Determination of in vitro hydrogen sulphide production
The H2S produced by the 13 M. bovis isolates was determined using lead acetate detection strips as previously described (Großhennig et al.,2016). Briefly, growing cells were harvested and resuspended in 1ml 1x PBS (pH 7.4) supplemented with L-cysteine. Sterile filter paper strips impregnated with lead acetate were affixed to the inner wall of the test tubes above the level of the liquid culture. An aliquot without L-cysteine served as the control. After 18 h of incubation at 37oC, the test strips were read and photographed.