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Comparative studies of natural groups of organisms

(g) Nitrogen fixation and nitrification bacteria of the genus Pseudomonas are
in the soil used in cleaning oil-contaminated water
Some bacteria, besides being decomposers as they feed on oil spills.
are important in fixing atmospheric nitrogen
into a form that can be utilised by plants (j) Biodiversity studies
by the process known as nitrogen fixation. Bacteria may be one of the most abundant
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Examples of nitrogen fixing bacteria are and species-rich groups of organisms
Azotobacter, Clostridium, and Rhizobium. that mediate many critical ecosystem
Some bacteria convert ammonia into processes. They contribute significantly
nitrates in the soil by the process known to the global biodiversity, given the
as nitrification. Nitrosomonas convert existence of numerous species of bacteria.
ammonia into nitrite, which later gets The position and role of each species
oxidised to nitrates by Nitrobacter. The in the ecosystem cannot be underrated.
two processes are important in agriculture, Cyanobacteria initiated early life on land
because nitrogen is one of the elements as they were the first organism to produce
required by plants in large quantity for oxygen from photosynthesis. Such oxygen
growth and other physiological processes. was used by early aerobic organisms.
Nitrogen contributes largely in improving
agricultural yields. (k) Medical application
Some bacteria such as Streptococcus are
(h) Bioindicator in detecting water used in the process of manufacturing
pollution antibiotics, such as Streptomycin.
Cyanobacteria blooms in ponds can Streptococcus lactis ferments milk to
be used as bioindicator, since they are produce lactic acid, which prevents growth
sensitive to water pollution. Changes in of harmful bacteria in the stomach, by
abundance of cyanobacteria in aquatic maintaining the acidic environment in the
ecosystems can serve as indicators of stomach. Lactic acid prevents bacterial
water pollution. vaginosis, thus preventing Urinary Tract
infection (UTI). Starch, in the form of
(i) Biotechnology and genetic amylose is produced for industrial uses
engineering by bacteria. For example Escherichia coli
Bacteria can be used to alter and replicate or E. coli are used in the mass production
genes that are then introduced into of asparaginase enzyme, which has also
plant or animals. Bacterial systems lend a medical application in chemotherapy
themselves to genetic manipulation in part against lymphoblastic leukemia.
because of their rapid reproduction rates.
Thermus aquaticus (Taq) is a thermal stable (l) Symbiotic association with other
bacterium, which is used to produce DNA organisms
polymerase. DNA polymerase enzyme is Some bacteria, such as cyanobacteria
used in amplification of short segments of live in association with fungi in which
DNA through polymerase chain reaction the former synthesise food through
(PCR). Some genetically engineered

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