Abstract:

Molecular biological methods and morphology was applied to identify a halophilic endophytic fungal strain
named Salicorn 35 isolated from Salicornia bigelovii in this study. The 18S and ITS1-5.8S-ITS4 rDNA were PCR amplified
and subjected to monoclonal sequence analysis after the extraction of its DNA genome. By comparison with the sequences
obtained in NCBI database, a phylogenetic tree was established using sequence analysis software MEGA5 combined with
morphological analysis. The fungus Salicorn35 was identified as Fusarium solani. The fermentation conditions of Salicorn 35
for producing antioxidants with high activity were optimized by using Plackett-Burman (PB) design, steepest ascent path
design and response surface methodology. The optimal medium consisted of 1.5% yeast extract, 2.7% peptone, 40% potato,
3% maltose, 1% mannitol, 1.5% glucose, 1.0% monosodium glutamate and 6.0% sodium chloride at pH 5. The maximum
DPPH radical scavenging activity of fermentation products produced from the optimal culture medium was 76.75%, which
was significantly higher than before the optimization (57.77%).

Key words: endophytic fungi, molecular identification, phylogenetic analysis, antioxidant activity, response surface methodology