The manganese‐precipitating activities of a marine bacillus (strain SG‐1) are enhanced by interaction with solid surfaces. When not attached to surfaces, SG‐1 exhibits little or no ability to oxidize manganese. After the bacteria attach to any of a variety of surfaces (e.g., glass beads, frosted glass, sand grains; and calcite crystals), manganese is rapidly precipitated and removed from solution. Attached and manganese‐precipitating cells are morphologically distinct from free‐swimming or non‐precipitating cells.