Just want to know what are the pigmented bacteria in soil which can produce a natural coloring agent that benefit for some industries.
Dear Afif,
I very simple technique was described by Cope 1951 (J. Bacteriol. 62 515–517): Place five grams samples of soil in sterile Petri dishes and soak with sterile distilled water. Sterile polished or precooked rice grains are sprinkled over the surface of the soil and the plates incubated at 23–25°C for five days. At the end of the incubation period, the rice grains are partially covered with purple colonies indicating the presence of Chromobacterium sp. The purple color is due to violacein, a purple pigment that has antioxidant activity and thus maybe interesting for commercial purposes.
Regards
There are some nice reviews on microbial pigments:
Malik et al (2012) International Journal of Microbial Resource Technology 1(4):361-365.
Joshi et al. (2003) Indian Joprnal of Biotechnology 2(3):262-369
However, some important species are not mentioned in the text, e.g. Micrococcus, Kocuria; forming red, orange, or yellowish pigments; used by the organisms as UV protectant or anti-freeze agent
Dear Afif,
we used this method frequently in a practical course with students and it always worked, at least with agricultaral soils. The method is not specific, but highly selective for Chromobacterium and Janthinobacterium spp. As far as I know violacein is produced within cells and can be extracted from lysates for example with butanol. A very simple alternative method was proposed by Rottori and Duran (World Journal of Microbiology and Biotechnology, Volume 14, Issue 5 , pp 685-688) who cultured Chromobacterium violaceum on cotton carpets, which were thereafter extracted with ethanol to extract the prodiuced pigment.
If you are interested in rather the pigments than the source (soil in your case) I recommend collecting air samples instead of soils samples. Many airborne microbes form pigments. Possible functions: Besides photosynthesis (of course!) they might play a role in UV protection (see Tong and Lighthart (1997) Photochemistry & Photobiology 65:103-106); pathogenicity, virulence, or resistance to antibiotics (see Liu and Nizet (2009) Trends in Microbiology 17:406-413, Schloss et al (2010) DNA & Cell Biology 29:533-541); or act as anti-freezing agent.
If you are after a non-selective isolation of pigmented bacteria, particularly ones not well characterized, try a standard soil isolation procedure like adding a soil sample to 100 mls of Na pyrophosphate, which acts as a mild surfactant, then plate out dilutions of this on growth media, like 0.1x TSB + agar or R2A, then isolate the pigmented colonies. Don't just take the fast growing ones, keep the plates a few weeks and look for slower growing strains. Everyone works on the fast growing ones :). A wide variety of pigmented types will show up. Screening them for commercial purposes is another whole issue.
Dear Mr. Richard Snyder thank you very much for your answer. So that is for some bacteria, now I wanna know further, how about pigmented fungi such as Monascus sp. or else? What is the best method to make the fungi grow well and produce the pigments? Can I use the agroindustrial wastes as the carbon source?
Afif, you can use virtually anything (well, except plastics) to grow microorganisms. the easiest way is just to boil what ever your source material is to make soup, then add agar or use as liquid broth. This is how early microbiologists, and especially protozoologists grew cultures, by making such "infusions" hence the name "infusorians" that was early on attached to protozoa. Any such broth medium can be used, and indeed if you make you own different from the standard commercial media like LB, TSB or R2A, Brain heart infusion, etc., you will get different organisms responding to novel substrates. So if you take the agro waste and make broth with it, that would be a good way to look for pigmented organisms utilizing those carbon sources. I cannot help you with fungal culture, but I have seen plenty growing in infusions of various types. I suspect with some antibiotics against the prokaryotes in the medium you could preferentially grow the fungi. Search on-line for fungi culture methods.
I suggest using a customized "soil extract medium" whereby you take soil, add distilled water, mix and allow to settle, pour off the liquid containing some soil, autoclave, add sterile tempered agar and pour plates. This medium should contain nutrients and minerals that might be missing in a regular culture medium
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