High-Throughput Screening of Streptomyces virginiae Strains Using Microtiter Plates for the High-Titer Production of Virginiamycin

Abstract

Normally, cultivation of most Streptomyces species for the purpose of mutant-screening is an arduous process, needing a large amount of material. Moreover, the quantitative analysis of corresponding metabolites is done using HPLC, which is both expensive and time-consuming, and hence not ideal for screening of large numbers of isolates. A novel two-step high-throughput screening strategy has been designed to efficiently identify high-titer virginiamycin-producing mutants of Streptomyces virginiae. The high-throughput screening strategy described here can be used to cultivate a large number of mutant S. virginiae strains in 24-well deep-well microtiter plates and rapidly evaluate a large number of strains with varying virginiamycin titers. This is done based on the cylinder-plate bioassay method using Micrococcus luteus CMCC (B) 28001 as an indicator without compromising the accuracy. After one round of microwave-mediated mutagenesis, S. virginiae strain number 74 identified from nearly 1244 isolates, was shown to have the highest titer. The titer of virginiamycin was approximately 61.26 ± 2.53 mg/L, which is nearly three times compared to the value for the parent strain. Thus, this approach holds promise in facilitating the screening of high-titer virginiamycin producing strains.

Keywords:

• Bioassay
• high-throughput screening
• microtiter plate
• Streptomyces virginiae
• virginiamycin

Additional information

Funding

This study was financially supported by the Key Research and Development Project of Anhui Province (grant No. 1804a07020122, 1704f0704067), the Academic Funding for Top Talents in Disciplines (Specialties) of Anhui Provincial Higher Education Institutes (grant No. gxbjZD35), and the Scientific Research Project of Huainan Normal University (grant No. 2018xj13zd).