The production of biodegradable polymers as alternatives to petroleum-based plastics has gained significant attention in the past years. To this end, polylactic acid (PLA) constitutes a promising ...alternative, finding various applications from food packaging to pharmaceuticals. Recent studies have shown that d-lactic acid plays a vital role in the production of heat-resistant PLA. At the same time, the utilization of renewable resources is imperative in order to decrease the production cost. This review aims to provide a synopsis of the current state of the art regarding d-lactic acid production
fermentation, focusing on the exploitation of waste and byproduct streams. An overview of potential downstream separation schemes is also given. Additionally, three case studies are presented and discussed, reporting the obtained results utilizing acid whey, coffee mucilage and hydrolysate from rice husks as alternative feedstocks for d-lactic acid production.
This study introduces to a one-step process for the fermentative production of L(+)-lactic acid from mixed restaurant food waste. Food waste was used as carbon and nitrogen source in simultaneous ...saccharification and fermentation (SSF) using Lactobacillus sp. or Streptococcus sp. strains for L(+)-lactic acid production. Waste consisted of (w/w) 33.5% starch, 14.8% proteins, 12.9% fat and 8.5% free sugars. Lactobacillus sp. strains showed a productivity of 0.27–0.53 g L−1 h−1 and a yield of 0.07–0.14 g g−1 of theoretically available sugars, while Streptococcus sp. more efficiently degraded the food waste material and produced lactic acid at a maximum rate of 2.16 g L−1 h−1 and a yield of 0.81 g g−1. For SSF, no enzymes were added or other hydrolytic treatments were carried out. Outcomes revealed a linear relationship between lactic acid concentration and solid-to-liquid ratio when Streptococcus sp. was applied. Statistically, from a 20% (w/w) dry food waste blend 52.4 g L−1 lactic acid can be produced. Experimentally, 58 g L−1 was achieved in presence of 20% (w/w), which was the highest solid-to-liquid ratio that could be treated using the equipment applied. Irrespective if SSF was performed at laboratory or technical scale, or under non-sterile conditions, Streptococcus sp. efficiently liquefied food waste and converted the released nutrients directly into lactic acid without considerable production of other organic acids, such as acetic acid. Downstream processing including micro- and nanofiltration, electrodialysis, chromatography and distillation gave a pure 702 g L−1 L(+)-lactic acid formulation.
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•An isolated Streptococcus sp. strain converted food waste efficiently into lactic acid.•Max. productivity was 2.16 g L−1 h−1 and yield was 0.81 g g−1 of available sugars.•Increase in solid-to-liquid ratio resulted in increased lactic acid titer.•A solid-to-liquid ratio of 20% (w/w) gave 58 g L−1 lactic acid.•Downstream processing resulted in a 702 g L−1 optical pure L(+)-lactic acid solution.
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•New concept of cascadic use of food waste was investigated.•SHF and SSF approaches for LA have been executed.•Yield and productivity were slightly higher for SHF compared to ...SSF.•Integration of biogas production from fermentative residues.•Preliminary economic and environmental assessment of the proposed two-step biorefinery process.
This work concerns the investigation of the sequential production of lactic acid (LA) and biogas from food waste (FW). LA was produced from FW using a Streptococcus sp. strain via simultaneous saccharification and fermentation (SSF) and separate enzymatic hydrolysis and fermentation (SHF). Via SHF a yield of 0.33gLA/gFW (productivity 3.38gLA/L·h) and via SSF 0.29gLA/gFW (productivity 2.08gLA/L·h) was obtained. Fermentation residues and FW underwent anaerobic digestion (3wt% TS). Biogas yields were 0.71, 0.74 and 0.90Nm3/kgVS for FW and residues from SSF and SHF respectively. The innovation of the approach is considering the conversion of FW into two different products through a biorefinery concept, therefore making economically feasible LA production and valorising its fermentative residues. Finally, a mass balance of three different outlines with the aim to assess the amount of LA and biogas that may be generated within different scenarios is presented.
