Lactic Acid Production Process Research Articles

Optimizing Lactic Acid Production Through Dynamic Simulation in Repeated-Batch Fermentation System

In this study, we explored the lactic acid production from molasses through a repeated-batch fermentation process using dynamic simulation. Our investigation revealed that sugar concentrations ranging from 50 to 150 g/l significantly impacted the dynamic profiles of sugar consumption concentration, microbial Enterococcus faecalis RKY1 growth, and lactic acid production. Through dynamic simulation, we identified the optimal inlet sugar concentration as 68 g/l (equivalent to 130 g/l molasses), resulting in a lactic acid average productivity of 3.9 g/l h (3-repeated batch). The simulation demonstrated the viability of a sustainable lactic acid production process using Enterococcus faecalis RKY1, enabling the repeated-batch fermentation process for multiple cycles. Comparative analysis with continuous fermentation indicated that repeated-batch fermentation offers a superior alternative, characterized by higher substrate conversion to lactic acid. This study contributes valuable insights into optimizing lactic acid production processes, emphasizing the efficiency and sustainability of the repeated-batch fermentation approach.

Lactic Acid Production Using Sugarcane Juice as an Alternative Substrate and Purification through Ion-Exchange Resins

The commercial importance of lactic acid (LA) is due to its versatility, especially in the food industry, and for being the precursor of poly-lactic acid, which demands a high-quality LA precursor. The overall LA production process still has some bottlenecks related to costs; thus, alternative substrates such as sugarcane juice may reduce the cost of the fermentation medium and provide a favorable environment for the Lactobacillus pentosus strain, which continues to be explored. In this context, this work presents the process of producing LA from sugarcane juice. The LA purification method is also described using different ion-exchange resins, both in packed columns and in a stirred tank. The fermentation kinetics showed the highest LA production of 113.74 g/L in 96 h, in which a productivity of 1.18 g LA/L∙h was reached. Among the purification techniques, the combined use of Amberlite IR120 and IRA-67 resins under agitation in a stirred tank was the best condition, and resulted in a final LA concentration of 189.11 g/L after 120 min, with 95% LA mass recovery. This result demonstrates a simplified way to use ion-exchange resins safely and in a controlled environment, and with process scale-up viability.

Multi-criteria analysis of cell-recycle based continuous lactic acid production process

ABSTRACT This study focuses on the optimization of the cell-recycle based continuous lactic acid (LA) fermentation production process with the estimation of improved kinetic parameters. The non-dominated sorting genetic algorithm II (NSGA-II) is used considering seven variables and five imposed constraints for multi-objective optimization (MOO) study. Three objectives namely LA productivity, substrate conversion, and yield are formed for the maximization purpose. Three different cases are constructed by using a combination of two bi-objectives and one tri-objective optimization problem, and the modified differential evolution (MDE) algorithm is used to individually optimize each case. Pareto ranking is carried out for MOO, and the best optimal solution is determined using the technique for order preference by similarity to the ideal solution (TOPSIS) method. The highest value of volumetric productivity of LA (184.363 kg/m3.h) is reported in case-4a. The highest yield (1.176) is reported in case-2, while the highest substrate conversion (0.963) is reported in case-1.

A novel nonlinear sliding mode observer to estimate biomass for lactic acid production

Abstract This study deals with the problem of estimating the amount of biomass and lactic acid concentration in a lactic acid production process. A continuous stirred tank bioreactor was used for the culture of Lactobacillus helveticus. A nonlinear sliding mode observer is proposed and designed, which gives an estimate of both the biomass and lactic acid concentrations as a function of glucose uptake from the culture medium. Numerical results are given to illustrate the effectiveness of the proposed observer against a standard sliding-mode observer. It was found that the proposed observer worked very well for the benchmark bioreactor model. Also, the numerical results indicated that the proposed estimation methodology was robust to the uncertainties associated with un-modelled dynamics. These new sensing technologies, when coupled to software models, improve performance for smart process control, monitoring, and prediction.

H2 O2 feeding enables LPMO-assisted cellulose saccharification during simultaneous fermentative production of lactic acid.

