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Lojananan N, Cheirsilp B, Intasit R, Billateh A, Srinuanpan S, Suyotha W, Boonsawang P. Successive process for efficient biovalorization of Brewers' spent grain to lignocellulolytic enzymes and lactic acid production through simultaneous saccharification and fermentation. BIORESOURCE TECHNOLOGY 2024; 397:130490. [PMID: 38403168 DOI: 10.1016/j.biortech.2024.130490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/20/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
This study aimed to increase the value of brewers' spent grain (BSG) by using it as feedstock to produce lignocellulolytic enzymes and lactic acid (LA). Twenty-two fungal strains were screened for lignocellulolytic enzyme production from BSG. Among them, Trichoderma sp. showed the highest cellulase activity (35.84 ± 0.27 U/g-BSG) and considerably high activities of xylanase (599.61 ± 23.09 U/g-BSG) and β-glucosidase (16.97 ± 0.77 U/g-BSG) under successive solid-state and submerged fermentation. The processes were successfully scaled up in a bioreactor. The enzyme cocktail was recovered and characterized. The maximum cellulase and xylanase activities were found at pH 5.0 and 50 °C, and the activities were highly stable at pH 4-8 and 30-50 °C. The enzyme cocktail was applied in simultaneous saccharification and fermentation of acid-pretreated BSG for LA production. The maximum LA obtained was 59.3 ± 1.0 g/L. This study has shown the efficient biovalorization of BSG, and this approach may also be applicable to other agro-industrial wastes.
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Affiliation(s)
- Nattha Lojananan
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
| | - Benjamas Cheirsilp
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.
| | - Rawitsara Intasit
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
| | - Asma Billateh
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
| | - Sirasit Srinuanpan
- Center of Excellence of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Wasana Suyotha
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
| | - Piyarat Boonsawang
- Center of Excellence in Innovative Biotechnology for Sustainable Utilization of Bioresources, International Program of Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
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Kim S, Kim JC, Kim YY, Yang JE, Lee HM, Hwang IM, Park HW, Kim HM. Utilization of coffee waste as a sustainable feedstock for high-yield lactic acid production through microbial fermentation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169521. [PMID: 38141985 DOI: 10.1016/j.scitotenv.2023.169521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/27/2023] [Accepted: 12/17/2023] [Indexed: 12/25/2023]
Abstract
Lactic acid is an important industrial precursor; however, high substrate costs are a major challenge in microbial fermentation-based lactic acid production. Coffee waste is a sustainable feedstock alternative for lactic acid production via microbial fermentation. Herein, the feasibility of coffee waste as a feedstock was explored by employing appropriate pretreatment methods and optimizing enzyme combinations. Coffee waste pretreatment with hydrogen peroxide and acetic acid along with a combination of Viscozyme L, Celluclast 1.5 L, and Pectinex Ultra SP-L achieved the 78.9 % sugar conversion rate at a substrate concentration of 4 % (w/v). Lactiplantibacillus plantarum WiKim0126-induced fermentation with a 4 % solid loading yielded a lactic acid concentration of 22.8 g/L (99.6 % of the theoretical maximum yield) and productivity of 0.95 g/L/h within 24 h. These findings highlight the viability of coffee waste as an eco-friendly resource for sustainable lactic acid production.
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Affiliation(s)
- Seulbi Kim
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea; Department of Agricultural Chemistry, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Jong-Cheol Kim
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea
| | - Yeong Yeol Kim
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea; Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Jung Eun Yang
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea
| | - Hee Min Lee
- Kimchi Industry Promotion Division, World Institute of Kimchi, Gwangju 61755, Republic of Korea
| | - In Min Hwang
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea
| | - Hae Woong Park
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea
| | - Ho Myeong Kim
- Technology Innovation Research Division, World Institute of Kimchi, Gwangju, Republic of Korea.
