Insights into Common Octopus (Octopus vulgaris) Ink Proteome and Bioactive Peptides Using Proteomic Approaches
Supervisors: Camino Gestal, Sonia Dios (CSIC-Vigo)
The common octopus (Octopus vulgaris) is nowadays the most demanded cephalopod species for human consumption. This species was also postulated for aquaculture diversification to supply its increasing demand in the market worldwide, which only relies on continuously declined field captures. In addition, they serve as model species for biomedical and behavioral studies. Body parts of marine species are usually removed before reaching the final consumer as by-products in order to improve preservation, reduce shipping weight and increase product quality. These by-products have recently attracted great attention due to discovery of the presence of several relevant bioactive compounds. Particularly, the common octopus ink has been described as antimicrobial and antioxidant properties, among others. In this study, the advanced proteomics discipline was applied to generate a common octopus reference proteome for the screening of potential bioactive peptides from fishing discards and by-products such as ink. A shotgun proteomics approach by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using an Orbitrap Elite instrument was used to create a reference dataset from octopus ink. A total of 1,432 different peptides belonging to 361 non-redundant annotated proteins were identified. The final proteome compilation was investigated by integrated in-silico studies, including gene ontology (GO) term enrichment, pathways, and networks studies. Different immune functioning proteins involved in innate immune system such as ferritin, catalase, proteasome, Cu/Zn superoxide dismutase, calreticulin, disulfide isomerase, heat shock protein, etc. were found in ink protein networks. Additionally, the potential of bioactive peptides from octopus body parts that are usually discarded was addressed. These bioactive peptides can exert health beneficial properties such as antimicrobial, antioxidant, antihypertensive and antitumoral and are therefore considered as lead compounds for the development of pharmacological, functional foods or nutraceuticals.

Keywords: Octopus; Octopus vulgaris; ink; by-product; shotgun proteomics; mass spectrometry; protein-based bioinformatics; bioactive peptides