*2.1. Sample Collection*

Soil samples were collected from a field situated in Bama yao Autonomous County, Hechi City, Guangxi zhuang Autonomous Region (24◦15 N, 107◦26 E). The collected soil samples were brought to the laboratory in sterile bags and kept at 4 ◦C until further analysis. Before isolation of actinomycetes, the soil samples were air-dried at room temperature.

#### *2.2. Screening and Isolation of Actinomycetes*

The soil sample (5 g) was mixed with 45 mL distilled water and followed by an ultrasonic treatment (160 W) for 3 min. The soil suspension was incubated at 28 ◦C and 250 rpm on a rotary shaker for 30 min. Subsequently, the supernatant was collected and subjected to serial dilutions from 10−<sup>2</sup> to 10<sup>−</sup>5. Each dilution (200 μL) was spread on a plate of humic acid-vitamin (HV) agar [25] supplemented with cycloheximide (50 mg L<sup>−</sup>1) and nalidixic acid (20 mg L−1). Colonies were transferred and purified on International *Streptomyces* Project (ISP) medium 3 [26] and stored for a long time in glycerol suspensions (20%, *v*/*v*) at −80 ◦C after 14 days of aerobic incubation at 28 ◦C.
