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

Production of lactic acid by continuous electrodialysis fermentation with a glucose concentration controller

Optimized feeding schemes of simultaneous saccharification and fermentation process for high lactic acid titer from sugarcane bagasse

Lactic Acid as a platform chemical has broad application in various industries, especially in the production of Poly Lactic Acid (PLA) for biodegradable plastic. Empty fruit bunch (EFB), abundant by product from palm oil mill industry, is one of potential feedstock to be used in the production of lactic acid from lignocellulose biomass. EFB contains high cellulose and hemicellulose about 37– 59.7% w/w and 16–28% w/w, respectively. The aim of this paper is to study the effects of the operating conditions, such as temperature, reaction time, biomass loading, and catalyst concentration on the yield of lactic acid using barium hydroxide as alkaline catalyst. EFB pretreatment with steam explosion was applied to remove lignin content. The results showed that pretreatment reduced the lignin content from 22.66% to 9.69% w/w. Meanwhile, hemicellulose and cellulose increased from 14.40% to 16.40% w/w and 29.37% to 63.57% w/w, respectively. The highest yield of lactic acid was 21.57% C-mol, achieved by using 0.25 M Ba(OH)2 as the catalyst, with 5% w/v biomass loading, temperature 240°C, during 4 h reaction times. The yield was approximately equal to yield of lactic acid (~ 20%) compared with Pb2+ as the catalyst for EFB conversion although the later catalyst produced fewer by products during conversion.

Subsequent improvement of lactic acid production from beet molasses by Enterococcus hirae ds10 using different fermentation strategies

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.

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

Direct lactic acid production from household food waste by lactic acid bacteria

Lactic acid fermentation from food waste with indigenous microbiota: Effects of pH, temperature and high OLR

Characterization of inulin hydrolyzing enzyme(s) in commercial glucoamylases and its application in lactic acid production from Jerusalem artichoke tubers (Jat)

Lactic acid is widely used in the food, chemical, textile, and pharmaceutical industries. New applications of lactic acid for the manufacture of biodegradable polymers have increased the demand for it. Lactic acid can be produced from cheese whey and starchy and lignocellulosic biomass via microbial fermentation with lactic acid bacteria (LAB) or fungi. Pure sugar and cheese whey can be directly fermented by lactic acid bacteria, while liquefaction and enzymatic saccharification of starchy biomass and pretreatment and enzymatic hydrolysis of lignocellulosic biomass are required for lactic acid production from biomass. Amylolytic lactic acid bacteria can direct convert starchy biomass to lactic acid. Lactic acid bacteria and methods used for lactic acid production from different feedstocks are summarized in this paper. Lactic acid productivity of 6.34 and 4.87 g/l·h and yields of 0.98 g/g lactose and 0.97 g/g glucose were obtained from cheese whey and wheat starch, respectively, using cell-recycle repeated batch fermentation by Lactobacillus sp. RKY2. Lactic acid bacteria such as Lactobacillus pentosus, Lactobacillus brevis and Lactococcus lactis can ferment glucose to lactic acid by homolactic fermentation and also effectively convert xylose or arabinose to lactic acid and acetic acid by heterolactic fermentation. The process for lactic acid production from lignocellulosic biomass needs to be improved to increase the lactic acid yield and productivity.

In this study, we found that p-coumaric acid (p-CA), ferulic acid (FA), and condensed tannins were released from rice straw during saccharification. The presence of polyphenols prolonged the lag phase and lowered the productivity of lactic acid. p-CA was identified as a key inhibitor. Tannins had a lower inhibitory effect than p-CA; FA had little inhibitory effect. Acid, alkaline, and ball milling pretreatments elicited different levels of polyphenol release from rice straw. Due to the different levels of polyphenol release in the pretreatment step, the enzymatic hydrolysates contained different concentrations of polyphenols. Compared with fermentation with a synthetic medium, fermentation with the hydrolysates of ball-milled rice straw provided much lower productivity and yield of lactic acid due to the presence of polyphenols. Removal of these compounds played an important role in lactic acid fermentation. When rice straw was alkaline pretreated, the hydrolysates contained few phenolic compounds, resulting in high productivity and yield of lactic acid (1.8g/L/h and 26.7g/100g straw), which were comparable to those in a synthetic medium. This indicates that there is a correlation between removal of phenolic compounds and efficiency in lactic acid fermentation.

