# Biodegradation potential of used motor oil by mixed bacterial community: optimization, emulsification activity, bioelectrochemical and metagenomics analyses using single chamber microbial fuel cell

## TL;DR

This paper explores using a microbial fuel cell to simultaneously break down used motor oil and generate electricity, offering a sustainable waste treatment solution.

## Contribution

A novel single-chamber microbial fuel cell system is introduced for UMO biodegradation and bioelectricity generation.

## Key findings

- An optimized bacterial culture degraded UMO by about 80% under specific conditions.
- A maximum voltage of 257 mV and power density of 36.6 mW/m² were achieved, correlating with UMO removal.
- Firmicutes, especially Bacillus, dominated the biofilm, playing a key role in hydrocarbon breakdown.

## Abstract

Used motor oil (UMO) is a dangerous environmental pollutant that needs to be treated effectively. This work introduces a novel approach for producing bioelectricity and UMO biodegradation simultaneously in a single-chamber microbial fuel cell (SCMFC) using native mixed bacterial cultures.

Under certain conditions (2% oil, 1% peptone, 4% inoculum, 21 days), the optimized bacterial culture degraded UMO by about 80%. Through bioelectrochemical studies, a maximum voltage of 257 mV and a power density of 36.6 mW/m² were demonstrated, showing a strong correlation between UMO removal and electricity generation. Moreover, metagenomic data showed that Firmicutes, particularly Bacillus, dominated the biofilm at roughly 65%. Fourier Transform Infrared (FTIR) and Gas Chromatography-Mass Spectroscopy (GC-MS) verified the breakdown of complex hydrocarbon molecules, highlighting their crucial role in UMO biodegradation and bioenergy production. The effective elimination of UMOs and simultaneous power generation, supported by metagenomic and biochemical tests, showed the microbial activity and hydrocarbon breakdown.

The results suggest SCMFC technology as a sustainable solution for managing petroleum waste while producing renewable energy.

The online version contains supplementary material available at 10.1186/s12934-025-02889-5.