Fig. 9.

Qualitative detection of extracellular L-asparaginase secretion by S. thinghirensis WAE1 cultured in modified M9 solid medium. L-asparaginase activity was visualized using a pH indicator dye phenol red, where enzymatic hydrolysis of L-asparagine resulted in localized alkalinization and consequent color change from yellow to pink surrounding colonies after (a) 3 days and (b) 7 days of incubation. Control plates showed (c) inoculated medium lacking phenol red (positive control), and (d) uniform yellow coloration for uninoculated medium containing phenol red (negative control)