Food and Sex

Nutrition
As a heterotrophic organism, this species can acquire its nutrients through its cell wall from either its aquatic environment or from its host, but it cannot produce its own food. This classifies it as either a primary consumer or parasite. Since it is a facilitative bacteria, it can breakdown its nutrients either aerobically or anaerobicly through respiration or fermentation. Once digested, the nutrients are stored as starch, like most other proteobacteria.

In aquatic environments, it commonly forms a biofilm on the surface of the water, on the surface of suspended detritus, and on the sediment surface. These areas are favorable because microorganisms accumulate more heavily on these surfaces and Aeromonas hydrophila tends to grow more rapidly where there are nutrient components of low molecular weight. For example, algae that is found on the surface of water attracts the bacteria which feed on this important primary producer. Additionally, it is able to utilize a large variety of biopolymers, such as proteins, carbohydrates, and lipids which are found most conveniently on decomposing aquatic macrophytes. In a host, it is also able to break down hemoglobin for nutrient uptake. Even though it has adapted strongly to living in a host, when it is exposed to such rich nutrients in water, it can multiply and survive just as well in aquatic environments.

Reproduction
This organism uses binary fission as a means of reproduction. This is a relatively quick and simple process and many bacteria undergo this type of asexual reproduction. First, the cell copies its genetic material (DNA). The two copies are then sent to the opposite ends of the cell. Then, proteins that enable the division of the cell to take place assemble in the middle of the cell (the division line). The cytoplasm then divides and a new cell wall is synthesized. Reproduction occurs due to signals from the bacteria which are usually triggered when it has entered a host, but may also be triggered in response to extensive nutrients as a free-living organism. In these cases, it typically begins to reproduce rapidly to form a colony or biofilm. In aquatic environments, the rate of reproduction depends on residual disinfectant, dimensions of the network, residence time, water temperature, and concentration and type of food sources available. For example, in mildly harsh environments such as cold temperature (5°C), the bacteria usually do not get damaged or die, but they do not expend their energy on reproduction. Lastly, interfering with the steps of binary fission is a potential target in creating antibiotics for bacterial infections like this. However, because the bacteria are able to multiply so rapidly, they are able to quickly build resistance to antibiotics through the selection of resistant mutants. For more on antibiotic resistance, due to either natural selection or improper antibiotic usage, check out this ScienceDaily article.

Next, there are many adaptations that allow this species to survive and reproduce so successfully.

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