Abstract: KONG Qing-tao*, SANG Hong, LIU Fang, ZHANG Min, WANG Le, DENG De-quan, SHEN Yong-nian, LV Gui-xia, LIU Wei-da. *Department of Dermatology, Nanjing General Hospital of Nanjing Military Command, Nanjing 210002, China Corresponding author: SANG Hong, Email: shzwqzsl@163.com 【Abstract】 Objective To investigate the effect of oxygen concentration on the capsule of Cryptococcus neoformans. Methods Three concentrations （15%, 8%, 0） of oxygen were achieved by using AnaeroPack system. The atmospheric oxygen level （21%） served as the normal oxygen concentration. Five standard strains, including BLS71 （serotype A）, BLS63 （serotype B）, ATCC32609 （serotype C）, ATCC34874 （serotype D） and YD53 （serotype AD）, as well as one clinical isolate of C. neoformans were cultured on either traditional Sabouraud medium （non-inducing conditions） or 10% Sabouraud medium buffered to pH 7.3 with 10 mmol/L 3-（N-morpholino） propanesulfonic acid （capsule-inducing conditions） at 37 ℃ under the four oxygen concentrations for three days. An Olympus microscope was used to observe the formation of capsules, and the size of capsules was measured. Results With the exception of YD53, all the strains formed obvious polysaccharide capsules under the four oxygen levels. Under non-inducing conditions, there was a significant difference in the size of capsules formed by the standard strains BLS71, BLS63, ATCC32609 and the clinical isolate between the four oxygen concentrations （all P < 0.01）. The standard strains BLS71, BLS63 and the clinical isolate formed smaller size of capsules under the anaerobic condition （no oxygen） compared with the other three oxygen concentrations （21%, 15%, 8%, all P < 0.05）. Conclusion Hypoxia may inhibit the formation of capsules by C. neoformans. 【Key words】 Cryptococcus neoformans; Oxygen; Capsulatus

Key words: capsule