Biology Reference
In-Depth Information
compounds reduces water turbidity (Haung, 2003).
Bacillus
based products
are now commercially available which can degrade organic matter in a
aquaculture pond at a faster level (
Fig. 8.1
) (Moriarty et al., 2005).
Flacobacterium, Pseudomonas,
Alteromonas, Vibrio
Bacillus
multiplies in the
intestine of shrimp and on
decaying algae and waste
feed pellets and faeces.
Algae
Bacillus
Added at
1000/ml
Feed
with
probiotic
Bacillus
Shrimp
Water
Faece
Sediment
Bacillus
oxidizes waste organic matter
Little organic matter accumulates
(Source: Moriarty et al., 2005)
Fig. 8.1
Effect of
Bacillus
at high population density in the pond for organic matter from
algae, feed and animals. Specially selected
Bacillus
displaces pathogenic
Vibrio
(Moriarty et
al., 2005).
Color image of this figure appears in the color plate section at the end of the topic.
Microbial Remediation of Nitrogenous Compounds
Nitrogen applications in excess of pond assimilatory capacity can
lead to deterioration of water quality through the accumulation of
nitrogenous compounds (e.g., ammonia and nitrite) with toxicity to fi sh
and shrimp (Antony and Philip, 2006). The principal sources of ammonia
are fi sh excretion and sediment fl ux derived from the mineralization
of organic matter and molecular diffusion from reduced sediment,
although cyanobacterial nitrogen fi xation and atmospheric deposition
are occasionally important (Ayyappan and Mishra, 2003). Nitrifi cation
proceeds in two steps as follows:
NH
4
+
+ 1
1
/
2
O
2
NO
2
-
+ 2H
+
+ H
2
O
NO
2
+
11/
2
O
2
NO
3
-
