One option that works for bacteria, and should theoretically also work for microalgae, is to grow them in a chemostat.  If you increase the dilution rate until it is just below the washout rate, you should select for faster growing cells.  You can do this via serial batch transfer culturing as well, but the chemostat should be significantly faster.  You can easily detect any improvement in the growth rate by monitoring the outflow spectroscopically.  The down side of this method is that you might select for mutants that lack the property you are interested in.  For instance if you are looking to optimize growth of an algae for the production of biofuel, it is quite possible that you will select for mutants that produce less, so they can grow faster.  

Thank you very much for kind info sir,chemostat method some of Microalgal industry using for higher biomass production but they are lacking ability to High Amount of Lipid accumulation in microalgal cell.

Use insulin in your media it will

Hi Diana ,

Thank you so much for kind info. right now i am growing micro algal in BG11 medium at 25±1°C and under cool white fluorescent illumination at an incident light intensity 1.2 ± 0.2 klux i.e. photosynthetically active radiation  is a synchronizing with 16 h light and 8 h dark photo-period.

Kiran

Elsayed sir, i didnt think so is work for autotrophic culturing as well as economic. i did find lit. supporting economic and autotrophic culturing if you hv plz send me.

Changing the maximum specific growth rate can only be done through laboratory evolution or genetic modification as this is an intrinci parameter of your organsim. Changing the specific growth rate is possible by adjusting the cultivation conditions. Getting the specific growth rate close to its maximum required controlling T, pH, salinity at optimum, preventing nutrient limitation, and finally (but most tricky) having oversaturating light conditions (typically over 200 micromol par-photons per m2 per s for most eukaryotic green microalgae) in your entire cultivation system...without having regions where the light intensity is so high that photoinhibition occurs. In batch growth that becomes increasingly difficult when biomass increases, so indeed use chemostats or turbidostats for this. Practically you will always be quite a bit below the maximum specific growth rate.

From an outdoor production point of view there is no problem of not reaching the maximal specific growth rate, because areal light supply is a given and you would like to use that light as efficiently as possible, which happens at operational settings that are resulting in pretty low specific growth rates. Here, think about adjusting light path length, and biomass concentration and daily harvesting strategy for finding the optimal yield on light.

More info: Have a look at the papers from our group or join our course Microalgae Process Design in June or July 2015.

You might be interested in the "flashing light effect" >> for an example see http://www.ncbi.nlm.nih.gov/pubmed/24511694