Biology Reference
In-Depth Information
Rhodospirillaceae: Rhodospirillum, Rhodopseudomonas, Rhodomicrobium
Chromatiaceae: Chromatium, Thiocystis, Thiosarcina,Thiospirillum, Thiocapsa,
Lamprocystis, Thiodictyon, Thiopedia, Amoebobacter, Ectothiorhodospira .
Chlorobiaceae: Chlorobium, Prosthecochloris, Chloropseudomonas, Pelodictyon,
For bioremediation of H 2 S toxicity, the bacterium that belongs to
Chromatiaceae and Chlorobiaceae can be mass cultured and can be
applied as pond bioremediators. Being autotrophic and photosynthetic,
mass culture is less expensive and the cultured organisms can be adsorbed
on to the sand grains and applied so that they may reach the bottom of the
pond to enrich the hypolimnion and ameliorate H 2 S toxicity (Boyd and
Silapajarn, 2006).
Microbial Remediators as Disease Controlling Agents
In recent years, there has been growing interest in biocontrol of microbial
pathogens in aquaculture using antagonistic microorganisms. A study
on the role of antagonistic bacteria, especially the co-existing bacteria, as
biocontrol agents appears worthwhile in lieu of the negative impacts of
antibiotics (Abraham et al., 2001). Most probiotics proposed as biological
control agents in aquaculture belong to the lactic acid bacteria ( Lactobacillus,
Carnobacterium, Enterococcus etc.), Vibrio ( Vibrio fl uvialis ), Bacillus , and
Pseudomonas . This subject has been elaborately discussed in Chapter 7 of
Volume 1 of this 2-volume series by Austin and Brunt (2009).
Microorganisms both Gram positive and Gram negative have been tested
for their effi cacy as microbial remediators in aquaculture by various
workers ( Table 8.1 ) . Bacillus is the most commonly used organism followed
by Aeromonas and Pseudomonas. These microorganisms are mass multiplied
in bioreactor by either solid state or submerged fermentation.
Solid State Fermentation
Solid state fermentation refers to the process where growth and production
of bio-remediating microorganisms occur on the surface of solid materials.
This process occurs in the absence of “free” water, where the moisture is
absorbed to the solid matrix such as rice husk, wheat bran, dried cow
dung, etc. Solid state fermentation is usually carried out in an uncontrolled
environment with no provision for maintaining pH, temperature, aeration,
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