we correlate the current applied between the electrodes to the removal of phenolic compounds or protein from aqueous solutions, but the principle can also be applied to other biological compounds such as plant pigments and sugars. Simple and time-dependent models were developed based on the complex formation between these biological substances and the aluminium hydroxide gel phase. The models developed represent a good agreement with experimental data (R(2) as high as 0.992). Besides construction of the models, the effect of pH on the efficiency of removal of proteins and phenolic compounds was evaluated. It was found that this parameter has significant effect on the efficiency of the electrocoagulation and the maximal removal efficiency for bovine serum albumin and phenolic compound catechin was observed at pH 8.0.

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The use of recombinant proteins has increased greatly in recent years, as have the number of techniques and materials used for their production and purification. The principal advantage of using plants as bioreactors is the cost of the recombinant protein production, which is about 1000-fold lower as in the case of using CHO cells commonly applied in industry today. Among the different types of "green" bioreactors being studied today, there is a general consensus among scientists that production in green plant tissues such as leaves is more feasible. However, the presence of chlorophyll and phenolic compounds in plant extracts, which can precipitate and denature the proteins besides damaging separation membranes and gels, makes this technology impracticable on a commercial scale. Electrochemically produced aluminium hydroxide gel can be used to adsorb these compounds, and pre-purify recombinant synthetic green fluorescent protein (sGFP) produced in Nicotiana benthamiana leaves. Removal efficiencies of 99.7% of chlorophyll, 88.5% of phenolic compounds, and 38.5% of native proteins from the N. benthamiana extracts were achieved without removing sGFP from the extracts. Since electrochemical preparation of aluminum hydroxide gel is a cost-effective technique, its use can substantially contribute to the development of future production platforms for recombinant proteins produced in green plant tissues of pharmaceutical and industrial interest.