Highest Lactic Acid Yield Research Articles

Production of L (+) Lactic Acid by Lactobacillus casei Ke11: Fed Batch Fermentation Strategies

Lactic acid and its derivatives are widely used in pharmaceutical, leather, textile and food industries. However, until now there have been few systematic reports on fed-batch fermentation for efficient production and high concentration of l-lactic acid by lactic acid bacteria. This study describes the obtainment of L (+) lactic acid from sucrose using the Lactobacillus casei Ke11 strain through different feeding strategies using an accessible pH neutralizer such as CaCO3. The exponential feeding strategy can increase lactic acid production and productivity (175.84 g/L and 3.74 g/L/h, respectively) with a 95% yield, avoiding inhibition by high initial substrate concentration and, combined with the selected agent controller, avoids the cellular stress that could be caused by the high osmotic pressure of the culture media. The purification of the acid using charcoal and celite, followed by the use of a cation exchange column proved to be highly efficient, allowing a high yield of lactic acid, high removal of sugars and proteins. The described process shows great potential for the production of lactic acid, as well as the simple, efficient and low-cost purification method. This way, this work is useful to the large-scale fermentation of L. casei Ke11 for production of l-lactic acid.

Copper oxide functionalized chitosan hybrid hydrogels for highly efficient photocatalytic-reforming of biomass-based monosaccharides to lactic acid

Much attention has been focused on the photocatalytic-reforming of biomass to produce high-value chemicals due to their unique merits. In this study, we report a freezing-thawing strategy for the preparation of an alkaline CuO-chitosan hybrid hydrogel (CuO@CS-H). The synergism between CuO and alkaline chitosan hydrogel led to a highly efficient photocatalytic-reforming of xylose to lactic acid under a weak alkaline system, and the highest lactic acid yield is 81.6 %. The retained lactic acid yield was about 91.2 % after being used nine times. The reaction system is universal for the production of lactic acid from biomass-derived pentoses and hexoses, and O2− plays a major role in the synthesis of lactic acid. Industrial production of lactic acid via the as-proposed system was shown to be feasible according to a two-thousand-fold scale-up experiment. This work initiates a novel strategy of photocatalytic synthesis of lactic acid from biomass-based monosaccharides.

Magnesium Oxide-Catalyzed Conversion of Chitin to Lactic Acid.

Although chitin, an N‐acetyl‐D‐glucosamine polysaccharide, can be converted to valuable products by means of homogeneous catalysis, most of the chitin generated by food processing is treated as industrial waste. Thus, a method for converting this abundant source of biomass to useful chemicals, such as lactic acid, would be beneficial. In this study, we determined the catalytic activities of various metal oxides for chitin conversion at 533 K and found that MgO showed the highest activity for lactic acid production. X‐ray diffraction analysis and thermogravimetry‐differential thermal analysis showed that the MgO was transformed to Mg(OH)2 during chitin conversion. The highest yield of lactic acid (10.8 %) was obtained when the reaction was carried out for 6 h with 0.5 g of the MgO catalyst. The catalyst could be recovered as a solid residue after the reaction and reused twice with no decrease in the lactic acid yield.

Ca(OH)2 induced a controlled-release catalytic system for the efficient conversion of high-concentration glucose to lactic acid

