Production of Raw Starch-Digesting Amylolytic Preparation in Yarrowia lipolytica and Its Application in Biotechnological Synthesis of Lactic Acid and Ethanol

Abstract

Sustainable economy drives increasing demand for raw biomass-decomposing enzymes. Microbial expression platforms exploited as cellular factories of such biocatalysts meet requirements of large-volume production. Previously, we developed Yarrowia lipolytica recombinant strains able to grow on raw starch of different plant origin. In the present study, we used the most efficient amylolytic strain as a microbial cell factory of raw-starch-digesting (RSD) amylolytic preparation composed of two enzymes. The RSD-preparation was produced in fed-batch bioreactor cultures. Concentrated and partly purified preparation was then tested in simultaneous saccharification and fermentation (SSF) processes with thermotolerant Kluyveromyces marxianus for ethanol production and Lactobacillus plantarum for production of lactic acid. These processes were conducted as a proof-of-concept that application of the novel RSD-preparation supports sufficient starch hydrolysis enabling microbial growth and production of targeted molecules, as the selected strains were confirmed to lack amylolytic activity. Doses of the preparation and thermal conditions were individually adjusted for the two processes. Additionally, ethanol production was tested under different aeration strategies; and lactic acid production process was tested in thermally pre-treated substrate, as well. Conducted studies demonstrated that the novel RSD-preparation provides satisfactory starch hydrolyzing activity for ethanol and lactic acid production from starch by non-amylolytic microorganisms.

Identification of Cellulose-Degrading Bacteria and Assessment of Their Potential Value for the Production of Bioethanol from Coconut Oil Cake Waste

“…Cellulose hydrolases are naturally produced by microorganisms and can convert cellulosic biomass into fermentable sugars [ 3 ]. There is a great demand for cellulose-degrading microorganisms in industrial applications, so searching for biomass-degrading bacteria from different environments is a key research focus [ 26 ]. In this work, we aimed to isolate cellulolytic bacteria from environmental systems to degrade COC.…”

Nutrient biomass production from agro-industrial residues using Yarrowia lipolytica: screening and optimization of growing conditions

“…The Y. lipolytica's potential for producing amylase, that is, an enzyme that degrades starch into simpler sugars, was tested (Gęsicka et al, 2020). None of the strains tested showed any amylolytic potential, as there was no halo around the colonies.…”

A low-cost production, characterization, and application of raw starch degrading enzyme from the thermophilic filamentous bacterium, Laceyella sacchari P43

“…Starch is one of the most abundant carbohydrates found in higher plant biomass, second only to cellulose, and is extensively utilized as a substrate for sugar syrup manufacture for various purposes, such as bioethanol, lactic acid, and fermentation foods [1][2][3]. The two main steps in most starch-based bioprocesses are (i) starch liquefaction, which typically involves thermostable α-amylase gelatinizing the starch substrate at 80-105°C.…”