(called biofilters) are actively encouraged
and inoculated to contain beneficial bacteria
such as Nitrosomonas and Nitrobacter, which
convert organic material from fish waste into
plant-usable nutrients.
Biofilms contain both dead and live microbes
and a variety of secreted compounds such
as polysaccharides, proteins, DNA, lipids,
minerals, and other components from the
environment, all of which form complex
and resistant layers. Biofilms begin life as
free –floating bacteria that are common in
most water supplies. These bacteria attach to
surfaces and are not particular about where
they take up residence. In plant production
systems, bacteria are often attracted to the
organic material contained in root exudates
that act as a food source, thus roots are often
rapidly colonized.
Bacteria in Aquaponics
Many people look at aquaponics systems
and all they see is fish and plants. Much is
written about this and many people define
aquaponics as the “combination of fish and
plants”. The fact is that there is a third, and
equally important group, whose management
is often completely ignored: bacteria! While
most people acknowledge bacteria, usually
AgriKultuur |AgriCulture
the nitrifying genera, as being necessary
to aquaponics systems there is often little
acknowledgement of the true importance of
many other species of bacteria and almost no
methods are deployed for their management.
Aquaponicists will often talk about nitrifying
bacteria and while there are several genera of
bacteria that will oxidise Ammonia to Nitrite
and Nitrite to Nitrate the most common genus
mentioned is Nitrosomonas and Nitrobacter
respectively.
Positive bacteria have four main benefits for
areas like fish intestine lining and plant root
tissue.
1. Preventing bad bacteria from taking hold.
If the surface is already occupied by a good
bacterium then the bad bacteria cannot
take hold.
2. Promoting surface health. They can aid
in breakdown of organic material that
may get on the surface as well as actively
assisting tissue health.
3. Being antagonistic to bad bacteria. Many
positive bacteria do not only prevent bad
bacteria taking hold but actively antagonize
bad bacteria, so they are removed from
the environment.
4. Improving nutrient uptake and health.
17