Cis,cis-muconic acid (MA) is a chemical that is recognized for its industrial value and is synthetically accessible from aromatic compounds. This feature provides the attractive possibility of ...producing MA from mixtures of aromatics found in depolymerized lignin, the most underutilized lignocellulosic biopolymer. Based on the metabolic pathway, the catechol (1,2-dihydroxybenzene) node is the central element of this type of production process: (i) all upper catabolic pathways of aromatics converge at catechol as the central intermediate, (ii) catechol itself is frequently generated during lignin pre-processing, and (iii) catechol is directly converted to the target product MA by catechol 1,2-dioxygenase. However, catechol is highly toxic, which poses a challenge for the bio-production of MA. In this study, the soil bacterium Pseudomonas putida KT2440 was upgraded to a fully genome-based host for the production of MA from catechol and upstream aromatics. At the core of the cell factories created was a designed synthetic pathway module, comprising both native catechol 1,2-dioxygenases, catA and catA2, under the control of the Pcat promoter. The pathway module increased catechol tolerance, catechol 1,2-dioxygenase levels, and catechol conversion rates. MA, the formed product, acted as an inducer of the module, triggering continuous expression. Cellular energy level and ATP yield were identified as critical parameters during catechol-based production. The engineered MA-6 strain achieved an MA titer of 64.2 g L−1 from catechol in a fed-batch process, which repeatedly regenerated the energy levels via specific feed pauses. The developed process was successfully transferred to the pilot scale to produce kilograms of MA at 97.9% purity. The MA-9 strain, equipped with a phenol hydroxylase, used phenol to produce MA and additionally converted o-cresol, m-cresol, and p-cresol to specific methylated variants of MA. This strain was used to demonstrate the entire value chain. Following hydrothermal depolymerization of softwood lignin to catechol, phenol and cresols, MA-9 accumulated 13 g L−1 MA and small amounts of 3-methyl MA, which were hydrogenated to adipic acid and its methylated derivative to polymerize nylon from lignin for the first time.
•Metabolic engineering of Pseudomonas putida for enhanced catechol tolerance and conversion efficiency.•Metabolic engineering of Pseudomonas putida for enhanced cis,cis-muconic acid (MA) production from mixtures of aromatics and lignin hydrolysates.•Pilot-scale production of kilograms of MA in a fed-batch process at 98% purity.•First time demonstration of the entire value chain from lignin to nylon.
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•Hydrolysis of coffee pulp recovered 70–80% of available sugars.•Lactic acid production from hydrolysate was investigated at 2L and 50L scales.•At 50L scale productivity was highest ...at 4.0gL−1h−1.•The yield was 0.78g lactic acid per gram of sugar consumed.•Downstream processing resulted in a 937gL−1 optical pure l(+)-lactic acid solution.
In this study, the lignocellulosic residue coffee pulp was used as carbon source in fermentative l(+)-lactic acid production using Bacillus coagulans. After thermo-chemical treatment at 121°C for 30min in presence of 0.18molL−1 H2SO4 and following an enzymatic digestion using Accellerase 1500 carbon-rich hydrolysates were obtained. Two different coffee pulp materials with comparable biomass composition were used, but sugar concentrations in hydrolysates showed variations. The primary sugars were (gL−1) glucose (20–30), xylose (15–25), sucrose (5–11) and arabinose (0.7–10). Fermentations were carried out at laboratory (2L) and pilot (50L) scales in presence of 10gL−1 yeast extract. At pilot scale carbon utilization and lactic acid yield per gram of sugar consumed were 94.65% and 0.78gg−1, respectively. The productivity was 4.02gL−1h−1. Downstream processing resulted in a pure formulation containing 937gL−1l(+)-lactic acid with an optical purity of 99.7%.
This work deals with the disturbed construction process, evaluated using the parameters cost, time, and quality. The aim is to transfer the actual situation of the disturbed construction process into ...a structured construction process. In this context, the possibility of data analysis and the associated creation of a resilient initial situation is demonstrated. One factor, time, is classified into a measurability with the possibilities of Gantt and Lean Construction Management. A representation of the monetary situation is the determination of additional costs. Here, the best case and worst case are presented and evaluated. The execution of the quality requires the comparison with the fictitious, planning quality defaults at project initiation and the now under consideration of the default costs and dates possible degree of fulfilment. The realization at the considered object has the following initial situation. Construction delay approx. 1 year, delta costs approx. 250 million euros, quality approaches were revised and partly reduced. This was the base for the creation of a schedule. The milestones from the Gantt schedule were incorporated into the system for the Lean Construction system. The monitoring between the milestones or intermediate goals was measured in the target-actual comparison.
