Salmonella isolation with Rappaport's medium after pre-enrichment in buffered peptone water using a series of inoculum ratios.
The ability of malachite green/magnesium chloride broth (Rappaport's medium) to isolate salmonellas from 25 ml quantities of sewage-polluted natural water was investigated. Samples were first pre-enriched in buffered peptone water and varying volumes of inoculum from the pre-enrichment culture were inoculated into Rappaport's broth. Inoculum ratios in the range 1:2000 to 1:10 were examined. The inoculum ratio denotes the ratio of the volume of inoculum to the volume of fluid medium into which it is introduced. Optimum results were obtained with the 1:2000 ratio, although the salmonella isolation rate was only slightly less with the 1:500 and 1:100 ratios. The 1:2000 inoculum ratio was obtained with a graduated loop holding approximately 0.005 ml of fluid. Use of a loop for inoculation has advantages in speed of performance and safety of manipulation.
D001431:Bacteriological Techniques; D003470:Culture Media; D010461:Peptones; D012475:Salmonella / Q000254:growth & development / Q000302:isolation & purification*; D012722:Sewage; D014871:Water Microbiology
D003470:Culture Media; D010461:Peptones; D012722:Sewage