Hi Nehal,

First thing is that what kind of pollutant you are studying either it is pesticide, fertilizer or industrial waste mixed in wetland water. or???

Secondly , agar medium will not help to judge the diatoms strength or survival rate in polluted water. You can go by Assay Mediums. you prepare the mediums with different concentrations of that particular pollutant in conical flasks, pour diatoms into it and incubate for specific periods. test it and identify the life cycle of diatoms poured in different concentrations and compare it with control samples. This will provide that a particular species could survive in what kind of concentrations of pollutant.

then the study could be done on specific diatom survived in highly polluted water.

Diatoms are not easy to culture.........u can try in microalgae.......

Nehal Shah: "after a few days they disappeared and a fungus developed."

If it's easier to obtain, why don't you study the fungus (instead of diatoms)?

To answer your title question: a quick search reveals

U. M. Cowgill, D. P. Milazzo, B. D. Landenberger (1989) Toxicity of nine benchmark chemicals to Skeletonema Costatum, a marine diatom. Environmental Toxicology and Chemistry 8(5): 451–455

and many many more. So yes, one can study the impacts of pollutants in the lab with diatoms.

As regards the possibility of growing them, diatoms can be tricky...but at the same time, silica is often left out of culture media to ensure that there is no accidental diatom growth. You could look more carefully at your technique (see ref below) or you could simply purchase a strain from one of the many algal culture collections.

R Anderson (2005) Algal culturing techniques. Academic Press.

You really need to make some effort to review the literature and phrase a question in a form that can be answered! Diatoms have been used to as toxicological indicators for 65 years. The type of growth/experiment is critical-are you doing water column or benthic work? Single species versus assemblage? I have one paper on here you can use for enrichment bioassays and for toxicology testing (epiphytic algae in former, planktonic as the latter). Please do think about your question and put a reasonable effort into the literature-you will learn more! PZ

Maybe you can try to make erlen cultures in liquid medium (eg WC, Dauta) supplemented with silica, or in aquaria on hard susbtrates (pebbles, glass slides...) depending on the life habits of the species studied.

I would also suggest other algae, like cyanobacteria for example, since they are much easier to manipulate and to control in closed environments. Otherwise, the suggestion by Yamini Verma seems most appropriate!

Svetislav Krstic: "cyanobacteria for example, since they are much easier to manipulate and to control in closed environments"

In the present stage may be he will study the fungus developed in the dish he used.

If the fungus disappear, too, then he can study the dish.

And after that he can study whatever appears there...

In this way, may be it will be a very complex research, even if no one will know: why were the pollutants the target-subject?

After u fing growth in plate medium transfer it into liquid medium.

More clarification needed about the question. If I consider the diatoms you wanted culture were from marine origin, F/2 medium will be best choice. You can use seawater to culture them. Get some sea water sample, isolate individual cells and place in petriplates with medium separately. After a week you can inoculate from this to flask. Same procedure you may probably be able to use for fresh water diatoms also.

I agree that cyanobacteria are a lot easier to look after. I have found diatoms a pest to grow in the lab.

Phaeodactylum tricornatum will grow well in the lab but it is a laboratory weed and produces only a remnant frustule. It will grow well on agar and so is easy to keep and clean up. If you are interested in growth and PS measurements using oxygen electrodes or a PAM Phaeodactylum is fine. If you want to look at pretty frusules it is no good. Then there is the problem that it is a lab weed. The results you get with it might have very little relevance to other diatoms.

I have Thalassiosira growing but rather ominously nothing I have ever done with it has ever been publishable.

On several occasions I have wanted to work on a freshwater diatom. Never met one that was easy to look after. Do not ask why not.

I think field studies is better to detect toxycologic effects on diatoms than laboratory studies. There are many diatom indices to evaluate the water quality withouth using any physical or chemical parameters. We have a few studies about this topic that you can reach them from my publications section.

