Various Pigment Types of Synechococcus Cyanobacteria from Across the World's Oceans

Studies have been done by the University of Warwick that show that bacteria that are crucial to ocean life can shift their color like chameleons to match different colored light across the world’s seas. This is a very intriguing concept, but also very amazing too. It is found that blue light is prevalent in the open ocean (obviously), while green light is prevalent in coastal and equatorial waters. Red light is prevalent in estuaries. The bacteria Synechococcus cyanobacteria contains specific genes that allow it to adapt their pigments to the light sources that are available! Therefore, this bacteria that lives in the open ocean has adapted to take in primarily blue light, whereas the bacteria in estuaries take in red light and bacteria in coastal and equatorial waters take in green light. S. cyanobacteria uses light to capture carbon dioxide from the air and produce energy for the marine food chain. Their genes are altered in such a way so as to thrive in any part of the world’s oceans.

Figure 1: SEM of Synechococcus cyanobacteria

The light that is absorbed is determined by a multitude of factors. One is the tilt of the Earth and the direction of the light from the sun to the Earth. Refraction plays a role to the bending of light. The geography also seems to play into part of the reason as to the light absorbance changes. Blue light is most prevalent in the open ocean, as it penetrates into the deep waters (it is the deepest penetrating wavelength). The prevalence of light changes depending where on the planet you go. In estuaries, says researcher David Scanlan, the light is often red, whereas in warm equatorial and coastal waters, the light is more green. The bacteria have adapted to utilize the changing light intensities to produce efficiently around the globe.

Figure 2: Various pigment types of Synechococcus cyanobacteria from across the world's oceans, grown in culture at the University of Warwick

Scanlan and colleagues analyzed specific gene sequences from S. cyanobacteria in the different water samples from around the globe. What they found was the same genes in bacteria living thousands of miles apart around the globe. The genes are known as “chromatic adaptor” genes, and they are abundant in ocean dwelling S. cyanobacteria which enables “these color-shifting microorganisms to change their pigment content in order to survive and photosynthesize in ocean waters.” If the same bacteria is in the open oceans, warm equatorial waters, coastal waters, and in estuaries, being able to efficiently produce oxygen from carbon dioxide is a useful adaptation. It would be seemingly wasteful to spend more energy in coastal waters or even estuarine waters to photosynthesize blue light if it isn’t the most prevalent light wavelength. The same goes with trying to photosynthesize red light in the equatorial waters, or green light in the open ocean.

Scanlan says that “finding [these bacterial] cells capable of dynamically changing their pigment content in accordance with the ambient light color … gives us a much deeper understanding of those processes essential to keep the ocean ‘engine’ running.” It is understood that paying attention to these microorganisms will help us better predict how the oceans will react in the future to a changing climate with increasing levels of carbon dioxide. If anything, these “key primary producers are potentially excellent bio-indicators of climate change.”

Source for Article:

https://www.eurekalert.org/pub_releases/2018-02/uow-ob022118.php 

Source for Figure 1: 

https://www.sciencesource.com/archive/Synechococcus-Cyanobacteria--SEM-SS2582898.html#/SearchResult&ITEMID=SS2582898 

Battles Under the Sea

            A battle under the sea brings up iconic images; sharks and whales and other large animals fighting for their lives. However, this battle occurs deeper than what these animals could reach; roughly one mile below the ocean to be specific. In the deep darkness of the bathypelagic, a war is happening…a microbial war. It’s been recently discovered that viruses are attacking hydrothermal bacteria with one goal, their stores of sulfur.

A typical hydrothermal vent 

(Photo credit: NOAA)

            Bacteria and viruses have been enemies for as long as both have existed, but this is anew an interesting front in these battles. Deep-sea hydrothermal bacteria are still very unusual and not very well-known, and this is the first time that this sort of virus-bacteria relationship has been seen, since chemosynthetic bacteria are a rare lot.

