| Congresso Brasileiro de Microbiologia 2023 | Resumo: 603-2 | ||||
Resumo:Limonene is the main component of orange essential oil and is obtained by pressing the orange residue ⟨ peel, bagasse and seed ⟩ after juice extraction. Approximately 1.96 m3 of wastewater is generated for every ton of processed fruits due to the enormous amount of water needed for orange juice preparation. Limonene is a common compound of citrus fruit processing wastes which is known to be an antibacterial agent and thus can disrupt or even cause the failure of the anaerobic process This study characterized the microbial community present in the bench scale horizontal flow anaerobic immobilized biomass reactor ⟨HAIB⟩ used in the removal of limonene. The HAIB was filled with three support materials ⟨coal, polyurethane foam and gravel⟩ , which were inoculated with anaerobic sludge. The concentration of limonene in the substrate affluent to the HAIB ranged from 10 mg ⁄L to 500 mg ⁄L. The molecular biology analysis was carried out by next-generation sequencing ⟨Illumina⟩. The analysis of 16S rRNA showed the presence of 22 OTUs ⟨based on ≥97% sequence identity⟩ , distributed in 24 phyla, 23 classes, 53 orders, 59 families and 57 genera, considering three different matrices. Higher percentages of relative abundance of the phyla were observed: Synergistetes ⟨43% to 57%⟩, Proteobacteria ⟨32% to 42%⟩, Firmicutes ⟨7% to 8%⟩ and Acidobacteria ⟨2% to 3%⟩. Actinobacteria, Bacterioidetes and Chloroflexi had the lowest relative abundances, between 1% and 2%. Among Bacteria domain genera, the most representative, with the highest relative abundance in the three-support media, were Pseudomonas ⟨10.6% to 18.4%⟩,Klebsiella ⟨about 1.03%⟩, and vadinCA02 ⟨0.96% to 1.2%⟩. Among Archaea domain, Methanosaeta ⟨0.86% to 1.34%⟩ had the highest relative abundances in the system. The metabolic versatility of Pseudomonas makes them an important bioremediation agent by being capable of metabolizing xenobiotic and chemical toxic compounds, thus having great prominence for the limonene removal in the HAIB reactor. Concerning the archaeal communities, methanogenic Archaea, the low relative abundance can be justified by low methane contents ⟨10.1% to 13.2%⟩. A greater number of genera in the sample of biomass removed from mineral coal when compared to the biomass of foam and gravel. Therefore, the type of support medium did not affect the microbial richness and population diversity involved in the degradation of D-limonene in the HAIB reactor. The microbial population characterized in the bioreactor ⟨HAIB⟩ was able to biotransform D-limonene, with high removal efficiencies ⟨> 95% ⟩ from 10 mg ⁄L to 500 mg ⁄L. However, anaerobic digestion was not complete, and D−limonene was not completely converted into methane and CO2.
Palavras-chave: degradation of D-limonene, next-generation sequencing, orange essential oil, Pseudomonas, terpene Agência de fomento:SÃO PAULO RESEARCH FOUNDATION (FAPESP) | |||||