I think you could consider to us 2-3 antibiotics simultaneously. There are many publications on no-effect concentrations of antibiotics in ecotox literature from the last decade.

Another option is to periodically treat the culture with UV-C (254 nm). Algae are generally not inactivated by UV doses (eg. 80 mJ/cm2) that are used for bacteria in water treatment.

Thank you so much Henrik,

Do you think the antibiotics would not affect the algae

is possible that the antibiotic affects the chemical composition and the development of macroalgae in the laboratory.

You can test to use for a short period mechanical treatments with chemical treatments for disinfection of culture.

Many papers describe various ways to obtain axenic cultures (bacteria free) eg. http://onlinelibrary.wiley.com/doi/10.1111/j.1440-1835.2008.00520.x/pdf

Is important to emphasize that performing the techniques of cultivation affect the physiology and compounds produced by macroalgae e.g. http://www.scielo.br/scielo.php?pid=S1806-66902014000100007&script=sci_arttext

All the suggestions so far are good options. Cocktails of Antibiotics often work well but many require active bacterial growth to be effective, so you may need to add a low concentration of organic carbon sources such as peptone or yeast extract to media during treatment. As many algae do not tolerate the organic very well, you then need to rinse/wash or dilute after treatment with antibiotics.

Likely success is very much dependent on the type and species of algae. Some species simply do not grow well or survive at all without their associated microbial community, and treatment with antibiotics may kill the algal cells by removing their obligate associates.

If the species is small, it may Grow well on solid growth medium, then you have a wealth of additional options for purification by traditional plating methods used for bacteria and Cyanobacteria. However, determining whether your algae are actually completely free of bacteria is always difficult. But perhaps complete elimination is not necessary for your purposes?

Good luck

Dear Chris

Thank you so much for your suggestions, It is really informative.

I just wonder what is the solid growth medium

Many thanks in advance

Bacterial contamination in unialgal cultures can be removed through the addition of antibiotics such as penicillin or rifampicin. You can test whether the bacteria are eliminated by plating the cultures on nutrient agar.

Many thanks Rita, I willdefinitly try your suggestions

Best regards

I would like to help you with this, I have done a considerable amount of work with algae. First I would like to know, what strain are you using, have you isolated the bacterial contamination, what are you feeding your algae, and is it open or closed system?

Dear Abdul-Hamid,

I think its important to know the type of algae, some time you can eliminated the growth of Bacteria if you change the % of the used agar, in addition to usage of antibiotics.

Regards

That was my thought. You could restrict the growth of bacteria by eliminating or reducing the bacteria's food source. We had great success with Chlamydomonas reinhardtii, we used a very simple mixture of 20:20:20 fertilizer with water. No specialized agar, or anything with glucose, and never had a problem with contamination. When glucose was used, contamination was very high.

Dear Christina and Fikrat

Thank you so much for your help and suggestions

the Algae strain called Chromera velia

I hope this will help, Many thanks in advance

Dear Abdul-Hamid,

A agree with Fikrat about impotence of algae’s type. Therefore, I would like to refer to some papers devoting this problem.

1) http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2009.00708.x/full

2) http://www.aslo.org/lomethods/free/2011/0478.html

Incubate the algae culture in inorganic media prefarably liquid media and isolate it on enriched semi solid media and then again mass culture the media into same purified inorganic liquid media.

U can get list of media required at www.Utex.org for reference

Try to devoid algae with any source of organic source as bacteria can utilize the same as energy source and lead to contamination, algae being photosynthetic can utilize inorganic nutrient media for growth.

Dear Ambarish

Thank you so much for your assistant, I really appreciate it

Do you think that the anti-biotic will affect the algae growth ????

Chromera velia grows well on solidified algal culture medium in my lab. Use f/2 or K or L1 medium solidified with 0.7-0.8% Difco Bacto agar (important to use high quality low ash content agar for microalgae). Alternatively you can use 0.4% agarose. Autoclave filtered seawater with the agar/agarose, cool to approx. 50 degrees and then add the F/2 nutrients (no silicate needed) as a concentrated solution (e.g. 100x conc), mix gently and pour your plates quite thick as you need to incubate for a few weeks (not days) to see colonies that you can begin to isolate and purify.

A simple approach Ive used successfully for other microalgae grown on solid mediim is to place 3-4 different AB discs close together on the plate surface and inoculate colonies in between . Incubate for a few weeks and isolate actviely growing Chromera colonies (brown) from the inhibition zones close in between the AB discs.

My experience is, however, that Chromera grows very poorly after any serious attempts to remove bacteria, therefore you may find that it is impossible to generate completely bacteria-free cultures.

Cheers

Chris

Dear Chris

Thank you so much for your explanation, it is really very informative answer.

Best regards

Also growth of algae can exceed other organisms if u provide optimal conditions for its growth such as ph, light intensity,

can use antibacterial solution

You find your query in " Algal Culturing Techniques" Edited by

Robert A. Andersen, 2005.

Dear Fikrat

Thank you so much for your help, This great

Best regards

What groups/species are you purifying?

Bob Anderson's book (mentioned in earlier posts) is a good starting point, however, the best approach and likely success is very much dependent on the type of alga you are trying to purify.  Some species/groups of algae are dependent on their symbiont/associate bacteria for growth.  The capacity to grow the species on a solid medium also opens up a range of different techniques can use.

cheers

chris

Dear Chris

Thank you so much for your help, I really appreciate it

after i tested the antibiotic , how can i use it in large scale purification?

and can i use different conc. of chlorine water?