            So, why do these bacteria target the sulfur in these bacteria? Well, the answer lies in the viruses’ desire to reproduce; turning the bacteria into a virus factory in a sense. What they do is they will force the bacteria to consume all of its sulfur reserves, and then use the resulting energy to create as many viruses as possible. The bacteria will inevitably die from this process, releasing all of the newly created viruses into the open to repeat the process.

            Interestingly enough, this sort of relationship has been seen before, namely in the shallow ocean water. There is a similar virus that target photosynthetic bacteria in order to reach the same end goal. So, it’s interesting to see the parallel between the two viruses, especially when it comes to their mechanism for reproducing.

            So, what are researchers doing about this? Well, currently Gregory Dick, a University of Michigan microbiologist and oceanographer, and his team are currently analyzing the DNA of the bacteria and viruses in order to better understand the mechanism of this invasion. After collecting samples from the hydrothermal vents found near the Gulf of California and the Western Pacific, Dick has begun taking a look at the DNA samples he’s gathered, and believes he may have found what the virus is doing.

            Dick and his team believe that the virus is targeting the SUP05 genes found in the bacteria. This comes as no surprise to Dick, as the SUP05 genes are responsible for creating the proteins necessary to use sulfur to create energy. By targeting this gene, the virus can overexpress it, forcing the bacteria to burn through its supply of sulfur faster than it would ever need to naturally.

Riftia pachyptila, a polychaete typically found around hydrothermal vents have an organ with chemosynthetic bacteria instead of a gut.

(Photo credit: Wikimedia Foundation)

            So, what does this mean, what can be gained from this research? Well, Dick believes that this shows that these viruses are actually very important in the long term survivability of these bacteria. Dick and his team believe that these viruses act as “agents of evolution”, allowing for gene transfer between the chemosynthetic bacteria, a theory first proposed about photosynthetic bacteria found in the shallows by David Garrison, a program director for the National Science Foundation. Without these viruses, the bacteria would rarely receive gene transfer, and a disease could cause catastrophic damage to the bacterial population, which could cause an entire collapse of the hydrothermal vent community, since they rely on these bacteria for primary production.

References: 

http://www.sciencedaily.com/releases/2014/05/140501151019.htm

Micro-Organismal Degradation of Oil Spills

BP Deepwater Horizon Oil Spill- Google Map Image (www.eoearth.org)

Oil spills like the Exxon-Valdez and BP Deepwater Horizon incidents are devastating to aquatic and terrestrial wildlife.  Much research has been done surrounding the most effective way of cleaning up oil slicks and/or plumes in the water and the shoreline.  With petroleum hydrocarbons occurring naturally in the environment, microorganisms are professionals at degrading these compounds.  Hundreds of species of bacteria and fungi are capable of breaking down petroleum hydrocarbons with the help of dispersants and fertilizers.  Although weathering processes and degradation by microorganisms are very effective, patches of highly weathered oil likely will remain in some environments.  In remediation, decisions to rely upon microbial oil biodegradation should be driven by risk to the environment and not just the presence of detectable hydrocarbons.    

In the first study I will reference in my talk, the researchers found that temperature had a greater effect than nutrient addition when degrading petroleum hydrocarbons.  They support the finding that there is an immediate change in bacterial community structure when crude oil is released into the water column.  They also noted that certain species that are “hydrocarbonoclastic” function at a range of 4-20°C, so organisms can be used to bioremediate the area seasonally.

The second study I found had a related author from the first paper, and this study quantified changes in concentrations of hydrocarbonoclastic bacteria in response to intervention strategies applied to external organisms.  Intervention strategies included adding nutrients, bioemulsifers, and bioaugmentation with other types of bacteria.  Overall, nutrient and bioemulsifier addition proved to be a synergistic mixture.  Alcanivorax enhanced degradation significantly over Thalassolituus, but the use of the synergistic mixture and the bacteria would improve mitigation strategies.

