Background: A sequential statistical strategy was used to optimize tannase production from Aspergillus tubingensis using tea stalks by solid-state fermentation.

Results: First, through a Plackett-Burman design, inoculum size and incubation time (among seven tested variables) were identified as the most significant factors for tannase yield. The effects of significant variables were further evaluated through a single steepest ascend experiment and central composite design with response surface analysis. Under the optimal conditions, the experimental value of 84.24 U/gds closely matched the predicted value of 87.26 U/gds.

Conclusions: The result of the statistical approach was 2.09 times higher than the basal medium (40.22 U/gds). The results were fitted onto a second-order polynomial model with a correlation coefficient (R2) of 0.9340, which implied an adequate credibility of the model.