The present study shows that Tween 80 serves as a good carbon source of slowly growing mycobacteria.
The basic media used were sterilized by autoclaving at 120°C for 20 minutes. They were dissolved before its use by heating in a water bath, and added with additional carbon or nitrogen sources, which were sterillized separately by heating at 100°C for 10 minutes. The medium was poured at 8 ml quantities into tubes (17 by 170 mm), and re-sterilized at 100°C for 10 minutes. The pH was adjusted to 7.0 by adding 10% KOH (and if necessary 10% HC1). The medium was inoculated with one loopful of the test organism, and the growth in it was observed after incubation at 37°C for 4 weeks.
1. When Tween 80 was used as carbon source, use of glutamate as nitrogen source supported the growth of almost all mycobacteria, except for fresh isolates of M. tuberculosis. Use of ammonium sulfate supported the growth of mycobacteria except for M. tuberculosis, M. bovis and M. kansasii. Nitrite supported growth of many slowly growing mycobacteria, although it was reported that in the presence of glycerol, it did not support the growth of slowly growing my cobacteria. The use of nitrate supported the growth of all mycobacteria except for M. tuberculosis (and M. bovis) (Table 1). It was remarkable that M. xenopi showed good growth in the presence of Tween 80 as carbon source, in spite of poor growth of this organism on Ogawa egg medium and Löwenstein-Jensen medium.