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News Article

Producing biofuel from bacteria

Could cyanobacteria become a new, clean source of energy?

Production of renewable biofuels from microbiological processes has attracted significant attention in recent years, due to increasing concerns regarding depleting reserves of fossil fuels and the environmental consequences of their extraction and use.  A Bay Area company has patented a group of three cyanobacteria that, when grown together, can produce high quantities of sugar that can then be used for generating biofuels.  Sandia National Laboratories is helping HelioBioSys Inc. to determine whether farming them on a large scale is achievable. 

Demand for clean, domestically produced renewable energy has resulted in a significant amount of research on algae.   Algae is particularly desirable for use as a biofuel, because it doesn’t compete with food crops for land, water or other resources.  In addition, the water which is used to grow algae is not usually suitable for use in agriculture.  Algae farms can produce significant volumes of biomass, so they can be harvested and converted into chemicals, fuels or other bio-based products. 

HelioBioSys Inc. is working with cyanobacteria, which was mistaken for algae until the early 1900’s.  Like algae, colonies of cyanobacteria grow in water and have been incorrectly referred to as “blue-green algae.” But unlike algae, marine cyanobacteria can excrete large quantities of sugar directly into the water where they grow.

According to Ryan Davis, a Sandia biochemist, a typical algae operation might grow 1 gram of biomass per litre.  However, small-scale testing on these cyanobacteria shows that they can produce between 4 to 7 grams of sugar per litre of biomass, an increase of up to 700 percent.  Therefore, it would appear that growing cyanobacteria for sugars is more efficient than growing biomass. Also, filtering out the sugar from the water is a much simpler and therefore less expensive process than extracting lipids from large quantities of algal biomass. Sugar is more easily converted into a variety of chemicals and fuels and cyanobacteria does not require additional fertilizer to create sugars.  These cost-savings could make biofuels more competitive with petroleum in future.

In order to maximise the sugar production from cyanobacteria, it needs to be better understood. HelioBioSys founders Rocco Mancinelli and David Smernoff say they chose to grow a community of three cyanobacteria rather than focus on a single organism because communal systems better resemble nature. They say that when in communities, cyanobacteria are stronger and are more likely to survive changes in the environment, as well as contamination and predation.  Sandia is helping them to test this idea.      

According to the team, the cyanobacteria have already proved successful in closed, controlled, sterile laboratories.  The organisms are now being grown in large raceway systems that resemble long bath tubs.  While located indoors, the raceways are exposed to the air, so predation could prove challenging.

Ryan Davis explains that “giant bowls of sugar water generally don’t last long in nature.  We can understand where we can prevent bacterial overload and stop the sugars from being consumed by things we don’t want to grow.”

Unlike “true” algae, cyanobacteria have the ability to fix nitrogen from the atmosphere, which helps to support their growth and eliminates the need for additional fertilizers. 

The team are trying to understand whether each of the three cyanobacteria performs a specific function for the group, such as producing most of the sugars or fixing the nitrogen.  The cyanobacteria require sunlight for growth, but Davis believes that one of the cyanobacteria could be largely responsible for acting like a sunscreen, protecting the colony against light levels when they get too high. 

Sandia is also exploring other factors, such as micronutrient requirements or whether there are certain triggers for sugar production that could be controlled.   If successful, the next step will involve testing the cyanobacteria outdoors in large ponds.  Once the technology has been proven in an outdoor environment, HelioBioSys hopes to license or sell the technology.

Interested in finding out more about this topic? Subscribers to Environmental Impact can use the search string cyanobacteria and biofuels which retrieves over 170 results. A selection of these is provided in the further reading section below.

Article details

  • Author(s)
  • Stephanie Cole
  • Date
  • 25 September 2017
  • Source
  • DOE/Sandia National Laboratories
  • Subject(s)
  • Biofuels