The growing global demand for food, coupled with diminishing arable land and environmental concerns, requires the development of sustainable agricultural practices. While urban controlled environment agriculture is effective for plant agriculture, sustainable approaches in circular farming for animals are underdeveloped. Photosynthetic microorganisms (PMO's), such as microalgae and Cyanobacteriota (Spirulina), in mixed populations can be harnessed in photobioreactors within conventional animal houses to utilize exhaust components for growth.

We investigated the capacity of the PMOs to transform animal housing emissions into valuable biomass as well as potential community shifts in the mixed population.[1] To this end, a suspended, innovative cone-shaped, helical tubular photobioreactor was introduced into a chicken coop and demonstrated its efficiency in purifying exhaust air while producing Spirulina.

Metagenomics analysis revealed the impact of the chicken house exhaust on the algal culture and provided insights into the NH3 metabolism. The taxonomic classification of the microbial community in the photobioreactor revealed a predominance of bacterial organisms before aeration, with a notable shift to a more diverse community, including eukaryotic species, after exposure to exhaust air from the chicken coop. The emergence of Viridiplantae, and Stramenopiles, particularly Chlorella and diatoms, suggests a significant impact on the microbial composition influenced by the exhaust air.

References:

[1] T. Glockow, M. Velaz Martín, L. Meisch, D. Kapieske, K. Meissner, M. Correa Cassal, A.-K. Kaster, K. S. Rabe, C. M. Niemeyer, A photobioreactor for production of algae biomass from gaseous emissions of an animal house, Appl. Microbiol. and Biotechnol., 2023.