The marine sponge’s dull facade masks a surprisingly complex creature. Just ask Detmer Sipkema, a lanky, 6’6″ post-doctoral chemical engineering student from the Netherlands, who looks beyond the sponge’s quotidian uses to the medicinal.
“They sit on the bottom of the sea and look like they do nothing, but they’re really doing a lot,” says Sipkema, explaining that marine sponges are among the most abundant sources of active compounds discovered in the past 20–30 years. They contain thousands of compounds with potential pharmaceutical applications, such as cancer treatments, antivirals, and antibiotics. But only recently have researchers discovered these rich compounds are not produced by the sponges themselves, but by the bacteria living in their bodies.
Sipkema likens sea sponges to “little biotopes,” with as many as 50 species of bacteria living inside a single sponge. To explore the bacteria’s medicinal potential, researchers need to replicate them, but growing bacteria in the lab is notoriously difficult. With most studies reproducing just 0.1 to 2 percent of the bacteria present in a sponge, Sipkema’s ability to culture 10 percent is gaining international attention.
He uses three cultivation methods on a sponge native to coastal California and Oregon. Nutrient plating, which employs 17 media including the ubiquitous agar jelly many remember from high school science classes, is the most common form of cultivation. But Sipkema also works with liquid cultures, in which bacteria are suspended in a liquid nutrient, and with filter cultures that mimic the filter-feeding characteristic of sponges (a one-kilogram sponge can filter up to 24,000 liters of seawater a day). His is the first step in finding more effective ways of culturing the sea sponge’s bacteria to develop powerful new medicines for extensive pharmaceutical use.