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Cell Cycle Management 27

This is the third post in a series of blogs titled ‘Bottlenecks, Trafficbocks and Deadends’ intended to address Algae Commercialization barriers.

Please check out for my previous posts at:   http://www.oilgae.com/club/users/Gopinelli/blogs/1207  (Bottlenecks, Trafficbocks and Deadends)

and

http://www.oilgae.com/club/users/Gopinelli/blogs/1212 (Scaling up)

Cell Cycle Management

In natural day-night conditions many algae species complete one cell cycle per day. In many such colonies exponential growth is observed during early hours of the light period, which is followed by a decline in growth rate. Similarly, maximum cell division is observed during early hours of dark period.  This indicates that actual cell cycle duration of the species is less than one day. 

Dark and light periods longer than actual cell cycle duration of the species have the following impacts:

  1. The colony consumes maximum carbon dioxide during exponential growth and carbon consumption declines as growth rate declines. In the absence of continuous growth monitoring and carbon dioxide dispensing accorgingly, achievement of projected carbon mitigation is difficult. Expulsion of unutilized carbon dioxide through the media will also increse system footprint.
  2. Day-night cycles longer than actual cell cycle of the species causes cells medtabolize on cell matter, affecting energy efficiency of the system.
  3. Longer exposures can increase chances of photo-inhibition, fouling and culture collapse.

 In fact, cell cycle duration of algae vary from species to species. There are some algae strains available with depositories that can, all growth conditions provided at optimum levels, complete one cell division during every 90 minutes. The major issue with this species is exposing the strain to alternate dark and light periods of appropriate durations (that is one dark period and one light period during every 90 minutes). Theoretically this species can undergo 16 cell cycles per day, under night time artificial lighting and multiply biomass nearly 64,000 times within 24 hours. At a very conservative 10 cell cycles per day, 1000 fold biomass multiplication is possible.

But, how can it be achieved?

First, you need to synchronize the metabolic activity of the colony to maintain majority of the cells in same growth phase.

Then, introduce the synchronized colony to alternate dark and light periods, maintaining active light period 24/7.

A practical approach is continuously introducing a lab-synchronized colony to a closed loop bioreactor system capable to provide alternate dark and light periods and provide artificial lights during night and low light hours. Dark chamber and light chamber of a bioreactor in the system bioreactor system should have a volume proportion corresponding to the proportion of actual dark and light period of the species. Media flow rate is to be adjusted in such a way that the colony stays in the dark chamber at least for a duration corresponding to the dark period of the species and in the light chamber at least for a duration corresponding to the light period.

 Short cell cycle and artificial lighting during night has the following advantages:

  1. Reduce crop period, several fold improvement in biomass yield.
  2. Round-the-clock carbon consumption at consistent rate.
  3. Improves System energy efficiency.
  4. Minimizes risks of photo-inhibition, and culture collapse.

My closed loop continuous flow bioreactor system features the capability to provide alternate dark and light periods corrensponding to actual cell cycle duration of the colony, continuously, under night time artificial lighting. The system can be adjusted to match any cell cycle duration and any micro algae species.

*** Please check out for my upcoming blog post in the series- Be a Farmer

Mon May 30 2011 08:22:47 PM by Gopinelli 2002 views
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