Preparation of environmental probiotic factor γ-polyglutamic acid via microbial fermentation using Baijiu brewing steamer bottom water as a basic substrate

Abstract

Abstract 1) Purpose: Steamer bottom water is the main component of wastewater in the Baijiu industry. 2) Methods: In this study, γ-PGA was synthesized through fermentation using steamer bottom water as a substrate to address wastewater treatment problems and costs in Baijiu enterprises. A new, cheap raw material and process of γ-PGA production were developed. 3) Results: The γ-PGA yield was 48.29 g/L, which was 1.98 times higher than that before optimization. We detected 12 volatile substances in the fermentation broth; acetic acid, 2,3-butanedione, 2-methyl-butanoic acid, and acetoin were recognized as plant probiotics. The N, P, K, and total nutrient (sum of N, P, and K) contents were 4,100, 3,405, 885, and 8,390 mg/L, respectively; the number of viable Bacillus subtilis was 4.5×107 CFU/mL. 4) Conclusion: Therefore, steamer bottom water of Baijiu brewing can completely replace water as a fermentation medium solvent to produce γ-PGA. Moreover, the fermentation broth is a potential functional organic fertilizer.