composed of proteases, lipases, and nucleases. It is easy to cultivate these
bacteriolytical myxobacteria on the surface of mineral agar substrates. It was
established that Mycococcus xanthus uses genetically determined chemotaxis to
attack the prey and that the predation is stimulated by a close contact with the
prey’s cells. The myxobacteria also predate on cyanobacteria, as described by
C. Burnham et al. (1981), he experimented with a cyanobacterium of the genus
Phormidium and Myxococcus xanthus.
In general, myxobacteria are quite effective antagonists for phytoplankton,
because they limit phytoplankton multiplication. Predation has been studied in detail
for higher animals but studied relatively rarely in prokaryotes. It is assumed that
predation could also have led to the origin of eukaryotic cells. In addition, there also
exist cellulolytic myxobacteria that decompose plant polysaccharide cellulose. However, they are very hard to cultivate.
15.7.3 Protozoan Predation
Protozoa prey on bacteria and this activity plays a very important role in the
regulation of bacterial populations in water environments, specifically in a quantitative limitation of bacterial numbers. Agneta Andersson and her coworkers
(Andersson et al. 1986), and Patricia Menon along with her coworkers (Menon
et al. 2003), estimated that protozoa (inclusive of flagellates and ciliata) can kill up to
90% of autochthonous and allochthonous bacteria in fresh water and seawater
ecosystems. The predation speed depends on the temperature and on the very nature
of the predation population. The speed of predation grows proportionally with the
temperature between 12 and 22
C. Often, Gram-positive bacteria are predated upon
less than are the Gram-negative ones.
Amoebas belong to the broad group of organisms known as Rhizopoda and, more
recently, to the group Tubulinea. They are one-cell eukaryotes that consume microbial prey by phagocytosis and at the same time they play an important role in
microbial nutritional chains. Amoebas are natural grazers of cyanobacteria and for
their growth they require presence of heterotrophic bacteria as the source of cobalamin, i.e., vitamin B 12 . The best-known species include Amoeba proteus and
Amoeba leningradensis.
15.7.4 Carnivorous Fungi
There are predatory fungi that can catch microscopic organisms, for instance,
nematodes. The prey microorganism is caught and killed in loops of the mycelia.
The fungus then sucks nutrients out of the prey. Some of the species and genera of
carnivorous fungi include Zoophagus insidians, Zoophagus pectosporus, Stylopage,
Zoopage, and also Harpella as well as Arthrobotrys. They can be found in the soil, in
decomposing plant material, and in water. Their prey can be nematoda or Rhizopoda,
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V. Klaban
bacteriolytical myxobacteria on the surface of mineral agar substrates. It was
established that Mycococcus xanthus uses genetically determined chemotaxis to
attack the prey and that the predation is stimulated by a close contact with the
prey’s cells. The myxobacteria also predate on cyanobacteria, as described by
C. Burnham et al. (1981), he experimented with a cyanobacterium of the genus
Phormidium and Myxococcus xanthus.
In general, myxobacteria are quite effective antagonists for phytoplankton,
because they limit phytoplankton multiplication. Predation has been studied in detail
for higher animals but studied relatively rarely in prokaryotes. It is assumed that
predation could also have led to the origin of eukaryotic cells. In addition, there also
exist cellulolytic myxobacteria that decompose plant polysaccharide cellulose. However, they are very hard to cultivate.
15.7.3 Protozoan Predation
Protozoa prey on bacteria and this activity plays a very important role in the
regulation of bacterial populations in water environments, specifically in a quantitative limitation of bacterial numbers. Agneta Andersson and her coworkers
(Andersson et al. 1986), and Patricia Menon along with her coworkers (Menon
et al. 2003), estimated that protozoa (inclusive of flagellates and ciliata) can kill up to
90% of autochthonous and allochthonous bacteria in fresh water and seawater
ecosystems. The predation speed depends on the temperature and on the very nature
of the predation population. The speed of predation grows proportionally with the
temperature between 12 and 22
C. Often, Gram-positive bacteria are predated upon
less than are the Gram-negative ones.
Amoebas belong to the broad group of organisms known as Rhizopoda and, more
recently, to the group Tubulinea. They are one-cell eukaryotes that consume microbial prey by phagocytosis and at the same time they play an important role in
microbial nutritional chains. Amoebas are natural grazers of cyanobacteria and for
their growth they require presence of heterotrophic bacteria as the source of cobalamin, i.e., vitamin B 12 . The best-known species include Amoeba proteus and
Amoeba leningradensis.
15.7.4 Carnivorous Fungi
There are predatory fungi that can catch microscopic organisms, for instance,
nematodes. The prey microorganism is caught and killed in loops of the mycelia.
The fungus then sucks nutrients out of the prey. Some of the species and genera of
carnivorous fungi include Zoophagus insidians, Zoophagus pectosporus, Stylopage,
Zoopage, and also Harpella as well as Arthrobotrys. They can be found in the soil, in
decomposing plant material, and in water. Their prey can be nematoda or Rhizopoda,
256
V. Klaban