The catalytic conversion of carbohydrate to platform chemicals, e.g. lactic acid (LA), is the key to unlock the potential of biomass. In this study, we report that the combination of Ba(OH)2 and Ca(OH)2 can efficiently catalyse high-concentration (> 0.5 M) of glucose to relatively high yield of LA (> 40 %) under mild conditions (60 °C). Both glucose conversion and LA yield were sensitive to the pH of the catalytic system. A high loading of Ba(OH)2 led to a high initial pH of the reaction solution, resulting in serious side reactions. While, a low loading of Ba(OH)2 led to a quike decrease of OH− and Ba2+ both of which were continuously consumpted by the formed LA. The combination of Ca(OH)2 with Ba(OH)2 could significantly improve LA yield, since Ca(OH)2, with limited solubility, could act as a controlled-release catalyst for the real-time supply of OH− and Ca2+. OH− was indispensable for glucose isomerization to fructose as well as for fructose retro-aldol reaction to C3 intermediates. Ca2+ could combine with LA to form stable calcium lactate, liberating Ba2+ to catalyse the conversion of C3 intermediates to LA. Under the preliminary optimized reaction conditions, the yield of LA could be reached to 42.55 % and 38.32 % from 0.5 M and 1 M glucose, respectively. This catalytic system has advantages of mild reaction condition, short reaction time, and capable of conversion of high-concentration substrates, enabling it with a great potential for practical applications.

Lignin-based activated carbon-supported metal oxide catalysts in lactic acid production from glucose

In this study, heterogeneous biomass-based activated carbon-supported metal oxide catalysts were prepared and tested for lactic acid production from glucose in aqueous solution. Activated carbons were produced from hydrolysis lignin by chemical (ZnCl2) or steam activation and modified with a nitric acid treatment and Sn, Al, and Cr chlorides to obtain carbon-based metal oxide catalysts. The modification of the carbon support by nitric acid treatment together with Sn and Al oxides led to an increase in lactic acid yield. The highest lactic acid yield (42 %) was obtained after 20 min at 180 °C with the Sn/Al (5/2.5 wt.%) catalyst on steam-activated carbon treated by nitric acid. Reusability of the catalyst was also studied with the conclusion that the deposition of carbonaceous byproducts and leaching of Al oxides led to a decrease in catalyst selectivity to lactic acid.

γ-Valerolactone-introduced controlled-isomerization of glucose for lactic acid production over an Sn-Beta catalyst

GVL (<20.0 wt%) invoked a controlled isomerization of glucose to fructose, thus resulting in a low fructose intermediate concentration and enabling full interaction between fructose and the Sn-Beta catalyst with a high lactic acid yield of 74.0 wt%.

Encapsulation of Lactobacillus rhamnosus in Polyvinyl Alcohol for the production of L-(+)-Lactic Acid

Poly(vinyl alcohol) (PVA) was investigated as a carrier for Lactobacillus rhamnosus ATCC 7469 cells for application in L-(+)-lactic acid (LA) fermentation on low-cost food industry by-products. Brewer’s spent grain (BSG) and malt rootlets (MR) hydrolysates, with the addition of brewer’s yeast, brewer’s yeast extract, or malt rootlets extract and soy lecithin were evaluated as media for LA fermentation. PVA concentrations of 5, 10 and 15% were evaluated and the optimal concentration was further used. Obtained PVA biocatalyst (BC) was applied in batch and repeated batch fermentations of BSG and MR hydrolysate. During 12 consecutive batch fermentations, the BC showed high mechanical stability and minor loss of activity while achieving high LA yield (97%) and productivity (2.1 g/L h-1). The study suggests that the immobilized L. rhamnosus cells in PVA cryogel can be successfully used in stable repeated batch fermentations on low-cost fermentation media without the loss of cell activity and LA fermentation capability.

Efficient biorefinery process for lactic acid production from date wastes with alleviating substrate inhibition effect using thermo-alkaline repeated batch fermentation

