Banca de DEFESA: JOSE APARECIDO DE SOUSA BERNARDINO LEITE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JOSE APARECIDO DE SOUSA BERNARDINO LEITE
DATE: 17/04/2026
TIME: 09:00
LOCAL: Videoconferência
TITLE:

Formulation of a bacterial consortium for the degradation of heavy petroleum.

KEY WORDS:

bacterial consortium, bioremediation, heavy oil, quorum sensing, hydrocarbon biodegradation, cross-feeding, metabolic synergy, flux modeling

PAGES: 93
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Oil contamination poses a critical challenge for bioremediation due to its high viscosity. Heavy oil exacerbates this issue through recalcitrance and the prevalence of complex fractions that hinder biodegradation. Against this backdrop, formulating microbial consortia based on integrated genomic and functional data emerges as a promising biotechnological strategy. This study aimed to develop a bacterial consortium capable of degrading heavy oil (16° API) for bioremediation applications. The methodology followed a strategic selection workflow, starting with genomic screening of 68 sequenced isolates using the eggNOG-mapper and BioRemPP platforms, which identified 6,337 genes associated with aliphatic, aromatic, and polycyclic aromatic hydrocarbon (PAH) metabolism, revealing broad functional diversity. Functional screening using a redox assay with 2,6-dichlorophenolindophenol (DCPIP) showed that 34 isolates achieved >50% degradation rates, confirming adaptive potential. Based on pathway diversity, degradation efficiency, and the absence of antagonism in cross-streak tests, three isolates were selected for the BMC consortium: Micrococcus luteus BD1 and Acinetobacter baumannii ssp. oleum ficedula BD54, and Ochrobactrum oleinvorans BD61. The final BMC formulation outperformed binary combinations and individual isolates. Microcosm assays (15 days) using total oil and grease (TOG) analysis revealed that BMC reduced residual oil by 77%, a statistically superior reduction compared with the BD54 (60%), BD61 (58%), and BD1 (59%) monocultures. This performance was supported by synergistic biosurfactant production, with BMC achieving an emulsification index (E24%) of 82.5% and an oil displacement area of 2.81 cm², along with significantly higher biofilm production (p = 0.0001). Genomic analysis using antiSMASH identified canonical quorum sensing systems (LuxI/LuxR in BD54 and AIP-type signaling in BD1), which are essential for coordinating cell adhesion and the production of amphiphilic molecules. Genome-scale metabolic modeling (GEMs) and flux balance analysis (FBA) in KBase revealed a biological buffering mechanism in which the consortium stabilized proton flux (−1.06 µmol/gDCW/h), neutralizing BD61's acidifying tendency and BD1's alkalizing tendency, mitigating acid stress and preserving oxidative enzyme activity. RT-qPCR transcriptional dynamics, normalized by biomass, demonstrated that BMC efficiency stems from metabolic division of labor and biphasic regulation in BD1. Initially, alkane oxidation occurs via FAD-binding monooxygenases and alcohol dehydrogenase (
adh), with metabolic relief evidenced by reduced adh transcriptional cost per cell in the consortium despite higher total degradation than in monoculture. With alkane depletion, late-phase transition processes aromatic intermediates via quinol monooxygenase and benzoate 1,2-dioxygenase, configuring cross-feeding that prevents toxic byproduct accumulation and ensures continuous mineralization. Aromatic degradation genes benD (BD54) and pcaH (BD61) exhibited synergistic induction, sustained by continuous exchange of intermediates between strains, thereby maintaining elevated expression levels throughout the experiment in the consortium, unlike in monocultures. The BMC consortium serves as a robust bioremediation tool, demonstrating that interspecific cooperation reduces metabolic bottlenecks and promotes continuous mineralization of complex HCs. The 77% heavy-oil degradation efficiency results from quantifiable synergistic interactions: biosurfactant-enhanced bioavailability, enzymatic complementarity in alkane/aromatic pathways, cross-feeding-mediated toxicity mitigation, and microenvironmental pH stabilization.

COMMITTEE MEMBERS:
Externa à Instituição - ADRIANA URURAHY SORIANO
Externa à Instituição - CAROLINA FONSECA MINNICELLI
Presidente - 1149647 - LUCYMARA FASSARELLA AGNEZ LIMA