Top-down enrichment strategies as driver of bacterial diversity of cultures with high aromatic compound degrading potential

FESTA S; CUADROS-ORELLANA SARA, GRANADA MARINA , QUEVEDO-GALLARDO CLAUDIO, COLMAN DEBORA, MORELLI IRMA S.; COPPOTELLI BIBIANA M.

Laussane

Simposio; 18th International Symposium on Microbial Ecology- ISME18,; 2022

ISME International Society of Microbial Ecology

When microbial cultures are required for biotechnological purposes, focus is going toward the use of enriched natural communities owning to their functional stability and efficiency. The aim of this study was to determine the relevance of different top-down strategies in pyrene degrading enrichment culture selection as driver of the metabolic bacterial diversity, and its influence on pyrene degrading efficiency. Three enrichment cultures were obtained by sequential transfers with pyrene from a hydrocarbon-contaminated soil. Incubation time and dilution factor for each culture were as follows: 7 days and 1:10 dilution for r-EF18P and 28 days with 1:10 and 1:2 for r-k-MS19P10 and k-MS19P2. Diversity and functional potential was assessed by 16S rRNA gene metabarcoding (Illumina-QIIME2) and shotgun metagenomics (Illumina-Trimmomatic/Megahit/Prokka/Kaiju/Binnacle/CheckM). Even though pyrene degradation kinetic (HPLC-UV) was different among cultures, all managed to degrade more than 95% after 21 days. Metabarcoding analysis showed as predominant class Gammaproteobacteria in r-EF18P and r-k-MS19P10 (77,9% and 56,3% respectively) and Bacilli (40,3%) in k-MS19P2. High quality metagenome assembled genomes were recovered (27), mainly assigned to Gammaproteobacteria and Alphaproteobacteria. Several Rieske non heme-iron-dependent oxygenases, assessed by AromaDeg database were found in r-k-MS19P10 while in r-EF18P extradiol dioxygenases were predominant. Aromatic compound degradation related genes were predominantly assigned to Alpha, Beta and Gammaproteobacteria in r-EF18P and Alphaproteobacteria, Betaproteobacteria and Actinobacteria in r-k-MS19P10 and k-MS19P2. Strong positive correlations were assessed though co-occurrence network analysis (SCNIC-SparCC) among these classes. Top-down conditions were found to have decisive effects on bacterial diversity selection and consequently on aromatic compound degradation potential and efficiency.