Modeling and Optimization of Lactic Acid Production using Cashew Apple Juice as Substrate

The production of lactic acid by Lactobacillus casei B-442 was studied and modeled. Sugar feedstock was provided using cashew apple juice, an alternative glucose and fructose feedstock that proved to yield high concentrations of lactic acid. The fermentations were carried out in a 1-L fermenter under constant agitation (150 rpm) and controlled pH (6.5). Lactic acid production was evaluated through a dynamic study, varying the initial concentration of sugar in the range of 20 to 60 g/L. Biomass, reducing sugars, and lactic acid concentration were measured throughout the experiments. The highest production of lactic acid (59.3 g/L) was obtained operating the fermentation with 60 g/L of reducing sugar from the cashew apple juice. A rigorous kinetic model was developed for batch fermentation of cashew apple juice for lactic acid production by L. casei B-442. The growth of biomass and lactic acid production were affected by substrate limitation, substrate inhibition and lactic acid inhibition. The model assumed growth- and non-growth-associated lactic acid production and a term for microorganism death was also included in the model. Parameters of the kinetic model were determined based on experimental data by using the least mean squares method and Levenberg–Marquardt algorithm. The model validation was performed and the model was statistically able to fit the profiles for growth of biomass, sugar consumption and lactic acid production. The optimization of the process, using the model, was carried out and the optimum operating conditions aiming highest productivity, lowest production cost and highest gross profit are presented.     

白酒酿造过程中Lactobacillus panis乳酸合成关键环境因子的鉴定

Lactobacillus panis是酱香型白酒酿造过程中主要产乳酸微生物。然而,不同环境因子对L.panis乳酸合成及乳酸合成途径关键基因的表达尚未有相关研究。作者分析了温度、乳酸、乙醇及葡萄糖4种不同的发酵过程相关的典型环境因子对L.panis乳酸产量的影响。结果表明,不同环境条件能够显著调节L.panis的生长和乳酸产量,且乳酸和乙醇是酿造过程中其乳酸合成的关键影响因素。当添加10.0 g/L乳酸后,L.panis的乳酸产量最高,达到12.3 g/L;当添加体积分数4.0%乙醇后,L.panis的乳酸产量最低,仅为7.2 g/L。使用实时荧光定量PCR方法对不同条件下L.panis乳酸合成相关基因的表达进行分析,结果表明添加乳酸能够显著上调包括编码L-乳酸脱氢酶和D-乳酸脱氢酶的ldhL和ldhD在内的乳酸合成基因的表达。然而,添加乙醇会导致L.panis乳酸合成相关基因的整体显著下调。分析调控乳酸合成的关键环境因素,对于白酒酿造过程中乳酸和酿造微生物群落调控及白酒质量控制具有重要意义。     

Cashew Apple Juice as Substrate for Lactic Acid Production

The aim of the present work was to investigate the use of cashew apple juice as a low cost substrate for Lactobacillus casei B-442 cultivation and lactic acid production. Ammonium sulfate was employed as the only exogenous nitrogen source. The effect of cashew apple juice reducing sugars and ammonium sulfate concentration and the fermentation pH and temperature on biomass formation, lactic acid production, and productivity were evaluated. The highest productivity (2.36 g/L.h) was obtained applying 50 g/L of reducing sugar from the cashew apple juice supplemented with 6 g/L of ammonium sulfate. The process yield was about 95% when fermentation was carried out at 37 °C with pH controlled at pH 6.5 using NaOH (120 g/L).     

Utilization of <Emphasis Type="Italic">Echium amoenum</Emphasis> Extract as a Growth Medium for the Production of Organic Acids by Selected Lactic Acid Bacteria

Gol-gavzaban (Echium amoenum Fisch. & Mey.) is an indigenous herbal plant, related to the Boraginaceae family, cultivated historically in Iran. In this study, the suitability of Echium extract as a raw material for production of fermented juice by four strains of lactic acid bacteria (Lactobacillus paracasei, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus delbrueckii) was examined. Echium extract was inoculated with these bacteria and incubated at 30 °C for 24 h. Changes in microbial population, pH, acidity, sugars, and organic acids metabolism were measured during the fermentation process. Results showed that all of the selected bacteria were capable to grow well in Echium extract without any supplementation. They all metabolized sugars including glucose, fructose and sucrose simultaneously. L. paracasei showed more affinity to sugar consumption at almost 45.2%, 38%, and 21.6% of initial glucose, fructose, and sucrose concentration, respectively. Lactic acid was produced immediately after the fermentation started. L. plantarum, L. delbrueckii, and L. acidophilus produced 6.8, 6.6, and 6.4 g/l lactic acid, respectively, which were significantly higher than that produced by L. paracasei (5 g/l). On the other hand in the case of acetic acid, L. paracasei produced significantly greater quantities in comparison with other strains (4.48 g/l). It was proved that E. amoenum was a desirable media for the production of some organic acids by all these bacterial strains.     

