Heterologous expression of bacteriocin E-760 in Chlamydomonas reinhardtii and functional analysis

The use of antimicrobial peptides (AMPs) synthesized by bacteria (bacteriocins) is an alternative for combating multidrug resistant bacterial strains and their production by recombinant route is a viable option for their mass production. The bacteriocin E-760 isolated from the genus Enterococcus sp. has been shown to possess inhibitory activity against Gram-negative and Gram-positive bacteria. In this study, the expression of a chimeric protein coding for E-760 in the nucleus of C. reinhardtii was evaluated, as well as, its antibacterial activity. The synthetic gene E-760S was inserted into the genome of C. reinhardtii using Agrobacterium tumefaciens. A transgenic line was identified in TAP medium with hygromycin and also by PCR. The increment in the culture medium temperature of the transgenic strain at 35 °C for 10 minutes, increased the production level of the recombinant protein from 0.14 (Noninduced culture, NIC) to 0.36% (Induced culture, IC) of total soluble proteins (TSP); this was quantified by an ELISA assay. Recombinant E-760 possesses activity against Staphylococcus aureus in 0.34 U log, Streptococcus agalactiae in 0.48 U log, Enterococcus faecium in 0.36 U log, Pseudomonas aeruginosa in 2 U log and for Klebsiella pneumoniae, the activity was 0.07 U log. These results demonstrate that the nucleus transformation of C. reinhardtii can function as a stable expression platform for the production of the synthetic gene E-760 and it can potentially be used as an antibacterial agent.