A Few Facts About Sponges

When you hear the word “sponge,” what comes to your mind? Probably the sponge you use for dishwashing or the one you use while bathing, right? These are artificial sponges, made of synthetic materials. In the past, we used sponges from the ocean, called marine sponges, for these common tasks.

Marine sponges are invertebrate animals, meaning that they do not have a spine or skull. Some sponges live fixed to the ocean sediment or to the surfaces of rocks and never move during their lifetimes. Sponges can be of different shapes, sizes, and colors [1]. These animals can inhabit the deep sea, where there is little to no light, or they can live in shallower regions that are more exposed to sunlight.

Did you know that sponges feed by filtration? Instead of mouths, they have small holes called pores spread over their bodies. These holes allow water to enter, move to the inside of the sponge, and then exit through an opening in the top of the sponge. As the water travels through their bodies, the sponges absorb oxygen and other nutrients dissolved in the water.

Do Sponges Live Alone?

While a sponge may appear to be living alone attached to its rock or the ocean bottom, it is not alone! Invisible to the naked eye, microscopic organisms live inside sponges. These microorganisms include bacteria, archaea, fungi, and viruses, and they perform important jobs for the sponges, including helping them with nutrient digestion and producing vitamins that are crucial for the sponges’ diets. The microorganisms also release defensive substances that protect sponges against natural predators, competitors, and harmful microorganisms (Figure 1A) [1].

What do the sponges’ microscopic buddies receive in exchange for this help? It has been estimated that a 1 kg sponge can filter up to 24,000 liters of water per day! Because of this large volume of water, sponges accumulate more nutrients in their bodies than they need. This plentiful food helps the microorganisms within the sponges to produce their helpful substances (Figure 1B).

What Are Enzymes?

Did you know that microorganisms, plants, and people all have something in common? They all produce substances called enzymes. Enzymes are special molecules that make chemical reactions happen faster. The job of some enzymes is to break down large molecules into smaller pieces. The enzymes produced by the microorganisms living inside sponges are what allow these microorganisms to perform their helpful activities, like breaking down large nutrients into vitamins and other substances that the sponges can easily absorb!

Scientists have discovered that the enzymes produced by sponge microorganisms not only benefit the sponges—they can be extremely helpful to humans, too! Humans have found many uses for these microbial enzymes. Microbial enzymes have some advantages over plant and animal enzymes. First, microorganisms produce enzymes in large quantities, and it does not take much time or space to grow microorganisms in the lab. Also, enzymes from microorganisms can be active and stable under harsh conditions. Finally, microbial enzymes are not toxic to humans [2].

How Are Enzymes Used?

The use of microbial enzymes in industrial processes has received increasing attention over the past few years. This is because using these enzymes can reduce waste and cause less damage to the environment.

Did you know that enzymes are used to create many of the products we encounter in our daily lives? For example, they are used in the production of animal food, medicines, detergents, and paper [3]. Amylase is one type of enzyme that is frequently used in industry, because it can break down starch, which is a large, complex sugar, into smaller, more useable bits. In bread baking, amylase helps the dough to rise, which creates bread that is easier to chew and that lasts longer on our kitchen shelves [2].

Lipase is another interesting enzyme. It works by breaking down fat molecules called lipids. Some factories just throw away lipids, which are hard to break down or wash off. Lipase can help to clean up these oily pollutants [2]. In the food industry, lipase digests the fat in cheese, which can make some cheeses more delicious and help them to keep their nice aromas and tasty flavors longer.

There has only been a small amount of research done on enzymes that come from the microorganisms living in marine sponges. The microbial enzymes that have been studied so far are potentially very useful. They have been isolated from sponges living in some of the most extreme marine environments (Figure 2) [3].

In 2017, a new enzyme called esterase was discovered, which is produced by a bacterium living in a sponge 760 m deep [4]! This enzyme is active in the presence of high amounts of salt, relatively high pH (8–10) and at low temperatures (4–20°C). How could we use this enzyme? Esterase could be used to make detergents that are good for washing things in cold water. These “cold detergents” are ideal for removing stains like blood and sweat.

In 2018, a new enzyme called a protease was identified in the archaeaHalococcus [5]. Isolated from an Indian sponge, Halococcus is known to love salt. The protease breaks down proteins into smaller pieces, and it was found to have its greatest activity when it was in a solution three times saltier than seawater! Surprisingly, the protease was most active at 70–80°C, so this incredible enzyme could be ideal for processes that depend on high temperatures [5]. In the leather industry, this protease could remove the hair from animal hides, decreasing the use of toxic chemicals that are normally released into the environment. In the baking industry, this protease also could help to make low-gluten flour for people who need to eat a gluten-free diet [5].

Conclusion

So now you know that marine sponges are invertebrate animals and do not live alone. Microscopic partners live inside sponges, with mutual collaboration between them. Furthermore, these microorganisms have adapted to the marine environment, developing unique molecule-breaking capabilities. Therefore, marine microbial enzymes are adapted to extreme conditions such as high or low temperatures, high pressures, high salinity, and a wide pH range. These characteristics mean that enzymes can be used to make certain industrial processes greener and cheaper. Despite these great qualities, there is still not much research being done on these enzymes [2]. Enzymes produced by microorganisms that live in sponges must be studied in more detail, so that the most important uses can be identified for the benefit of man and the planet!

Funding

This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, grant number: 88887.613831/2021-00), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, grant numbers: 152901/2019-1, 306395/2020-7), and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (grant numbers: E-26/202.144/2020, E-26/200.948/2021, E-26/211.284/2021, E-26/203.773/2021).

Glossary

Invertebrate: ↑ Animals that are characterized by the absence of a spine and skull. Marine sponges and octopuses are examples of invertebrate animals.

Filtration: ↑ Process of obtaining oxygen and nutrients through the entry of seawater that circulates through the sponge body and exits through the upper opening.

Enzymes: ↑ Special proteins that make chemical reactions happen faster.

Amylase: ↑ Amylase is an enzyme that is capable of breaking starch into smaller bits. This enzyme is also present in the saliva of humans, where it starts the process of digestion.

Lipase: ↑ Lipase is an enzyme which function is to turn the fat in smaller molecules. This enzyme plays essential roles in digestion of lipids in living organisms.

Esterase: ↑ Esterase is an enzyme that helps break down smaller and simpler fat molecules.

Protease: ↑ Protease is an enzyme that speeds up the reaction of breaking proteins in smaller pieces and it is present in plants, human beings and microorganisms.

Archaea: ↑ Microorganisms that live in extreme habitats, including thermal cracks at 100°C and the digestive tracts of cows.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.