Two acidic, thermophilic GH28 polygalacturonases from Talaromyces leycettanus JCM 12802 with application potentials for grape juice clarification

- Two highly active GH28 polygalacturonases from T. leycettanus JCM 12802 can retained stability in high temperature of 60 °C, which is superior over most fungal polygalacturonases.
- Two highly active GH28 polygalacturonases from T. leycettanus JCM 12802 can effect in grape juice clarification, which represent excellent additive candidates in the food industry.
- Two highly active GH28 polygalacturonases from T. leycettanus JCM 12802 were perform synergistic effect in pectin degradation and clarification of grape juice.

Efficient hydrolysis of pectic materials to sugars requires the synergistic action of endo- and exo-polygalacturonases. Two novel polygalacturonases (exo-TePG28a and endo-TePG28b) were identified in Talaromyces leycettanus JCM12802, overexpressed in Pichia pastoris, and characterized in this report. The specific activities of TePG28a and TePG28b towards polygalacturonic acid were 280 ± 9 and 25,900 ± 502 U/mg, respectively. Both enzymes exhibited optimal activities at pH 3.5 and retained highly stable over a broad pH range of 2.0-7.0. Distinct from most fungal polygalacturonases that have low temperature optima, TePG28a and TePG28b were optimally active at 70 °C. When treated the grape juice with the enzyme combination (the unit ratio of TePG28a:TePG28b was 1:4), higher pectin-degrading efficiency (up to 140%) was achieved, and light transmittance was improved from 14% to 82%. These favorable enzymatic properties make TePG28a and TePG28b attractive for the applications in the juice industry.