Alternative methods were evaluated for chitin isolation from Acheta domesticus. Chemical demineralization was compared to fermentation with Lactococcus lactis, citric acid treatment, and microwave ...treatment, leading to a degree of demineralization of 91.1 ± 0.3, 97.3 ± 0.8, 70.5 ± 3.5, and 85.8 ± 1.3%, respectively. Fermentation with Bacillus subtilis, a deep eutectic solvent, and enzymatic digestion were tested for chitin isolation, generating materials with less than half the chitin content when compared to alkaline deproteinization. Chitosan was produced on a large scale by deacetylation of the chitinous material obtained from two selected processes: the chemical treatment and an alternative process combining L. lactis fermentation with bromelain deproteinization. The chemical and alternative processes resulted in similar chitosan content (81.9 and 88.0%), antioxidant activity (59 and 49%), and degree of deacetylation (66.6 and 62.9%), respectively. The chitosan products had comparable physical properties. Therefore, the alternative process is appropriate to replace the chemical process of chitin isolation for industrial applications.
Lignocellulosic biomass from agricultural residues is a promising feedstock for lactic acid (LA) production. The aim of the current study was to investigate the production of LA from different ...lignocellulosic biomass. The LA production from banana peduncles using strain
with yeast extract resulted in 26.6 g LA·L
, and yield of 0.90 g LA·g
sugars. The sugarcane fermentation with yeast extract resulted in 46.5 g LA·L
, and yield of 0.88 g LA·g
sugars. Carob showed that addition of yeast extract resulted in higher productivity of 3.2 g LA·L
·h
compared to without yeast extract where1.95 g LA·L
·h
was obtained. Interestingly, similar LA production was obtained by the end where 54.8 and 51.4 g·L
were obtained with and without yeast extract, respectively. A pilot scale of 35 L using carob biomass fermentation without yeast extract resulted in yield of 0.84 g LA·g
sugars, and productivity of 2.30 g LA·L
·h
which indicate a very promising process for future industrial production of LA.
Xylo-oligosaccharides are sugar oligomers with 2~7 xylose units considered non-digestible fibers that can be produced from biodegradable and low-cost biomass like wheat straw. An integrated approach ...consisting of hydrothermal pretreatment, alkaline treatment, enzymatic treatment and the combinations thereof was applied to overcome the recalcitrance structure of the wheat straw and allow selective fractioning into fermentable sugars and xylo-oligosaccharides. The hydrolysates and processed solids were chemically characterized by High-performance liquid chromatography and Ion chromatography, and the results were expressed as function of the severity factor and statistically interpreted. The concentration of fermentable sugars (glucose, xylose, arabinose) was the highest after the combination of alkaline and enzymatic treatment with xylanase (18 g/L sugars), while xylo-oligosaccharides (xylotriose and xylotetraose) were released in lower amounts (1.33 g/L) after the same treatment. Refining experiments were carried out to obtain a purified fraction by using anion and cation exchange chromatography. The polymer adsorber resin MN-502 showed efficient removal of salts, phenols and furan derivatives. However, the xylo-oligosaccharides yields were also slightly reduced. Although still requiring further optimization of the treatments to obtain higher purified oligomer yields, the results provide information on the production of xylo-oligosaccharides and fermentable sugars from wheat straw for potential use in food applications.
Lactic acid is a high-value molecule with a vast number of applications. Its production in the biorefineries model is a possibility for this sector to aggregate value to its production chain. Thus, ...this investigation presents a biorefinery model based on the traditional sugar beet industry proposing an approach to produce lactic acid from a waste stream. Sugar beet is used to produce sugar and ethanol, and the remaining pulp is sent to animal feed. Using
in a continuous fermentation, 2781.01 g of lactic acid was produced from 3916.91 g of sugars from hydrolyzed sugar beet pulp, with a maximum productivity of 18.06 g L
h
. Without interfering in the sugar production, ethanol, or lactic acid, it is also possible to produce pectin and phenolic compounds in the biorefinery. The lactic acid produced was purified by a bipolar membrane electrodialysis and the recovery reached 788.80 g/L with 98%
/
purity.
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