**5. Biological pretreatment**

Conventional methods for chemical and physical pretreatments require expensive reagents, equipment, and high energy. On the other hand, biological pretreatment requires live microorganisms for the treatment of lignocellulosic material, and this method is more environment friendly and consumes less energy. There are certain microorganism present in nature that exhibit cellulolytic and hemicellulolytic abilities. White-rot, soft-rot, and brown fungi are known for lignin and hemicellulose removal with a very little effect on cellulose. White rot is able to degrade lignin due to the presence of lignin degrading enzymes like peroxidases and laccases. Carbon and nitrogen sources are involved in the regulation of these degrading enzymes [41]. Cellulose is commonly attacked by brown rot, whereas white and soft rot target both lignin and cellulose contents of plant biomass. Commonly used white-rot fungi species are *Pleurotus ostreatus, Ceriporiopsis subvermispora, Ceriporia lacerata, Pycnoporus cinnabarinus, Cyathus cinnabarinus*, and *Phanerochaete chrysosporium. Basidiomycetes* species including *Bjerkandera adusta, Ganoderma resinaceum, Trametes versicolor, Fomes fomentarius, Irpex lacteus, Lepista nuda*, and *Phanerochaete chrysosporium* are also tested, and these species showed high efficiency for delignification [41, 99].

Pretreatment of wheat straw was studied by Hatakka [100]. The results showed 13% conversion of wheat straw into sugars by *Pleurotus ostreatus* in duration of 5 weeks, whereas *Phanerochaete sordida* and *Pycnoporus cinnabarinus* showed almost the same conversion rate but in less time. For degradation of lignin in woodchips and to prevent cellulose loss, cellulase-less mutant of fungus *Sporotrichum pulverulentum* was developed [101]. Delignification of Bermuda grass by white-rot fungi *Ceriporiopsis subvermispora* and *Cyathus stercoreus* was studied that resulted in 29–32 and 63–77% improvement in delignification [102]. During the secondary metabolism in fungus *P. chrysosporium*, two lignin degrading enzymes, lignin peroxidase and manganese-dependent peroxidase, are produced in response to carbon and nitrogen limitation. Extracellular filtrates of various white-rot fungi contain these two enzymes.

**31**

**Author details**

Pakistan

Iran

Muhammad Nauman Aftab1

and Meisam Tabatabaei4

provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*, Irfana Iqbal2

3 Faculty of Science, Bartın University, Bartın, Turkey

\*Address all correspondence to: nauman535@yahoo.com

1 Institute of Industrial Biotechnology, Government College University, Lahore,

2 Department of Zoology, Lahore College for Women University, Lahore, Pakistan

4 Agricultural Biotechnology Research Institute of Iran (ABRII), AREEO, Karaj,

, Fatima Riaz1

, Ahmet Karadag3

*Different Pretreatment Methods of Lignocellulosic Biomass for Use in Biofuel Production*

*DOI: http://dx.doi.org/10.5772/intechopen.84995*

*Different Pretreatment Methods of Lignocellulosic Biomass for Use in Biofuel Production DOI: http://dx.doi.org/10.5772/intechopen.84995*
