In-silico molecular investigation of Nannochloropsis microalgae cellulose synthase under salinity conditions and in-vitro evaluation of the proportionate effects on cellulose production.

Nannochloropsis is a microalgae with more than substantially 60-70% cellulose in its cell wall, making it a potential candidate for nanocellulose sustainable production. This study examined the effects of salts in seawater and their role on Nannochloropsis gaditana and Nannochloropsis oculata cellulose synthase activity using In-silico and In-vitro approaches for the first time. Deep-learning-based AlphaFold2 predicted model was selected as the most reliable 3D structure. Molecular docking results revealed that none of the selected ligands occupied the binding site predicted for the native substrate of the enzyme, uridine-diphosphate. To validate the In-silico results, experiments were conducted to investigate the impact of salinity stress (NaCl, NaNO₃ and NaHCO₃) on the cell growth and cellulose production. The assessment tools included a UV-visible spectrophotometer and a hemocytometer, with a modified Jayme-Wise method used for cellulose extraction. The results indicated that the following concentrations of 0.443 mol/L, 0.457 mol/L, and 0.469 mol/L of NaCl, 0.072 mol/L, 0.077 mol/L, and 0.082 mol/L of NaNO3, 0.0021 mol/L, 0.0022 mol/L, and 0.0023 mol/L of NaHCO₃ did not lower the growth rate nor the cellulose yield of N. oculata and notable enhancement in growth was observed in cultures supplemented with 0.0023 mol/L NaHCO₃. Furthermore, when NaCl (0.457 mol/L and 0.469 mol/L), NaNO₃ (0.082 mol/L) and NaHCO₃ (0.0022 mol/L and 0.0023 mol/L) were individually introduced to the culture, cellulose yield increased up to five times compared to the control group.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-025-04329-y.