Acid Phosphatase Produced by Trichoderma harzianum in Solid Fermentation Using Millet

The absorption of organic phosphorus from the environment and its efficient use requires the action of a large class of enzymes called acid phosphatases. Fungi can convert insoluble phosphorus into soluble forms during the acidification and chelation stages or through hydrolysis mediated by phosphatase enzymes. These enzymes are obtained from plants, animal cells, and microorganisms. Acid phosphatases (AcPases) have their optimum pH of action being less than 6.00. This study evaluated the production and extraction of acid phosphatases using solid fermentation (FES) with Trichoderma harzianum supported in millet. Preliminary tests were fundamental in analyzing the enzyme production potential of the T. harzianum strain, where the best results were for millet. Using a Central Composite Design (CCD), it was possible to develop equations for responses to acid phosphatase activity (U/mL) and dry biomass (g/L) using the variables: millet mass, inoculum concentration, and moisture. The best results were for solid fermentation, using the millet substrate with cultivation in sterile distilled water and extraction with Tween 80, where there was a growth of biomass and enzymatic activity, whose optimized final values were 9.27 ± 0.53 g/L and 36.09 ± 0.61 U/mL, respectively, after 9 days of solid fermentation.