Yes it is possible if you plan to find some toxicity level of your target pollutant, or if you plan to investigate the effect of some water pollutant on phytobenthos you may design a field experiment. Some biodiversity indices maybe use to quantify diatom responses to pollution in wild. Generally, diatom culture needs silica, so you need to add it to the media..i used to culture some marine microalgae under closed environment in my lab and i regularly autoclave the water source for the media and other apparatus. this will free your culture from bacteria and fungus

I do not know what a culture media you are using. I assume a good one for diatom growth. If so, there is some tricks to get pure cultures deprived of fungi. Once you have poured the sample onto de agar plate, check it day after day under a dissecting microscope (50x at least). Do not use transmitted light but illumination from above! Prepare a paper half white and half black. Put this paper under the Petri dish. Fungal hifae are very difficult to pinpoint if you use transmitted light or homogeneous black or white background. But with the black and white device I suggest you you can get an effect similar to phase contrast. You will be able to check all the agar surface and detect fungal hifae. Then select a colony of diatoms not invaded by the fungi, select a very small sample with an entomological needle and transfer it to a PD with the same medium you are using. Well, we eliminate de fungi. If the algae doesnt grow in the new condition, your problem is the culture medium, not the fungi. Or, perhaps, that the algae needs some byproducts of fungal metabolisms... More problems.. ha! Best!

We use f-2 medium for marine diatom treated with antibiotic. Maintaining the diatoms is more challenging compared to cyanobacteria and chlorophytes, and the growth is also slower. There are many diatom indices and they are great bioindicators, but taxonomic expertise is needed to make accurate assumption and conclusion in the field studies.

Since a long time ,e.g Hons (1959) in Texas University used diatom populations as a measure of water quality; also the is a wealthy of data about diatomic index applied in river to estimate the degree of pollution

If you can collect intertidal samples from muddy sites (diatom biofilms) , you can do a lab examining diatom movement and this can be affected by added toxins such as heavy metals. Student are asked to measure the average speed of recognizable cells (don't really need to identify spp but some like Gyrosigma are obvious) then prepare a slide with added pollutant and see if the rate changes...did for us (heavy metals) ! Hay paper is only slightly relevant but interesting in terms of the speed calculation and relevance.

Hello Nehal

Yes you can culture diatoms in the lab and expose them to known concentrations of your desired pollutant and check their growth and other physiological activities over a period of time (acute/ chronic). Then you can go for determining the effective concentration (EC50) of that pollutant. However, there are so may criteria you need to follow while doing such toxicity experiments. It is suggested to introduce the toxicant to an exponentially growing population (axenic) of a diatom (in F/2 medium for marine diatoms) to start with.

I have a publication that you may refer to:

https://www.researchgate.net/publication/233842410_Short_term_studies_on_effect_of_water_soluble_fractions_of_diesel_on_growth_of_Chaetoceros_calcitrans_Paulsen?ev=prf_pub

Also you please refer to:

1. http://144.206.159.178/FT/166/72466/1238316.pdf

2. http://www.environment-agency.gov.uk/static/documents/Research/DTAmarinewateralgae-225.pdf

3. http://www.scielo.br/pdf/bjoce/v47n2/03.pdf

4. http://perm.ug.gda.pl/file.php/1/2009_11_580_Latala_etal_ILs_plankton.pdf

5. http://www.ajbpr.com/issues/volume2/issue2/FINAL%2019.pdf

Good luck

Dola.

You have been great help Dola madam,

I shall soon disturb you again for this work.

Thankyou very much.regards.....nehal

Two issues may be the problem with ur experimental approach or procedures. The first is the purity of ur strain and agar media, and the LC50 used for the study if any. If the toxicant is new to you, it is recommended u run a range finding test, then find the LC50, and use nominal fractions of the LC50 to run ur bioassay. As much as possible take care of potential confounding factors.

please do not focus only diatoms, you can also select the fast growing microalgae like chlorella, BGA etc...

for field sampling pls check the paper of Dr. Wu WU, N., SCHMALZ, B. & FOHRER, N. (2011): Distribution of phytoplankton in a German lowland river in relation to environmental factors. May-2010 Journal of Plankton Research. Available online Nov. 2010, 33(5): 807-820. (ISI 1.707)

Diatoms as indicators of pollution have been used for many years- the work by Hustedt is a place to start.  Exposure studies of algae have been done extensively by the US EPA (largely Selenastrum-a green) but the design is similar.  Basically you need to find a pollution free area, and isolate the species you will work with.  Then, expose to the toxicant with the single difference being your toxicant.  So make sure you have a carrier control, etc for dilution, and all conditions are the same for the isolates (exponential phase!).  I have some papers using this approach in my list.  Happy holidays-good luck!  PZimba