Filaments and Bacteria...
Volume - 3...

Introduction to Filament Identification...

Filament Identification...

In order to identify many of the following filament characteristics, the mixed liquor must be examined under 100 X using immersion oil. It is difficult to see many of these characteristics under lower magnifications.

Filament Shape and Length...

Filaments may be long, short, smoothly curved, coiled, irregularly bent, straight, or bundled.

Individual Cell Shape...

Filamentous bacteria are made up of a chain of cells. The shape of the individual cells is a characteristic that can help us to identify the different filamentous bacterial types. Cell shape may be round, square, rectangular, oval, or discoid.

Cell Septa...

The cell septa is the "line" which separates each individual cell which makes up the bacterial filament. The septa are clearly seen in some filaments an is very difficult to see in others. Some septa are "indented" and some are not. Indentations and the ability to clearly see the cell septa are other characteristics which can help us to identify the different filamentous bacteria.

Motility...

Motility is the ability of an organism to produce motion or to move. Beggiatoa spp is only one filamentous bacterium found in activated sludge that is motile.

Intercellular Granules...

Some filaments store by-products as intercellular granules (mostly sulfur granules). Sulfur granules can be seen very clearly under phase contrast and are found usually in septic wastes. Sulfur granules are commonly found in Beggiatoa, Thiothrix and type 021N.

Branching...

Branching may be "true" or "false". If a filament has true branching the intercellular fluids will flow freely throughout all the branches of the filament. Intercellular fluids cannot flow through false branches. In false branching the filament are simply attached to each other simulating a branch. There are only two filaments which exhibit branching; one has true branching and the other false. Nocardia spp has true branching and Sphaerotilus natans exhibits false branching.

Sheath...

The cells of some filamentous organisms are contained in a tight fitting sheath. The easiest way to detect a sheath is to look for "missing spaces" between the cells. Some filaments which have a sheath are Haliscomenobactor hydrosis, Sphaerotilus natans, type 1701, type 0041, and type 0675.

Attached Growth...

Some filaments have bacterial cells attached along the side, perpendicular to the filament. There are three filaments on which this commonly occurs. Type 0041, type 0675, and type 1701.