Novel combination of feed enzymes to improve the degradation of Chlorella vulgaris recalcitrant cell wall

Abstract

In this study, a rational combination of 200 pre-selected Carbohydrate-Active enzymes (CAZymes) and sulfatases were tested, individually or combined, according to their ability to degrade Chlorella vulgaris cell wall to access its valuable nutritional compounds. The disruption of microalgae cell walls by a four-enzyme mixture (Mix) in comparison with the control, enabled to release up to 1.21 g/L of reducing sugars (p < 0.001), led to an eight-fold increase in oligosaccharides release (p < 0.001), and reduced the fluorescence intensity by 47% after staining with Calcofluor White (p < 0.001). The Mix treatment was successful in releasing proteins (p < 0.001), some MUFA (p < 0.05), and the beneficial 18:3 n -3 fatty acid (p < 0.05). Even if no variation was detected for chlorophylls (p > 0.05), total carotenoids were increased in the supernatant (p < 0.05) from the Mix treatment, relative to the control. Taken together, these results indicate that this four-enzyme Mix displays an effective capacity to degrade C. vulgaris cell wall. Thus, these enzymes may constitute a good approach to improve the bioavailability of C. vulgaris nutrients for monogastric diets, in particular, and to facilitate the cost-effective use of microalgae by the feed industry, in general.

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

“…To quantify the amount of reducing sugars released, the 3,5-dinitrosalicylic acid (DNSA) method (Miller, 1959) was used, as described by Coelho et al (2019).…”

“…The thermostability analysis was performed, according to Coelho et al (2019). As the temperature of incubation increased, the amount of protein in the supernatant reduced.…”

“…Chlorophyll a, chlorophyll b and total carotenoids were quantified in supernatant and residue fractions from A. platensis suspension, after control and Mix treatments, as reported by Hynstova et al (2018) with slight modifications as described by Coelho et al (2019). …”

“…The fatty acid profile and content of supernatant and residue fractions of A. platensis suspension after control and Mix treatments were determined, as described by Coelho et al (2019).…”

“…The concentration of A. platensis suspension was 20 g/L. The preparation of microalga cell suspension included a pre-wash step with phosphate-buffered saline (PBS), followed by centrifugation and resuspension of the microalgae pellet in PBS, as described by Coelho et al (2019).…”