Coffee silverskin as a substrate for biobased production of biomass and hydrogen by Escherichia coli

Abstract

Currently, coffee consumption reached 9.92 million tons, being responsible for the generation of huge amounts of waste associated with coffee bean processing steps and further operations. Coffee silverskin (CS) and spent coffee grounds having high organic content are generated as a result of roasting and brewing processes. Escherichia coli wild-type and septuple mutant (ΔhyaB ΔhybC ΔhycA ΔfdoG ΔldhA ΔfrdC ΔaceE) growth and hydrogen production were investigated in mediums containing 20 to 200 g L À1 CS with dilutions, hydrolyzed for 25 or 45 min. During utilization of CS, hydrolysate phenolic and flavonoid content does affect bacterial growth, moreover, shorter hydrolyzing was more optimal for biomass generation. Highest specific growth rate of 0.64 ± 0.02 h À1 was observed in wild-type cells when 5 times diluted 200 g L À1 CS was applied to yield 0.495 ± 0.015 g L À1 biomass. Prolonged

Value-Added Products from Coffee Waste: A Review

“…Previous studies have also reported the production of bio-butanol from coffee silverskins. However, the use of coffee silverskin and SCGs for bio-butanol production can be prohibitively difficult, especially when compared to other raw lignocellulosic materials, which are widely available in large amounts [65,66]. Additionally, bio-H 2 production of coffee silverskin using E. coli with the yield of 2.15 mL/g raw coffee silverskin was reported by Trchouian group [67,68].…”