A two-enzyme constituted mixture to improve the degradation of Arthrospira platensis microalga cell wall for monogastric diets

The main goal of this study was to test a rational combination of pre-selected carbohydrate-active enzymes (CAZymes) and sulphatases, individually or in combination, in order to evaluate its capacity to disrupt Arthrospira platensis cell wall, allowing the release of its valuable nutritional bioactive compounds. By the end, a two-enzyme constituted mixture (Mix), composed by a lysozyme and a α-amylase, was incubated with A. platensis suspension. The microalga cell wall disruption was evaluated through the amount of reducing sugars released from the cell wall complemented with the oligosaccharide profile by HPLC. An increase of the amount of reducing sugars up to 2.42 g/L in microalgae treated with the Mix relative to no treatment (p < .05), as well as a 7-fold increase of oligosaccharides amount (p < .001), were obtained. With resort of fluorescence microscopy, a 36% reduction of fluorescence intensity (p < .001) was observed using Calcofluor White staining. In the supernatant, the Mix caused a 1.34-fold increase in protein content (p = .018) relative to the control. Similarly, n-6 polyunsaturated fatty acids (PUFA) (p = .007), in particular 18:2n-6 (p = .016), monounsaturated fatty acids (MUFA) (p = .049) and chlorophyll a (p = .025) contents were higher in the supernatant of microalgae treated with the enzyme mixture in relation to the control. Taken together, these results point towards the disclosure of a novel two-enzyme mixture able to partial degrade A. platensis cell wall, improving its nutrients bioavailability for monogastric diets with the cost-effective advantage use of microalgae in animal feed industry.