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Llamas M, Greses S, Magdalena JA, González-Fernández C, Tomás-Pejó E. Microbial co-cultures for biochemicals production from lignocellulosic biomass: A review. BIORESOURCE TECHNOLOGY 2023; 386:129499. [PMID: 37460020 DOI: 10.1016/j.biortech.2023.129499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/12/2023] [Accepted: 07/15/2023] [Indexed: 07/31/2023]
Abstract
Global reliance on fossil oil should shift to cleaner alternatives to get a decarbonized society. One option to achieve this ambitious goal is the use of biochemicals produced from lignocellulosic biomass (LCB). The inherent low biodegradability of LCB and the inhibitory compounds that might be released during pretreatment are two main challenges for LCB valorization. At microbiological level, constraints are mostly linked to the need for axenic cultures and the preference for certain carbon sources (i.e., glucose). To cope with these issues, this review focuses on efficient LCB conversion via the sugar platform as well as an innovative carboxylate platform taking advantage of the co-cultivation of microorganisms. This review discusses novel trends in the use of microbial communities and co-cultures aiming at different bioproducts co-generation in single reactors as well as in sequential bioprocess combination. The outlook and further perspectives of these alternatives have been outlined for future successful development.
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Affiliation(s)
- Mercedes Llamas
- Biotechnological Processes Unit, IMDEA Energy, Madrid, Spain
| | - Silvia Greses
- Biotechnological Processes Unit, IMDEA Energy, Madrid, Spain
| | - Jose Antonio Magdalena
- LBE, Univ Montpellier, INRAE, 102 avenue des Étangs, F-11100 Narbonne, France; Vicerrectorado de Investigación y Transferencia de la Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Cristina González-Fernández
- Biotechnological Processes Unit, IMDEA Energy, Madrid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, University of Valladolid, Dr. Mergelina, s/n, Valladolid 47011, Spain; Institute of Sustainable Processes, Dr. Mergelina, s/n, Valladolid 47011, Spain
| | - Elia Tomás-Pejó
- Biotechnological Processes Unit, IMDEA Energy, Madrid, Spain.
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Huang Y, Wang Y, Shang N, Li P. Microbial Fermentation Processes of Lactic Acid: Challenges, Solutions, and Future Prospects. Foods 2023; 12:2311. [PMID: 37372521 DOI: 10.3390/foods12122311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/26/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
The demand for lactic acid and lactic acid-derived products in the food, pharmaceutical, and cosmetic industries is increasing year by year. In recent decades, the synthesis of lactic acid by microbials has gained much attention from scientists due to the superior optical purity of the product, its low production costs, and its higher production efficiency compared to chemical synthesis. Microbial fermentation involves the selection of feedstock, strains, and fermentation modes. Each step can potentially affect the yield and purity of the final product. Therefore, there are still many critical challenges in lactic acid production. The costs of feedstocks and energy; the inhibition of substrates and end-product; the sensitivity to the inhibitory compounds released during pretreatment; and the lower optical purity are the main obstacles hindering the fermentation of lactic acid. This review highlights the limitations and challenges of applying microbial fermentation in lactic acid production. In addition, corresponding solutions to these difficulties are summarized in order to provide some guidance for the industrial production of lactic acid.
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Affiliation(s)
- Yueying Huang
- Key Laboratory of Functional Dairy, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yu Wang
- Key Laboratory of Functional Dairy, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Nan Shang
- College of Engineering, China Agricultural University, Beijing 100083, China
| | - Pinglan Li
- Key Laboratory of Functional Dairy, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
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Chauhan S, Mitra S, Yadav M, Kumar A. Microbial production of lactic acid using organic wastes as low-cost substrates. PHYSICAL SCIENCES REVIEWS 2023. [DOI: 10.1515/psr-2022-0159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Abstract
Lactic acid is a natural organic acid with diverse of applications in food, pharmaceutical, cosmetics, and chemical industry. Recently, the demand of lactic acid has been grown due to its utilization for polylactic acid production. Microbial production of lactic acid production is preferable due to optical purity of product, utilization of low cost substrates, and low energy requirement. Lignocellulosic biomass and other organic wastes are considered potential raw materials for cost-effective production of lactic acid. The raw materials are either hydrolyzed by enzymes or dilute acids to release the reducing sugars that are fermented in to lactic acid. This review has been focussed on microbial production of lactic acid using different organic wastes as low cost substrate.
