True
nitrifying bacteria are strictly aerobic autotrophs.
They can only use nitrogen from inorganic sources
such as ammonia and nitrite. Nitrosomonas (ammonia-oxidizers)
and Nitrobacter (nitrite-oxidizers) are the most common.
Heterotrophic
bacteria are generally considered to be organic sludge
degraders. They are mostly from the genera Bacillus
and Pseudomonas. Most of these are facultative anaerobes;
meaning they can function with or without oxygen.
They will do completely different functions depending
on the level of dissolved oxygen present.
Heterotrophic “nitrifiers” prefer to obtain
their nitrogen from organic sources such as decomposing
organic debris. Those that can convert ammonia do
so only when an organic nitrogen source is not available.
This is unlikely to happen in an aquarium or pond
where fish are present. The explosion of “nitrifying”
bacteria products in the industry is due to research
that some heterotrophs can use ammonia-nitrogen. However,
this is under ideal laboratory conditions
Heterotrophic “nitrifiers” generally cannot
utilize nitrites. Only a few species are capable of
reducing nitrite to free nitrogen, but, under strictly
anaerobic conditions.
Scientific studies indicate that, depending on species,
between one thousand to one million heterotrophic
bacteria cells are required to perform the same ammonia
conversion rate as one Nitrosomonas bacteria cell.
Fritz-Zyme #7 has
a cell count of 30 million bacteria per ounce, 50%
of which is Nitrosomonas and 50% Nitrobacter. To obtain
the same ammonia conversion rate, a competitive product
composed of heterotrophic “nitrifiers” would
require the addition of 15 trillion bacteria. This
would probably require several gallons of another
product. No quantity of heterotrophic “nitrifiers”
would reduce the generated nitrites.
Heterotrophic
“nitrifiers” can also operate in the reverse
direction; that is they can convert nitrate to nitrite
or ammonia, especially during times of low dissolved
oxygen levels. In a pond, this could potentially happen
during the hours before sunrise when DO levels are
at their lowest.
There
are no dry forms of any bacterial product that can
contain viable Nitrosomonas and Nitrobacter cells.
Unlike heterotrophs, they cannot form spores so they
cannot survive any type of drying or freeze-drying
process.
