The general aim of the PhD project is to enhance the utilization of white-rot fungi in the pretreatment of lignocellulosic agriculture wastes by identifying the most potential fungal species and optimum substrate types and conditions. This project is part of the research programme ‘Food for thought, thought for food: More meat and milk from straw’ and lead by dr. John Cone (Animal Nutrition Group, Wageningen University) and dr. Anton Sonnenberg (Laboratory of Plant Breeding, Wageningen University).
Lignocellulosic biomass from agriculture wastes has a great potential to be utilized as feedstock to ruminants. In many developing countries, these lignocellulosic crop residues, mainly cereal straws and stovers have long been used as ruminant feeds. Cereal straws normally contain at least 70% of carbohydrates which make them a potential source of energy for ruminants.
However, due to their high neutral detergent fiber and lignin content, these feedstock have relatively lower digestibility and energy values. High lignin content is considered as the most responsible factor for reducing the digestibility of straws and also forages. Therefore, it is important to remove or modify lignin for an efficient utilization of the “locked” polysaccharides from the lignocellulose by ruminants, besides improving their palatability. To achieve this, there are different pretreatment methods, including physical, chemical and biological approaches. Among these, a fungal pretreatment has attracted research interest because of its potential advantage, particularly of its economic and environmental importance.
Fungi, especially white-rot species have been shown to be efficient lignin degraders, altering the lignocellulose structures. The variations within the white-rot fungi species in degrading lignin are due to the fact that there are differences in the degradation mechanisms, namely selective and non-selective. However, this classification is not necessarily exclusive, as it may represent a broad range, overlapping among different species and strains. The delignification mechanism of white-rot fungi is probably best characterized by the production of lignin modifying enzymes. The capabilities of the white-rot fungi to produce these enzymes are vary widely. The efficiency of the fungal pretreatment can also be affected by the variation in the substrates themselves. Different straw varieties, maturity stage, environmental factors and management practices have considerable effects on the lignin composition of the harvested straws.
Nazri Nayan graduated from University Putra Malaysia in Biomedical Sciences and then obtained his Master degree in Animal Physiology from the same university. He is currently enrolled as a PhD candidate at the Animal Nutrition Group, Wageningen University with a scholarship from the Ministry of Education, Malaysia.