In the current work, date wastes were used for lactic acid (LA) production under thermo-alkaline conditions to overcome some fermentation challenges. Amongst 27 bacterial isolates that produced LA from date juice, isolate D-218 exhibited better growth stability and LA production under various stressed conditions. This isolate was characterized as Bacillus coagulans D-218 using physiological and molecular identification methods. In batch fermentation mode, strain D-218 could not completely utilize 80 g/L of the total sugar and produced only 45.8 ± 2.8 g/L of LA at LA productivity of 0.214 g/L.h and high residual sugar (29.2 g/L) was unutilized in the fermentation media. Different repeated batch fermentations with different initial sugar concentrations and gradual increase in sugar concentrtions were conducted to maximize LA productivity. Starting with 60 g/L of total sugar, four runs of repeated batch fermentations were conducted that enhanced the LA productivity (70%) to 0.49 g/L.h. Another 9 runs were initiated with 40 g/L which further improved LA productivity that reached up to 0.77 g/L.h. Surprisingly, initiating fermentations with 20 g/L of total sugar successfully attained long-term fermentation (18 runs) with high LA yield and productivity without carbon loss of initiated startup sugar of date waste. In this process, strain D-218 could completely consume 80 g/L sugars with high LA production titer (72.9 ± 0.56 g/L), yield (0.92 g/g), and productivity (0.71 g/L.h). This study is the first to exploit date waste in a cost-effective system for high-titer lactic acid production under thermo-alkaline conditions (pH 9.0; 50 °C) and to report repeated batch fermentation for LA production from date wastes.

Fermentative Production of Lactic Acid as a Sustainable Approach to Valorize Household Bio-Waste

Source-sorted organic portion of municipal solid waste (bio-waste) can be fermented to lactic acid, a platform chemical widely used in the production of biodegradable polymers, green solvents and chemicals. In the present study, fermentation of bio-waste using lactic acid producing bacterium (LAB) Lactobacillus delbrueckii was investigated. Results showed that adding 10% (v/v) of L. delbrueckii as LAB inoculum along with pH adjustment to 6.2 had the highest lactic acid yield (0.65 g/g total sugars). Nevertheless, pH adjustment without bio-augmentation could also result in relatively high yield of lactic acid (0.57 g/g total sugars). Furthermore, enzymatic hydrolysis was applied to boost the lactic acid production slightly increasing the yield to 0.72 g/g total sugars. Thus, fermentative production of lactic acid can be achieved without the addition of enzymes to reduce production costs. Overall, the results indicate that bio-waste could be a suitable substrate for the production of lactic acid.

Heterogeneous Catalytic Synthesis of Methyl Lactate and Lactic Acid from Sugars and Their Derivatives.

Recent developments in sugar transformations to methyl lactate and lactic acid are critically summarized. The highest yield of methyl lactate from glucose obtained over Sn(salen)/octylmethyl imidazolium bromide catalyst was 68 % at 160 °C whereas the highest yield of lactic acid of 58 % was achieved over hierarchical Lewis acidic Sn‐Beta catalysts at 200 °C under inert atmosphere. In addition to the desired products also humins are formed in water whereas in methanol alkyl glucosides‐ and ‐fructosides as well as acetals were generated, especially in the presence of Brønsted‐acidic sites. The main challenges limiting the industrial feasibility of these reactions are incomplete liquid phase mass balance closure, complicated product analysis and a lack of kinetic data. In addition to reporting optimized reaction conditions and catalyst properties also catalyst reuse and regeneration as well as kinetic modelling and continuous operation are summarized.

Mixed Oxide Catalyst for the Oxidation of Glycerol to Lactic Acid: Influence of the Preparation Method and Calcination Temperature

The selective oxidation reaction of glycerol to produce lactic acid is a high-temperature reaction, and requiring a catalyst with high thermal stability. The mixed metal oxide is one of the potential catalysts to be explored. In this study, prepared CaCe supported on ZrO2 catalyst with two preparation methods (co-precipitation and impregnation), and calcination temperatures (800 and 600 °C) were investigated. The oxidation reaction of glycerol to lactic acid was carried out at 250 °C for 2 h in a base-free condition using pure glycerol as a reactant. The catalysts were characterized using XRD, TGA, XPS, SEM and basicity test to evaluate and correlate the physical and chemical properties with their catalytic performance. It was found that the catalyst prepared by co-precipitation and calcined at 800 °C exhibited the highest catalytic performance. The high lactic acid yield of 38.8 and 95% glycerol conversion were achieved. The catalyst was successfully developed with sufficient porosity and high intensity of mixed metal structure that contributed to the desired high performance. Improvement in the basicity and formation of surface oxygen vacancies was attributed to cationic Ce4+/Ce3+ elements leading to the promotion of lactic acid yield and high glycerol conversion.

