RVSEB

• Rappaport  vassiliadis Salmonella enrichment broth.
• Selective isolation of salmonella and shigella species.
• It is not recommended for the enrichment of Salmonella Typhi.
• This is modification of Vassilaids Broth 10/43⁰C
• RVSEB = 25/37⁰C
• Soypeptone was replace enzamatic digist of casein.
• Low pH medium (pH 5.2± 0.2).
• Sterilization temperature -115⁰C

Composition                                                                            Grams/liter

Papaic digest of soya been meal (soy peptone)-------------------4.5

Sodium chloride ----------------------------------------------------------7.2

Potasium phosphate mono basic ------------------------------------1.44

Magnisium chloride---------------------------------------------------- 36.00

Malachite green -------------------------------------------------------0.036g

pH = 5.2 ± 0.2 at 25⁰C

• Papaic digest of soya been meal (soy peptone) or  S₂  peptone  source of nitrogen general growth medium.
• Magnisium chloride raise the Osmatic pressure.
• Malachite green higly resistance and inhibitory to other organisums.
• Potasium phosphate  -pH balance buffer
• Salmonella typhi and Salmonella choleraesuis also sensitive to malachite green  and may be inhibited.
• S.enterica Red colored colonies is formed.
• E.coli Yellow colour colonies is formed.

Note : The selectivity of the medium is due to the presence of malachite green, high osmotic pressure, and a low pH. The high concentration of magnesium chloride raises osmotic pressure and in combination with malachite green inhibits bacteria other than salmonella spp. The low pH of the medium increases selectivity by inhibiting accompanying flora including intestinal bacteria.