The third paper specifically relates the growth in population of λ-Proteobacteria to the Deepwater Horizon oil spill in the Gulf of Mexico.  With the spill being completely underwater as a plume rising to the surface, deep sea λ-Proteobacteria who degrade petroleum, increased due to the spill.  Changes in hydrocarbon composition with distance from the source and incubation experiments with environmental isolates demonstrated faster than expected hydrocarbon biodegradation rates at 5°C.  Based on these results, intrinsic bioremediation of the oil plume in the deep-water column without substantial oxygen drawdown is possible.

I am still researching some more primary literature to add to my talk.  This may include some supplementary information on other clean-up methods used besides bioremediation and more information about the biological implications of oil spills.

Good Bacteria Turns Bad

This article ties in with the presentation that i will be presenting on next week. Coral bleaching is the whitening of coral, from the loss of their symbiont. Coral bleaching is an increasing problem due to the increased water temperatures. Coral reefs are very important to the human economy and to a vast diversity of animals.

This article talks about the bacteria that live on coral reefs, in normal conditions these bacteria produce a mucus layer that protects the corals. This mucus layer prevents the corals from getting infections from bacteria. However, with the increasing temperature of the water the mucus layer breaks down and the good bacteria are replaced with pathogenic (bad) bacteria. This model has also shown that once the water temperatures return to normal the pathogenic bacteria remain on the corals. The mechanism is not quite understood to explain the pathogenic bacteria remaining on the corals when temperatures return to normal. The water temperatures have been increasing over the past years and many steps need to be taken to improve coral reef habitats before they are lost forever.

Good Bacteria Turns Bad

Are marine microbes our answer to plastic pollution?

Microbes are the most numerous of marine organisms, and recent studies are underway to see just how these organisms interact with plastics in the ocean. Plastic pollution is a big problem, because in the environment, it can take thousands of years to break down. Over time, the size of plastic decreases in the ocean because of natural forces wearing on it. The tiny fragments are dangerous because they can absorb toxins that can be ingested by marine animals. Researchers at the University of Sheffield and the Center for Environment, Fisheries, and Aquaculture science are providing evidence that the type of microbes that grow on these plastic fragments significantly varies from the microbial groups that colonize the wider environments. These microbes may be contributing to the breakdown of plastic pollution and toxins in the marine environment. Using DNA experiments, these researchers are finding that plastic is quickly colonized by many species of bacteria that together form a biofilm along the plastic surface. This biofilm is only formed by certain types of marine bacteria. It's going to take more research to fully understand the impact these bacteria have on plastic pollution, but these experiments could offer insight into the impacts of plastic pollution on the global environment.
Picture from: http://www.surfrider.org/kauai/SR_Kauai/RiseAbovePlastics_files/Snapshot%202008-04-14%2016-30-34.jpg

Are Bioluminescent Bacteria Behind Milky Seas Legend?

For several Centuries, sailors have told stories of so called "milky seas." These 'milky seas' seemed to be glowing a dim white light. According to the log of the S.S. Lima as it sailed off the coast of Somalia 11 years ago, they were surrounded by waters that appeared as a field of snow or clouds in all directions. Scientist have been able to go back and look at satellite pictures at the time of this voyage and were able to find pictures confirming the glowing sea. Scientist say that this glow is caused by bioluminescent bacteria. One might ask how many bioluminescent bacteria would it take to light up the seas? Well if one were to cover the earth in a 4 inch layer of sand and then count all of the individual grains of sand in that layer, thats how many it would take. These glowing seas typically only last a few days are usually found in the Indian Ocean.

Scientist hypothesize that the bacterium Vibrio harveyi is responsible for this bioluminescence. There are dinoflagellates that will give off light as well. These organisms however must be physically stimulated to produce a brief flash of light. V. harveyi seem to give off a continuous light on their own. One hypothesis that is mentioned for the bacterium to continuously glow is to attract fish so they can enter their guts and live there.

The article and a minute long video can be found here.