Lactic acid production from lactose by Lactobacillus plantarum: kinetic model and effects of pH, substrate, and oxygen

The optimal conditions of lactic acid fermentation of undiluted oil palm trunks (OPTs) juice by L. rhamnosus TISTR 108 were investigated. The conditions with and without nutrient supplementation were studied. In the condition of no nutrient supplementation, fermentation at 10 % inoculum, 40°C and pH of 6.5 could enhance growth and lactic acid production. The highest lactic acid yield and productivity were obtained at 0.78 g g-1 and 1.36 g l-1h-1, respectively. However sugars were found to remain in fermentation broth and the fermentation time was prolonged to 72 h. In the condition of nutrient supplementation, 10 g l-1 of yeast extract, 5 g l-1of peptone and salts were added into the fermentation process. It was found that the fermentation time was shortened to 21 - 54 h and the sugars were completely consumed. The highest lactic acid yields and productivities were achieved at 0.82 - 0.85 g g-1 and 2.47 - 3.83 g l-1h-1, respectively. doi:10.14456/WJST.2015.23

Lactic acid (LA) fermentation requires a neutralizer for a physiologically acceptable range. However, a neutralizer generates a large amount of gypsum, an environmental pollutant. Furthermore, the downstream processing is complicated and expensive, comprising 50-70% of the total cost. We previously developed a Lactobacillus delbrueckii FM1, which can produce undissociated LA without neutralizer. Here, we improved FM1 by adaptive evolution at pH4.5, which generated Adp FM1 showing an ~ 1.80-fold increase in LA production compared to FM1. The LA production via fed-batch fermentation yielded 36.2g/L of LA, with a productivity of 0.500g/L/h. However, cell viability was reduced due to the acidic pH and/or end-product inhibition. Therefore, an in situ LA recovery process using an extractive solvent was employed to maintain cell viability. Adp FM1 produced 49.2g/L of LA via in situ LA-extractive fed-batch fermentation, which was ~ 1.4-fold higher than that without LA extraction. Adp FM1 provided a total LA productivity of 0.512g/L/h in 96h. Among the tested strains, Adp FM1 exhibited the highest H+-ATPase activity and a 415-fold increase in H+-ATPase gene expression compared to the parent strain. These results suggest that the in situ LA extractive fermentation process will ease downstream processing and prove to be a more economical and environmentally friendly option compared to the present fermentation. To our knowledge, this is the first report on the production of undissociated L-LA by Lactobacillus using an in situ recovery process, with high LA production levels and productivity.

Microbial bioconversion of agro-industrial wastes to green chemicals has become an important objective in industrial biotechnology for lowering the product costs. Therefore, in this work, beet molasses was used as a potential raw material for lactic acid (LA) production by a newly isolated bacterium, Enterococcus faecium S6. The pretreatment of molasses with EDTA has exhibited the highest effectiveness for bioconversion to LA. The optimal medium components and culture conditions were established. Supplementation of molasses by yeast extract (YE) and ammonium chloride have achieved LA production of 11.90 g/L at a yield of 0.71 g/g-consumed sugars and a productivity of 0.33 g/L/h. Various approaches were used for the optimization of relevant factors affecting l-LA production in batch fermentations. Using classical “one-factor-at-a-time” approach, the optimal factors were as follows: sugar concentration, 40 g/L; pH, 7.0; 40 °C; and inoculum size, 10% (v/v) achieving LA at 29.7 g/L. The effects of these five fermentation parameters were further investigated by response surface methodology (RSM) to maximize LA production. The optimized fermentation conditions by RSM were as follows: sugar concentration, 65 g/L; YE, 0.625 g/L; temperature, 42 °C; pH, 6.75; and inoculum size, 9.5% (v/v) that achieved LA production of 41.5 g/L. Further improvements were achieved using repeated batch fermentation that has conducted for 16 runs. Using seed culture pre-adapted to the actual fermentation conditions in repeated batch fermentation led to enhanced LA production with a shorter process time compared to batch fermentation. These results achieved a maximum LA of 64.7 g/L with high yield (0.94 g/g of consumed sugars) and productivity (2.16 g/L/h). This study presented a cost-effective and long-term fermentative production of LA from beet molasses.