Comparison of Conventional SPC Method with Resource Saving SP-SDS Method for Micro Flora Enumeration

Author(s): Patel P. A and Panchal H. K

Abstract: We propose a simple technique for micro flora enumeration from diverse sample with no prior idea of viable count and require less consumable. This technique is termed as Single Plate - Serial Dilution Spotting (SP-SDS). The objective of this research was to compare the accuracy and fidelity of SP-SDS method vs. standard plate count (SPC) method by statistical analysis. For pure culture, serial dilutions were prepared from 0.1 O. D and 20 μl aliquots of six dilutions were applied as 10-15 micro drops in six sectors over agar medium in 9 cm Petri plates. For liquid or colloidal sample, the sample was directly used as stock. For solid samples 10% w/v suspension was used. Dilutions and plating were done as described for pure cultures and incubation was done for 24 hours. Following incubation at least one dilution level yielded 6-60 CFU per sector comparable to SPC method. Method was tested on diverse bacteria, yeast and composite samples like food, milk, marine water, sewage, soil etc. SP-SDS gave better results in comparison with SPC with respect to all pure cultures and composite samples. SP-SDS offered wider application over alternative method SPC.

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