Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by synthetic bacterial communities: effects of biodiversity on multifunctionality and robustness

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, toxic and recalcitrant compounds generated from biological and anthropogenic processes. The environmental exposure to these persistent organic pollutants has led to the evolution of specific microorganisms that are able to use PAHs as the sole source of carbon and energy. Soils are commonly co-contaminated by different classes of PAHs and heavy metals that require robust bioaugmentation formulations to guarantee effective biodegradation. This study seeks to use artificial PAH-degrading bacterial consortia to investigate the impact of microbial community biodiversity and niche dimensionality on the system functionality. System robustness against heavy metal disturbances will also be correlated to community biodiversity. In this work, we used three different bacterial strains to construct consortia, i.e., Sphingomonas sp. strain LB126, Novosphingobium sp. strain LH128, Mycobacterium sp. strain LB501T (Bastiaens, Springael, et al., 2000, AEM). The biodegradation abilities and robustness of mono-, co- and tri-cultures are assessed in liquid aerobic incubations using a mixture of PAHs (fluorene, phenantrene and anthracene) in the presence or absence of disturbances. Positive relationships between species richness, functional diversity and functional robustness (PAHs biodegradation) are observed due to a positive net biodiversity effects driven by functional complementarity and differential perturbation responses