Gallic acid and tannase accumulation during fungal solid state culture of a tannin-rich desert plant ( Larrea tridentata Cov.)

Abstract

Larrea tridentata (Sesse & Mocino ex DC.) Coville, also known as Larrea, gobernadora, chaparral, or creosote bush, is a shrubby plant which dominates some areas of the desert southwest in the United States and Northern Mexico and its use has not been exploited and standardized. In this study, gobernadora was studied to evaluate its potential use for support of solid state culture. Influence of two minimal media added with gobernadora powder as the sole carbon source and inducer of tannin-degrading enzymes was evaluated. Cultures were initially 70% moisture, had a pH of 5.5 and were inoculated with Aspergillus niger Aa-20 at 2 × 10 7 spores per gram of media. Analysis of pH, moisture, tannin uptake, gallic acid accumulation and tannase production were evaluated. Results indicated a high content of condensed (39.4% dm) and hydrolysable (22.8% dm) tannins. Invasion capacity of fungal growth was of 0.15 mm h −1. Tannase production reached values of 1040 U l −1 at 43 h of culture. During the first 48 h of culture, the concentration of gallic acid accumulation was 0.33 g l −1. Gobernadora is a potential source of gallic acid and tannase production by solid state culture; however, further optimization of the process is needed.