Isolation and characterisation of an unusual bacterium, allied to the soil bacterium Bacillus benzoevorans, from feedlot manure pads in Australia

Strains of bacteria were obtained by anaerobic enrichment from feedlot manure pads and were phenotypically characterized. Colonies had a cotton wool or hairy appearance. When cultures grown in liquid media were exposed to a drying atmosphere, they produced a pellicle comprised of a cross-meshed array of cells. Colonies on agar media also produced spiral sheets of cells held well above the agar surface. The strains were Gram positive, according to ultrastructural features from transmission electron micrographs and KOH solubility, but Gram negative by Gram stain. The 16S rDNA from strain YEO5 was determined and is 99·3% similar to the type strain of Bacillus benzoevorans. The inability of our strains to grow aerobically and lack of endospores differentiated them from previously isolated strains of B. benzoevorans. In freshly broken feedlot pad material, a white, hairy coating of the exposed surface appeared within a few hours. We hypothesize that this is due to the insoluble extracellular matrix material produced by this Bacillus sp. to avoid desiccation and, additionally, the bacterial covering is responsible for retaining odours within the pad material