Simultaneous saccharification and fermentation (SSF) is a well-known strategy for valorization of lignocellulosic biomass. Because the fermentation process typically is anaerobic, oxidative enzymes found in modern commercial cellulase cocktails, such as lytic polysaccharide monooxygenases (LPMOs), may be inhibited, limiting the overall efficiency of the enzymatic saccharification. Recent discoveries, however, have shown that LPMOs are active under anoxic conditions if they are provided with H2 O2 at low concentrations. In this study, we build on this concept and investigate the potential of using externally added H2 O2 to sustain oxidative cellulose depolymerization by LPMOs during an SSF process for lactic acid production. The results of bioreactor experiments with 100 g/L cellulose clearly show that continuous addition of small amounts of H2 O2 (at a rate of 80 µM/h) during SSF enables LPMO activity and improves lactic acid production. While further process optimization is needed, the present proof-of-concept results show that modern LPMO-containing cellulase cocktails such as Cellic CTec2 can be used in SSF setups, without sacrificing the LPMO activity in these cocktails.

New efficient meta-fermentation process for lactic acid production from municipal solid waste

BackgroundThe global market for lactic acid is witnessing growth on the back of increasing applications of lactic acid for manufacturing polylactic acid. Indeed, the lactic acid market is expected to reach 9.8 billion US dollars by 2025. The new concept of meta-fermentation has been proposed in recent years as an alternative to fermentation with pure cultures, due to multiple advantages such as lower susceptibility to contamination, no need for sterilization of culture media or lower raw material costs. However, there are still challenges to overcome to increase the conversion efficiency, decrease formation of by-products and facilitate fermentation control. In this context, the purpose of the study was to develop a robust meta-fermentation process to efficiently produce lactic acid from the OFMSW, stable at pre-industrial scale (1500 L). To maximize lactic acid production, operating conditions (pH, HRT) were modified, and a novel bioaugmentation strategy was tested.ResultsA LAB-rich inoculum was generated with LAB isolated from the digestate and grown in the laboratory with MRS medium. After feeding this inoculum to the digester (bioaugmentation), lactic acid accumulation up to 41.5 gO2/L was achieved under optimal operating conditions. This corresponds to more than 70% of the filtered COD measured in the digestate. The amount of lactic acid produced was higher than the volatile fatty acids under all feeding strategies applied.ConclusionsThe operating conditions that enhanced the production of lactic acid from mixed cultures were 55ºC, 2 days HRT and pH 4.8–5.7, with pH-control once a day. The bioaugmentation strategy improved the results obtained in the prototype without applying reinoculation. Lactic acid was the main product along with other carboxylic acids. Further improvements are needed to increase purity as well as lactic acid concentration to reach economic feasibility of the whole process (digestion of OFMSW and downstream).

Relay photo/thermal catalysis enables efficient cascade upgrading of sugars to lactic acid: Mechanism study and life cycle assessment

Chemocatalytic conversion of biomass-based saccharides to lactic acid (LA) is one of the prospective routes for biomass valorization, but generally suffers from harsh reaction conditions with relatively low selectivity toward CC bond cleavage. Herein, a novel ternary heterostructure g-C3N4/N-TiO2/NiFe-LDH (NTCN/LDH) photocatalyst prepared by a simple wet-chemical method was demonstrated to be high-performance for cascade upgrading of various biomass sugars to LA (up to 99.0 % yield) in H2O at 60 °C under visible-light irradiation for a short time (≥15 min). A relay photo/thermal catalytic mechanism was mainly responsible for the superior performance of NTCN/LDH in LA production, as elucidated by DFT calculations, in which NTCN/LDH provided suitable Lewis acid sites (i.e., adsorption sites) for thermocatalytic sugar isomerization (e.g., glucose-to-fructose conversion), while the constructed double type-II heterojunction could regulate the type and count of the formed reactive oxygen species (dominantly ·O2−) to achieve precise photocatalytic C3-C4 bond breaking. The scale-up test could still maintain 92 % LA yield of the first-time experiment, indicating the eximious industrialization potential of the versatile NTCN/LDH catalyst. In addition, the life cycle assessment illustrated that the entire system has less impact on the environment than the current industrial LA production process.

