Isolation and screening of cellulolytic fungi  for the pretreatment of lignocellulosic biomass (agro-waste) for biogas production

Tawakalt Ajoke  Fagbayi; Henry  Boyo; Titilola Fausat  Salisu; Joy  Okpuzor

Tawakalt Ajoke Fagbayi Department of Cell Biology & Genetics, University of Lagos, Akoka
Henry Boyo Department of Physics Covenant University, Ota, Ogun State
Titilola Fausat Salisu Department of Zoology and Environmental Biology, Olabisi Onabanjo University, Ago-Iwoye, Ogun State
Joy Okpuzor Department of Cell Biology and Genetics, University of Lagos, Akoka, Nigeria

Keywords: Agrowaste, Pretreatment, Biogas, Fungi isolates, Solid State Fermentation (SSF)

Abstract

Agricultural waste (agrowaste), an abundant waste in Nigeria and Africa, is gradually replacing crude oil World wide through its bioconversion into biogas (methane gas) and biofuels (biodiesel) as an alternative source of energy. The only limitation encountered is the need for a pretreatment prior the process of biogas and or biodiesel production due to presence of lignocelluloses in the waste. . This study presents an investigation of the ability of different fungi isolates to degrade the lignocellulosic component of plantain trunk wastes through biological pretreatment. Five fungi isolates were isolated from the decomposing agrowaste (plantain wastes) and were screened for cellulolytic activities on selective CMC agar using the plate screening method. Aspergillus niger exhibited the highest cellulolytic activity on the CMC agar at pH 4 with an ICMC value of 1.55 followed by Trichoderma spp with an ICMC value of 1.31, while the reverse was observed for the cellulolytic activity on the CMC agar at pH 5, with T. spp exhibiting the highest ICMC value of 1.45 and A. niger with an ICMC value of 1.25. While the other isolated fungi isolates, Aspergillus flavus, Aspergillus fumigatus, and Rhizopus stolonifer, exhibited no definite cellulolytic activities. The inocula of both A. niger and T. spp were used for the pretreatment of the plantain trunk waste, separately and jointly using the Solid State Fermentation (SSF) technique for a week. The highest reduction in lignin and cellulose content was observed when the waste was pretreated with both fungi isolates (in equal proportions) with a reduction of 28.59% (18.85% to 13.4%) and 43.77% (59.22% to 33.0%), respectively followed by pretreatment with T. spp with 22.44% (18.85 to 14.62%) and 43.77%(59.22 to 39.61%) reductions and A. niger with 18.3% (18.85 to 15.4%) and 31.8% (59.22 to 40.38%) reductions, respectively. Thus, co- digestion or pretreatment of waste with two or more fungi, will be most favourable for the biological pretreatment of lignocellulosic waste (agrowaste) prior biogas production.