title: Wastes from bioethanol and beer productions as substrates for l(+) lactic acid production - A comparative study.
abstract: Waste substrates from bioethanol and beer productions are cheap, abundant and renewable substrates for biorefinery production of lactic acid (LA) and variability in their chemical composition presents a challenge in their valorisation. Three types of waste substrates, wasted bread and wasted potato stillage from bioethanol production and brewers' spent grain hydrolysate from beer production were studied as substrates for the production of l(+) LA and probiotic biomass by Lactobacillus rhamnosus ATCC 7469. The correlation of the content of free alpha amino nitrogen and the production of LA was determined as a critical characteristic of the waste media for efficient LA production by L. rhamnosus on the substrates which contained equal amount of fermentable sugars. A maximal LA productivity of 1.54gL(-1)h(-1) was obtained on wasted bread stillage media, whilst maximal productivities achieved on the potato stillage and brewers' spent grain hydrolysate media were 1.28gL(-1)h(-1)and 0.48gL(-1)h(-1), respectively. A highest LA yield of 0.91gg(-1) was achieved on wasted bread stillage media, followed by the yield of 0.81gg(-1) on wasted potato stillage and 0.34gg(-1) on brewers' spent grain hydrolysate media. The kinetics of sugar consumption in the two stillage substrates were similar while the sugar conversion in brewers' spent grain hydrolysate was slower and less efficient due to significantly lower content of free alpha amino nitrogen. The lignocellulosic hydrolysate from beer production required additional supplementation with nitrogen.
authors.affiliation: Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia. Electronic address: adjukic@tmf.bg.ac.rs.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Djukić-Vuković
authors.affiliation: Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia.
authors.forename: Dragana
authors.initials: D
authors.lastname: Mladenović
authors.affiliation: Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia.
authors.forename: Miloš
authors.initials: M
authors.lastname: Radosavljević
authors.affiliation: Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia.
authors.forename: Sunčica
authors.initials: S
authors.lastname: Kocić-Tanackov
authors.affiliation: Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Pejin
authors.affiliation: Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia.
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Mojović
mesh_terms: D001515:Beer; D056804:Biofuels; D018533:Biomass; D001939:Bread; D002241:Carbohydrates / Q000737:chemistry; D002523:Edible Grain / Q000737:chemistry*; D005285:Fermentation; D019649:Food Industry / Q000379:methods*; D005735:Garbage; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D019344:Lactic Acid / Q000737:chemistry*; D052201:Lacticaseibacillus rhamnosus; D009584:Nitrogen / Q000737:chemistry; D012037:Refuse Disposal; D011198:Solanum tuberosum; D013696:Temperature; D062065:Wastewater
chemical_list: D056804:Biofuels; D002241:Carbohydrates; D007220:Industrial Waste; D019344:Lactic Acid; D009584:Nitrogen; D062065:Wastewater
keywords: Biorefinery; Brewers’ spent grains; Free alpha amino nitrogen; Lactic acid; Probiotics; Stillage