Effects of Different Strain Immobilization Methods on Protease Production of Aeromonas Hydrophila MSB16

Abstract

Introduction: Microbial strain immobilization has some benefits like the repeatability and cost-effectiveness of strain recovery in the fermentation process. The present study aimed to investigate the effects of Aeromonas hydrophila MSB16 immobilization on its protease production.Materials and Methods: The best method for immobilizing MSB16 was selected using five different polymers including alginate, alginate-polyvinyl alcohol, alginate-polyvinyl alcohol-calcium carbonate, alginate-γ-Al2O3 nanoparticles, and carboxymethylcellulose. The best immobilization method was selected based on the ability of protease production of immobilized cells through the one-factor-at-a-time approach. Then, the selected method was optimized using the surface response methodology (RSM). Finally, the data were analyzed by Design Expert 11 software and the analysis of variance.Results: According to the results of RSM, the immobilized strain in a polymer containing 3% alginate - 3% polyvinyl alcohol - 3% calcium carbonate showed the highest protease production (205/32 U/mL). The second-order model was statistically significant based on the F-values ​​(25.95) and p-values (0.0001). The high determination coefficient (0.9584) and the non-significance lack of fit (0.7818) confirmed the accuracy of the model. The MSB16 protease production was affected by calcium carbonate and polyvinyl alcohol concentrations and had an inverse relationship with calcium carbonate.Discussion and Conclusion: The statistical optimization of the MSB16 immobilization method led to a 2.13-fold increase in its protease production than the free cells.

Keywords

• strain immobilization
• sodium alginate
• polyvinyl alcohol
• calcium carbonate
• response surface methodology