The effect of inoculation and additives on D(−)‐ and L(+)‐lactic acid production and fermentation quality of guineagrass (Panicum maximum Jacq) silage

Two experiments were carried out to study the influence of storage time, glucose and urea additions ( Experiment 1 ) and lactic acid bacteria inoculation with and without glucose addition ( Experiment 2 ) on the production of lactate isomers and fermentation quality of guineagrass (Panicum maximum Jacq) silage. All silages in both experiments were well preserved, as indicated by lower pH and little or no butyric acid. In Experiment 1 , addition of glucose or urea did not significantly affect the pH of silages (P > 0.05). Urea addition tended to reduce acetic acid content and greatly increased NH₃ − N content. L (+)‐Lactic acid was produced predominantly in the first 3 days of ensiling, but D (−)‐lactic acid increased gradually until 1 month after ensiling. Thereafter all silages became stable. In Experiment 2 , inoculation of Lactobacillus casei or L rhamnosus with or without glucose reduced D (−)‐lactic acid and increased L (+)‐lactic acid of silages. The proportions of L (+)‐lactic acid in these silages were higher than 80% of total lactic acid. L plantarum alone or in combination with glucose promoted D (−)‐lactic acid production and decreased the proportion of L (+)‐lactic acid. Glucose addition alone tended to reduce the proportion of L (+)‐lactic acid in both experiments. © 2000 Society of Chemical Industry     

Lactobacillus salivarius for Conversion of Soy Molasses into Lactic Acid

The feasibility of conversion of soy molasses, a low value by-product of soy protein production, to lactic acid by fermentation with Lactobacillus salivarius was investigated. The basic environmental parameters affecting growth and lactic acid production were determined. Lactic acid production in soy molasses was optimal at pH 5.6 and 42°C. Addition of 0.5% yeast extract to soy molasses reduced fermentation time from 36 to 10 hr and increased lactic acid production by 30%.     

Optimization of Lactic Acid Production by Lactobacillus delbrueckii through Response Surface Methodology

ABSTRACT: This article describes the optimization through response surface methodology of a low-cost medium based on Corn Steep Liquor (CSL) for lactic acid production by Lactobacillu delbrueckii NRRL B445. The effect of the fermentation time was also considered. A maximum lactic acid concentration (93.4 g/L) was predicted using 15 g of CSL/L and 6 g of yeast extract/L at a fermentation time of 80.1 h. However, the maximum productivity (3.50 g/L/h) was predicted by using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L alone and 24 h, achieving a maximum economical productivity of 229.7 g of lactic acid per hour and considerable savings in nutrients.     

West African sorghum beer fermented with Lactobacillus delbrueckii and Saccharomyces cerevisiae: shelf‐life and consumer acceptance

The fermentation profiles, shelf‐life and consumer acceptance of traditional West African sour sorghum beer (pito) fermented with pure commercial starter cultures of lactic acid bacteria (L. delbrueckii) and yeast (Saccharomyces cerevisiae) were evaluated. The beers from this ‘pure culture’ approach were compared with the spontaneous fermentation of pito wort. Lactic acid formation, pH change and extract utilisation were monitored during fermentation. Lactic acid content was used as a measure of sourness to establish the spoilage level of over‐sourness. Further, regression models relating sourness to the time the drink was kept were used to predict the shelf‐life. Consumer acceptance of the product was evaluated using a novel nine‐point hedonic scale. The pure culture and traditionally fermented beers followed similar lactic acid and fermentation profiles but strain‐specific differences were observed. Similar levels of pH, lactic acid level and extract utilisation were achieved. An improvement in shelf‐life of two days was found over traditionally fermented pito. There was no statistical difference between the two pito products for overall liking and taste. However, there was a preference for the aroma of the pure culture pito. It is suggested that the use of pure cultures will facilitate the scale‐up of pito production. © 2019 The Institute of Brewing & Distilling     

Ethanol production from carob pods by Saccharomyces cerevisiae

The production of ethanol from carob pods extract by Saccharomyces cerevisiae in static and shake flask fermentation was investigated. Shake flask fermentation proved to be a better fermentation system for the production of ethanol than static fermentation. The external addition of nutrients into the carob pods extract did not improve the production of ethanol. The maximum concentration of ethanol (75 g/l) was obtained at an inoculum amount of 0.3%, a pH of 4.5, 30°C and an initial sugar concentration of 200 g/1. Under the same fermentation conditions both sterilized and non‐sterilized carob pods extract gave the same final ethanol concentration.     

