Comparative evaluation of native biomass and processing residues of Limnospira platensis as biofertilizers for a model leafy crop
摘要
The development of sustainable biofertilizers based on phototrophic microorganisms requires a better understanding of the agronomic potential of different biomass-derived products. This study presents a comparative assessment of the effects of native biomass and cell debris of the cyanobacterium Limnospira platensis B-12619 on the growth and physiological status of garden cress (Lepidium sativum) under controlled conditions. Root application of native L. platensis biomass stimulated plant morphometric parameters and enhanced aboveground biomass accumulation compared with the control. Weekly application of 10 mg cyanobacterial biomass increased dry aboveground biomass of L. sativum from 15.9 ± 1.9 mg in the control to 95.9 ± 8.4 mg after 50 days of growth. Processing residues (cell debris) remaining after phycobiliprotein extraction also promoted plant growth, but their effects were weaker, resulting in approximately 2–threefold lower biomass accumulation relative to native biomass treatment. Native biomass application reduced anthocyanin accumulation, a stress marker in L. sativum, from 5.60 ± 0.30 to 0.27 ± 0.08 mg g−1 dry weight after 50 days, indicating reduced physiological stress and an improved plant adaptive status. Estimated biofertilizer efficiency reached 37 – 51% for native biomass variants but did not exceed 19 – 22% for cell debris, suggesting limited nutrient bioavailability in the insoluble fraction. The use of culture supernatant without adequate pretreatment may induce adverse changes in the soil microenvironment, highlighting the importance of technological optimization of biofertilizer prior to agronomic application. The results demonstrate the potential integration of phycobiliprotein production and biofertilizer generation within a unified L. platensis biorefinery approach.