Bottom-up Construction and Screening of Algae-bacteria Consortia for Volatile Organic Compounds (VOCs) Biodegradation

Microbial communities have been exploited in various fields of studies associated with agriculture, the food industry, human health and other related fields. Engineering of microbial communities is an emerging field of research motivated by finding stable and efficient microbial systems as tools to achieve different biological tasks such as bioproduction and bioremediation. Algae and bacteria communities, in particular, are of interest due to the vast metabolic diversity of bacteria, the significant variety of bioproducts derived from algae, as well as the widespread interactions between algae and bacteria in natural systems. However, the successful designing of microbial communities not only underlies a profound understanding of microbial activities but also requires efficient approaches to piece together the known microbial traits to give rise to more complex systems. This project aims to address the lack of efficient methodologies for identifying and engineering algae bacteria consortia with unique functions, while also responding to the requirement of the industrial sponsor, Freeland Horticulture Ltd., which is motivated to combine waste woody and herbaceous biomass combustion with greenhouse CO2 enrichment to achieve efficient heating, plant growth enhancement, waste reduction, and CO2 capture. This study demonstrated the bottom-up integration of environmentally isolated phototrophic microalgae and chemotrophic bacteria as artificial consortia to bio-degrade selected representative volatile organic compounds (VOCs) that are of most concern in woody and herbaceous biomass combustion. A high throughput screening method based on 96-well plate format was developed for discovering consortia with bioremediation potential. Screened exemplar consortia were verified for VOCs degradation performance, among which certain robust consortia achieved 90.7%, 92.15 % and near 100% removal (7-day) of benzene, toluene, and phenol, respectively, with initial concentrations of 100 mg/L. VOCs degradation by consortia were mainly attributed to certain bacteria including Rhodococcus erythropolis, and Cupriavidus metallidurans, and directly contributed to the growth of microalgae Coelastrella terrestris (R= 0.82, P<0.001). This work revealed the potential of converting VOCs waste into algal biomass by algae-bacteria consortia constructed through a bottom-up approach. The screening method enables rapid shortlisting of consortia combinatorial scenarios without prior knowledge about the individual microorganisms or the need for interpreting complex microbial interactions.