Dear Mr. Cadoux.

Feasibility of large continuous algal culture depends on several variables.

I hope that this answer helps to you.

Best regards, 

Gustavo G.

Thank you very much for your advices Gustavo,

The bioreactor set is already in place and not tightly controlled (no air control) from an aseptic point of view. Therefore the aim is to limit the contamination by using antibiotics. I will test cultures with antibiotics in the lab before the inoculation of the larger reactor especially if the antifugal agents are harmful to Chlorophyceae. And inoculate at the maximal microalgae cell concentration possible. 

Best regards

Too much of anything can be harmful, be careful with the intent to use the maximum amount of inoculate as possible. Though removal is your intent, depending on the conditions of your laboratory setup with the aseptic or axenic intent your algal strains may have different results.

Like humans when we get sick I found that I like the lights not so bright, and the temperature warmer when I am taking my medication to get well. I say this as the Algae will not respond to the inoculate the same as previous occurrences with different conditions of the PBR and the room conditions including the inoculates temperate conditions. Record all conditions of activity even though your only working on solving your algae conditions. Mixing the inoculate with out taking in all the 'sudden changes' in laboratory conditions can result in flat lining your culture completely.

Dear Gabriel,

maybe you could try the aquarium trick of adding hydrogen peroxide in a little concentration.

Good luck with your work,

Davide

I dont understand what you mean. If you mean a true continuous culture you will need an equal volume of medium every 12 hours as this is the generation time of the algae you mention. If you mean continual culture and have it open to the air, you will not be able to keep it axenic!

Thank you for all your answers,

Keith, I mean true continuous culture in closed photobioreactor with air injection. Thus I should add antibiotic mix with the nutrients to keep it as clean as possible but I'm unsure about their dose and their harmfulness against algae (as Gustavo said earlier, the antifugal seems quite harmful).

Dear Gabriel,

I don't think either keeping large microalgal culture axenic or using antibiotics as means of axenization is practical for some reasons (see following paper):

1. Bacteria/fungi is everywhere and it's nearly impossible to protect your microalgal culture from them for long time. You can have axenic culture at the beginning and later found out that your culture is not axenic at all, and sometimes not even unialgal.

2. Treatment with antibiotics/antifungal reagent can't kill all the bacteria/fungi. They just can make them grow really slow or reduce their cell number to really small number but they NEVER can kill them completely. So, treating with antibiotics/antifungal reagent CAN'T guaranty the culture totally axenic once the contaminants start show up.

3. Antibiotics/antifungal reagent is not only toxic to bacteria/fungi but also toxic to microalgae and can also induce mutagenesisin microalgae.

4. This method is too expensive and can also induce antibiotics resistance, consider your large culture volume.

Article Axenic cultures for microalgal biotechnology: Establishment,...