Bacterial Associations

Bacterial symbiosis and associations vary to some of the most extreme habitats found on the plant. Ranging from tropical rain forests with colonies of ants working together to harvest a farm that supplies nutrients they need to live, to the hydrothermal vents that allow bacteria to oxidize sulfur and otherwise toxic metals to a usable form of energy. As the world evolved for millions of years some of the most basal life forms, bacteria among them, were not lost but used in virtually every way imaginable. These symbioses can range from mutually beneficial relationships to parasitic relationships that will ultimately kill their host. Some of these symbionts are looked into a little further in the following studies…

Bonnie Bassler: The Secret, Social Lives of Bacteria
*The Fun Side of Bacteria*

Rhizobia and host plant are symbionts that are necessary for survival of each organism. In return for the bacteria’s production of usable nitrogen, the plant produces carbon in its usable form and a protective environment, often referred to as nodules within its own roots. In order for this symbiosis to commence signals must both be excreted and received by each of the two organisms and a remarkable cascade continues in a variety of ways. In LysM-Type Mychorrizal Receptor Recruited for Rhizobium Symbiosis in Nonlegume Parasponia by Op den Camp et al. concluded that the myc factor and the nod factor at one point were joined but separated and now seen as initiating a very similar pathway in different ways.

Lys M- Type Mychorrizal Receptor

Riftia pachyptila live around hydrothermal vents in the East Pacific Ocean. These sea worms have developed an oblate symbiotic relationship with sulfide oxidizing bacteria. As the Riftia grow they absorb the surrounding sea water that contain these bacteria. Overtime the bacteria collect in specialized tissue called a trophosome, where they can be used in the respiration process. In this paper, these organisms were studied to ultimately look at what molecular components were present in the various tissues of the worm body through SSH and PCR techniques. The study looked specifically at trophosome tissue, plume tissue, and body tissue and their various makeups. The research concluded that there were specific transcript differences in each of the tissues.

Riftia Pachapitila

Some species live miles below the photic zone but still must be able to obtain organic material. Since they cannot receive sunlight for photosynthesis, they must be getting their food from another source. An obligately photosynthetic chemotrophic bacterial anaerobe is able to convert inorganic materials to make CO2 which is necessary for photosynthesis. Results showed that GSB1 contains chlorosomes which are light harvesting structures. Also, scientists were able to determine that this cluster of GSB1 was previously undiscovered and that it required elemental sulfur, anaerobiosis,H2S, light (from vents) and CO2 in order to grow.

Hydrothermal Vents

Euprymna scolopes and Vibrio fischeri have an obligate mutualism with one another. The squid gives the Vibrio fischeri bacteria with a safe place to reside and nutrients, while the Vibrio fischeri provide the squid with bio luminescence which provides camouflage and protection to the squid. The squid follows a diel cycle where it expels the Vibrio fischeri from its light organ right before dawn and by mid afternoon the Vibrio fischeri are replenished. The scientists in this paper addressed the transcriptional, metabolic, and physiological aspects of the symbiosis between Euprymna scolopes and Vibrio fischeri and determined if they followed a diel pattern.

Squid and Vibrio fischeri

The human microbiome has evolved from bacteria that originally developed in anaerobic environments, long before the development and rise of Homo sapiens. Phylogenetic analysis completed by a team of Montreal-based researchers attempted to reveal just how far back in time mitochondrial genetic information could be traced back, suggesting that mitochondria may have have been the original building block of animal based life before the hydrogenosome, an ATP-producing organelle found in bacterium. Through their research on Trichomonas vaginalis, they found that although they could not empirically exactly how far back mitochondria could be traced, characteristics evolving in each progressive lineage contributed to the success of the eukaryotic construction of the cell. The evolution of the eukaryotic cell and assisting bacterial lineages eventually supported the fact of a symbiotic relationship between human and bacteria, most actively studied in modern day research via the human gut. A wealth of microflora are now responsible for the manner in which humans respond directly to pharmaceutical drugs and other synthetic treatments. However, cometabolic activities between both species of bacteria and the organs supporting them must be continuously studied to understand exactly how our research has brought us from the building blocks of ATP production to the treatment of sicknesses and ailments that affect us everyday.

Human Microbiome and Individualized Response to Pharmaceuticals


Other examples of bacterial associations...

Symbiosis of Hydrothermal Vent Gastropods with Chemosynthetic Endobacteria
Gut Microbiota and the Development of the Brain
Gut Flora & The Immune System
Squid-Vibrio Symbiosis
Human Microbiome and Individualized Response to Pharmaceuticals