TABLE 3.
Expression of β-lactamase in developing cells pregrown in CYE plus ampicillina
| Elapsed time (days) | CYE-grown cells
|
CYE + ampicillin-grown cells
|
||
|---|---|---|---|---|
| Aggregate morphology | β-Lactamase activity | Aggregate morphology | β-Lactamase activity | |
| 0 | 1.6 | 15 | ||
| 1 | Mounds | 1.3 | Tight mounds | 7.0 |
| 2 | Tight mounds | 4.0 | Late tight mounds | 7.4 |
| 3 | Fruiting bodies | 7.0 | Fruiting bodies | 8.0 |
a
DZF1 cells were grown in CYE or CYE containing 100 μg of ampicillin/ml in 35-mm-diameter tissue culture plates for development in submerged culture. After 24 h of growth, the culture supernatant was aspirated. After being washed with 1.0 ml of MMC, the cells were overlaid with 2.0 ml of MMC and incubated at 28°C. At the intervals given in the table, the cells were scraped from the plates with a rubber policeman and harvested by centrifugation. Extracts were prepared, and β-lactamase was assayed as described in Materials and Methods. Activity is expressed in mmol/g/min.