Production of recombinant proteins in the cyanobacterium Synechococcus elongatus PCC 7942 using light intensity and magnetic fields as alternative inducers
Author: Arthur Cássio de Sousa Cardoso (Currículo Lattes)
Advisor: Dr. Luis Fernando Fernandes Marins
Abstract
Cyanobacteria are emerging as key alternatives in the search for accessible raw materials in sustainable aquaculture, contributing to atmospheric carbon dioxide capture and using it as an inorganic carbon source to increase biomass. Among them, cyanobacteria are particularly noted for their natural ability to integrate exogenous DNA into their genome, making them attractive biofactories for the production of recombinant proteins (RPs). However, the low yield of these biofactories remains one of the main obstacles to their broader application in biotechnological processes. This thesis aimed to improve the efficiency of the cyanobacterium Synechococcus elongatus PCC 7942 for RP production using different strategies to enhance expression. In the first study, the performance of a commercial nickel-inducible promoter (PnrsB) was evaluated in comparison to a native, constitutive promoter (PpsbA2) for the expression of the reporter protein ZsGreen1, under the influence of a 30 mT magnetic field (MF30). The results demonstrated that RP production in S. elongatus PCC 7942 can be enhanced using the native PpsbA2 promoter in combination with MF30 application. In the second study, different light intensities and exposure times were tested in cultures containing two native cyanobacterial promoters related to photosystem II (PpsbA1 and PpsbA2). It was observed that shorter exposure times could lead to higher RP yields with these promoters. Overall, PpsbA2 was more efficient than PpsbA1. When induced for 6 hours under higher light intensity (500 μmol m⁻² s⁻¹), PpsbA2 led to increased production of the target protein. The third study explored an innovative strategy to enhance biotechnological processes using photoautotrophic microorganisms, applying magnetic fields to boost RP production. The optimal conditions established in the second study were used with the PpsbA2 promoter, and significant increases in transcription levels (45%) and fluorescence (25–28%) were observed under the 30 mT magnetic field. The use of cyanobacteria combined with magnetic field application as a non-toxic, low-cost, and environmentally sustainable approach appears to be a promising tool to improve RP yields driven by native promoters. This thesis paves the way for further exploration of the molecular mechanisms influenced by magnetic fields, enhancing biomolecule production by cyanobacteria with commercial potential and applications in aquaculture.