# Biotransformation of Aliphatic and Aromatic Hydrocarbons by Aerobic Bacterial Strains Isolated from Brown Coal

## TL;DR

Scientists isolated bacteria from brown coal that can break down harmful hydrocarbons, suggesting potential for environmental cleanup.

## Contribution

The study identifies and characterizes lignite-indigenous aerobic bacteria with high biotransformation potential for various hydrocarbons.

## Key findings

- Rhodococcus opacus CUP11 and Rhodococcus sp. CUP17 showed the highest biotransformation versatility.
- CUP17 achieved 81% diesel oil removal at 10 g/dm³ and 99% hexadecane removal at 2.5 g/dm³.
- CUP11 degraded 49% hexadecane and 48% pristane, indicating strong bioremediation potential.

## Abstract

Lignite collected from a brown coal deposit was colonized with fully aerobic bacteria exhibiting hydrocarbon biodegradation pathways. Six autochthonous strains were isolated and tested for tolerance and biotransformation potential towards various xenobiotics such as hexadecane, squalane, pristane, benzoic acid, naphthalene, phenanthrene, and diesel oil. After preliminary screening, four xenobiotic-resistant strains were selected (Rhodococcus opacus CUP11, Pseudomonas fluorescens CUP15, Sphingobacterium sp. CUP16, and Rhodococcus sp. CUP17) and further treated for 14 days under aerobic conditions with variant concentrations of each compound (1, 2.5, 5 and 10 g/dm3). Microbial population dynamics and xenobiotic level changes were monitored. Rhodococcus opacus CUP11 and Rhodococcus sp. CUP17 were the most metabolically versatile bacteria capable of biotransforming several xenobiotics. Among the best-performing strains, the highest degradation yields were obtained for CUP17 (81% removal of diesel oil applied at 10 g/dm3, 99% of 2.5 g/dm3 hexadecane and 27% of 1 g/dm3 squalane), and CUP11 (49% of 10 g/dm3 hexadecane and 48% of 1 g/dm3 pristane). The strain CUP16 utilized squalane (33% at 1 g/dm3). The results suggest that the lignite-indigenous bacteria may be applicable for bioremediation of persistent xenobiotics in environmental cleanup projects.