The study, published in AMB Express, combined rice bran and sugar beet pulp extracts with whey powder and corn steep liquor to build waste-based fermentation media.
The team, led by Akbar Ghadamkhani, Majid Javanmard Dakheli and Amir Pourfarzad, formulated three candidate media, labelled WBM5, WBM8 and WBM11. Each contained the solid-derived components at 5, 8 and 11 grams per litre respectively, paired with corn steep liquor at 15, 20 and 25 millilitres per litre. These formulations were benchmarked against both a base medium and standard de Man, Rogosa and Sharpe (MRS) medium, the commercial staple widely used to cultivate lactic acid bacteria.
Among the waste-based options, WBM8 delivered the strongest overall performance. It reached an optical density at 600 nanometres of 5.48 and a cell count of 3.91 × 10⁹ colony-forming units per millilitre.
Postbiotic output told a similar story. WBM8 produced 2.65 grams per litre of lactic acid, 0.79 grams per litre of acetic acid, a total phenolic content of 165.67 milligrams gallic acid equivalents per litre, and 265 milligrams per litre of soluble protein. MRS yielded more lactic acid at 3.11 grams per litre and slightly more soluble protein at 281.67 milligrams per litre, while total phenolic content was statistically indistinguishable between the two media.
Antioxidant activity, a key functional attribute of postbiotics, was effectively matched. WBM8 showed a DPPH radical-scavenging IC50 of 450 micrograms per millilitre and a ferric-reducing antioxidant power of 200 micromoles of Fe²⁺ per gram of dry weight, versus 478 micrograms per millilitre and 190 micromoles of Fe²⁺ per gram for MRS. The researchers reported that these antioxidant indices did not differ significantly between the two media, with p-values above 0.05.
Substrate utilisation was also efficient: approximately 87 percent of the initial soluble sugars in WBM8 were consumed during fermentation. Multivariate analyses of the measured profiles supported a distinct and favourable character for WBM8 among the waste-based formulations, although the authors noted that these analyses remain exploratory because of the limited number of treatment-level observations.
The work addresses a practical bottleneck in industrial biotechnology. Commercial culture media are a significant recurring cost in fermentation processes, and the demand for sustainable bioprocesses has pushed researchers toward agro-industrial by-products as alternative substrates.
By demonstrating that a single optimised blend can support bacterial growth, organic acid production and antioxidant-rich postbiotic formation at levels competitive with MRS, the study offers a route to lower-cost postbiotic manufacturing. The authors conclude that WBM8 provided the most favourable balance among the waste-based formulations and generated a postbiotic profile competitive with MRS for several functional attributes, positioning combined agro-dairy waste as a credible feedstock for sustainable bioprocesses.
Subject of Research: Using combined agro-dairy by-products as fermentation media for Lactiplantibacillus plantarum growth and postbiotic production
Article Title: Agro-dairy waste valorization for postbiotic production by Lactiplantibacillus plantarum
Article References: Ghadamkhani, A., Dakheli, M. J., & Pourfarzad, A. (2026). Agro-dairy waste valorization for postbiotic production by Lactiplantibacillus plantarum. AMB Express. https://doi.org/10.1186/s13568-026-02127-0
Image Credits: AI Generated
DOI: 10.1186/s13568-026-02127-0
Keywords: Lactiplantibacillus plantarum, postbiotics, agro-dairy waste, rice bran, sugar beet pulp, whey powder, corn steep liquor, lactic acid, antioxidant activity, MRS medium, fermentation, sustainable bioprocesses
News Source: Alan Morgan. (October 28, 2026). Research report: Agro-dairy waste valorization for postbiotic production by Lactiplantibacillus plantarum. Scienmag.
