Kunert J
Department of Biology, Medical Faculty of Palacký University, Olomouc, Czechoslovakia.
J Basic Microbiol. 1987;27(4):207-13. doi: 10.1002/jobm.3620270410.
The dermatophyte Microsporum gypseum was cultivated on two liquid media enriched with 50 to 1000 micrograms/ml free L-cystine. The presence of cystine in concentrations above 250 micrograms/ml (gelatin medium) or 500 micrograms/ml (glucose-glutamate medium) inhibited the growth. In all variants, however, cystine was utilized from the very beginning of growth and exhausted completely until stationary phase. The rate of cystine metabolization grew with its concentration to 500 micrograms/ml but decreased again with 1000 micrograms/ml. The excess sulfur was oxidized and excreted back into the medium mainly as inorganic sulfate. Moreover, sulfite was also produced which immediately reacted with the residual cystine in the medium giving rise to S-sulfocysteine. Sulfite excretion was higher in the initial phases of growth and on the medium with poorer growth (gelatin medium). The sulfate-to-sulfite ratio was different on the two media used but was little influenced by cystine concentration. The excretion of strongly acidic compounds (sulfate, sulfite, and S-sulfocysteine) reduced the usual alkalinization of the medium in the course of growth.
将皮肤癣菌石膏样小孢子菌接种于两种添加了浓度为50至1000微克/毫升游离L-胱氨酸的液体培养基中。当胱氨酸浓度高于250微克/毫升（明胶培养基）或500微克/毫升（葡萄糖-谷氨酸培养基）时，其生长受到抑制。然而，在所有实验变体中，从生长开始胱氨酸就被利用，并在稳定期前被完全耗尽。胱氨酸的代谢速率随其浓度增加至500微克/毫升，但在1000微克/毫升时又下降。过量的硫被氧化，主要以无机硫酸盐的形式排泄回培养基中。此外，还产生了亚硫酸盐，它立即与培养基中残留的胱氨酸反应生成S-磺基半胱氨酸。在生长初期以及在生长较差的培养基（明胶培养基）上，亚硫酸盐的排泄量更高。在两种所用培养基上，硫酸盐与亚硫酸盐的比例不同，但受胱氨酸浓度的影响较小。强酸性化合物（硫酸盐、亚硫酸盐和S-磺基半胱氨酸）的排泄减少了生长过程中培养基通常的碱化现象。