A Combined Thermochemical and Microbial Process for Recycling Polylactic Acid Polymer to Optically Pure l-Lactic Acid for Reuse

Polylactic acid polymer (PLA) produced from renewable resources can be recycled at the end of life to constituent monomer, optically pure lactic acid (LA), by a combination of chemical and biological processes. Efficient application of this closed loop of LA-PLA plastics-LA can minimize accumulation of plastics waste that pollute land and oceans. Temperature-dependent hydrolysis of PLA in water to LA follows apparent first order decay kinetics after a short lag. A modified Gompertz equation can explain the overall hydrolysis process. Alkali increased the rate of hydrolysis of PLA and reduced the length of lag period compared to water alone. The stoichiometry of base added to LA released was 1.0. The highest lactic acid yield was 0.95 g g−1 of PLA. d-LA in the syrup obtained after hydrolysis of PLA-plastics was removed using an engineered Escherichia coli to produce a l-LA syrup with an optical purity ≥ 99%. These results show that thermochemical hydrolysis of PLA-based plastics to LA with optimum amount of base followed by bio-based purification to l-LA is an effective method of recycling PLA-plastics for reuse.

Biochemical analysis of some fruit peels and comparison of Lactic acid production by authochthonous Lactic acid bacteria using fruit peels

Waste to wealth is a common trend in the world today. This work reports the utilization of waste fruit peels for production of lactic acid using authochthonouslactic acid bacteria. Peels of mango, orange and banana were prepared in powdered form, pretreated with HCl and added as carbon source for lactic acid production. The proximate analyses of the substrates were done. The organisms used for fermentation were isolated from spoilt banana and identified using biochemical and molecular tools. These organisms were grown using different growth factors over a period of eight days with initial pH of 6.0. Growth factors were then varied in order to optimize the yield of lactic acid. Percentage production of lactic acid was determined every 24 hours. The optimized conditions were then combined for further comparison. Isolated Lactobacillus plantarumand Lactobacillus caseiwere used for the production of lactic acid. The carbohydrate content of mango, banana and orange peels (62.48%, 55.34% and 57.06% respectively) showed that it was sufficient for use as a carbon source. The highest yield of lactic acid (27.10%) was at pH 6.0 with 2g of substrate and 1 ml inoculum at day six by Lactobacillus caseiwhile the highest yield by Lactobacillus plantarum (23.85%) was at pH 6.0, with 4g of substrate and 2 ml inoculum at day six. The highest production of lactic acid was derived when mango peels were used. The results of this study showed that lactic acid can be produced using mango, orange and banana peels.

Production of lactic acid on enzymatic hydrolysates of cellulose-containing raw materials

The production of lactic acid by the microbiological method using as the basis of the nutrient medium hydrolysates of cellulose-containing raw materials is a promising, but poorly studied area of modern biotechnology. Plant or lignocellulose raw materials are considered to be very useful for the production of a variety of microbiological synthesis products. Lignocellulosic raw materials are recognized as the most used carbohydrate material due to renewability and large volumes of production. The possibility of producing of lactic acid on enzymatic hydrolysates of cellulose-containing raw materials (wheat straw, waste paper, mixed substrate) is shown. It is established that hydrolysates of all types of cellulose-containing raw materials allow to obtain lactic acid and probiotic preparations. The yield of lactic acid depends on the type of raw material used. The highest yield of lactic acid is observed when using an unclarified waste paper hydrolyzate as the basis of the nutrient.

