Biomedical Engineering Reference
In-Depth Information
(2) Poly-D-galactose
It has been found that some strains (
Bacillus subtilis
, rumen bacteria, and fungi)
can degrade poly-D-galactose. Typical strains include
Sclerotium rolfsii, Rhizopus
niveus,
and
Bacillus subtilis.
(3) Poly-D-mannose
There are plenty of microorganisms capable of degrading poly-D-mannose, such
as human intestinal bacteria, rumen bacteria, protozoa, saprophytic fungi, and
plant pathogenic fungi, also including
Bacillus subtilis, Aspergillus niger
,
Rhizopus
niveus
, and so on.
(4) Poly(1-3)-
-D-xylose
The microorganisms that can degrade poly(1-3)-
“
-D-xylose are mainly marine
bacteria, green algae, brown algae, red algae, and terrestrial fungi. Typical microor-
ganisms are marine bacteria and
Chaetomium globosum
.
“
(5) Poly-(1-4)-
“
-D-xylose
Poly-(1-4)-
-D-xylose is the dominating form of hemicellulose; therefore, many
microorganisms can degrade such substances, for example, marine and terrestrial
bacteria and rumen fungi. Typical strains include
Bacteroides ovatus
, spore myx-
omycetes,
Mucus cocci
,
Aspergillus niger
,
Trichoderma viride
, rough
Neurospora
,
Myrothecium verrucaria
, and
Coniophola cerebella
.
In short, the microbial degradation of hemicellulose is rapid in nature. Prior to
cellulose decomposition, much hemicellulose generally has been decomposed. But,
in terms of final decomposition, cellulose can be decomposed completely, but hemi-
celluloses only partially. There is almost no cellulose in humus or peat; however,
a large amount of hemicellulose is often left because general microorganisms are
devoid of the ability to decompose polygalactose [
14
].
“
3.1.3
Lignin-Degradable Microorganisms
Because of the complicated structure and connection between the structural units,
which mostly ether bonds or a carbon-carbon bond, lignins are not suitable for
degradation by hydrolysis. So, microbial degradation of lignin is significantly
different from the enzyme-catalyzed hydrolysis reaction of general biopolymers,
which is a series of enzyme-catalyzed and non-enzyme-catalyzed, nonspecific redox
processes. Many studies have confirmed that lignin cannot be used as the sole carbon
source of microorganisms. The degradation of lignin always occurs in the process
of secondary metabolites, and the energy required for the synthesis of enzymes used
in the degradation of lignin is provided by the hydrolysis of carbohydrates.
Therefore, lignin-degradable microorganisms can also decompose cellulose and
hemicelluloses, which is the result of the evolution of biological adaptation. There-
fore, lignin microbial degradation inevitably involves the decomposition of cellulose
and hemicellulose. Lignin-degradable microorganisms generally refer to those that
