Extraction and characterization of chitin, chitosan, and protein hydrolysate from the invasive Pacific blue crab, Portunus segnis (Forskål, 1775) having potential biological activities.

The diversity of marine biomasses is a set of exploitable and renewable resources with application in several sectors. In this context, a co-culture based on three protease-producing bacterial isolates, namely Aeribacillus pallidus VP3, Lysinibacillus fusiformis C250R, and Anoxybacillus kamchatkensis M1V strains, was carried out in a medium based on the blue swimming crab Portunus segnis bio-waste. Proteases production was optimized using a central composite design (CCD). The highest level of proteases production obtained was 8,809 U/mL in a medium comprising 75 g/L of Portunus segnis by-product powder (Pspp). The biological value of Pspp and its obtained derivatives were evidenced via accredited protocols. The recovered protein hydrolysate (PHyd) was found to be active towards radical scavenging power and against angiotensin I-converting enzyme (ACE). The blue crab chitin (BC) extraction efficiency was achieved with a yield of 32%. Afterwards, chitosan was prepared through chitin N-deacetylation with a yield of 52%, leading to an acetylation degree (AD) of 19% and solubility of 90%. In addition, chitosan is found to be active against the growth of all pathogenic bacteria tested.