Abstract:

A water extraction-alcohol precipitation method to extract water-soluble polysaccharides from the dry testa of
Salicornia bigelovii Torr. was developed in this study. The extraction process was optimized by investigating polysaccharide
yield as a function of extraction time, extraction temperature and solid to solvent ratio using combination of one-factor-ata-
time experiments and response surface methodology. Minimal inhibitory concentrations (MICs) of crude polysaccharides
from S. bigelovii Torr. testa against Staphylococcus aureus and Escherichia coli were detected by microwell plate method. The
results showed that polysaccharide yield was affected in decreasing order by the three factors: extraction temperature, solid to
liquid ratio and extraction time. An extraction temperature of 87 ℃, a solid to liquid ratio of 1:57 (g/mL) and 5 h extraction proved
optimal. Experiments carried out under the optimized conditions led to an extraction yield of (13.03 ± 0.63) mg/g, agreeing with
the predicted value (12.42 mg/g), indicating that the response surface model has good prediction ability for the extraction of
polysaccharides from the testa of Salicornia bigelovii Torr.. Minimal inhibitory concentrations (MICs) of the crude polysaccharides
against S. aureus and E. coli were 50 and 100 mg/mL, respectively, suggesting potent antibacterial activity.

Key words: Salicornia bigelovii Torr., testa, polysaccharide, extraction, response surface analysis, antimicrobial activity