Combinations of Banana Peel, Molasses, and Brewer’s Yeast as an Alternative Growth Media for Escherichia coli ATCC 25922

Abstract

The exorbitant cost of commercially prepared growth media in microbiology researches has led to the formulation of cost efficient alternative growth media. This study formulated four general growth media using combinations of banana peel extract, molasses, and brewer's yeast: banana peel with blackstrap molasses agar (BMA), banana peel with brew’er's yeast tablet agar (BYA), banana peel, blackstrap molasses and brewer’s yeast agar (BMYA), and blackstrap molasses with brewer’s yeast agar (MYA). It evaluated the growth of Escherichia coli ATCC 25922 on the different formulations through the determination of the cultural and morphological characteristics and the population density. Nutrient Agar (NA) served as the control culture medium to assess the efficiency of the alternative growth media prepared. Using the Miles and Misra method, broth cultures of E. coli (~10s cfii/ml) w'ere cultivated on BMA, BYA, BMYA, MYA and NA and incubated for 24 hours at 37°C. The cultural characteristics of E. coli (opaque, colorless, entire margin, convex elevation, and circular in shape) in all the different media were similar with those of NA. Microscopic observations of gram-stained bacterial smears showed that cells growm in BYA were longer (-4.0 urn) than those grown in NA (-3.0 um). The cells grown on the other media were shorter compared to NA, the smallest of which was observed in MYA (-2.0 um). Results showed that the population density of E. coli on MYA (8.5 x!0s cfu/ml), was higher than those grown in NA (6.75 xlO8 cfu/ml). The lowest population density was observed on BMYA (3.75 xlO8 cfu/ml). These suggest that all four media formulated can support the growth of E. coli. However, the best alternative growth medium for E. coli was that cultured with BMA as it closely resembled the characteristics of the cells grown in NA.