Agriculture Reference
In-Depth Information
production (Bernal et al. 1998; Sánchez-Monedero et al. 2001). As the
organic matter passes through the gizzard of the earthworm it is grounded
into a fine powder after which the digestive enzymes, microorganisms and
other fermenting substances act on them further aiding their breakdown
within the gut, and finally passes out in the form of “casts” which are later
acted upon by earthworm gut associated microbes converting them into
mature product, the “vermicomposts” (Dominguez and Edwards 2004).
Earthworms, grouped under phylum annelida are long, narrow, cy-
lindrical, bilaterally symmetrical, segmented soil dwelling invertebrates
with a glistening dark brown body covered with delicate cuticle. They are
hermaphrodites and weigh over 1,400-1,500 mg after 8-10 weeks. Their
body contains 65% protein (70-80% high quality 'lysine rich protein' on
a dry weight basis), 14% fats, 14% carbohydrates, and 3% ash. Their life
span varies between 3-7 years depending upon the species and ecologi-
cal situation. The gut of earthworm is a straight tube starting from mouth
followed by a muscular pharynx, oesophagus, thin walled crop, muscular
gizzard, foregut, midgut, hindgut, associated digestive glands, and ending
with anus. The gut consisted of mucus containing protein and polysaccha-
rides, organic and mineral matter, amino acids and microbial symbionts
viz., bacteria, protozoa and microfungi. The increased organic carbon, to-
tal organic carbon and nitrogen and moisture content in the earthworm gut
provide an optimal environment for the activation of dormant microbes
and germination of endospores etc. A wide array of digestive enzymes
such as amylase, cellulase, protease, lipase, chitinase and urease were re-
ported from earthworm's alimentary canal. The gut microbes were found
to be responsible for the cellulase and mannose activities (Munnoli et al.
2010). Earthworms comminutes the substrate, thereby increases the sur-
face area for microbial degradation constituting to the active phase of ver-
micomposting. As this crushed organic matter passes through the gut it get
mixed up with the gut associated microbes and the digestive enzymes and
fi nally leaves the gut in partially digested form as “casts” after which the
microbes takes up the process of decomposition contributing to the matu-
ration phase (Lazcano et al. 2008).
Association of earthworms with microbes is found to be complex. Cer-
tain groups of microbes were found to be a part of earthworm's diet which
is evidenced by the destruction of certain microbes as they pass through
