β-mannanase was produced mainly by Aspergillus species and can degrade the β-1,4-mannose linkages of galactomannans. This study was undertaken to enhance mannanase production using talcum and aluminum oxide as the microparticles, which control cell morphology of recombinant Aspergillus sojae in glucose and carob extract medium. Both microparticles improved fungal growth in glucose and carob pod extract medium. Aluminum oxide (1 g/L) was the best agent for glucose medium which resulted in 514.0 U/ml. However, the highest mannanase activity was found as 568.7 U/ml with 5 g/L of talcum in carob extract medium. Increase in microparticle concentration resulted in decreasing the pellet size diameter. Furthermore, more than 10 g/L of talcum addition changed the filamentous fungi growth type from pellet to pellet/mycelium mixture. Results showed that right type and concentration of microparticle in fermentation media improved the mannanase activity and production rate by controlling the growth morphology.

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Mannanases, one of the important enzyme group for industry, are produced by numerous filamentous fungi, especially Aspergillus species with different fermentation methods. The aim of this study was to show the best fermentation method of β-mannanase production for fungal growth in fermenter. Therefore, different fermentation strategies in fed-batch fermentation (suspended, immobilized cell, biofilm and microparticle-enhanced bioreactor) were applied for β-mannanase production from glucose medium (GM) and carob extract medium (CEM) by using recombinant Aspergillus sojae. The highest β-mannanase activities were obtained from microparticle-enhanced bioreactor strategy. It was found to be 347.47 U/mL by adding 10 g/L of AlO to GM and 439.13 U/mL by adding 1 g/L of talcum into CEM. The maximum β-mannanase activities for suspended, immobilization, and biofilm reactor remained at 72.55 U/mL in GM, 148.81 U/mL in CEM, and 194.09 U/mL in GM, respectively. The reason for that is the excessive, and irregular shaped growth and bulk formation, inadequate oxygen transfer or substrate diffusion in bioreactor. Consequently, the enzyme activity was significantly enhanced by addition of microparticles compared to other fed-batch fermentation strategies. Also, repeatable β-mannanase activities were obtained by controlling of the cell morphology by adding microparticle inside the fermenter.

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