A bioreaction–diffusion model for growth of marine sponge explants in bioreactors

Nutrient-dependent growth underpinned the Ediacaran transition to large body size

Macroscale rangeomorph fossils, with characteristic branching fronds, appear (571 Myr ago) after the Gaskiers glaciation (580 Myr ago). However, biological mechanisms of size growth and potential connections to ocean geochemistry were untested. Using micro-computerized tomography and photographic measurements, alongside mathematical and computer models, we demonstrate that growth of rangeomorph branch internodes declined as their relative surface area decreased. This suggests that frond size and shape were directly responsive to nutrient uptake.

Cultivation of sponges, sponge cells and symbionts: achievements and future prospects

Marine sponges are a rich source of bioactive compounds with pharmaceutical potential. Since biological production is one option to supply materials for early drug development, the main challenge is to establish generic techniques for small-scale production of marine organisms. We analysed the state of the art for cultivation of whole sponges, sponge cells and sponge symbionts. To date, cultivation of whole sponges has been most successful in situ; however, optimal conditions are species specific. The establishment of sponge cell lines has been limited by the inability to obtain an axenic inoculum as well as the lack of knowledge on nutritional requirements in vitro. Approaches to overcome these bottlenecks, including transformation of sponge cells and using media based on yolk, are elaborated. Although a number of bioactive metabolite-producing microorganisms have been isolated from sponges, and it has been suggested that the source of most sponge-derived bioactive compounds is microbial symbionts, cultivation of sponge-specific microorganisms has had limited success. The current genomics revolution provides novel approaches to cultivate these microorganisms.

Farming sponges to supply bioactive metabolites and bath sponges: a review

Sponges have been experimentally farmed for over 100 years, with early attempts done in the sea to supply "bath sponges". During the last 20 years, sponges have also been experimentally cultured both in the sea and in tanks on land for their biologically active metabolites, some of which have pharmaceutical potential. Sea-based farming studies have focused on developing good farming structures and identifying the optimal environmental conditions that promote production of bath sponges or bioactive metabolites. The ideal farming structure will vary between species and regions, but will generally involve threading sponges on rope or placing them inside mesh. For land-based sponge culture, most research has focused on determining the feeding requirements that promote growth. Many sea- and land-based studies have shown that sponges grow quickly, often doubling in size every few months. Other favorable results and interesting developments include partially harvesting farmed sponges to increase biomass yields, seeding sexually reproduced larvae on farming structures, using sponge farms as large biofilters to control microbial populations, and manipulating culture conditions to promote metabolite biosynthesis. Even though some results are promising, land-based culture needs further research and is not likely to be commercially feasible in the near future. Sea-based culture still holds great promise, with several small-scale farming operations producing bath sponges or metabolites. The greatest potential for commercial bath sponge culture is probably for underdeveloped coastal communities, where it can provide an alternative and environmentally friendly source of income.