Lactic acid production by simultaneous saccharification and fermentation of alfalfa fiber

Lactic acid was produced by simultaneous saccharification and fermentation (SSF) of liquid hot water (LHW)-pretreated and non-LHW-pretreated alfalfa fibers. The Lactobacillus plantarum and L. delbrueckii strains produced 0.464 and 0.354 g of lactic acid per g of dry matter of alfalfa fiber, respectively, by non-LHW pretreatment. L. xylosus and L. pentoaceticus produced lower yields of lactic acid from the same amount of alfalfa fiber, however, their acetic acid production was higher. These Lactobacillus strains did not require any additional nutrients during SSF of non-LHW-pretreated alfalfa fiber. After LHW pretreatment, the "raffinate" cellulosic fraction of alfalfa required additional nutrients for lactic acid production by SSF. Both L. plantarum and L. delbrueckii produced 0.606 and 0.59 g of lactic acid per g of dry matter of fiber, respectively. However, the "extract" soluble hemicellulosic fraction of alfalfa produced 0.38 to 0.62 g of lactic acid per g of dry matter extract during SSF and did not require nutrient supplementation. These results suggest that during the LHW pretreatment, alfalfa fiber nutrients are lost in cellulosic fractions but retained in hemicellulosic extract fractions.     

Improvement of L(+)‐lactic acid production from cassava wastewater by Lactobacillus rhamnosus B 103

BACKGROUND: L (+)‐Lactic acid is used in the pharmaceutical, textile and food industries as well as in the synthesis of biodegradable plastics. The aim of this study was to investigate the effects of different medium components added in cassava wastewater for the production of L (+)‐lactic acid by Lactobacillus rhamnosus B 103. RESULTS: The use of cassava wastewater (50 g L^?1 of reducing sugar) with Tween 80 and corn steep liquor, at concentrations (v/v) of 1.27 mL L^?1 and 65.4 mL L^?1 respectively led to a lactic acid concentration of 41.65 g L^?1 after 48 h of fermentation. The maximum lactic acid concentration produced in the reactor after 36 h of fermentation was 39.00 g L^?1 using the same medium, but the pH was controlled by addition of 10 mol L^?1 NaOH. CONCLUSION: The use of cassava wastewater for cultivation of L. rhamnosus is feasible, with a considerable production of lactic acid. Furthermore, it is an innovative proposal, as no references were found in the scientific literature on the use of this substrate for lactic acid production. Copyright © 2010 Society of Chemical Industry     

OPTIMIZATION OF THE LACTIC ACID FERMENTATION OF HYDROLYZED COD GURRY WITH MOLASSES

ABSTRACT The purpose of this study was to determine the optimum concentration of blackstrap molasses required in conjunction with the use of several species of homofermentative lactic acid bacteria in the fermentation of hydrolyzed cod gurry. Blackstrap molasses at a concentration of 7.5% was found to be optimum for achieving a successful lactic acid fermentation of hydrolyzed cod gurry. Among the three homofermentative lactic acid bacteria studied (Lactobacillus plantarum, Pediococcus acidilactici and Streptococcus faecium) L. plantarum resulted in the most rapid fementation. S. faecium was the least desirable bacterium on the basis of fermentation rates and extent of pH decrease after 72 h of incubation. All three organisms failed to utilize significantly the sucrose derived from molasses, even though sucrose was the most abundant carbohydrate in the molasses. P. acidilactici was unable to utilize sucrose when present as a sole carbohydrate, while L. plantarum and S. faecium decreased the pH in broth cultures with sucrose as a sole carbohydrate. These results suggest that glucose in molasses functions as a repressor of invertase formation in L. plantarum and S. faecium, and that the use of derepressed mutants should allow a significant decrease in the amount of molasses required for a satisfactory fermentation.     