One-pot d-lactic acid production using undetoxified acid-pretreated corncob slurry by an adapted Pediococcus acidilactici

Inhibitor tolerance is still a bottleneck for lactic acid bacteria in lignocellulose biorefinery, while it is hard to obtain one engineered strain with strong tolerance to all inhibitors. Herein, a robust adapted d-lactic acid producing strain Pediococcus acidilactici XH11 was obtained by 111 days’ long-term adaptive evolution in undetoxified corncob prehydrolysates. The adapted strain had higher inhibitors tolerance compared to the parental strain, primarily due to its increased conversion capacities of four typical aldehyde inhibitors (furfural, HMF, vanillin, and 4-hydroxybenzaldehyde). One-pot simultaneous saccharification and co-fermentation was successfully achieved using the whole slurry of acid-pretreated corncob without solid–liquid separation and detoxification, by applying the adapted P. acidilactici XH11. Finally, 61.9 g/L of d-lactic acid was generated after 96 h’ fermentation (xylose conversion of 89.9 %) with the overall yield of 0.48 g/g dry corncob. This study gave an important option for screening of industrial strains in cellulosic lactic acid production processes.

Solvent-free synthesis of a zirconium-carbon coordination catalyst for efficient aqueous-phase production of lactic acid from xylose

It is highly desirable but of challenge to develop an efficient process for lactic acid (LaA) production from xylose performed in water. Herein, a novel catalyst prepared via a facile solvent-free coordination route is developed to efficiently produce LaA from xylose in water. The structural properties of the prepared catalyst and the reaction conditions are systematically investigated. The production rate of LaA at 190 °C in water is up to 1.8 h−1, outperforming the most recent reports (below 1.1 h−1). Detailed experimental and characteristic studies reveal that the presence of Lewis acidic sites and basic sites in the catalyst structure can not only lower the energy barrier of xylose conversion but also boost the efficient conversion of the active reaction intermediates into LaA. The findings of this work will provide a new approach for the efficient production of LaA from carbohydrates.

Innovative Reactive Distillation Process for the Sustainable Purification of Lactic Acid

Lactic acid is commonly used in a wide range of fields, such as cosmetics, pharmaceutical products, chemistry, and food. During recent years, its use for new applications, such as the production of biodegradable and biocompatible polymers, green solvents, and oxygenated chemicals, have received considerable attention. However, the relatively high production cost of lactic acid hinders many large-scale applications. It is necessary to develop more efficient methods of separation and purification to cheapen lactic acid production processes. The main objective of this study is to investigate the use of process intensification, particularly the reactive distillation process, for a sustainable purification of lactic acid. To do so, there have been proposed, on the one hand, four intensified alternatives in which synthesis and design are based on thermal couplings and, on the other hand, three alternatives looking for water mass integration. Design and optimization of those modified configurations are carried out employing a stochastic optimization method, using as objective functions some metrics associated with the concept of sustainability (economics, environmental, and inherent safety indexes). A study on the dynamic performance of the configurations through the use of singular value decomposition is carried out in a complementary way. The results in the first redesign stage show improvements in all performance indexes. However, a great difference between the implementation of a thermal coupling that substitutes a condenser instead of a reboiler has been identified. The best scheme, based on a sustainability framework, resulted in a modified process, including a dividing wall column-based scheme.

Математическое моделирование нестационарности биотехнологического получения молочной кислоты: устойчивость

The article presents the calculated ratios of indicators determining the stationary states of the lactic acid production process. Three technologies that are most often mentioned in scientific publications are identified: the technology of using strains of microorganisms to produce biomass is a technology that is extremely rarely used; the fairly common technology of using strains of microorganisms to produce lactic acid with the consumption of the main substrate (most often glucose); the promising technology of obtaining lactic acid using, in addition to the main substrate, a component that reproduces the main substrate in the synthesis process. For each technology, the equations of material balance for stationary and non-stationary conditions, a generalized differential equation for non-stationary conditions, and a characteristic equation are given. The formulas for estimating the coefficients of differential equations and the coefficients of the characteristic equation are also given. The equations for non-stationary conditions according to the last two technologies are based on the use of the Taylor series expansion of functions with the preservation of only the first terms of the expansion, i. e. deviations from stationarity in small. The characteristic equation is formed using the eigenvalues . The methodology for all three technologies is given, which allows us to assess the stability of the considered stationary state – the Hurwitz method. For all three technologies, numerical results are obtained for estimating the coefficients of the characteristic equations Pi. Tabular values of the coefficients are given, according to which stability estimates for the dilution rate of 0.1 h–1, 0.2 h–1, 0.3 h–1 are obtained using determinants according to the Hurwitz matrix. The results of numerical estimates for the stability of stationary states for all three technologies are presented. The estimates were based on the indicators of constants published in scientific studies.

