Meta‐fermentation system with a mixed culture for the production of optically pure l‐lactic acid can be reconstructed using the minimum isolates with a simplified pH control strategy

Abstract

Meta‐l‐lactic acid fermentation from non‐treated kitchen refuse was reconstructed using a combination of isolated bacterial strains under several pH control strategies. The meta‐fermentation system was successfully reconstructed using a combination of Weizmannia coagulans MN‐07, Caldibacillus thermoamylovorans OM55‐6, and Caldibacillus hisashii N‐11 strains. Additionally, a simplified constant pH control strategy was employed, which decreased fermentation time and increased production. The optimum pH (6.5) for the reconstructed meta‐fermentation was favorable for the respective pure cultures of the three selected strains. The l‐lactic acid production performance of the reconstructed meta‐fermentation system was as follows: concentration, 24.5 g L−1; optical purity, 100%; productivity, 0.341 g L−1 h−1; yield, 1.06 g g−1. These results indicated that constant pH control was effective in the reconstructed meta‐fermentation with the best performance of l‐lactic acid production at pH optimal for the selected bacterial growth, while the switching from swing pH control would suppress the activities of unfavorable bacterial species in un‐isolated meta‐fermentation.

Global trends and future prospects of lactic acid production from lignocellulosic biomass

“…Microbial fermentation, serving as the primary pathway for LA production from LCB, has garnered significant attention, with related author keywords attracting substantial focus. Notably, “ Bacillus coagulans ”, which has been reclassified as Weizmannia coagulans , 27 emerged in 2007 and subsequently experienced explosive growth in related articles, securing the eighth position between 1991 and 2022. W. coagulans , a LA-forming bacterial species with a history spanning over a century since its first report, has found extensive application in the production of l -LA.…”

“…They offer inherent advantages, including the distribution of metabolic burdens through division of labor, improved efficiency in converting complex substrates, and modularity. 27,92 The co-culture of B. coagulans and L. rhamnosus for LA production from cassava bagasse resulted in signicantly improved LA concentration, productivity, and yield, reaching 112.5 g L −1 , 2.74 g L −1 h −1 , and 0.88 g g −1 , respectively, surpassing the outcomes of mono-culturing each bacterium. 93 Collectively, previous studies indicate that genetic engineering approaches and mixed culture systems play a signicant role in enhancing both the productivity and yield of LA.…”

Compost-derived thermophilic microorganisms producing glycoside hydrolase activities as new potential biocatalysts for sustainable processes

“…For instance, in the work by Tashiro et al [67], the authors applied a bacteria consortium from marine-animal-resource composts rich in Bacillus strains on kitchen waste, an abundant and sustainable biomass resource, to produce l-lactic acid. A combination of the strains Weizmannia coagulans MN-07, Caldibacillus thermoamylovorans OM55-6, and Caldibacillus hisashii N-11 from marine-animal-resource composts in combination with a pH control strategy was used by Yue et al [68] for the same final product, given the role of l-lactic acid as a precursor in the production of polylactic acid. Another interesting area of research applies the functional thermophilic bacteria isolated from compost to animals.…”