Hi everybody
I'm trying to culture Nannochloropsis oceanica CCMP1779 (axenic) under heterotrophic conditions. For the methodology I'm following previous studies where they cultured other Nannochloropsis spp. and trying to do it under the same conditions. Briefly I inoculated some phototrophically (f/2) growing culture into a new medium made of f/2 and 2g/L glucose and incubated in the dark. However nothing has been growing for 2-3 weeks, while the dark/light control (in the same medium) grows very fast. Therefore Nannochloropsis is clearly not growing heterotrophically and the problem does not come from the medium.
Does anyone have any suggestion on how to grow Nannochloropsis heterotrophically? are there substrates more suitable than glucose for heterotrophic cultivation? Is it possible that other Nannochloropsis spp. can grow heterotrophically while N. oceanica can't?
Maybe a different substrate eg, citric acid will be consumed - as a part of Citric acid cycle. Also it would be interesting to check the behavior on a yeast extract - tripton based medium. According to the literature and my experiences as well, several algae does not consume glucose, only a part of them can be breeded on heterotrophic way.
Hi Istvan. Ok thanks for your suggestion. Which concentrations of citric acid or yeast extracts do you recommend? These substrates are mostly used for heterotrophic bacteria and I did not find much in literature about the use of yeast extracts/citric acid to grow microalgae heterotrophically. Also do you think f/2 is still a good substrate to supply N, P, and minor elements?
Hi Sergio,
We managed to grow Chlorella in medium containing 5-5 g/l yeast extract and tripton. In separate test 5 g/l sodiumacetate was applied with minerals successfully. I am not familiar with seawater just I guess some sea water strains can behave similarly
Hi Istvan, hi Harold, thanks for your answer. I'm now growing it in LB broth (yeast+tripton) in seawater and will see how it grow. Yes Harold, I think my strain (CCMP1779 N. oceanica) is unable to uptake glucose in contrast to other Nannochloropsis species. I will also test other Nannochloropsis species then
Hi Sergio. Do you know the reason for inhibition of glucose uptake?
I am having the same problem with Chlorella vulgaris.
Thanks
I was following this discussion and would like to know whether you managed to culture oceanica under heterotrophic condition?
Dear Sasha,
Even in the literature I have found such statement that C. vulgaris does not consume glucose. In other communications it was succeeded. Probably the ability depends not only on species but special strains of one species.
Sergio,
In case of citric acid or acetate probably 5 g/l is OK, nevertheless the pH adjustment is inevitable, eg. at pH 6 a lot of acetate will escape during autoclaving.
How did you manage further on?
Hi Istvan, thank you for your reply.
Can you please add the papers you have come across that quotes about C. vulgaris not consuming glucose
Dear Sasha, I am sorry as I looked through my folders, I did not find. It was an old article from seventies as I remember. Nevertheless sequencing alters much the relevance of previous publications. Currently also it could be valid: we have C. vulgaris strains with so different properties, that maybe they are to species. Also from culture collections we have two different C. sorokiniana strains one of them grows on 40 C degree, the other has an optimum at 28 degree C, morphology is not equal at all.
Dear all, thanks for the suggestions and sorry for the late answer. I finally did not succeed to grow Nannochloropsis with glucose.
I think the inhibition might be to the difficulty in transporting glucose inside the cell.
Sergio