Plant growth promoting traits
2.3.1. Qualitative and quantitative determination of ACC deaminase
activity
ACC-deaminase activity of the isolated strains was detected on
plates with DF minimal medium containing 1-aminocyclopro-
pane-1-carboxylate (ACC) as the sole source of nitrogen (Penrose
and Glick, 2003). The plates were incubated at 28 C in the dark for
5 days. Growth of the isolates on DF agar medium amended with
ACC was taken as a qualitative indicator of the efficiency of selected
isolates to utilize ACC and to produce ACC deaminase. For the
detailed quantitative determination of ACC deaminase activity, the
protocol described by El-Tarabily (2008) was carried out. After
determining the amount of protein and a-ketobutyrate (a-KB), the
enzyme activity was expressed as micromoles of a-KB per
milligram of protein per hour of the active isolates.
48 S. Qin et al. / Applied Soil Ecology 93 (2015) 47–55