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Affiliation(s)
- Sushmita Chauhan
- Department of Biotechnology, School of Engineering and Technology , Sharda University , Greater Noida , India
| | - Shreya Mitra
- Department of Biotechnology, School of Engineering and Technology , Sharda University , Greater Noida , India
| | - Mukesh Yadav
- Department of Biotechnology , Maharishi Markandeshwar (Deemed to be University) , Mullana-Ambala , Haryana , India
| | - Amit Kumar
- Department of Biotechnology, School of Engineering and Technology , Sharda University , Greater Noida , India
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Yamanushi M, Shimura M, Nagai H, Hamada-Sato N. Antihypertensive effects of abalone viscera fermented with Lactiplantibacillus pentosus SN001 via angiotensin-converting enzyme inhibition. Food Chem X 2022; 13:100239. [PMID: 35498971 PMCID: PMC9040014 DOI: 10.1016/j.fochx.2022.100239] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 01/21/2022] [Accepted: 02/01/2022] [Indexed: 11/04/2022] Open
Abstract
L. pentosus SN001-fermented abalone viscera reduced blood pressure in vivo. L. pentosus SN001-fermented abalone viscera did not affect rat blood composition. L. pentosus SN001-fermented abalone viscera had a good safety profile. Uracil was identified from L. pentosus SN001-fermented abalone viscera.
Abalone viscera, which accounts for more than 20% of body weight, is typically discarded. With increases in abalone aquaculture production, novel uses for abalone viscera are needed. Here, we evaluated the effects of abalone viscera fermented with Lactiplantibacillus pentosus SN001 on angiotensin-converting enzyme (ACE) activity and blood pressure elevation in spontaneously hypertensive rats. The fermented product significantly reduced systolic blood pressure compared with the control. There were no significant differences in blood glucose, triglyceride, total cholesterol, or high-density lipoprotein cholesterol levels; alanine aminotransferase activity; and aspartate aminotransferase activity between the fermented product and control groups. Uracil was isolated and identified from the fermented product. Uracil may be the active component. Overall, L. pentosus SN001-fermented abalone viscera showed sustained inhibitory effects on blood pressure elevation but did not alter blood components after long-term intake. These results provide insights into the safety of L. pentosus SN001-fermented abalone viscera as a food product.
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Affiliation(s)
- Mayu Yamanushi
- Course of Safety Management in Food Supply Chain, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan
| | - Mariko Shimura
- Research and Development Department, Bull-Dog Sauce Co., Ltd., 3-6-1, Mitsuwa, Kawaguchi-shi, Saitama 334-0011, Japan
| | - Hiroshi Nagai
- Department of Ocean Sciences, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan
| | - Naoko Hamada-Sato
- Course of Safety Management in Food Supply Chain, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan.,Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan
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Yankov D. Fermentative Lactic Acid Production From Lignocellulosic Feedstocks: From Source to Purified Product. Front Chem 2022; 10:823005. [PMID: 35308791 PMCID: PMC8931288 DOI: 10.3389/fchem.2022.823005] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/21/2022] [Indexed: 01/10/2023] Open
Abstract
The second (lignocellulosic biomass and industrial wastes) and third (algal biomass) generation feedstocks gained substantial interest as a source of various value-added chemicals, produced by fermentation. Lactic acid is a valuable platform chemical with both traditional and newer applications in many industries. The successful fractionation, separation, and hydrolysis of lignocellulosic biomass result in sugars’ rich raw material for lactic acid fermentation. This review paper aims to summarize the investigations and progress in the last 5 years in lactic acid production from inexpensive and renewable resources. Different aspects are discussed—the type of raw materials, pretreatment and detoxification methods, lactic acid-producers (bacteria, fungi, and yeasts), use of genetically manipulated microorganisms, separation techniques, different approaches of process organization, as well as main challenges, and possible solutions for process optimization.
