Enhanced Lincomycin Titer Through Knockout of GntR Family Regulator SLCG_2790 Combined With Fermentation Optimization in an Industrial Strain of Streptomyces lincolnensis L‐427

In this study, lincomycin A (Lin-A), a lincosamide antibiotic primarily synthesized by Streptomyces lincolnensis, was selected as a model to demonstrate a combined genetic regulation and process engineering strategy for production improvement. The GntR-family transcriptional regulator SLCG_2790 was identified as a negative modulator of Lin-A biosynthesis. Disruption of SLCG_2790 in the industrial strain S. lincolnensis L-427 led to enhanced Lin-A accumulation, accompanied by increased transcriptional levels of mycothiol and ergothioneine biosynthesis genes. Metabolic flux analysis revealed an 83.6% elevation in pentose phosphate pathway activity compared to the parental strain. Despite the observed reduction in mycelial growth resulting from SLCG_2790 deletion, fermentation performance was significantly improved through medium optimization using Plackett-Burman design, steepest ascent, and response surface methodology. The optimized conditions yielded a 38.1% increase in Lin-A production in shake-flask culture, along with an accelerated onset of physiological activity. In a 5-L bioreactor, the engineered strain achieved a maximum Lin-A titer of 3640.6 mg/L, representing a 101.4% improvement over the parental strain cultured in the original medium. These findings underscore the potential of transcriptional regulation coupled with rational process optimization to overcome metabolic constraints and enhance antibiotic production in actinomycetes.