Co-cultures with integrated in situ product removal for lactate-based propionic acid production

Abstract

Propionic acid (PA) is a valuable organic acid for the food and feed industry, but no bioproduction at industrial scale exists so far. As product inhibition is a major burden for bioprocesses producing organic acids, in situ product removal (ISPR) is desirable. Here, we demonstrate a new strategy to produce PA with a co-culture coupled with ISPR using electrodialysis. Specifically, Bacillus coagulans first produces lactic acid (LA) from sugar(s) and LA is converted to PA using Veillonella criceti. Applying ISPR to the mentioned co-culture, the specific PA yield was increased from 0.35 to 0.39 g g −1 compared to no ISPR usage. Furthermore, the productivity was increased from 0.63 to 0.7 g L −1 h −1 by applying ISPR. Additionally, it was shown that co-consumption of xylose and glucose led to a higher PA productivity of 0.73 g L −1 h −1 , although PA yield was only increased slightly up to 0.36 g g −1 .

Biochemical conversion of Brassicacarinata biomass to organic acids

“…Moreover, having proven the fermentability of carinata‐derived glucose, metabolites other than those organic acids could also be produced by selecting an appropriate fermentation microorganism. Although CM hydrolysate is a promising feedstock according to the present study, further work is needed to reduce the cost of fermentation through process optimization, including co‐fermenting both glucose and xylose derived (Wei et al, 2016), co‐fermenting biomass hydrolysate and glycerol under high cell density fermentation conditions (Ammar et al, 2020), and incorporating bioprocessing tools (Blanc & Goma, 1987; Jin & Yang, 1998; Selder et al, 2020; Suwannakham & Yang, 2005) and metabolic engineering techniques (Ammar et al, 2014; Guan et al, 2018; Liu et al, 2020; Wang, Ammar, et al, 2015; Wang et al, 2015; Wei et al, 2016).…”

Propionic Acid

“…Veillonella criceti as a Gram-negative bacterium can convert lactate to propionate with high productivity rate of 39 g/(L•h) (74). Bacillus coagulans and Lactobacillus zeae are able to convert glucose or other carbon sources to lactate (74,75).…”

“…Veillonella criceti as a Gram-negative bacterium can convert lactate to propionate with high productivity rate of 39 g/(L•h) (74). Bacillus coagulans and Lactobacillus zeae are able to convert glucose or other carbon sources to lactate (74,75). The mutant strain of Bacillus coagulans has shown high final titre (145 g/L), yield (0.98 g/g) and d-lactate purity (99.9 %) (76).…”

“…The mutant strain of Bacillus coagulans has shown high final titre (145 g/L), yield (0.98 g/g) and d-lactate purity (99.9 %) (76). To avoid product and substrate inhibition, PA (product) and lactate (substrate) should be removed from fermentor and kept at low concentrations (74).…”

“…Many different types of carbon sources as the substrate can be considered as the most expensive conventional raw materials in the fermentation process (Table 1 (11,14,23,24,30,58,74,(88)(89)(90)(91)(92)(93)(94)(95)(96)). sources could be proposed as an effective strategy for increasing PA production through kinetics alterations.…”