Use of spent brewer's yeast in L‐(+) lactic acid fermentation

The application of by‐products from the brewing industry in lactic acid (LA) production was investigated in order to replace expensive nitrogen sources (such as yeast extract) with cheaper and renewable nitrogenous materials such as brewer's yeast (BY). In this study, brewer's spent grain (BSG) hydrolysate was used for L‐(+)‐LA fermentation by Lactobacillus rhamnosus ATCC 7469. The effect of pH control during the fermentation and the addition of various BY contents (5–50 g/L) in BSG hydrolysate on fermentation parameters was evaluated. BY addition significantly increased free amino nitrogen (FAN) concentration (by 25.2% at 5 g/L to 616% at 50 g/L). A strong positive correlation between FAN concentration in the hydrolysate and concentration of L‐(+)‐LA produced was observed (correlation coefficient of 0.913). A high cell viability of L. rhamnosus ATCC 7469 (1.95–3.32 × 10⁹ CFU/mL at the end of fermentation) was achieved in all fermentations with the addition of brewer's yeast. The addition of BY increased L‐(+)‐lactic acid yield and volumetric productivity up to 8.4% (5 g/L) and 48.3% (50 g/L). The highest L‐(+)‐LA yield (89%) and volumetric productivity (0.89 g/L h^?1) were achieved in fermentation of BSG hydrolysate with 50 g/L of BY. © 2019 The Institute of Brewing & Distilling     

利用一株凝结芽孢杆菌发酵酸解玉米秸秆生产乳酸

该研究拟考察凝结芽孢杆菌（Bacillus coagulans）利用玉米秸秆生物炼制乳酸的效果。以凝结芽孢杆菌CGMCC No.7635为菌种,利用2%硫酸预处理后的玉米秸秆为碳源、20 g/L酵母粉为氮源,添加20 FPU/g纤维素酶后开展糖化发酵生产乳酸实验。结果表明,发酵65 h后可获得乳酸含量为（38.38±1.03） g/L,其中L-乳酸光学纯度为（99.23±0.22）%。进一步使用补料发酵工艺,添加经预处理的玉米秸秆,可最终获得乳酸含量为（82.56±1.28） g/L。建立的玉米秸秆生物炼制乳酸工艺操作简单、产物浓度高,具有工业应用潜力。     

Identification of microorganisms producing lactic acid during solid‐state fermentation of Maotai flavour liquor

Lactic acid is the main acid produced during the Maotai liquor brewing process, influencing the quality of the base liquor and fermentation process. However, the microorganisms responsible for lactic acid production have not been identified. In this work, the dynamic changes in bacterial community structure in the Zaosha round (second sorghum feeding and fermentation) of the brewing process were analysed by 16S rRNA high‐throughput sequencing. Results show that lactic acid bacteria (LAB) and Bacillus spp. are the dominant bacteria in the brewing process, where Bacillus spp. are found in the early stage, whilst LAB are found throughout the brewing process. Furthermore, 10 types of LAB and five Bacillus spp. were isolated from Zaopei (a mixture of fermented grains including sorghum and wheat) by a culture‐dependent method. Lactobacillus panis accounts for 68% of the LAB, and Bacillus amyloliquefaciens for 54% of Bacillus spp. Solid‐state fermentation experiments were performed with L. panis and B. amyloliquefaciens and lactic acid production was consistent with the accumulation of lactic acid in Zaosha. The results showed that L. panis was the main producer of lactic acid in pits, while B. amyloliquefaciens plays an important role in the production of lactic acid in the early stages of fermentation. The approach used in this study may facilitate the identification of key microorganisms with specific functionality involved in other food and beverage fermentation processes. © 2018 The Institute of Brewing & Distilling     

Changes in Numbers and Kinds of Lactic Acid Bacteria During Ripening of Kefalotyri Cheese

Changes in lactic acid bacteria in ripening Kefalotyri cheese were studied. Throughout ripening lactobacilli and enterococci counts were high (lactobacilli 10⁶-10⁹/g, enterococci 10⁴-10⁷/g). Leuconostocs, lactic streptococci and betabacteria disappeared early in ripening. Leuconostoc lactis and Streptococcus thermophilus prevailed intitially (23% and 13%, respectively). Enterococcus faecium, Lactobacillus casei and L. plantarum became predominant with ripening. After 4 months ripening, E. faecium were dominant (35.5%) followed by L. plantarum (18.4%) and L. casei subsp. casei (15.8%). Results suggested that a starter consisting of both lactic acid bacteria that disappeared early and lactic acid bacteria that survived throughout ripening should be preferable for the production of Kefalotyri cheese.     

