Biomedical Engineering Reference
In-Depth Information
3.2.1
Protozoa
Protozoa are members of the most primitive and the lowest groups in the animal
kingdom. There are 31,000 types in existence. Most of the individuals are small and
only can be observed with the aid of a microscope; the smallest is only 2-3
m. The
protozoans are widely distributed in oceans, lakes, rivers, canals, stagnant rainwater,
and moist soil. There are also a large number of protozoa in the digestive tracts of
higher herbivores and invertebrates. Protozoa can secrete cellulase and cellobiase
(CB), so wood fiber can be broken down into glucose and other products.
3.2.2
Invertebrates
Invertebrates that can degrade lignocelluloses include arthropods, annelids, and
mollusks. Invertebrates degrade cellulose by the cellulase secreted mainly by the
concomitant symbiotic bacteria, fungi, and protozoa in their digestive tract as well
as by themselves. Termites, earthworms, and
Ampullarum crossean
are introduced
as examples next.
3.2.2.1
Termites
Termites, insect-feeding cellulosic feedstocks, cause serious harm and economic
loss in many areas, including city buildings, gardens, and trees. But, they are also
insects with a powerful life force and wide distribution; they are easily carried and
spread and are important to the natural world's material cycle. In nature, termites,
especially soil-dwelling termites, decompose dead plants and deciduous cellulosic
feedstocks and accelerate material recycling around the clock in a large number
of individuals. The growth of several kinds of termite species is beneficial for the
growth of edible fungi. Termites can play a role in medicine, including providing
vitality, strengthening the kidney and spleen, providing dehumidification, and as
a sedative. In addition,
Macrotermes barneyi
Light and
Odontotermes formosanus
exist in the soil of the copper mining district and are conducive to prospecting for
copper because they are indicative of copper.
Termites are a class of social insects. There is strict division of labor within the
population. Their abilities to produce cellulase are different. They are attributed
to soil-dwelling termites and soil-wood-amphibious termites. There are dry-wood
termites with lower water requirements; soil-wood-amphibious termites; and water-
dependent strongly soil termites that have the major part of the population often
hidden below the surface, eating underground grass, roots, or vegetation. Many
species of termites have a strong vitality and can survive a harsh environment, even
adapting to environmental changes voluntarily and changing their living habits to
obtain survival [
21
].
