Biomedical Engineering Reference
In-Depth Information
the decomposition of cellulose by anaerobic bacteria. The decomposition rate was
53 %, and the main product was glucose.
The number of cellulose-decomposing bacteria is low in alpine meadow soil.
The number of cellulose-decomposing bacteria changes with the soil temperature,
and it is highest between July and September. Compared with natural grassland,
the number of cellulose-decomposing bacteria is reduced an average of 51 %
compared to degraded pasture. Cellulose-decomposing bacteria are extremely rare
in swamp meadow soils. Cellulose-decomposing bacteria show different decompo-
sition degrees for cellulose, plant roots, and litter. A seasonal change of cellulose-
decomposing bacteria is obvious. From the end of November to the following April,
the cellulose decomposition rate is only 1.89 %, and the number of cellulose-
decomposing bacteria gradually increases with increase of soil temperature, as does
the decomposition rate of cellulose. The decomposition rate in August is 55.69 %. It
reaches 16.98 % in September and only 0.67 % in November. The soil temperature is
the primary factor affecting cellulose decomposition. The alpine meadow cellulose
decomposition is carried out from June to September. The cellulose decomposition
in these 4 months accounts for 91.5 % of the total annual amount of decomposition.
The decomposition rate of humilis grassroots and litter is the highest in the
first month of the first year, with the roots decomposing 26.55-29.84 % and litter
20.34-22.95 %. Then, it quickly reduces during the next month. After 4 months, the
monthly decomposition rates of root and litter drops to 2.16-6.47 % and 1.60 %-
5.92 %, respectively. After 142 days, the plant root decomposition is 38.46-42.91 %
of the original weight, and litter was 45.86-46.39 %. The decomposition rate of
plant root decreases with soil depth.
3.8.2
Cellulose Microbes and Carbon Cycle of Earth's
Ecosystems
Natural substances experience a reciprocating cycle between inorganic matter and
organic matter. Photosynthetic organisms transfer inorganic matter into organic
matter through photosynthesis to fulfill the needs of humans and animals. Then,
microorganisms decompose the ecological debris and transform it into inorganic
materials to fulfill the needs of green plants. Organisms, especially microorganisms,
promote the carbon cycle, so that different forms of carbon can transform into each
other, and the CO
2
in the atmosphere will not be depleted, maintaining life.
Microorganisms in nature play an important role in the material cycle. Microbial
decomposition of organic matter and animal and plant respiration all can emit CO
2
,
but more than 80 % of it is generated by microbial activity. If there is no microbial
decomposition of organic matter, there will be increasing organic matter on Earth.
Not only will the limited CO
2
in the air soon be depleted by plant photosynthesis, but
also the cycle of other inorganic elements in Earth's ecosystem will be interrupted.
