[Lignite microorganisms].

Area of Science:

• Microbiology
• Geomicrobiology
• Biogeochemistry

Context:

• Lignite, a precursor to coal, is often considered a geologically stable environment.
• Subsurface microbial life is crucial for understanding biogeochemical cycles.
• Investigating microbial communities in deep geological formations provides insights into extremophile survival strategies.

Purpose:

• To demonstrate the presence and abundance of viable microorganisms in lignite samples.
• To characterize the microbial community composition (bacteria and fungi) within lignite.
• To assess the impact of environmental conditions (moisture) on microbial activity and diversity in lignite.

Summary:

• Direct microscopy revealed approximately 10(7) bacterial cells per gram in lignite samples from a 10m depth, with 70% exhibiting intact cell membranes, indicating an anabiotic state.
• Bacterial genera including Bacillus, Rhodococcus, Arthrobacter, Micrococcus, Spirillum, and Cytophaga were isolated, alongside fungal genera Penicillium and Trichoderma.
• Moistening lignite increased microbial respiration and abundance but not generic diversity, suggesting the microorganisms are autochthonous (native) to the lignite.

Impact:

• This study provides the first evidence of a substantial, viable microbial community within deep lignite.
• The findings contribute to understanding microbial life in deep subsurface environments and the potential role of lignite as a microbial habitat.
• Characterizing autochthonous microorganisms in lignite has implications for geomicrobiology and understanding carbon cycling in sedimentary environments.