Microalgae reckon one of the most promising organisms due to their numerous applications in biotechnology, such as, their biomass utilization to extract various primary and secondary metabolites. These compounds benefit the food and pharmaceutical industries and the energy field, such as, biofuel and hydrogen gas production. Therefore, it is necessary to find various sustainable ways to actively preserve the isolates and productive strains with purity for an extended period without affecting their genetic characteristics and productive ability to grow and regenerate. The latest study aimed to compress several microalgae to form alginate beads using sodium alginate with five types of pure algal cultures, i.e., Scenedesmus quadricauda, Scenedesmus dimorphus, Chlorella vulgaris, Chlorococcum humicola, and Chlamydomonas sp. The vitality and activity of all the strains studied through the storage period showed the success of preparing alginate beads and staying viable for 18 months at 4 °C in the refrigerator under dark conditions. Therefore, encapsulating microalgae with sodium alginate is a possible and helpful method for preserving algae isolates for a prolonged period in a pure form. The survival of algae in alginate beads is an essential step to apply in the future as one of the viable methods to preserve pure algae isolates for a long time.

Keywords: Scenedesmus, Chlorella, Chlorococcum, Chlamydomonas, microalgae, alginate bead, sodium alginate, long-term storage

Key findings: Encapsulating microalgae with sodium alginate is a possible and valuable method for preserving algae isolates for a long time in a pure form. The process successfully prepared alginate beads and stayed viable for 18 months at 4 °C in the refrigerator under dark conditions.