Inoculation conditions improved the pectinase productivity in Aspergillus niger LB-02-SF solid-state cultivation

Abstract

In this work, the pectinase production by Aspergillus niger LB-02-SF was evaluated in relation to the inoculation conditions of solid-state cultivations carried out in Becher flasks and in rotating drum bioreactor. From the inoculation by spore suspension in the concentration of 7 × 107 spore/100 g of wet medium (gwm), which is standard inoculum condition, were evaluated: different concentrations of spore suspension (from 7 × 104 to 7 × 108 spore/100 gwm), solid vegetative inoculum using 50 and 100 gwm of fermented solid medium (obtained from 48 h of A. niger cultivation in Becher flasks, in a humidified atmosphere, 30 °C) and liquid vegetative inoculum in the proportions of 5 and 10% (v/w) (obtained from 18 h of A. niger cultivation at 300 rpm, 28 °C). In comparison to the standard condition, with the use of the lowest spore concentration (7 × 104 spore/100 gwm), 100 gwm of solid vegetative inoculum and 10% (v/w) of liquid vegetative inoculum, higher pectinases productivities were observed, around 48, 42 and 85%, respectively. The results obtained indicate that the three inoculation strategies defined are alternatives to increase the enzyme productivity and to facilitate the inoculum preparation stage aimed at applying this process on an industrial scale.