Immobilized microalgae (MA) are widely used for the production of biomass and high value-added metabolites, the biocapture of nutrients and heavy metals, and for the destruction of organic pollutants in wastewater. The use of chitosan (CH) as a carrier for MA cultivation has many advantages, including its availability, non-toxicity, biodegradability, biocompatibility and high sorption capacity. However, for successful CH application, it is crucial to increase the cost-effectiveness of microalgae–chitosan systems as compared to traditional technologies. One of the prospective approaches is the synthesis of composites on the basis of chitosan and natural polysaccharide-containing wastes (PCWs) like apple pomace (AP) and mycelium (M), which are the main by-products in the apple juice processing industry and in mushroom farming.
A CH solution and an AP or MM suspension in 2% (w/w) acetic acid were mixed in a 1:3, 1:1, or 3:1 ratio, cross-linked with glutaraldehyde, and freeze-dried to prepare porous and solid composite sponges. The chlorophyte strain Lobosphaera IPPAS C-2047 served as the object in the present work. To reveal the effect of CH/PCW ratio on MA attachment and biocompatibility, we followed the kinetics of MA immobilization. The proportion of unattached cells was deduced from measurements of chlorophyll content in Lobosphaera cell suspensions after their incubation with the composites. Immobilization efficiency was defined as percentage of attached cells calculated relative to the control.
After 24 h incubation, the immobilization efficiency of composites with 25% AP and 25%, 50% M was 25–35% higher as compared to additive-free CH, while composites with 75% of AP and M showed the lowest immobilization efficiency.
We concluded that AP and M additives have prospective features for CH-based composite production in terms of their low cost and sustainability. oreover, their addition resulted in the enhancement of MA immobilization efficiency.
This research was supported by the Russian Science Foundation (grant №23-44-00006).
