Chen Sanfeng

Medium optimization for nitrogen fixer Paenibacillus sp. 1-49

Objective Paenibacillus sp. 1-49 is a nitrogen-fixing bacterium that has the potential as a fertilizer. However, it grows poorly (OD600≤1) in both mineral medium and rich medium. To achieve high-yield biomass, we optimized fermentation medium for Paenibacillus sp. 1-49. Methods Plackett-Burman Design and Central Composite Design in response surface methodology were used to optimize medium composition. Results The optimal fermentation medium contained:(per liter) 36.22 g Sucrose, 5.31 g Tryptone, 10.92 g Yeast Extract, 0.51 g MgSO4, 3.5 g NaCl, 0.02 g Na2MoO4 and 0.02 g FeSO4. The maximum OD600 of 10.280±0.009 was obtained in shake flask fermentation, reached 94.6% of the predicted value. Conclusion We succeeded in using a response surface methodology to optimize the fermentation medium for Paenibacillus sp. 1-49. Our results will be useful for largescale fermentation of this strain and other Paenibacillus spp.