Production of L(+) lactic acid from sweet sorghum,date palm,and golden syrup as alternative carbon sources

Lactic acid production has been carried out using (a) Lactobacillus delbruckii, (b) optimal production medium comprised of 10% carbon source derived from sweet sorghum (SS) (Sorghum bicolor)/golden syrup (GS; molasses after glucose crystallization)/date palm (DP) juice (Phoenix dactylifera L.), 1% yeast extract, 0.6% sodium acetate, 0.5% KH₂PO₄, and 0.5% MgSO₄ · 7H₂O, (c) in batch mode, (d) at 45 ± 1°C, 150 rpm, anaerobic condition, and pH 5.5 ± 0.1, and (e) sterilized CaCO₃ powder at regular intervals for neutralization to promote optimal utilization of sugar. The lactic acid (LA) productivity was higher from the use of GS and less from SS as well as DP juice. Decolorization of carbon sources prior to use in fermentation gave LA, meeting food grade specifications.     

培养基pH调控法高密度发酵唾液乳杆菌XH4B研究

本研究以MRS培养基为基础,通过优化碳、氮源及无机盐的配方和用量,再结合补料发酵,最终实现唾液乳杆菌XH4B高密度培养的目的。以乳酸菌的生物量为指标,同时考查发酵液pH值、乳酸含量等,最终确定酵母粉和蔗糖为最佳氮、碳源,同时增加乙酸钠用量至2%、磷酸二氢钠0.6%,可以对发酵液酸化时提供一定的缓冲作用。采用优化的PY-Suc培养基,唾液乳杆菌XH4B的生物量最高能达到6.91 g/L,明显高于MRS培养基的5.01~6.30 g/L(P0.05)。等量补料培养并且采用NaOH中和发酵液pH值时,乳酸最高积累速度可以达到5.958 g/(L·h),但是随着培养时间延长,积累速度迅速下降。发酵酸化较严重时(乳酸含量9~10 g/L),唾液乳杆菌XH4B的生物量积累变缓。结论:优化MRS培养基,并加大乙酸钠、磷酸二氢钠等能够缓冲发酵液的无机盐用量,结合补料发酵,可以实现唾液乳杆菌XH4B的高密度培养。     

Lactic Acid Production from Cane Molasses by Lactobacillus delbrueckii NCIM 2025 in Submerged Condition: Optimization of Medium Component by Taguchi DOE Methodology

Lactic acid production parameter optimization was performed using cane molasses by design of experiment (DOE) with the help of Qualitek-4 software with bigger is better as quality characteristics with eight media components at three levels in submerged culture condition. Eight factors with three levels studied were yeast extract, CaCO₃, MnSO₄, pH, Temperature, molasses, urea, and Tween 80. These factors were optimized based on their S/N ratios obtained from Qualitek-4 software and their significant individual interactions, and interactions with each other have been studied. Effects of mixed N₂ sources, Tween 80, and MnSO₄ have been studied by their individual interactions and interactions among themselves. Lactic acid production was significantly affected by interactions of two factors such as temperature-urea, pH-CaCO₃, temperature-Tween 80, but individually they have minimum impact on lactic acid production. Individually pH, yeast extract, molasses, and urea are the most significant factors in lactic acid production. Lower amount of CaCO₃ and MnSO₄ and Tween 80 enhanced lactic acid production. The expected yield of lactic acid under optimal condition was 98.66% and the actual yield was 96.8%. Overall 6% improvement in yield has been observed when compared with same (mutant) species grown on cane molasses with productivity of 3.15 g/l.h.     

Effects of Lactobacillus casei and Alterations in Fermentation Conditions on Biosynthesis of Glucuronic Acid by a Dekkera bruxellensis-Gluconacetobacter intermedius Kombucha Symbiosis Model System

A combination of Dekkera bruxellensis and Gluconacetobacter intermedius is used as a model system to emulate the microbial symbiosis between yeast and acetic acid bacteria in kombucha, and to study glucuronic acid (GlcUA) production in this system. In the current study, the addition of Lactobacillus casei and variations in the fermentative conditions, such as sucrose concentration, temperature and duration, were examined to evaluate their effects on GlcUA formation. Results showed that L. casei acts as a supporter species and stimulated GlcUA production in the kombucha symbiosis model to levels 54.1% greater than in the control. Varying the fermentation parameters also affected GlcUA production. Therefore, the range of each factor value was screened and restricted to achieve a higher amount of target acid, as it was 5–15%, 25–31°C, 3–7 days, and 5–7 units in sucrose concentration, temperature, fermentation time and initial pH value, respectively. These findings are an important step for optimizing GlcUA production by this model system.