Estimation method for serial dilution experiments

Abstract

Titration of microorganisms in infectious or environmental samples is a corner stone of quantitative microbiology. A simple method is presented to estimate the microbial counts obtained with the serial dilution technique for microorganisms that can grow on bacteriological media and develop into a colony. The number (concentration) of viable microbial organisms is estimated from a single dilution plate (assay) without a need for replicate plates. Our method selects the best agar plate with which to estimate the microbial counts, and takes into account the colony size and plate area that both contribute to the likelihood of miscounting the number of colonies on a plate. The estimate of the optimal count given by our method can be used to narrow the search for the best (optimal) dilution plate and saves time. The required inputs are the plate size, the microbial colony size, and the serial dilution factors. The proposed approach shows relative accuracy well within ±0.1log10 from data produced by computer simulations. The method maintains this accuracy even in the presence of dilution errors of up to 10% (for both the aliquot and diluent volumes), microbial counts between 10(4) and 10(12) colony-forming units, dilution ratios from 2 to 100, and plate size to colony size ratios between 6.25 to 200.

Production of polyhydroxyalkanoates (PHA) from a non‐lignocellulosic component of sugarcane bagasse: fueling a biobased economy

“…Bacterial strains were isolated by performing serial dilution and by the spread‐plating method. The soil samples collected were serially diluted to 10 −10 dilution in autoclaved double‐distilled water and 100 μl of the diluents was spread on nutrient agar plates . The agar plates were then kept in an incubator at 37 °C for 24–48 hours.…”

Biofouling of FeNP-Coated SWRO Membranes with Bacteria Isolated after Pre-Treatment in the Sea of Cortez

“…To determine the cultivable bacterial population and diversity of the unsterilized pretreated seawater, the serial dilution (1:10) method was used, preparing dilutions up to 10 −3 [26]. Finally, 1 mL of each dilution was dispersed, onto the NA prepared in the Petri dishes, and incubated for 24 h at 28 • C [27].…”

Soil Properties and Their Effect on Some Biological Activities in Abu Suberia Valley- Aswan, Egypt.

“…Counts of microorganisms were estimated by the dilution plate technique methods (Becky et al, 2001). The following microbial analyses (i.e., total bacterial count (TBC), total fungi count (TFC), total yeast count (TYC), total actinomycetes count (TAC), total thermophilic bacterial count (TTBC), total cellulolytic bacterial count (TCBC), total nitrifying bacterial count (TNBC) and total denitrifying bacterial count (TDBC) were carried out in all soil samples according to Ben-David & Davidson (2014) and Pious et al (2015).…”