Cellulase and xylanase production by co-culture of Aspergillus niger and Fusarium oxysporum utilizing forest waste

Abstract

Aim: The purpose of present work was to utilize lignocellulosic forest waste for cost-effective production of commercially important enzymes i.e. cellulase and xylanase by employing co-culture of Aspergillus niger F7 and Fusarium oxysporum F8 in solid state fermentation (SSF). Material and Methods: Fungal strains i.e. A. niger F7 and F. oxysporum F8 isolated from degrading forest litter were used as co-culture and their enzyme biosynthesis on forest waste was noticed. The prominent forest wastes i.e. Toona ciliata, Celtris australis, Cedrus deodara and Pinus roxburghii were procured from local forest and alkali (NaOH) pretreatment was given to these lignocellulosic substrates to simplify the crystalline cellulose present in them for higher yield of enzymes by fungal isolates. Two types of moistening agents i.e. tap water and modified basal salt medium (BSM) were used in the substrate in the ratio of 1:2 to evaluate their effect on enzyme production under SSF. Results: The maximum enzyme titers i.e. 787.89 U/g of cellulase and 669.08 U/g of xylanase were observed in C. australis as compared to untreated biomass which was 450.02 and 398.03 U/g of cellulase and xylanase respectively when tap water was used as moistening agent. Biodegradation of forest biomass under SSF was increased many folds when moistening agent i.e. tap water had been replaced with modified basal salt media (BSM). In BSM mediated degradation of forest waste with co-culture of A. niger and F. oxysporum, extracellular enzyme activity was increased up to 2219.55 U/g of cellulase and 1012.0 U/g of xylanase in pretreated C. australis wood. Conclusion: In untreated biomass enzyme production by fungi was quite low thus emphasizing the need of pretreatment for biodegradation of forest lignocellulosics. Significantly higher production of cellulase and xylanase using pretreated forest waste and modified BSM as moisture are main highlights of the present study which commercially may lead to cost effective production of these industrially important enzymes.