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Patel A, Shah AR. Integrated lignocellulosic biorefinery: Gateway for production of second generation ethanol and value added products. JOURNAL OF BIORESOURCES AND BIOPRODUCTS 2021. [DOI: 10.1016/j.jobab.2021.02.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Wang J, Huang J, Jiang S, Zhang J, Zhang Q, Ning Y, Fang M, Liu S. Parametric optimization and kinetic study of l-lactic acid production by homologous batch fermentation of Lactobacillus pentosus cells. Biotechnol Appl Biochem 2020; 68:809-822. [PMID: 32738151 DOI: 10.1002/bab.1994] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/25/2020] [Indexed: 11/10/2022]
Abstract
Parametric optimization always plays important roles in bioengineering systems to obtain a high product yield under the proper conditions. The parametric conditions of lactic acid production by homologous batch fermentation of Lactobacillus pentosus cells was optimized by the Box-Behnken design. The highest l-lactic acid yield was obtained as 0.836 ± 0.003 g/g glucose with the productivity of 0.906 ± 0.003 g/(L × H) under the optimum conditions of 34.7 °C, pH 6.2, 148 rpm agitation speed, and 9.3 g/L nitrogen source concentration determined by quadratic response surface with high accuracy. The adequate kinetic models of cell growth rate, lactic production rate, and glucose consumption rate were also established to describe the fermentation behavior of L. pentosus cells with the correlation coefficients of 09985, 0.9990, and 0.9989, respectively.
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Affiliation(s)
- Jianfei Wang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Jiaqi Huang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA.,The Center for Biotechnology & Interdisciplinary Studies (CBIS) at Rensselaer Polytechnic Institute, Troy, USA
| | - Shaoming Jiang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Jing Zhang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Quanquan Zhang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Yuchen Ning
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Mudannan Fang
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
| | - Shijie Liu
- Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, Syracuse, USA
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Žunar B, Trontel A, Svetec Miklenić M, Prah JL, Štafa A, Marđetko N, Novak M, Šantek B, Svetec IK. Metabolically engineered Lactobacillus gasseri JCM 1131 as a novel producer of optically pure L- and D-lactate. World J Microbiol Biotechnol 2020; 36:111. [PMID: 32656603 DOI: 10.1007/s11274-020-02887-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 07/02/2020] [Indexed: 12/17/2022]
Abstract
High-quality environmentally-friendly bioplastics can be produced by mixing poly-L-lactate with poly-D-lactate. On an industrial scale, this process simultaneously consumes large amounts of both optically pure lactate stereoisomers. However, because optimal growth conditions of L-lactate producers often differ from those of D-lactate producers, each stereoisomer is produced in a specialised facility, which raises cost and lowers sustainability. To address this challenge, we metabolically engineered Lactobacillus gasseri JCM 1131T, a bioprocess-friendly and genetically malleable strain of homofermentative lactic acid bacterium, to efficiently produce either pure L- or pure D-lactate under the same bioprocess conditions. Transformation of L. gasseri with plasmids carrying additional genes for L- or D-lactate dehydrogenases failed to affect the ratio of produced stereoisomers, but inactivation of the endogenous genes created strains which yielded 0.96 g of either L- or D-lactate per gram of glucose. In this study, the plasmid pHBintE, routinely used for gene disruption in Bacillus megaterium, was used for the first time to inactivate genes in lactobacilli. Strains with inactivated genes for endogenous lactate dehydrogenases efficiently fermented sugars released by enzymatic hydrolysis of alkali pre-treated wheat straw, an abundant lignocellulose-containing raw material, producing 0.37-0.42 g of lactate per gram of solid part of alkali-treated wheat straw. Thus, the constructed strains are primed to serve as producers of both optically pure L-lactate and D-lactate in the next-generation biorefineries.
