New record of reusing brewing by-product for biosynthesis of prodigiosin and its novel anti-pathogen fungi via in vitro tests and molecular docking study

Prodigiosin (PG)—a molecule with promising applications in many fields—was effectively biosynthesized in this study using a novel and eco-friendly fermentation substrate—i.e., beer brewing by-product (BBB). It was confirmed as a nutrient-rich substrate source of protein (22.18%), ash (10.1%), carbohydrate (1.98%), sugar, and abundant mineral elements. The cultural medium with a newly designed formula on a small flask containing 1.25% BBB/Casein (9/1), 0.025% FeSO 4 , and 0.125% Na 2 HPO 4 for a notable PG yield achieved 6230 mg/L after 48 h. PG production on a bioreactor system also enhanced yield by 1.16 folds (reaching 7220 mg/L) and shortened fermentation time (only taking 10 h). This pure pigment was isolated and identified by analyzing UV/vis absorption, MALDI-TOF MS, and HPLC. The obtained PG was used for antifungal tests. Notably, in this work, most of PG’s pathogen fungal inhibition activity are new findings. Of those, PG showed the most positive effect on Colletotrichum gloeosporioides F05 strain (causing on sweet potato roots) with inhibition rates of mycelial growth and spore germination achieved at 47 and 57%, respectively. In particular, PG also reduced resistance and wholly inhibited mycelium growth germinating from spores. Furthermore, PG showed the good interaction ability with multiple target proteins (CDC42, CYP51, CAS2, Pectate lyase B, and Beta tubulin) inhibiting C. gloeosporioides via docking simulation. The results of this study revealed useful scientific information related to the novel application of BBB in PG production and the new PG’s effects in the management of fungal pathogens in crops.