Biofilms on Liquid-Air Interfaces
Surface of Ponds
Figure 1.
An over fertilized pond or a shallow roadside puddle may produce a biofilm such as this. Composed largely of green algae, these biofilms are often referred to as microbial mats to distinguish them from films composed primarily of heterotrophic (non-photosynthetic) bacteria. Often quite transient the biofilms may seem to disappear as the puddle dries up. Nevertheless, the algae cells or cysts remain viable and will produce another mat when wet weather returns.
Liquid-Liquid Interfaces
Oil Drops Suspended in Water
Figure 2. Bacteria growing on and near an oil droplet suspended in water
It is fortunate that many microorganisms are capable of metabolizing hydrocarbons. Due to natural and human caused contamination large amounts of hydrocarbons are annually contaminating soil, fresh water and marine environments. Many genera of bacteria including Pseudomonas, Alcaligenes, and Flavobacterium are capable of mineralizing oil and other HCs to carbon dioxide and water. This image shows a population of bacteria actively degrading a droplet of oil suspended in water.