During one of my Expeditions on the internet, in search of some food for thought, I came across an article in the National Geographic on Mucilage.

AmoebaSounds strange, doesn’t it? That this unsavoury substance should take up the haloed space in a magazine such as NatGeo intrigued me. My curiosity did not disappoint me and I am sure those of you who share this trait with me will not be either. So, here goes. The article I was referring to deals with a rise in Marine Mucilage in the Adriatic Sea. This is an extension of the Mediterranean Sea, and it separates the Italian and Balkan peninsulas. Now, what is this Marine Mucilage? Like all problems this one too, starts out small. In the oceans and seas across the world, tiny aggregates of colloidal matter are known to form and have been given the rather poetic appellation of “Marine Snow”. These aggregates are mostly detritus that coalesce to form snowy particles and then settle down in a column of water.

Marine Mucilage in the Adriatic Sea

Marine Mucilage in the Adriatic Sea

So far this marine snow was not really a cause for concern. However, recently it has been noticed that global patterns in Climate change have resulted in an increase in the temperatures of ocean waters. Somehow this increase facilitates the formation of large, ephemeral masses of the Marine Snow that now metamorphose into huge blobs of unearthly looking Mucilage. This Mucilage sometimes even floats on the surfaces of oceans lending them a murky appearance. Unsuspecting swimmers might experience an eerie feeling of having encountered a Ghost underwater, if a blob comes within their swimming radius.

Scientists, struck by this sudden increase in the mass as well as numbers of these blobs began investigating this substance. They very soon came up with several components that form a part of the structure of these blobs. Common components were Carbohydrates and Proteins, followed by Lipids that seemed to be aggregation specific. Further structural studies carried out using techniques such as FTIR revealed presence of Lignins and Biogenic Silica Compounds along with metal ions such as Copper and Lead that seem to affect the aggregation process. In addition, Aromatic compounds and Chlorophyll pigments derived from marine algae were also identified.

Now, before my dear readers write me off, let me get to why this Mucilage is of interest to a Biotechnologist. The Marine Mucilage has now been identified as a source of potentially pathogenic Microbes and Viruses. BacteriaOne particular study, carried out to investigate diversity of Pathogens within the mucilage, found that Pathogens within the Mucilaginous Blob were not to be seen anywhere in the surrounding bodies of water. Scientists have speculated that some species such as Skeletonema costatum and Nitzschia closterium are responsible for the production of large quantities of Extracellular Mucilage. Further, these Blobs could shelter Potentially Pathogenic or opportunistic pathogens. One of the organisms that found within the blobs was Escherichia coli, a dangerous pathogen and an indicator of faecal Contamination. Further, a number of Viruses were also found to be harboured in the Mucilage.

Human activities have resulted into drastic changes in the environment and increasing ocean temperatures are a part of these. The appearance of Marine Mucilage is a sign of changes in a water body. Heating up of the water body makes it a stable environment for aggregation and Blob formation. If such a blob comes in contact with polluted waters near embankments, it might pick up pathogens like E. Coli or Vibrio. What interest me are the possible paths of Molecular Evolution that this situation might contain. I would like to venture a few thoughts on this subject.

Escherichia coli- Enteropathogen

Escherichia coli- Enteropathogen

Some workers have speculated that the environmental microbes would pose a competition to Enteropathogenic bacteria like E.coli allowing them to grow and flourish. However, what if the Mucilage persists for a relatively longer period of time? Will it then become possible for the pathogenic organism to evolve better means of fighting off the competing bacteria? Further, will they even go to extent of evolving mutually beneficial symbiotic associations that will enable the pathogens to actually benefit in future from the metabolic processes of those organisms that are today fierce competitors. We might see the evolution of a Biofilm-like situation where large numbers of metabolically diverse organisms co-exist harmoniously in nutrient deficient or otherwise non-conducive environments.

Vibrio cholerae- Enteropathogen

Vibrio cholerae- Enteropathogen

If this happens, we will have created an incubation ground for pathogens and opportunists to become stronger and more virulent. I also wonder what will happen to the few E.coli cells that will inevitably be separated from the microenvironment of the Mucilage. Most of the cells might die in the presence of higher concentrations of salt or the relatively cooler temperatures of the open oceans. But, equally inevitably, some among these might evolve to become Salt tolerant, temperature tolerant and will therefore have an increased capacity to stay for long periods in the water body. This will lead to increased water-borne transmission of these pathogens.

Paul Ewald, the leading Evolutionary biologist of our times has an interesting theory about evolution of pathogens and whether we can control the course of such an evolution. In a fascinating talk about Diarhhoea, (caused by E.coli, Vibrio etc ) he talks about the modes of transmission of diseases and why these are important in deciding the course of evolution of a pathogen. He says, person to person spread and food to person spread of the disease (Diarrhoea) requires the host (Humans) to be relatively healthy. If one is a healthy enough to move around a little, one would be able to spread the disease more effectively. In such cases, evolution will favour the selection of those strains of pathogens that are milder or less virulent. So in other words we might be sick but not fatally so.  However, if the pathogen is capable of being transmitted through water it really does not need the host to be healthy. So, such modes of transmission will favour selection of strains that are extremely virulent. He proves this by means of an elegantly explained case study. Coming back to Marine Mucilages, I am once again fascinated by the probability of extremely pathogenic strains of water-borne pathogens arising in the near future.

Paul Ewald- Evolutionary Biologist

Paul Ewald- Evolutionary Biologist

Another truly interesting facet of this Mucilage microenvironment is emergence of pathogenic viruses. Ocean waters are contaminated by a large number of pesticides and other complex, sometimes recalcitrant compounds. One property of these contaminants is the capacity to induce prophage state in viruses. One grasps the significance of this fact when one takes a closer look at the Vibrio cholerae germ. The capacity of this organism to produce an extremely strong toxin is responsible for its virulence. The genes for this toxin reside within a prophage. Without this, the bacterium will not be nearly so virulent. Bringing us back to the unique conditions created within the Marine Mucilage. It will bring into close proximity both virulent pathogens as well as Viruses. These viruses might be inherently pathogenic and might be maintained and transmitted via the Blobs. Or, they may be induced to become prophages in some bacterium that might emerge as a completely new strain of pathogen, or a more virulent version of an already existing one.

These speculations are fascinating as well as chilling, considering the fact that our fight against pathogens has been a long and tiring one. The quick mutation rate as well as increasing proximity to pathogens due to unhealthy living conditions has seen a surge in infectious diseases and zoonoses like never before. The last thing we need is another safe haven where pathogens can selectively evolve into more dangerous beings. However, Paul Ewald strongly believes that if we can predict the course of evolution of a pathogen, we can also influence this course and force the pathogen to evolve into a weaker instead of a stronger pathogen. For example, if we clean up our water bodies, we might prevent emergence of water-borne strains of pathogens. Thus, we will force them to rely on us (the host) to transmit them, probably favouring the selection of less virulent strains. This theory has been proved using a similar case study. When viewed with this logic it seems absurdly simple. But, implementation of these simple tricks requires collective will on our behalf and a deep understanding of how slight changes in environment brought about by our irresponsible lifestyles will ultimately lead to the emergence of newer, stronger, more resistant pathogens.

References:

1. http://cat.inist.fr/?aModele=afficheN&cpsidt=14570903  (Abstract only)

2. Paper on Skeletonema

References For Images:

1. www.ted.com/speakers/paul_ewald.html

2. www.ecoliblog.com/tags/e-coli-outbreak/

3. www.ismaran.it/…/NatEvMucillage.aspx

4. jpkc.njau.edu.cn/spwswx/cankao/ShowArticle.as..