High-Density Fermentation of Lactobacillus plantarum P6: Enhancing Cell Viability via Sodium Alginate Enrichment

<i>Lactobacillus plantarum</i> exhibits a wide range of beneficial physiological functions, including maintaining intestinal microbiota balance, reducing serum cholesterol, and promoting digestive health. According to the specific nutrient requirements of <i>Lactobacillus plantarum</i> P6, we investigated the effects of various carbon sources, nitrogen sources, trace elements, growth-promoting substances, as well as the initial pH and inoculum size on the growth of <i>Lactobacillus plantarum</i> P6 under fermentation conditions. The optimal growth conditions for <i>Lactobacillus plantarum</i> P6 were identified to facilitate high-density fermentation in small-scale fermenter production, achieving a cell concentration of 1.03 × 10¹¹ CFU/mL. This resulted in a 2.5-fold increase in bacterial wet weight, and fermentation time was reduced to 12 h when utilizing a specific medium enriched with 0.2% sodium alginate. It is hypothesized that sodium alginate forms a protective film around the bacterial cells, promoting cell aggregation and enhancing self-coalescence, potentially triggering a bacterial community effect. These results provide a basis for the industrial-scale high-density cultivation of <i>Lactobacillus plantarum</i>, offering potential for enhanced biotechnological applications.