AAT Bioquest

Direct bioconversion of brown algae into ethanol by thermophilic bacterium Defluviitalea phaphyphila

The biggest challenge humankind must overcome should it desire to build a sustainable world is the energy problem. While the unleashing of the world's resources in the service of energy production has caused unprecedented reductions in human suffering, it is no secret that dependence on oil is problematic, to put it lightly. As such, there has been a huge increase in the amount of research being done to try and find alternative sources of energy that are not subjected to the same restrictions as oil and other fossil fuels, mainly the significant investment of capital and requirement of large amounts of land and water. One promising alternative is brown algae. The chemical makeup of this sea plant means that if it were to be properly broken down, ethanol could be made using materials that require a fraction of the land and fresh water needed by other sources of biofuels, namely corn and sugar cane. To make ethanol, one needs sugar, and the sugar composition of brown algae is complex and includes alginate, mannitol, and laminarin. Alginate is unique to brown algae, while mannitol is a sugar alcohol form of mannose, and laminarin is a linear polysaccharide of mannitol-containing β-1,3-linked glucose. The promise for brown algae in ethanol production is quite high, yet currently little use is being made of this material, largely because the complex carbohydrates make it difficult to produce ethanol from the algae.

Thus, Ji et al. from Qingdao Institute of Bioenergy and Bioprocess Technology at the Chinese Academy of Sciences set out to determine if this process could be made easier by running a series of experiments designed to induce the breakdown of these complex carbohydrates and the production of the sugars needed to make ethanol. Previous efforts have been focused on genetic engineering, but the complexity and expense of this make it somewhat impractical. As a result, the research team wanted to look at one strain of brown algae, Defluviitalea phaphyphila Alg1 since, in their previous work, they found an untapped thermophilic bacterial resource in this strain. In order to test the effectiveness of Defluviitalea phaphyphila Alg1 in helping breakdown the complex carbohydrates of brown algae, the research team needed to carefully measure the presence of a number of substances, such as NAD+/NADH. To do this, they made use of the Amplite Fluorimetric Total NAD and NADH Assay Kit because of its known sensitivity and accuracy. By making use of an enzyme cycling reaction instead of relying on measuring NAD+/NADH absorption, this assay kit is far more sensitive and therefore much more accurate. For example, this assay has demonstrated high sensitivity and low interference with 570 nm excitation/590 nm emission.

Overall, the results of this study are quite promising; Ji's team found that Defluviitalea phaphyphila Alg1 can in fact serve as an effective way of using the sugars found in brown algae, making this the first thermophilic bacterium capable of doing this. These results offer great promise in the search for new energy sources, and because of the accuracy provided by tools such as the Amplite Fluorimetric Total NAD and NADH Assay Kit, researchers were able to confidently make a conclusion that could have a significant impact on overcoming one of the most difficult challenges facing today's global society.



  1. Ji, Shi-Qi, et al. "Direct bioconversion of brown algae into ethanol by thermophilic bacterium Defluviitalea phaphyphila." Biotechnology for biofuels 9.1 (2016): 81.

Original created on March 8, 2018, last updated on March 8, 2018
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