Abstract: Huguang microbial additive is comprised of strains of photosynthetic bacteria,including Rhodopseudomonas and Rhodospirillum. The essential technical parametersin batch culture,such as media,illumination,temperature,pH,aeration and inocula-tion ratio etc. were studied.In general,after incubation for 3-5 days under ap-propriate conditions,the culture became deep red in colur and the cell number inc-reased to about 109/ml.When preserved at room temperature for 6 months, themicrobial additive remained still effective:and when incubated at 40℃ and in darkcondition for 15 days most cells survive in culture.A simple method for quality assay of the microbial additive is presented.