The Advanced Performance of Microbial Consortium for Simultaneous Utilization of Glucose and Xylose to Produce Lactic Acid Directly from Dilute Sulfuric Acid Pretreated Corn Stover

Abstract

Background: Lignocellulosic feedstocks have attracted much attention as an alternative carbon source for lactic acid (LA) production with the advantages of ready availability, sustainability, and renewability. However, the production of LA from lignocellulose faces at least two major technical obstacles. The inhibitors derived from pretreatment of lignocellulose inhibit the growth of microorganism used in downstream hydrolysis and fermentation processes. In addition, most LA producers cannot to ferment pentose sugars and have carbon catabolite repression (CCR) effect. Microbial consortium with great robustness can use complex feedstocks displaying high bioconversion efficiency and has received great attention nowadays.Results: in this study, a thermophilic LA producing consortium DUT50 was enriched and employed to enhance the utilization of corn stover (CS). Enterococcus was the dominant family, accounting for 93.66% abundance in DUT50, and the abundance of Lactobacillus, Bacillus, Lactococcus and Trichococcus, accounted for 2.68% in total. This consortium was highly resistant to inhibitors up to 10.90 g/L derived from pretreatment of CS, metabolized hexose and pentose simultaneously without CCR effect. Based on consortium promising features, an efficient process of simultaneous saccharification and co-fermentation (SSCF) was developed to produce LA from acid-pretreated corn stover. The economical route avoided the operations of solid–liquid separation and detoxification. The key influential factors, including dry biomass and cellulase loading, corn steep liquor powder concentration, and the pre-hydrolysis time were investigated and optimized. The highest LA titer of 71.04 g/L with a yield of 0.49 g/g-CS was achieved at a dry biomass loading of 20% (w/v). This is the reported highest LA production from non-detoxified acid-pretreated corn stover via the SSCF process without wastewater generation. The interaction mode of Enterococcus was collaboration while the low abundance of Lactobacillus and Bacillus might metabolize xylose efficiently via the pentose phosphate pathway.Conclusions: Our results demonstrated the potential advantage of symbiosis and provided a feasible and economical route to produce LA from lignocellulosic biomass in industrial scale.

Enhancing plant growth promoting rhizobacterial activities through consortium exposure: A review

“…In rhizobacterial consortia, the diversity of biochemical reactions enhances the utilization of resources and brings down the formation of byproducts ( Zhang L. N. et al, 2019 ). Besides, in natural consortia, many members may metabolize harmful or toxic byproducts of primary substances like acetic acid which if not supplementary consumed will certainly waste the energy and carbon and also inhibit the production of biomass because of anion accumulation and acidification ( Sun et al, 2021 ).…”

Effects of thermophilic and acidophilic microbial consortia on maize steeping

“…Microbial consortia have been widely used in traditional food fermentation processes and the production of bulk chemicals and valuable products due to their ability to withstand environmental uctuations and perform complex tasks effectively (Hanemaaijer et al, 2015;Qian et al, 2020;Sgobba and Wendisch, 2020). Moreover, microbial consortia are applied in lactic acid production, offering advantages such as high adaptability to raw materials, simple nutrient requirement, and unaffected performance under non-sterile conditions (Sun et al, 2019;Sun et al, 2021). However, despite the previously mentioned reports, there is limited information regarding microbial diversity and communities interacting during counter-current steeping.…”