Harnessing originally robust yeast for rapid lactic acid bioproduction without detoxification and neutralization

Pangestu, Radityo; Kahar, Prihardi; Kholida, Lutfi Nia; Perwitasari, Urip; Thontowi, Ahmad; Fahrurrozi, -; Lisdiyanti, Puspita; Yopi, -; Prasetya, Bambang; Kondo, Akihiko

doi:10.1038/s41598-022-17737-4

Cited by 7 publications

(16 citation statements)

References 48 publications

(50 reference statements)

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“…After fermentation, a recovery step by acidification is needed to obtain L-LA, and subsequently one ton gypsum per ton L-LA is generated as byproducts. 41 From an industrial perspective, a concentration of 160 g/L L-LA, with a yield of 0.95 g/g glucose is economical for neutralization acidification process. The price of cornstarch, yeast extract, Ca(OH) 2 , and H 2 SO 4 is $470/t, $220/t, $120/t, and $48/t, respectively (https://www.chemanalyst.com/).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In the traditional l -LA fermentation method, Ca(OH) 2 is used as a neutralizer, which generates large amounts of calcium lactate instead of free acid form. After fermentation, a recovery step by acidification is needed to obtain l -LA, and subsequently one ton gypsum per ton l -LA is generated as byproducts . From an industrial perspective, a concentration of 160 g/L l -LA, with a yield of 0.95 g/g glucose is economical for neutralization acidification process.…”

Section: Resultsmentioning

confidence: 99%

“…Neutralizer addition is one of the most concerning bottlenecks in industrial LA production. The removal of neutralizing agents by employing an acid-tolerant host can not only reduce the environmental burden but also decrease total capital investment because an acidification reactor unit set after the fermentation stage is no longer required . Current industrial strains are not well equipped to cope with the harsh conditions which are needed to produce LA efficiently.…”

Section: Resultsmentioning

confidence: 99%

“…7,8 This neutralization and acidulation process inevitably increases the production cost of L-LA and pollutes the environment. 6,9 To solve these problems caused by low pH inhibition, alternative strategies, such as product in situ removal through membrane separation, solvent extraction, and electrodialysis, have been applied. However, these technologies are expensive and cannot be used for the commercial production of L-LA.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Biotechnology companies, including NatureWorks, Purac, and Galactic, have already produced and supplied l -LA at a half-a-million-ton scale annually. , During the production of l -LA, the pH decreases significantly due to the accumulation of acidic product, which severely inhibits cell growth. A large amount of neutralizers, such as calcium carbonate (CaCO 3 ) or calcium hydroxide (Ca(OH) 2 ), is required to maintain the pH value of the culture broth, forming calcium lactate. − For the recovery of l -LA from calcium lactate, a strong acid, such as sulfuric acid (H 2 SO 4 ), needs to be added, resulting in the generation of equimolar amounts of calcium sulfate (CaSO 4 ). , This neutralization and acidulation process inevitably increases the production cost of l -LA and pollutes the environment. , To solve these problems caused by low pH inhibition, alternative strategies, such as product in situ removal through membrane separation, solvent extraction, and electrodialysis, have been applied. However, these technologies are expensive and cannot be used for the commercial production of l -LA …”

Section: Introductionmentioning

confidence: 99%

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l-Lactic Acid Production via Sustainable Neutralizer-Free Route by Engineering Acid-Tolerant Yeast Pichia kudriavzevii

Zhang

Li²,

Liu³

et al. 2023

J. Agric. Food Chem.

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l-Lactic acid (l-LA) is a platform chemical obtained via microbial fermentation at a near-neutral pH value. Large amounts of neutralizers are required during this process, which increases the production costs in downstream processing as well as environmental burden. To address this challenge, an acid-tolerant yeast Pichia kudriavzevii E1 was isolated and metabolically engineered to produce l-LA without neutralizers. The genome of strain E1 was sequenced and a CRISPR-Cas9 system was developed in this newly isolated strain. Subsequently, the gene encoding pyruvate decarboxylase (pdc) was knocked out to subdue ethanol formation. Furthermore, the l-lactate dehydrogenase gene from Weizmannia coagulans 2-6 and the codon-optimized L-ldhA gene from Bos taurus were introduced into P. kudriavzevii E1 chromosome to redirect the ethanol fermentation pathway to l-LA production. Deletion of the dld(chr3) gene further increased the optical purity of l-LA. After optimizing fermentation conditions, the maximum titer of l-LA in the 5 L fermenter reached 74.57 g/L without any neutralizers, with an optical purity of 100% and a maximum yield of 0.93 g/g glucose. This is the first report of optically pure l-LA production without neutralizers and the engineered acid-tolerant yeast paves the way for the sustainable production of l-LA via a green route.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

l-Lactic Acid Production via Sustainable Neutralizer-Free Route by Engineering Acid-Tolerant Yeast Pichia kudriavzevii

Zhang

Li²,

Liu³

et al. 2023

J. Agric. Food Chem.

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Comparative responses of flocculating and nonflocculating yeasts to cell density and chemical stress in lactic acid fermentation

Pangestu,

Kahar,

Ogino

et al. 2023

Yeast

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While flocculation has demonstrated its efficacy in enhancing yeast robustness and ethanol production, its potential application for lactic acid fermentation remains largely unexplored. Our study examined the differences between flocculating and nonflocculating Saccharomyces cerevisiae strains in terms of their metabolic dynamics when incorporating an exogenous lactic acid pathway, across varying cell densities and in the presence of lignocellulose‐derived byproducts. Comparative gene expression profiles revealed that cultivating a nonflocculant strain at higher cell density yielded a substantial upregulation of genes associated with glycolysis, energy metabolism, and other key pathways, resulting in elevated levels of fermentation products. Meanwhile, the flocculating strain displayed an inherent ability to sustain high glycolytic activity regardless of the cell density. Moreover, our investigation revealed a significant reduction in glycolytic activity under chemical stress, potentially attributable to diminished ATP supply during the energy investment phase. Conversely, the formation of flocs in the flocculating strain conferred protection against toxic chemicals present in the medium, fostering more stable lactic acid production levels. Additionally, the distinct flocculation traits observed between the two examined strains may be attributed to variations in the nucleotide sequences of the flocculin genes and their regulators. This study uncovers the potential of flocculation for enhanced lactic acid production in yeast, offering insights into metabolic mechanisms and potential gene targets for strain improvement.

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Engineering yeast cell factories to produce biodegradable plastics and their monomers: Current status and prospects

Zhang,

Zeng

et al. 2023

Biotechnology Advances

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Harnessing originally robust yeast for rapid lactic acid bioproduction without detoxification and neutralization

Cited by 7 publications

References 48 publications

l-Lactic Acid Production via Sustainable Neutralizer-Free Route by Engineering Acid-Tolerant Yeast Pichia kudriavzevii

l-Lactic Acid Production via Sustainable Neutralizer-Free Route by Engineering Acid-Tolerant Yeast Pichia kudriavzevii

Comparative responses of flocculating and nonflocculating yeasts to cell density and chemical stress in lactic acid fermentation

Engineering yeast cell factories to produce biodegradable plastics and their monomers: Current status and prospects

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