I find Leptothrix ochracea very frequently in my samples. Especially in old samples, dense mats form on the surface and on the vessel wall. Leptothrix ochracea also likes to settle on the floating coverslip.

Leptothrix ochracea is an “iron bacterium” which is able to oxidize both iron and manganese. It forms long filaments of chain-like connected cells, which are surrounded by a gelatinous sheath. In young colonies, this gelatinous sheath is still thin and colorless. Later, this gelatinous sheath grows and becomes orange or brown due to iron and manganese deposits. The bacteria form a smooth tube in the middle in which they can also move. The bacteria are not described exactly in the literature. According to my measurements, they are 3.5-5.0 µm long and about 1.2 µm thick. Grains can be seen in the cells (s. fig. 2).

The gelatinous sheath does not appear to be very elastic. Filaments are often found which are smoothly broken (s. fig. 3). The ends of the filaments are not tapered, as is typical for the similar species Leptothrix discophora.