NOVELTY - The method comprises extracting biogas slurry from healthy livestock sewage, performing the anaerobic fermentation of the biogas slurry for 15 days to obtain residue and then carrying out solid liquid separating the residue for obtaining supernatant, preparing culture solution by adding the biogas slurry to a weight ratio of 3% using diacetate (1%), ammonium bicarbonate (4%), sodium bicarbonate and potassium sulfate (1%) where the culture solution has a pH of 7.5-8.5, and inoculating the culture solution into the transparent culture container such as bag or box.    USE - The photosynthetic bacteria are used for improving animal immunity, promoting growth of animals, inhibiting tumor cells and bacteria, improving the gastrointestinal environment, treating and preventing digestive disease and as virucides.    ADVANTAGE - The method ensures economical, efficient, rapid and easy culture of photosynthetic bacteria at high growth rate without pollution thus improving the needle mushroom polysaccharide powder in improving animal immunity.    DETAILED DESCRIPTION - The method comprises extracting biogas slurry from healthy livestock sewage, performing the anaerobic fermentation of the biogas slurry for 15 days to obtain residue and then carrying out solid liquid separating the residue for obtaining supernatant, preparing culture solution by adding the biogas slurry to a weight ratio of 3% using diacetate (1%), ammonium bicarbonate (4%), sodium bicarbonate and potassium sulfate (1%) where the culture solution has a pH of 7.5-8.5, and inoculating the culture solution into the transparent culture container such as bag or box and then adding weight of photosynthetic bacteria original liquid to the culture liquid of a vessel in the strain interior space of cultivation container after sealing in the culture room to culture at a culture room temperature of 20-30 degrees C for 72 hours. The culture vessel is provided with an incandescent lamp (60 W) along with the reduction of prolonging culturing time.