Mathematical Modeling of a Biotechnological Continuous Fermentation Process for Lactic Acid Production: A Review

Mathematical Modeling of a Biotechnological Continuous Fermentation Process for Lactic Acid Production: A Review

Lactic Acid Bacteria as A Bio Preservative: Importance and Production

Abstract: Biopreservation is the method of employing natural microflora and their antimicrobial compounds to extend the storage life and improve the safety of foods. Streptococcus lactis was the first pure strain of lactic acid bacteria which was isolated from milk by Liszt. He named it bacterium lactis. Lactic acid bacteria are gram-positive, acid-tolerant, have low Guanine-Cytosine content and are generally non-sporulating, non-respiring, either spherical cocci or rod-shaped bacilli bacteria that share most of them their metabolic and physiological characteristics. These bacteria are mostly present in decomposing plants and milk products. They have an increased tolerance to acidity. Most species are incapable of respiration and therefore media used for lactic acid bacteria include a carbohydrate source. At the end of carbohydrate fermentation, these bacteria give out lactic acid as a major end product. The review focuses on the process of lactic acid production by lactic acid bacteria and its expanding importance in a variety of disciplines. Keywords: Lactic acid bacteria, bio preservative, food, microflora

Generalized Relationships for Calculating the Elements of Sets of Input Indicators of the Inlet Characteristics of a Fermentation Process for Lactic Acid Production

Generalized Relationships for Calculating the Elements of Sets of Input Indicators of the Inlet Characteristics of a Fermentation Process for Lactic Acid Production

Production of nisin and lactic acid from the starch of sweet potato by simultaneous saccharification and fermentation with two stage pH adjustment

Nisin is an antimicrobial peptide which is widely used as preservative, while lactic acid is a natural organic acid applied in the food industry. The aim of this work was to study the process for nisin and lactic acid production from starch of sweet potato with simultaneous saccharification and fermentation (SSF) by Lactococcus lactis subsp. Lactis with two stage pH adjustment. The factors impacting the nisin and lactic acid production including starch concentration, glucosidase concentration, CaCO3 and Tween-80 were studied. The nisin titre reached a high of 2516.41IU/mL, while the lactic acid reached a high of 37.06g/L when the optimal conditions were 40g/L starch, 100U glucosidase/g starch, 2.5% CaCO3 and 1mL/L Tween-80. The lactic acid and nisin were separated by a two stage pH adjustment at last. The SSF of starch from sweet potato coupled with a two stage pH adjustment is a promising method to produce nisin and lactic acid.

High-efficient L-lactic acid production from inedible starchy biomass by one-step open fermentation using thermotolerant Lactobacillus rhamnosus DUT1908.

The purpose of this study was to establish a simplified operational process for lactic acid (LA) production from inedible starchy biomass by open fermentation using thermotolerant Lactobacillus rhamnosus DUT1908. One step simultaneous liquefaction, saccharification and fermentation (SLSF) was proposed to produce LA using aging paddy rice with hull (APRH) as feedstock. First, a robust microbial strain was obtained by adaptive laboratory evolution under high temperature stress. As a result, L. rhamnosus DUT1908 showed high thermotolerance up to 50°C and high efficiency of substrate utilization. Then, the performance of this thermotolerant L-lactic acid producing strain was demonstrated. Finally, various fermentation strategies were compared for LA production from APRH, including simultaneous saccharification and fermentation (SSF) and SLSF. In one-step open SLSF process, 107.8g/L lactic acid was obtained with a productivity of 3.4g/(L.h) and a yield to theoretical glucose of 0.89g/g. This is the highest yield and productivity of lactic acid reported on starchy residues, and provides an efficient route for the development of high value-added products.

