Polymers-transforming potential of a minimal lignocellulolytic bacterial consortium disclosed by genomeresolved metagenomics

Abstract

The metabolism of lignocellulose and plastics by engineered microbial communities is a topic of interest in ecology, biotechnology, and bioeconomy. In this study, the polymer-degrading capability of a minimal lignocellulolytic bacterial consortium (MELMC) was explored by genome-resolved metagenomics. Based on results, the MELMC was mostly composed by three bacterial members: Pseudomonas protegens (MAG1_74%), and two novel species closely affiliated with Paenibacillus sp. (MAG5_12%) and Ochrobactrum sp. (MAG4_6%). From them, only MAG1 was recovered as axenic culture. The high-quality circular genomes of these species (6.98, 5.26 and 2.52 Mbp) were functional annotated using different databases (CAZy, KEGG and eLignin), revealing that MAG5 and MAG1 have the potential to catabolize plant polysaccharides and lignin-derived compounds (e.g., catechol, vanillate and protocatechuate), respectively. Interesting, average amino acid identity and digital DNA¿DNA hybridization values for MAG5 suggested that it can belong to a novel genus (named Pristibacillus lignocellulolyticum, following the SeqCode Initiative). The MELMC capacity to transform plastics and its derived compounds was assess by two strategies: i) annotation of genomes with specific databases (PMBD and plasticDB); and ii) predicting enzymatic activity based structural similarities (using Simplified Molecular Input Line Entry Specification and Tanimoto coefficients), between lignin- and plastics-derived chemicals compounds. Genes related with depolymerization of polyurethane, polybutylene adipate terephthalate and polyethylene were found in MAG1. In addition, this member could catabolize phthalates, polyhydroxyalkanoates (PHAs)- derived monomers and terephthalic acid. The axenic culture of P. protegens could be a prospective strain for PHAs degradation and production of bio-based polymers in the frame of plastic upcycling.