Question

I am doing a report for "Isolation of Phototrophic Bacteria." I worked with R. rubrum which is a purple non - sulfur bacteria. We used an enrichment medium called "Ormerod's medium" which is a non-fermentable carbon source - malate. Could anyone explain to me how this works with this bacteria and what does the medium consist of.

Thank you!

Answer 1

The Ormerods medium consists of -

•2g/L Na-malate • 0.1g/L yeast extract • 0.2g/L MgSo4 × 7H2O •0.08g/L CaCl2 × H2O • 0.01g/L FeSO4 × 7H2O •0.9g/L K2HPO4 •0.6g/L KH2PO4 •1.25g/L (NH4)2 SO4 •0.02 g/L EDTA •0.028 g/L H3BO3 •0.021 g/L MnSO4x 4H2O •0.075 g/L Na2MoO4 x 2H2O •0.0024 g/L ZnSO4 x 2H2O •0.01 g/L Cu(NO3)2 x 3H2O •20g/L agar pH = 6.8-7.3

Rhodospirillim Rubrum is a phototrophic purple non-sulphur bacteria which show photoheterotrophic mode of metabolism. It means they grow in medium which contain readily usable organic compounds such as malate Or pyruvate using ammonia as nitrogen source.

Under phototrophic (anoxic/light) conditions, typical purple non-sulphur bacteria can gow photoautotrophic with H2 or low levels of sulphide as electron donors; a few species can use S2O3 or Fe2+ as photosynthetic electron donors.