Microalgae Growth – Overview of Key Parameters

Growing microalgae can seem complicated because there are so many factors that need to be just right for a successful algae culture.  In this article we are going to briefly explain some of these factors and why they are important.

Microalgae are an evolutionarily diverse group of organisms that come in many colours and shapes.  They are united by their small size (1 – 100 µm for single cells, larger for colonies) and their ability to photosynthesize.  Despite their diversity they have some common requirements for growth.

Light & C02

First, there are the ingredients for photosynthesis.  Photosynthesis is the process by which microalgae use energy from light to fix CO2 and produce sugars and oxygen.

So, if you want to grow algae photosynthetically, you need to make sure you have plenty of light and carbon (usually CO2) available.

Nutrients

In addition, microalgae require other nutrients to build their cells.  Nitrogen and phosphorus are in highest demand, plus silicon if you are growing diatoms.  But there are lots of other nutrients required in much smaller amounts, like metals and vitamins.

pH, Temperature and Salinity

It is also important to provide favourable abiotic conditions for the cells to grow.  The main factors to consider here are the pH, temperature and salinity of the culture media.  A good starting point for these parameters is to match the environment where your species would occur naturally. E.g. does it grow in the tropics or in the arctic?  Freshwater or marine?

Biosecurity

Another important consideration for culturing algae is biosecurity.  In this context biosecurity means the measures taken to prevent organisms other than the cultured species from getting into your algae culture.  For most applications algae is cultured as a single species, and it takes a lot of work to keep it that way!

Harvest Rate

Lastly, it is important to consider harvest – how often and how much should you harvest?  This depends on several factors like the growth rate of your species and the system you are using to grow it.  There are many approaches each with their own benefits and drawbacks.

To summarize, the important factors for microalgae culture we mentioned here are:

• Light
• CO2
• Nutrients
• pH
• Temperature
• Salinity
• Biosecurity 
• Harvest rate

In future blog posts we will be discussing these microalgae growth parameters in more detail, and how Industrial Plankton PBRs can keep them optimal for algae growth. So stay tuned!