The present invention relates to a method for obtaining a high titer of enzyme mixture comprising cellulases, hemicellulases and β-glucosidases in reutilization of waste water generated during hot water extraction of lignocellulosic biomass or biorefinery waste water using Penicillium funiculosum MRJ-16 mutant strain. The cellulose or lignocellulosic biomass used in the fermentation process is selected from the group consisting of rice straw, wheat straw, corn stover, cotton stalk or a combination thereof. The enzyme mixture obtained by the present process is used for the saccharification of acid pretreated lignocellulosic biomass.