Soybean okara: a sustainable and cost-effective alternative for potato dextrose agar and nutrient agar media

In the present method, we used okara, a by-product of the tofu or soya milk industry, as a cost-effective alternative to nutrient agar (NA) and potato dextrose agar (PDA), which are routinely used for bacterial and fungal cultivation in microbiology labs worldwide. Here, two okara-based media, namely okara bacterial (OB) and okara fungal (OF), were prepared by adding dextrose at 1 % and 2 %, respectively. Then, three distinct series of experiments were carried out to evaluate the use of okara as a microbiological media. Three different genera of bacteria and fungi were used, and growth experiments were carried out. Bacterial growth was measured through spectrophotometric absorbances, whereas fungal growth was measured based on diameter and biomass production. Further, we used okara-based media for the isolation and enumeration of bacterial and fungal populations from rhizosphere and endosphere. Finally, production economics were compared between okara-based media and readily available media. • Okara-based media supports significantly higher fungal growth and similar bacterial growth compared to readily available media. • Isolation and enumeration of bacteria and fungi with Okara media are possible. • Okara-based media was >85 % cost-effective than readily available media. • Okara-based media can be used for mass multiplication of beneficial bacteria and fungi.