Chloroidium sp. and Tetradesmus obliquus biomass for plant biostimulants: Extraction, characterization and bioactivity on seeds development

Summary

This study demonstrates that microalgal biomass from Chloroidium sp. and Tetradesmus obliquus, cultivated in anaerobic digestion digestate, can be efficiently extracted using Alcalase enzyme-assisted treatment to produce plant biostimulants. The bioactivity of these extracts on seed development varied by species and molecular weight fraction: T. obliquus activity on mustard was mediated by medium-sized peptides (3-100 kDa), whilst Chloroidium sp. required synergistic interaction across multiple molecular sizes to promote root growth. The findings underscore species-dependent variability in microalgal biostimulant efficacy.

Regional applicability

The study was conducted using laboratory methods with no geographic specification. The findings on microalgal biostimulant production and seed bioactivity are potentially transferable to United Kingdom agricultural and horticulture contexts, particularly where residual digestate nutrients and sustainable biostimulant sources are priorities, though field validation under UK growing conditions and regulatory assessment would be required before practical adoption.

Key measures

Protein extraction yields (%), molecular weight fractionation (<3 kDa, 3-100 kDa, >100 kDa), seed germination parameters, root growth metrics

Outcomes reported

The study evaluated protein extraction yields from two microalgae species using enzymatic methods and assessed the bioactivity of molecular-weight-fractionated extracts on mustard and wheat seed development. A dose-dependent relationship was observed between biostimulant potential and molecular size, with species-specific effects on root growth.

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