Aspergillus ibericus biomass production by submerged fermentation of Codium tomentosum hydrolysate

Abstract

Seaweeds are potential feedstocks for biorefinery approaches, owing to their carbohydrate content, high biomass production and lack of lignin content, which makes saccharification more feasible. The seaweed sugar-rich hydrolysates can be used to produce alternative protein sources, such as mycoprotein, to meet the increasing global protein needs in a sustainable way. Therefore, this study aimed to produce biomass of the filamentous fungus Aspergillus ibericus MUM 03.49, a non-mycotoxin producer, from a seaweed hydrolysate. Firstly, hydrothermal pretreatment of Codium tomentosum was performed in an autoclave, followed by enzymatic hydrolysis using the commercial enzyme cocktail Cellic® Ctec 2 or a fungal enzyme crude extract. With the commercial enzyme cocktail, the maximum saccharification of cellulose and xylan was obtained when using 500 U g1 (around 75% and 30%, respectively), while when using the fungal enzyme extract, around 100% cellulose and 50% xylan conversion were achieved with 180 U xylanase g1. The obtained sugar-rich hydrolysate was used as the culture medium for A. ibericus growth in a stirred tank bioreactor. Several values of volumetric oxygen mass transfer coefficients (kLa) were used, from 20 to 66 h1, and a maximum biomass yield of 85% was achieved in batch cultures. The fungal biomass recovered contains 28% (w/w, dry mass) protein, 28% ash and 3% lipids. Aspergillus ibericus biomass has great potential as a protein alternative source for several applications, including in the food and feed industries.