Yeast and lactic acid population relationship in palm wine and their effects on the production of ethanol in Enugu Ezike south eastern Nigeria

Palm wine produced traditionally and consumed by many people in the South eastern part of Nigeria is a whitish liquid formed by naturally fermenting the sugary sap from various palm plants. In this study, we evaluated the population of yeast and lactic acid bacteria in palm wine with regards to its ethanol concentration from three communities in Enugu Ezike, Enugu State. We monitored the isolation of microbial population as well as biochemical characteristics of fermenting palm wine samples using culture-dependent and culture-independent methods. The fermentation step was performed within time interval and completed after 48hrs. Its acidity increasedprogressively with the production of lactic and acetic acids by bacteria.During the fermentation, palm wine microbial numbers (log10 CFU/ml) varied between 1.6 x104 to 7.6 x107 for yeast and 4.5 x 104 to 7.8 x 107 for lactic acid bacteria respectively. Similarly, pH and alcohol level of palm wine samples during the fermentation varied between 3.0 to 5.8 and 0.2 to 5.3 respectively. Statistical analysis revealed that there was no significant difference in both yeast and lactic acid bacteria population at 24hrs. At this time, there was an increased metabolic activity, leading to an increase in ethanol production. At 36-48hrs, there was a slight decrease in both the lactic acid bacteria and the yeast, indicating a reduction in source of carbon.The analysis of the yeast and the lactic acid bacterial population revealed different yeast and bacterial population. Bacteria compete with yeast for nutrients during ethanol production process, potentially causing economic losses. Therefore, it is important to have a better understanding of the abundance and the change in population of lactic acid bacteria and yeast throughout the bio-ethanol process in order to achieve design a more efficient relationship in lactic acid, yeast and ethanol production processes.
 Keywords: Bacteria, ethanol, lactic acid, palm wine, yeast

Bioconversion of potato-processing wastes into an industrially-important chemical lactic acid

Lactic acid (LA) is an important biomolecule applied in food, pharmaceutical and chemical areas, mainly to produce biodegradable polymers, such as poly–lactic acid (PLA). In this work, an efficient fermentative process for LA production was developed using potato processing waste (PPW) hydrolysate with Lactobacillus pentosus. After optimization and kinetics studies, LA production reached 150 g/L with a productivity of 1.6 g/L.h in Erlenmeyer flasks. LA production was also conducted in STR where 110 g/L were reached with a productivity of 2.4 g/L.h. LA recovery consisted of a clarification step, with powdered activated carbon, with further precipitation at low temperature and acidification of calcium lactate for conversion to LA. The process was effective for contaminants' removal and clarification, and LA concentration to 416 g/L. Good perspectives for LA production, recovery and clarification were observed. Future studies will be carried out for LA purification and polymerization for PLA synthesis.

Life cycle and economic assessment of sugarcane bagasse valorization to lactic acid

In this work, detailed life cycle assessment (LCA) and techno-economic analysis (TEA) of a novel lactic acid (LA) production process from sugarcane bagasse is performed, with the objective of identifying process improvement opportunities. Moreover, this is first such study in the Indian context. Experimental data generated at the Vasantdada Sugar Institute (VSI) for upstream processes is combined with ASPEN Plus simulation of the downstream steps for a commercial plant producing 104 tonnes per day of LA. Equipment sizing is performed and costing is done using standard approaches. OpenLCA is used to develop the LCA model and Ecoinvent database is used to quantify life cycle impacts for 1 kg of LA. Different scenarios for the LA plant are studied. Results showed that the pretreatment stage was crucial from both economic and environmental perspectives. The total life cycle climate change impact for production of 1 kg of lactic acid was 4.62 kg CO2 eq. The product cost of LA was USD 2.9/kg, and a payback time of 6 years was achieved at a selling price of USD 3.21/kg. Scenario analysis has revealed that lactic acid plant annexed to a sugar mill led to significant environmental and economic benefits. Sensitivity analysis has identified opportunities to reduce the life cycle climate change impact to 2.29 kg CO2 eq. and product cost to USD 1.42/kg through reduced alkali consumption, higher solid loading, and reduced enzyme loading.

Estimating the Multiplicity of the Steady States of a Fermentation Process for Lactic Acid Production at a Given Concentration of the Component Producing the Main Substrate

Estimating the Multiplicity of the Steady States of a Fermentation Process for Lactic Acid Production at a Given Concentration of the Component Producing the Main Substrate