In this work, microbial sources can be used in the biotechnological synthesis of tannase. Microbial tannases are preferred because they are more stable and produced in higher yields than similar ones acquired from other sources. In addition, they can be exposed to genetic manipulation more easily than plants and animals. Tannase has a wide range of industrial uses, including food, and environmental biotechnology. Among 161 fungal isolates, two (SWP33 and T11) were chosen to produce more tannase and gallic acid (GA). Based on phenotypic and genotypic (18S rRNA gene sequencing) features, these isolates were identified as Aspergillus niger SWP33 and Penicillium griseoroseum T11. Maximum tannase (147.0 and 148.7 U/ml) and GA (255 and 258 mg/ml) production by A. niger SWP33 and P. griseoroseum T11: in the presence of tannic acid, were attained on the fourth and fifth days of fermentation, with specific enzyme and GA rates of 0.79 and 0.66 d-1 and 0.21 and 0.24 d-1, respectively. When grown on tannins-rich wastes as a low-cost medium to produce tannase and GA, tested strains favored solid-state fermentation than submerged fermentation. During 6 hours of incubation, fungal tannase demonstrated activity in decolorizing reactive blue 19 and red 24 textile dyes.