Cellulolytic enzyme and gut of termite endoglucanase and termite ,microbes involved

1. BY SREEREMYA.S

2.  Endogenous cellulase of termite origin (endo-
-1,4 glucanase and -glucosidase) which are
excreted from the salivary glands or the gut
have been identified and characterized in
both higher and lower termites. Molecular
analysis reveals these endogenous enzymes
are members of glycosyl hydrolase family 9
(GHF9).

3.  In higher termites the endogenous cellulolytic
activity meets the metabolic requirement. In
lower termites, substantial cellulolytic activity is
found in the hindgut. Thus the ingested cellulose
can be partially degraded by the endoglucanase
of termite origin, then unhydrolyzed cellulose
travels to the hind gut, where it can be
endocytosed and is fermented by the symbiotic
protists in lower termites. Termites grind and
crunch the ingested material, which may enhance
digestion by increasing the exposed surface area.

4.  TERMITES play a great role in terrestrial
ecosystem by recycling lignocellulosic
biomass, which refers to a mixture of
cellulose, hemicellulose and lignin.

5.  Termites are one of the most important soil
insects that efficiently decompose
lignocelluloses with the aid of their
associated microbial symbionts to simpler
form of sugars, which later can be fermented
to ethanol using yeasts. Termites are said to
dissimilate a significant proportion of
cellulose (74-99%) and hemicellulose (65-
87%) components of lignocellulose they
ingest (Ohkuma; 2003).

6.  Termites play an important role in the turnover
and mineralization of complex biopolymers, such
as wood and other cellulose and hemicelluloses
containing materials (Wenzel et al; 2002).
Lignocellusoe is the most predominant
component of the woody and dead plant
materials, as well as it is the most abundant
biomass on earth, especially in terrestrial
ecosystems. In contrast to cellulose, lignin
degradation does not appear to be important in
the gut of wood feeding
termites (Ohkuma; 2003).

7.  The term ‘cellulase’ traditionally includes two
types of enzymes, exoglucanase (primarily
cellobiohydrolase [EC 3.2.1.91] and
occasionally cellodextranase [EC 3.2.1.74])
that hydrolyses cellulose from its
nonreducing or reducing ends, and endo--
1,4-glucanase [EC 3.2.1.4] that hydrolyses
along the glucan chain of cellulose fibres
randomly. Cellooligosaccharides produced by
these enzymes are further hydrolysed to
glucose by -glucosidase (Tokuda et al; 2005).

8.  Carboxymethylcellulose, which measures
endo- -1,4- glucanase activity, is one of the
most popular artificial substrates for
measuring cellulase activity because of its
high solubility in water. Thus,
carboxymethylcellulose has been
preferentially used in most studies of cellulos
digestion in termites and other insects
(Tokuda et al; 2005).