Micro-organisms found in the wildfire-prone dry tropical forests of India are an exciting prospect for biochemical production, as they are accustomed to the challenging conditions following a forest fire. The enzymes they produce are likely to also have a higher-than-normal resistance to the substances released from biomass in high-temperature industrial processes. An EU and nationally funded project led by VTT Technical Research Centre of Finland, called IndZyme, is looking to study whether they are capable of breaking down agricultural waste better than commercial enzymes.
Converting the lignocellulose in biomass into fermentable sugars and ultimately biochemicals with the help of enzymes requires first breaking down the tough lignocellulosic structure. The technology already exists, but the inhibitors generated by the process reduce the effectiveness of the enzymes. Inhibitors are chemical compounds that prevent or hinder enzyme activity. Enzymes that are more resistant to inhibitors could help to lower enzyme costs and increase the sugar yield.
The Indian research partner in IndZyme, Vinstrom, has collected microbial cultures from wildfire-prone areas of Indian forests and proven that they have a higher-than-normal resistance to inhibitor chemicals. During the project, these microbial cultures will be screened for new, more inhibitor-resistant cellulase enzymes as well as LPMO enzymes, whose activity may even be boosted by inhibitor chemicals. The next step will be studying the efficiency of these new enzymes in breaking down agricultural waste, such as straw, into fermentable sugars. Their efficiency will be compared against the Trichoderma reesei enzymes, which are widely used in industrial applications, and enzyme mixtures. The project will involve developing new enzyme screening methods and producing new information about compounds that inhibit or promote enzyme activity.
Special attention will be given to lignin-based phenolic compounds, which are released at high temperatures during the pretreatment of lignocellulosic materials. These compounds are strong inhibitors of cellulase enzymes but can act as electron donors and therefore increase LPMO enzyme activity.
Lignocellulosic agricultural waste is among the most common renewable biomass resources. In Europe, wheat straw is one of the most abundant agricultural waste products. India has ample stocks of bagasse, the fibrous matter that remains after sugar cane stalks are crushed to produce sugar, but it is currently disposed of by incineration, causing considerable local emissions.