Enhanced bafilomycin A1 production in Streptomyces Griseobrunneus via protoplast fusion combined with high-throughput screening.

Bafilomycin A1 (Baf A1), a macrolide antibiotic, has garnered significant attention in medical fields as a specific and reversible V-ATPase inhibitor. To enhance the screening efficiency for high-yield Baf A1 strains of Streptomyces griseobrunneus after mutagenesis, a high-throughput screening model utilizing 48-well deep plates was established, with optimal fermentation conditions being a liquid volume of 3 mL for 4 d at 250 rpm. In this way, a high-yield mutant strain Y98 that produced 892.37 µg/mL Baf A1 was screened through protoplast fusion combined with 48-well deep plate fermentation technology, representing 1.22-fold, 1.42-fold, and 2.77-fold increases compared to AN-125, UV-21, and the original strain FIM-B0711, respectively. Transcriptomic sequencing analysis revealed potential mechanisms underlying the high yield of Baf A1 in mutant strain Y98 may be attributed to the upregulation of BafD and BafE in the type I polyketide structures pathway by 1.18 and 1.20 times, and the downregulation of ndh, nuoA, nuoB, nuoE in the oxidative phosphorylation pathway by 0.62, 0.72, 0.69, and 0.77 times, respectively. This study provides a novel strategy for enhancing Baf A1 production and generates valuable insights for the breeding of other Streptomyces strains.