Sorangium cellulosum

Sorangium cellulosum holds the record for the largest bacterial genome—13 million base pairs, three times larger than E. coli. This genomic enormity isn't random bloat; it encodes an unprecedented capacity for secondary metabolite production. S. cellulosum can synthesize hundreds of bioactive compounds, including epothilones used in cancer treatment. The social lifestyle that defines myxobacteria apparently supports—or requires—remarkable chemical diversity.

The connection between sociality and chemical complexity may reflect the demands of cooperative living. Social organisms must recognize kin, coordinate behavior, and defend group resources. Chemical signals serve all these functions. S. cellulosum's metabolic arsenal includes communication molecules, antibiotics targeting competing microbes, and compounds whose functions remain unknown. The genome devotes more space to secondary metabolism than any other known bacterium—approximately 10% of genes encode natural product biosynthesis.

Drug discovery has mined myxobacteria, and S. cellulosum in particular, for novel compounds. The epothilones, originally isolated from S. cellulosum, show activity against taxol-resistant cancers and have inspired multiple approved drugs. This pharmaceutical value emerges from the bacterium's ecological strategy: producing diverse compounds to manipulate its environment, attack competitors, and coordinate with relatives. Understanding why myxobacteria evolved such chemical diversity—and identifying the ecological functions of individual compounds—continues to yield both basic insights and practical applications.