1. Introduction Estimation of colony forming units (cfu) through serial dilution plating on a nutrient medium forms the most widely accepted method for monitoring cultivable bacteria and yeasts in different spheres of microbiology. Tested on diverse bacteria, composite samples and Saccharomyces cerevisiae, SP-SDS offered wider applicability over alternative methods like drop-plating and track-dilution for cfu estimation, single colony isolation and culture purity testing, particularly suiting low resource settings.

Following incubation, at least one dilution level yielded 6–60 cfu per sector comparable to the standard method involving 100 μl samples. For liquid samples 10 0–10 5 dilutions, and for colloidal suspensions and solid samples (10% w/v), 10 1–10 6 dilutions were used.

For pure cultures, serial dilutions were prepared from 0.1 OD (10 0) stock and 20 μl aliquots of six dilutions (10 1–10 6) were applied as 10–15 micro-drops in six sectors over agar-gelled medium in 9-cm plates.

We propose a simple technique for bacterial and yeast cfu estimations from diverse samples with no prior idea of viable counts, designated as single plate-serial dilution spotting (SP-SDS) with the prime recommendation of sample anchoring (10 0 stocks).

Serial dilution lab conclusion