Biological pretreatment and bioconversion of agricultural wastes, using ligninolytic and cellulolytic fungal consortia

ABSTRACT

Agricultural wastes have attractive potential as alternate energy sources. However, a major bottleneck is to identify eco-friendly treatment methodologies to utilize them. The large diversity of unexplored, novel, and potential microorganisms hold great promise and require periodic isolation and characterization of microorganisms for bioprospection. In this study, approximately 100 fungal isolates were tested for their lignocellulolytic enzyme activities, based on plate assay, followed by quantification of enzyme activity. From this, M2E (Inonotus tropicalis) and 2a (Cerrena unicolor) showed good growth and proficient ligninolytic activity; isolates GK1 (Chaetomium globosum) and GK2 (Chaetomium brasiliense) exhibited exceptional cellulolytic activity on lignocellulosic substrates such as rice straw and sugarcane bagasse. Consortia of the potential ligninolytic and cellulolytic isolates were set up to determine their ability to biodegrade the lignocellulosic substrates such as rice straw and sugarcane bagasse. The efficiency of the consortia was determined on the basis of the increase in enzyme activity; it was also evident through scanning electron microscopy, x-ray diffraction analysis of the degraded substrates, and the sugar yield. Experiments were also carried out to compare the biological with the physical pretreatment methods. The consortium of ligninolytic and cellulolytic marine-derived fungi developed in this study prove to have the potential for application in the effective utilization of agricultural wastes.

KEYWORDS:

• Agricultural wastes
• biological pretreatment
• enzymes
• fungal consortia, marine

Acknowledgments

The authors would like to thank Mr. Ram Murti Meena, Mr. Areef Sardar, and Mr. Girish Prabhu, CSIR-NIO, for technical support during sequencing, SEM, and XRD analysis. Rathinam Ramarajan would like to thank the director of CSIR-NIO, and head of BOD, CSIR-NIO, for granting her required permissions to carry out the work as a part of her M.Tech dissertation work in Industrial Biotechnology at National Institute of Technology Karnataka, Surathkal.

Funding

This study was funded by Council of Scientific and Industrial Research grant PSC0206. This is NIO's contribution number 5988.