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Affiliation(s)
- Bojan Žunar
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Antonija Trontel
- Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Marina Svetec Miklenić
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Juliana Lana Prah
- Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Anamarija Štafa
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Nenad Marđetko
- Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Mario Novak
- Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Božidar Šantek
- Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Ivan Krešimir Svetec
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia.
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Cubas-Cano E, González-Fernández C, Ballesteros I, Tomás-Pejó E. Efficient utilization of hydrolysates from steam-exploded gardening residues for lactic acid production by optimization of enzyme addition and pH control. WASTE MANAGEMENT (NEW YORK, N.Y.) 2020; 107:235-243. [PMID: 32325410 DOI: 10.1016/j.wasman.2020.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/26/2020] [Accepted: 04/01/2020] [Indexed: 05/12/2023]
Abstract
The expansion of urban green areas has boosted the accumulation of gardening lignocellulosic residues that could be potentially used to produce platform chemicals like lactic acid. However, when using lignocelluloses, pretreatment step, such as steam explosion, is often needed to favour sugar release. Considering that the conversion of glucose from cellulose has been widely addressed, this work is focused on the valorisation of the steam-exploded gardening liquid fraction rich in hemicellulosic sugars. Since oligomeric sugars are usually solubilized during steam explosion, an enzymatic hydrolysis step was required in some cases to increase the monosaccharides content. Although the presence of inhibitors released during pretreatment (e.g. formic acid) hindered hydrolysis yields, the addition of hemicellulases and the enzyme dosage optimization resulted in 85%, 89% and 95% of glucose, xylose and arabinose release from soluble oligomers, respectively. Lactobacillus pentosus CECT4023T was used for lactic acid fermentation of C6 and C5 sugars from the hydrolysate with the highest sugars concentration, that did not require enzymatic hydrolysis. Xylose consumption was hampered due to the inhibitory effect of acids that produced pH drop. Different pH control systems were applied and automatic NaOH addition in bioreactor resulted in 21 g L-1 of lactic acid (95% of the maximum theoretical yield) that implied 44% increase in lactic acid production when compared with flask fermentation. These results provide new insights for the valorisation of emerging lignocellulosic materials like gardening residues into high added-value products.
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Affiliation(s)
- Enrique Cubas-Cano
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935 Móstoles, Spain
| | | | | | - Elia Tomás-Pejó
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935 Móstoles, Spain.
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12
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Cubas-Cano E, González-Fernández C, Tomás-Pejó E. Evolutionary engineering of Lactobacillus pentosus improves lactic acid productivity from xylose-rich media at low pH. BIORESOURCE TECHNOLOGY 2019; 288:121540. [PMID: 31174085 DOI: 10.1016/j.biortech.2019.121540] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/20/2019] [Accepted: 05/21/2019] [Indexed: 06/09/2023]
Abstract
Since xylose is the second most abundant sugar in lignocellulose, using microorganisms able to metabolize it into bio-based chemicals like lactic acid is an attractive approach. In this study, Lactobacillus pentosus CECT4023T was evolved to improve its xylose fermentation capacity even at acid pH by adaptive laboratory evolution in repeated anaerobic batch cultures at increasing xylose concentration. The resulting strain (named MAX2) presented between 1.5 and 2-fold more xylose consumption and lactic acid production than the parental strain in 20 g L-1 xylose defined media independently of the initial pH value. When the pH was controlled in bioreactor, lactic acid productivity at 16 h increased 1.4-fold when MAX2 was grown both in xylose defined media and in wheat straw hydrolysate. These results demonstrated the potential of this new strain to produce lactic acid from hemicellulosic substrates at low pH, reducing the need of using neutralizing agents in the process.
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Affiliation(s)
- Enrique Cubas-Cano
- IMDEA Energy Institute, Biotechnological Processes for Energy Production Unit, 28935 Móstoles, Spain.
| | | | - Elia Tomás-Pejó
- IMDEA Energy Institute, Biotechnological Processes for Energy Production Unit, 28935 Móstoles, Spain
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