Increasing the Production of Volatile Fatty Acids from Corn Stover Using Bioaugmentation of a Mixed Rumen Culture with Homoacetogenic Bacteria

Abstract

Volatile fatty acids (VFA) are industrially versatile chemicals and have a major market. Although currently produced from petrochemicals, chemical industries are moving towards more bio-based VFA produced from abundant, cheap and renewable sources such as lignocellulosic biomass. In this study, we examined the effect of bioaugmentation with homoacetogenic bacteria for increasing VFA production in lignocellulose fermentation process. The central hypothesis of this study was that inhibition of methanogenesis in an in vitro rumen bioreactor fed with lignocellulosic biomass hydrolysate increases the hydrogen partial pressure, which can be redirected towards increased VFA production, particularly acetic acid, through targeted bioaugmentation with known homoacetogenic bacteria. In this study, methanogenesis during ruminal fermentation of wet exploded corn stover was initially inhibited with 10 mM of 2-bromoethanesulfonate (BES), followed by bioaugmentation with either Acetitomaculum ruminis and Acetobacterium woodii in two separate bioreactors. During the inhibition phase, we found that addition of BES decreased the acetic acid yield by 24%, while increasing headspace hydrogen from 1% to 60%. After bioaugmentation, the headspace hydrogen was consumed in both bioreactors and the concentration of acetic acids increased 45% when A. ruminis was added and 70% with A. woodii added. This paper demonstrates that mixed microbial fermentation can be manipulated to increase VFA production through bioaugmentation.

Integrating Torrefaction of Pulp Industry Sludge with Anaerobic Digestion to Produce Biomethane and Volatile Fatty Acids: An Example of Industrial Symbiosis for Circular Bioeconomy

“…For example, Kakar et al [38] reported a VFA yield of 1.53 g/g VS added during the AD of hydrothermally treated source separate organics. In another study, Murali et al [41] reported a total VFA yield of around 2.19 g/g VS during the anaerobic digestion of wet exploded corn stover while methanogenesis was inhibited using BES. There could be two possible reasons for high specific VFA yield in the case of torrefaction condensate.…”

“…Hydrothermally treated thickened waste-activated sludge 1.53 [38] Glucose (methanogenesis inhibition using H 2 O 2 ) 1.23 [39] Food waste (methanogenesis inhibition using 2-bromoethanesulfonate) 0.8 [40] Pretreated corn stover (methanogenesis inhibition using 2-bromoethanesulfonate) 2.19 [41] Pulp sludge torrefaction condensate (methanogenesis inhibition using 2-bromoethanesulfonate) 1.1-4.78 This study…”

Valorisation of CO2 into Value-Added Products via Microbial Electrosynthesis (MES) and Electro-Fermentation Technology

“…For the extraction of propionic acid, trioctylamine was used in supercritical CO 2 , high extraction productivity was achieved (97%-propionic acid), only a small portion vanished acid-amine complex formation. Pressure and temperature conditions need to be maintained as they have a high effect on productivity [213][214][215].…”

Enhancing Acetic Acid Production in In Vitro Rumen Cultures by Addition of a Homoacetogenic Consortia from a Kangaroo: Unravelling the Impact of Inhibition of Methanogens and Effect of Almond Biochar on Rumen Fermentations

“…It might offer a pathway to address two pressing challenges of the current times: agricultural productivity and climate change mitigation. Studies have been performed on the effect of microbial bioaugmentation in rumen cultures, particularly in vitro in semi-continuous bioreactor setups, where improvements in the productivity of acetic acid and other VFAs were observed [22]. The effects of bioaugmentation were promising, with a substantial increase in acetic acid productivity concurrent with a low hydrogen concentration in the headspace [22][23][24][25].…”

“…Among the array of biochar variants that hold economic appeal for integration into livestock feed additives in the USA is almond shell biochar, a waste from almond production. Almond shells and hulls are already today employed within the dairy industry as bedding and feed additives, respectively [22].…”