Stabilizing lactate production through repeated batch fermentation of food waste and waste activated sludge

Bio-valorization of organic waste streams, such as food waste and waste activated sludge, to lactic acid (LA) has recently drawn much attention. It offers an opportunity for resource recovery, alleviates environmental issues and potentially turns a profit. In this study, both stable and high LA yield (0.72 ± 0.15 g/g total chemical oxygen demand) and productivity rate (0.53 g/L•h) were obtained through repeated batch fermentation. Moreover, stable solubilization and increase in the critical hydrolase activities were achieved. Depletions of ammonia and phosphorus were correlated with the LA production. The relative abundance of the key LA bacteria genera (i.e., Alkaliphilus, Dysgonomonas, Enterococcus and Bifidobacterium) stabilized in the repeated batch reactor at a higher level (44.5 ± 2.53%) in comparison with the batch reactor (26.2 ± 4.74%). This work show a practical way for the sustainable valorization of organic wastes to LA by applying the repeated batch mode during biological treatment.

Transfer hydrogenation from glycerol over a Ni-Co/CeO2 catalyst: A highly efficient and sustainable route to produce lactic acid

Bimetallic Ni-Co catalysts supported on nanosized CeO2 were prepared and investigated as heterogeneous catalysts for the transfer hydrogenation between glycerol and various H2 acceptors (levulinic acid, benzene, nitrobenzene, 1-decene, cyclohexene) to selectively produce lactic acid (salt) and the target hydrogenated compound. The bimetallic NiCo/CeO2 catalyst showed much higher activity than the monometallic Ni or Co counterparts (with equal total metal mass), thus indicating strong synergetic effects. The interaction between the metallic sites and the CeO2 support was thoroughly characterised by means of transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) mapping, X-ray photoelectron spectroscopy (XPS), hydrogen-temperature programmed reduction (H2-TPR) and X-ray diffraction (XRD). Combining characterisation and catalytic results proved that the Ni species are intrinsically more active than Co species, but that incorporating Co into the catalyst formulation prevented the formation of large Ni particles and led to highly dispersed metal nanoparticles on CeO2, thus leading to the observed enhanced activity for the bimetallic system. The highest yield of lactic acid (salt) achieved in this work was 93% at 97% glycerol conversion (160 °C, 6.5 h at 20 bar N2, NaOH: glycerol = 1.5). The NiCo/CeO2 catalyst also exhibited high activity and selectivity towards the target hydrogenated products in the transfer hydrogenation reactions between glycerol and various H2 acceptors. Batch recycle experiments showed good reusability, with retention of 80% of the original activity after 5 runs.

Immobilization of Lactobacillus rhamnosus in polyvinyl alcohol/calcium alginate matrix for production of lactic acid.

Immobilization of Lactobacillus rhamnosus ATCC7469 in poly(vinyl alcohol)/calcium alginate (PVA/Ca-alginate) matrix using "freezing-thawing" technique for application in lactic acid (LA) fermentation was studied in this paper. PVA/Ca-alginate beads were made from sterile and non-sterile PVA and sodium alginate solutions. According to mechanical properties, the PVA/Ca-alginate beads expressed a strong elastic character. Obtained PVA/Ca-alginate beads were further applied in batch and repeated batch LA fermentations. Regarding cell viability, L. rhamnosus cells survived well rather sharp immobilization procedure and significant cell proliferation was observed in further fermentation studies achieving high cell viability (up to 10.7logCFUg-1) in sterile beads. In batch LA fermentation, the immobilized biocatalyst was superior to free cell fermentation system (by 37.1%), while the highest LA yield and volumetric productivity of 97.6% and 0.8gL-1h-1, respectively, were attained in repeated batch fermentation. During seven consecutive batch fermentations, the biocatalyst showed high mechanical and operational stability reaching an overall productivity of 0.78g L-1h-1. This study suggested that the "freezing-thawing" technique can be successfully used for immobilization of L. rhamnosus in PVA/Ca-alginate matrix without loss of either viability or LA fermentation capability.

Production of optically pure L(+)-lactic acid from waste plywood chips using an isolated thermotolerant Enterococcus faecalis SI at a pilot scale.

