High-throughput and genome-guided optimization of exopolysaccharide production in marine bacteria for sustainable biotechnology

Marine bacteria are an untapped resource for exopolysaccharides (EPS) with broad potential applications in biomedicine, bioremediation, and food industries. However, industrial utilization remains limited due to low yields and strain-specific variability. This study explores seven novel marine bacterial strains (<i>Limnobacter alexandrii</i> LZ-4, <i>Nioella ostreopsis</i> Z7-4, <i>Mesorhizobium alexandrii</i> Z1-4, <i>Marinobacter shengliensis subsp. Alexandrii</i> LZ-6, <i>Marinobacter alexandrii</i> LZ-8, <i>Memelialla alexandrii</i> LZ-28, and <i>Sulfitobacter alexandrii</i> AM1-D1) isolated from marine dinoflagellate microbiota. A genome-guided, high-throughput fermentation strategy was employed to optimize EPS production. Genomic analysis identified distinct EPS biosynthesis pathways (e.g., alginate and cellulose synthesis) and key genes (<i>algA/C/D, bcsB,</i> and <i>epsE/H/J</i>) involved in both the polymerization and the secretion of EPS. High-throughput screening under 50 fermentation conditions revealed sucrose and fructose as optimal carbon sources, with alkaline pH (7-9) significantly enhancing EPS yields (up to 159.6 µg/mL). Strain-specific optimization demonstrated that LZ-4 and Z7-4 achieved maximal EPS production at 28°C, whereas LZ-8 exhibited a high EPS production at 37°C. The study underscores the synergy between genomic insights and systematic screening, offering a scalable framework for rapid strain optimization. These findings pave the way for sustainable EPS bioproduction, reducing reliance on synthetic polymers and advancing industrial biotechnology in alignment with circular bioeconomy goals.IMPORTANCEThis study integrates genomic analysis with high-throughput fermentation to optimize exopolysaccharide (EPS) production in seven novel marine bacterial strains. By identifying key EPS biosynthesis genes and pathways, we tailored fermentation conditions using sucrose and alkaline pH, achieving yields up to 159.6 µg/mL. Strain-specific optimizations revealed significant enhancements in EPS production, highlighting the potential for sustainable industrial applications. This work bridges ecological insights with bioprocessing, offering a scalable framework for efficient EPS production that reduces reliance on synthetic polymers, advancing circular bioeconomy goals. The findings underscore the importance of marine microbial resources in biotechnology.