Optimization of Extraction Conditions and Bioactivity of Nannochloropsis Sp.Intracellular Polysaccharide
In order to study the extraction technology and biological activity of Nannochloropsis sp.intracellular polysaccharide(NOLP),the extraction conditions of NOLP were optimized by single factor combined with response surface method,the antioxidant and bacteriostatic activities of the extracted NOLP were tested.The results showed that the optimal extraction parameters were NaOH mass fraction 2.5％,solid-liquid ratio 1∶25 g/mL,ultrasonic power 100 W,ultrasonic time 10 min and water bath temperature 60 ℃.Under these conditions,the extraction rate of intracellular polysaccharide was(3.62±0.01)％.The antioxidant test results showed that the scavenging rate of 5 mg/mL intracellular polysaccharide to 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical was(78.57±0.85)％,and the scavenging rate of hydroxyl free radical was(22.48±0.65)％.The results of antibacterial test in vitro showed that NOLP had different degrees of inhibitory effects on Bacillus cereus,Bacillus subtilis and Escherichia coli.The Bacillus cereus with the strongest inhibitory effect was selected as the test bacterium,and the influence of polysaccharide on the cell membrane structure of the bacteria was measured.The test results showed that polysaccharide caused damage to the cell membrane structure of Bacillus cereus to a certain extent.The growth and reproduction of thallus were inhibited.The above results showed that the NOLP has good antioxidant activity and antibacterial activity.
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