Table 2.
Results of the MTT assay on K562 cells for the ZBY-3 and 30 mutant samples at 100 μg/mL a.
| Strain b | Condition for Selecting Mutant Strain c | IR% d (Mean ± SD, n = 3) | ||
|---|---|---|---|---|
| Ultrasound (W) | Neomycin (mg/mL) | Treated Time at 4 °C (h) | ||
| ZBY-3 | - | - | - | 1.8 ± 2.0 |
| u2n2h3-1 | 200 | 200 | 3 | 67.1 ± 2.3 * |
| u2n2h3-2 | 200 | 200 | 3 | 17.2 ± 3.3 |
| u2n2h3-3 | 200 | 200 | 3 | 62.9 ± 2.4 * |
| u2n2h3-4 | 200 | 200 | 3 | 61.4 ± 5.9 * |
| u2n2h12-1 | 200 | 200 | 12 | 6.0 ± 3.9 |
| u2n2h24-1 | 200 | 200 | 24 | 48.9 ± 6.9 * |
| u2n2h48-1 | 200 | 200 | 48 | 22.9 ± 2.2 ** |
| u2n2h48-2 | 200 | 200 | 48 | 14.9 ± 1.2 |
| u2n4h3-1 | 200 | 400 | 3 | 16.7 ± 2.8 |
| u2n4h12-1 | 200 | 400 | 12 | 72.0 ± 2.0 * |
| u2n4h12-2 | 200 | 400 | 12 | 83.3 ± 2.6 * |
| u2n4h24-1 | 200 | 400 | 24 | 32.5 ± 0.6 *** |
| u4n2h3-1 | 400 | 200 | 3 | 54.4 ± 8.4 * |
| u4n2h24-1 | 400 | 200 | 24 | 9.7 ± 1.8 |
| u4n2h24-2 | 400 | 200 | 24 | 71.1 ± 1.0 * |
| u4n2h48-1 | 400 | 200 | 48 | 43.1 ± 21.7 * |
| u4n2h48-2 | 400 | 200 | 48 | 2.4 ± 6.1 |
| u4n2h48-3 | 400 | 200 | 48 | 30.4 ± 8.9 *** |
| u4n2h48-4 | 400 | 200 | 48 | 55.7 ± 5.1 * |
| u4n4h3-1 | 400 | 400 | 3 | 60.8 ± 6.9 * |
| u4n4h3-2 | 400 | 400 | 3 | 71.3 ± 8.4 * |
| u4n4h12-1 | 400 | 400 | 12 | 49.8 ± 3.2 * |
| u4n4h24-1 | 400 | 400 | 24 | 38.5 ± 3.1 *** |
| u4n4h24-2 | 400 | 400 | 24 | 44.6 ± 35.7 * |
| u4n4h24-3 | 400 | 400 | 24 | 49.6 ± 2.7 * |
| u4n4h48-1 | 400 | 400 | 48 | 1.1 ± 17.8 |
| u4n4h48-2 | 400 | 400 | 48 | 12.9 ± 3.8 |
| u4n4h48-3 | 400 | 400 | 48 | 56.6 ± 5.8 * |
| u4n4h48-4 | 400 | 400 | 48 | 39.8 ± 1.8 *** |
| u4n4h48-5 | 400 | 400 | 48 | 22.3 ± 7.1 ** |
a Test samples are the EtOAc extracts of the parent ZBY-3 and its 30 mutant cultures; b The nomenclature of the mutants: u2 or u4 indicates the 200 or 400 W of output power of ultrasound irradiation; n2 or n4 indicates the 200 or 400 mg/mL of neomycin contained in the spore suspension. Arabic numerals between h and a hyphen indicate the treatment times (hours) of the spore suspension at 4 °C after ultrasound irradiation, Arabic numerals following a hyphen are the serial number of the mutants selected at the same treatment conditions; c The fresh ZBY-3 spore suspension with neomycin at the given concentration was subjected to ultrasound irradiation by 2 s of irradiation every 2 s with an 8-min duration cycle at the given output power, and the spores were further treated with the contained neomycin at 4 °C for the given times. Then, a 100-μL portion of the spore suspension was spread on PDA plates and incubated at 28 °C for 3–5 days to obtain the mutants by single colony isolation; d The triplicate MTT tests were carried out using samples from three rounds of individual fermentations upon the fourth, sixth and eighth passages of the 30 mutants and the parent ZBY-3 strain, respectively. The data marked with asterisks show the IR%: *, IR% > 40%; **, IR% in 30%–20%; ***, IR% in 40%–30%. Docetaxel was used as a positive control in the MTT assay, inhibiting the K562 cells with an IR% of 55.7 ± 16.9 at 100 μg/mL.