Developments are in the initial phase and more remains unknown than known. We have
tried to give the first steps in the development of processes for the production of sponge
metabolites under controlled conditions.
MARICULTURES
Descriptions of large-scale bath sponge maricultures in several parts of the world are
given in several publications (Cahn, 1948; Storr, 1964; Shubow, 1969; Vacelet, 1985;
Verdenal and Vacelet, 1990; Adams et al., 1995; Battershill and Page, 1996).
In New Zealand, progress is being made with maricultures of sponges for metabolite
production (Battershill et al., 1998; Pomponi 1999). Here, not only do sponges have to be
grown fast and economically, but they also need to be cultured in a manner which
promotes target metabolite synthesis. Recently, five species of marine sponges
(Latrunculia brevis, Lissodendoryx n.sp., Mycale murryi, Polymastia croceus and
Raspailia agminata) were grown in sea-based cultures with maintenance of target
metabolite synthesis (Battershill et al., 1998; Duckworth et al., 1998). In situ sponge
aquacultures, based on old methods to produce commercial bath sponges, are still the
cheapest and easiest way to obtain bulk amounts of sponge biomass. However, the
cultivation success of this method strongly depends on the unpredictable and often
suboptimal natural environment. Production of compounds for pharmaceuticals needs
well defined, controlled conditions in order to guarantee a defined product quality. For
this reason production of sponge metabolites should preferably be done in pure cultures.
SPONGE-CELL CULTURES: A FUTURE OPTION FOR
METABOLITE PRODUCTION
In vitro culture of sponges as axenic (i.e. free of bacteria and other microbial
contaminants) dissociated sponge cells or tissue will provide a clean, defined system for
the production of sponge metabolites, a prerequisite for the biotechnological production
of pharmaceuticals. Culture of animal cells and tissue is commonly used in biotechnology
and medical science. Until now, however, all attempts to establish a continuous cell line
from a sponge have failed. Primary cell cultures of sponges can be produced, but the
axenic, dissociated cells seem to lack the stimulus to divide, despite the use of very rich
media. In contrast to other animal cells (for instance mammalian cells and insect cells),
the primary sponge cell lines do not proliferate in media containing fetal calf serum. This
is in contradiction to the undetermined nature and strong regenerative power of sponge
cells, which are believed to be capable of forming a functional sponge from a single cell.
Phytohemaglutinin (a lectin that induces mitosis in mammalian cells) can be used to
stimulate cell division in primary cell cultures, but this only results in a few cell-division
cycles, after which the proliferation stops completely. The occurrence of microbial
contaminants further complicates the establishment of a clean cell line. Bacteria, fungi
and unicellular eukaryotes easily overgrow sponge cell cultures and can sometimes
hardly be distinguished from sponge cells. Because of these problems, cell culture must
Multiphase bioreactor design 512