Optimization of fermentation conditions of bacterium Pseudoxanthomonas indica H32

Abstract

Pseudoxanthomonas indica H32, constitutes the active component of a promising bioproduct candidate with biopesticide and biofertilizing activities. However, suitable fermentation conditions should be established to manufacture this product. Accordingly, the aim of this study was to optimize the fermentation conditions of bacterium Pseudoxanthomonas indica H32 in a 3 L bioreactor. The relevant parameters for strain growth, temperature (25–40 °C) and pH (6–9), were optimized using the response surface methodology (RSM). Additionally, the influence of air flow (0.5–1.5 vvm) and impeller stirrer speed (4.17–14.17 s − 1) in the volumetric oxygen transfer coefficient (KLa) were evaluated and then, in the P. indica H32 growth. The response variables were dry cell weight (DCW) and specific growth rate (µ). The results showed that P. indica H32 growth was significantly affected by the culture medium pH (p < 0.005). The optimum pH and temperature values were found at 7.4 and 34 °C, respectively. The conditions that increased KLa, were 12.17 s − 1 and 1.5 vvm, with a KLa value of 0.104 s − 1. This conditions ensured optimum strain growth of 5.496 g/L of DCW (5.E1010 CFU/mL), whereas µ was 0.403 h − 1. The findings of this study are a step forward in the development of P. indica H32 as biopesticide and biofertilizer.

Keywords

• Bioproducts
• Fermentation conditions
• Optimization
• Pseudoxanthomonas indica
• Response surface methodology (RMS)