To begin, peel off the outer layers of the scallions and discard the green leaves. Sterilize scissors with 75%ethanol, and cut the white part of the scallions into one to two centimeter diced pieces. Weigh 50 grams of diced scallions and place them into a food processor.
Add 50 milliliters of sterilized water into a food processor and grind the scallions five times for two minutes each. Using tweezers, transfer ten thirds instar larvae of Delia Antigua into a 10 milliliter centrifuge tube containing 10 milliliters of PBS. Grind the larvae with a disposable grinding pestle.
Pour the pasty scallion liquid and larval grinding liquid into a 500 milliliter conical flask. Wrap the flask mouth with two layers of transparent ceiling film and place the flask in a shaking incubator for 12 hours. Cut out seven layers of square gauze with 10 centimeter sides and stack them together to form a simple filter device.
After incubation, slowly pour the fermented scallion liquid onto the gauze, collecting the filtrate into a 500 milliliter flask. Place the wet filter paper on the Buckner funnel. Then pour the filtrate and perform suction filtration three times with different filter paper using a vacuum pump.
Perform another filtration using a 0.22 micron filter bottle and a vacuum pump. After filtration, screw on the cover of the suction filter bottle. Add 0.24 grams of choline chloride and 0.56 grams of L-ascorbic acid in a separate 10 milliliter centrifuge tube.
Then add three milliliters of deionized water and shake the tubes vigorously. Sterilize the solutions using a five milliliter syringe and three 0.22 micron syringe filters in 10 milliliter tubes. Add two grams of agri powder and six grams of TSB powder in a 500 milliliter conical flask.
Then add 100 milliliters of deionized water and stir the mixture using a glass rod until well mixed. Seal the flask using two layers of transparent sealing film. Wrap the fermented scallions and unfermented scallions in aluminum foil.
Sterilize the scallions and culture medium in an autoclave at 121 degrees Celsius for 20 minutes. While gently swirling the flask, pour the sterilized choline chloride, L-ascorbic acid solution, and filtrate into the culture medium. Add fermented and unfermented scallions into the culture medium and shake vigorously.
Finally, pour the diets into the 50 milliliter centrifuge tubes.
