Abstract
The yeast Pichia pastoris was cultivated under different dissolved oxygen (DO) levels (5, 15, 30 and 50% of the air saturation) to evaluate its impact on the production of the cell-wall polysaccharide chitin–glucan complex (CGC) and mannans. Decreasing the DO level from 50 to 15% had no significant impact on cell growth but substrate conversion into biomass was improved. Under such conditions, a mannans content in the biomass of 22 wt% was reached, while the CGC content in the biomass was improved from 15 to 18 wt%, confirming that the DO level also impacted on P. pastoris cell-wall composition. Overall mannans and CGC volumetric productivity values of 10.69 and 8.67 g/(L. day) were reached, respectively. On the other hand, the polymers’ composition was not significantly affected by decreasing the DO level. These results demonstrated that considerable energy savings can be made in the polysaccharide production process by reducing the DO level during cultivation of P. pastoris by improving the overall polymers’ productivity without altering their composition. This has impact on the polysaccharide production costs, which is of considerable relevance for process scale-up and products’ commercialization.
Highlights
Accepted: 19 January 2022Chitin–glucan complex (CGC) is a co-polymer composed of chitin and β-(1,3)-glucans.The combination of the two bioactive polysaccharides in the same macromolecule makeschitin–glucan complex (CGC) a promising biomaterial for several medical applications, due to its immunomodulator, antitumor, antioxidant and antimicrobial properties [1]
25.71 g/L was obtained by cultivation with a dissolved oxygen (DO) level of 15%, while lower dry cell weight (DCW) values
The decrease of the DO level from 50 to 15% resulted in a 15% improvement of the biomass production
Summary
Accepted: 19 January 2022Chitin–glucan complex (CGC) is a co-polymer composed of chitin and β-(1,3)-glucans.The combination of the two bioactive polysaccharides in the same macromolecule makesCGC a promising biomaterial for several medical applications, due to its immunomodulator, antitumor, antioxidant and antimicrobial properties [1]. Chitin–glucan complex (CGC) is a co-polymer composed of chitin and β-(1,3)-glucans. The combination of the two bioactive polysaccharides in the same macromolecule makes. CGC a promising biomaterial for several medical applications, due to its immunomodulator, antitumor, antioxidant and antimicrobial properties [1]. CGC has been used in pharmaceutical applications, such as the treatment of diabetes, obesity [2], heart diseases [3]. Mannans are polysaccharides mainly composed of mannose units. To CGC, mannans are an interesting material in the medical field, due to their immunological, antimutagenic and antioxidant properties [5]. Mannans can be used in food formulations due to their emulsifying and prebiotic effects [6]
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