Sustainable Peptone Substitution Using Tofu Dregs Flour for Lactobacillus plantarum Cultivation
Sakunda Anggarini*, Anindya Novilla Putri, Nimas Mayang Sabrina Sunyoto

Department of Agroindustrial Technology, Faculty of Agricultural Technology, Universitas Brawijaya
Jl. Veteran Malang 65145
*Email: s_anggarini[at]ub.ac.id

Abstract

Peptone is one of the most widely applied nitrogen sources in microbial fermentation, yet its high cost and unsustainable production limit its use in large-scale bioprocessing. Exploring alternative nitrogen sources derived from agroindustrial residues offers a promising pathway to reduce costs while supporting circular bioeconomy strategies. This study investigates tofu dregs flour, an abundant protein-rich by-product of soybean processing, as a sustainable substitute for conventional peptone in the cultivation of Lactobacillus plantarum, a lactic acid bacterium of broad industrial relevance. A series of liquid cultures containing graded concentrations of tofu dregs flour (5-30% w/v) were compared with commercial peptone and nitrogen-free controls. Cultures were incubated anaerobically at 37 degree celcius for 48 h with initial OD600 = 0.01, and samples were collected periodically. The optimal formulation (25% tofu dregs flour) significantly enhanced biomass accumulation, lactic acid production, and substrate utilization. These improvements were attributed to the high protein content and balanced nutrient composition of tofu dregs, in combination with enzymatic hydrolysis that improved nitrogen bioavailability. Compared with the peptone control, the optimized formulation not only increased growth performance but also demonstrated efficient substrate-to-product conversion, indicating its potential scalability. The findings highlight the feasibility of valorizing tofu dregs as a low-cost, sustainable peptone subtitute. This approach contributes to the development of sustainable fermentation processes and offers a practical solution for producing functional foods and microbial bioproducts in alignment with environmentally responsible agriculture and industrial biotechnology.

Keywords: Circular bioeconomy- Lactobacillus plantarum- peptone subtitute- sustainable fermentation- tofu dregs flour

Topic: Agricultural and bioprocess engineering