Polyphenols content of spent coffee grounds subjected to physico-chemical pretreatments influences lignocellulolytic enzymes production by Bacillus sp. R2

The objective of this study was to investigate the impact of polyphenols content changes issued after physico-chemical treatments of spent coffee grounds on lignocellulolytic enzymes production by Bacillus sp. R2. Total polyphenols of the collected substrates were extracted with water under autoclaving conditions. Results showed that polyphenols content of spent coffee grounds decreased with continued treatments. Untreated spent coffee grounds were the best substrate for cellulase and pectinase (1.33 ± 0.06 μ/ml and 0.32 ± 0.02 μ/ml respectively). A strong positive correlation was noticed between polyphenols content and cellulase and pectinase activities. However, xylanase and peroxidase correlated moderately with polyphenols content and their highest activities were registered with spent coffee grounds treated with boiling water and 1% EDTA (0.31 ± 0.002 μ/ml and 15.56 ± 0.56 μ/ml respectively). The obtained results indicate that polyphenols content of the pretreated substrates influences the production of lignocellulolytic enzymes by Bacillus sp. R2.