Sorting Algal Strains for High Lipid Content Using NIR

A recent post in Forbes by Chris Rhodes currently buzzing talks about a new method for identifying high lipid content strains of algae based on Near Infrared (NIR) spectroscopy. The near infrared wavelength spectrum occupies from 800–2500 nm, just below the region of visible light but above the usual mid-infrared, at 2500–30,000 nm.

NIR, which came into practical use in the 1950s as an analytical procedure, is less sensitive than normal (mid) IR but can penetrate samples more easily, requiring less analytical preparation. Algae can be examined in their raw state.

The NIR method is highly specific for the detection of different kinds of fatty acids and it is intended to develop a database of fingerprints for different fatty acid components in algal biomass, with which to analyze actual algae. The method offers the promise of a rapid and precise screening of algae directly rather than the time-consuming, cumbersome and error-prone present means for analyzing algae, and may prove pivotal in the development of a fuel industry based on algae.

A report in Chemistry World by Anna Lewcock describes research being done by the National Renewable Energy Labs (NREL) using NIR. “The preliminary work we have done involves taking some algae biomass and spiking it with a couple of different types of lipids, either triglycerides or phospholipids,” says NREL biofuels principal group manager Al Darzins. “We’ve then done NIR spectroscopy on those samples and the preliminary models that we’ve developed show that we have a very nice linear correlation [between] the amount of lipid that we added with regards to how much the model is predicting.”

The more samples used to generate the library, the more robust the model becomes. Once scaled up, it could create a rapid screening method that avoids laborious and time consuming wet chemical methods. “If you wanted to grow a hundred different organisms, doing that lipid analysis by wet chemistry would take months and months, whereas if you can use this [new technique], you can do it in a few minutes,” says Darzins.