Objective
Our goal is to develop a bioformulation that can be applied to flax stubble that will accelerate its decomposition to reduce its interference with the flax seeding process. We propose to isolate and characterize bacterial and fungal decomposers from local soils to design a formulation that accelerates decay under field conditions. Our objectives are to:
1) Use a soil baiting method to capture and isolate bacterial and fungal colonizers at early and late stages of straw decomposition.
2) Characterize microbial communities across the stages of decomposition using metagenomics to identify primary degraders and predict core and partner taxa.
3) Evaluate straw decomposition rates achieved by individuals and co-cultures of isolates in bioreactors simulating field conditions.
Project Description
Managing straw residue is the single biggest challenge associated with flax production. No straw management strategies currently exist that are both environmentally sustainable and economically feasible for producers. This study aims to characterize the microbial communities involved in the natural decomposition of flax straw. This information will be used to develop a bioformulation of lignocellulolytic microbes that can be applied to flax fields after harvest in order to accelerate straw decomposition. A set of nine bioreactors was constructed using soil and straw sampled from three flax fields in southern Saskatchewan and were incubated for 60 days. Following the incubation period, 16S and ITS amplicon sequencing were used to identify the bacterial and fungal taxa associated with straw decomposition. Cellulase activity of each of the identified isolates was assessed on carboxymethylcellulose (CMC) agar plates. In total, 57 isolates from flax field soil and 31 isolates from decomposing straw were successfully identified. Bacillus and Cystobasidium were the only non-pathogenic genera consistently associated with decomposing straw, making them strong candidates for a microbial bioformulation designed to accelerate flax straw decomposition. However, no significant differences were observed in decomposition rate between the three flax fields despite differences in microbial community structure, which suggests that functional redundancy exists within these communities. Additionally, low rates of straw decomposition despite the presence of cellulolytic microbes suggests that decomposition rate is limited by lignin breakdown. Our results have set the foundation for the development of a bioformulation that can be used to accelerate flax straw decomposition in the field.
