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previously known compounds were isolated from soft coral, Lemalia laevis
(El-Gamal et al., 2005). Polyaromatic alkaloids, known as lamellarins, have
been isolated from the marine ascidian, Didemnum spp. and the mollusk,
Lamellaria spp. New cytotoxic cyclicheptapeptide, mollamide and patellins
(cyclic peptides) have also been isolated from ascidians Didemnum molle
and Lissoclinum sp. collected on the Great Barrier Reef (Gross and Kong,
2006) Dercitin, an alkaloid, isolated from the sponge, Dercitus spp. has
been recognized to have anti-leukemic activity (Ireland et al., 2000; Ranga
Rao et al., 2006).
Sponge Culture
Owing to the discovery of many commercially important compounds
in sponges, there is increasing interest in production of marine sponge
biomass. In situ sponge aquacultures, based on conventional methods for
producing commercial bath sponge are still the earliest and least expensive
way to obtain sponge biomass in bulk. During the last 20 yr, sponges have
also been experimentally cultured both in the sea and in tanks on land
for their biologically active metabolites. Many studies have shown that
sponges grow quickly, often doubling in size every few months. Sea-based
culture holds great promise, with several small-scale farming operations
producing bath sponges or metabolites. These studies have focused on
identifi cation of the optimal environmental conditions that promote
production of bath sponges or bioactive metabolites. The ideal farming
condition will vary between species and regions, but will generally
involve threading sponges on rope or placing them inside a mesh. A
better-defi ned production system has been made for culturing sponges
in semi-controlled systems, but these still use unfi ltered natural seawater.
Other interesting developments include partially harvesting farmed
sponges to increase biomass yields, seeding sexually reproduced larvae
on farming structures, using sponge farms as large biofi lters to control
microbial populations, and manipulating culture conditions to promote
metabolite biosynthesis. An adequate supply of food seems to be the key
to successful sponge culture. Feeding diverse rather than a single type
of food had better effect on growth rate of the sponge (Duckworth, 2009;
Osinga et al., 1999) . Cell cultures of marine sponges might be considered
as an alternative to in situ culture. The advantage of cell cultures is that
they can be completely controlled and easily manipulated for optimal
production of the target metabolites. However, the technique is still in its
infancy and a continuous cell line has yet to be established. Laboratory
scale cultures have been standardized for bryozoan species, because of
the interest in bryostatin-1, a potent antineoplastic agent, produced by
the bryozoa, Bugula neritina (Liebezeit, 2005). As mentioned earlier, some
sponge metabolites are, in fact, produced by symbiotic bacteria or algae
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