Utilization of renewable and low-cost lignocellulosic wastes has received major focus in industrial lactic acid production. The use of high solid loadings in biomass pretreatment potentially offers advantages over low solid loadings including higher lactic acid concentration with decreased production and capital costs. In this study, an isolated Enterococcus faecalis SI with optimal temperature 42°C was used to produce optically pure L-lactic acid (> 99%) from enzyme-saccharified hydrolysates of acid-impregnated steam explosion (AISE)-treated plywood chips. The L-lactic acid production increased by 10% at 5L scale compared to the similar fermentation scheme reported by Wee et al. The fermentation with a high solid loading of 20% and 35% (w/v) AISE-pretreated plywood chips had been successfully scaled up to process development unit scale (100L) and pilot scale (9m3), respectively. This is the first report of pilot-scale lignocellulosic lactic acid fermentation by E. faecalis with high lactic acid titer (nearly 92gL-1) and yield (0.97kgkg-1). Therefore, large-scale L-lactic acid production by E. faecalis SI shows the potential application for industries.

Biodetoxification of Phenolic Inhibitors from Lignocellulose Pretreatment using Kurthia huakuii LAM0618T and Subsequent Lactic Acid Fermentation.

Phenolic inhibitors generated during alkaline pretreatment of lignocellulosic biomasses significantly hinder bacterial growth and subsequent biofuel and biochemical production. Water rinsing is an efficient method for removing these compounds. Nevertheless, this method often generates a great amount of wastewater, and leads to the loss of solid fiber particles and fermentable sugars. Kurthia huakuii LAM0618T, a recently identified microorganism, was herein shown to be able to efficiently transform phenolic compounds (syringaldehyde, hydroxybenzaldehyde, and vanillin) into less toxic acids. Taking advantage of these properties, a biodetoxification method was established by inoculating K. huakuii LAM0618T into the NH3/H2O2-pretreated unwashed corn stover to degrade phenolic inhibitors and weak acids generated during the pretreatment. Subsequently, 33.47 and 17.91 g/L lactic acid was produced by Bacillus coagulans LA204 at 50 °C through simultaneous saccharification and fermentation (SSF) from 8% (w/w) of NH3/H2O2-pretreated corn stover with or without K. huakuii LAM0618T-biodetoxification, indicating biodetoxification significantly increased lactic acid titer and yield. Importantly, using 15% (w/w) of the NH3/H2O2-pretreated K. huakuii LAM0618T-biodetoxified corn stover as a substrate through fed-batch simultaneous saccharification and fermentation, high titer and high yield of lactic acid (84.49 g/L and 0.56 g/g corn stover, respectively, with a productivity of 0.88 g/L/h) were produced by Bacillus coagulans LA204. Therefore, this study reported the first study on biodetoxification of alkaline-pretreated lignocellulosic material, and this biodetoxification method could replace water rinsing for removal of phenolic inhibitors and applied in biofuel and biochemical production using the alkaline-pretreated lignocellulosic bioresources.

Effective lactic acid production from waste paper using Streptococcus thermophilus at low enzyme loading assisted by Gleditsia saponin

Waste paper has considerable potential as a raw material for lactic acid (LA) production due to high cellulose content, abundance and low cost. In this study, four kinds of waste papers were used for LA production through simultaneous saccharification and fermentation (SSF) by Streptococcus thermophilus. The SSF of office paper achieved the highest LA concentration (39.71 g/L), while the highest LA yield was observed for magazine (99.56%), followed by office paper (82.85%). High LA concentration is unfavorable to total LA conversion because of product inhibition. However, the addition of Gleditsia saponin (GS) could obtain both high yield and high concentration of LA at a low enzyme loading, indicating that product inhibition could be moderated. A lactic acid yield of 86.30% was obtained from office paper at an enzyme loading of 9 FPU/g-cellulose with GS, which was higher than that of without GS at a higher loading of 18 FPU/g-cellulose.