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[Display omitted] • Two ALE methods were designed to boost the biodetoxification of P. variotii. • The evolved strain showed stronger degradation on high titers inhibitors. • The evolved strains showed upregulation of adh , acs , ach1 , and ackA. • Furfural residues were successfully bioconverted to lactic acid. High inhibitor concentrations in lignocellulose feedstock negatively affect the degradation rate of biodetoxification strains. This study designed two adaptive laboratory evolutions in solid substrate and liquid medium to boost the biodetoxification capacity of P. variotii to high titers of lignocellulose-derived inhibitors, resulting in two evolved strains AC70 and ZW70. The results showed that the evolutionary adaptation in liquid medium could better boost the acetic acid assimilation compared to that on solid substrate. Transcriptional analysis revealed that the evolved strains exhibited a significant upregulation of adh , acs , ach1 , and ackA directly related to the initial steps of acetate and furan aldehydes metabolisms. ZW70 strain can effectively remove the high concentration inhibitors cocktail from the hydrolysates derived from pretreated wheat straw and furfural residues. The biodetoxified hydrolysates by ZW70 were successfully used for cellulose chiral L-lactic acid production with the titers of ∼110 g/L, which were over 20 % higher than that detoxified by parental strain. [ABSTRACT FROM AUTHOR]

[Display omitted] • A versatile ML-driven strategy was provided for caproic optimization. • Four ML models applied to predict caproic acid production with XGBoost performed best. • Feature importance analysis revealed HRT and butyric acid concentration as determinants. • SHAP analysis revealed adding glucose benefit caproic with lactic acid co-fermentation. • AVPSO algorithm optimized process conditions for maximum caproic acid production of 8.64 g/L. In this study, four machine learning (ML) prediction models were developed to predict and optimize the production performance of caproic acid based on substrates, products, and process parameters. The XGBoost outperformed others, with a high R2 of 0.998 on the training set and 0.885 on the test set. Feature importance analysis revealed hydraulic retention time (HRT) and butyric acid concentration are decisive. The SHAP method offered profound insights into the interplay and cumulative effects of substrate composition, identified the synergistic effects between butyric acid and lactic acid, and emphasized adding glucose can benefit caproic with lactic acid co-fermentation. By integrating the Adaptive Variation Particle Swarm Optimization (AVPSO) algorithm, the optimal process conditions to achieve a maximum caproic acid production of 8.64 g/L was obtained. This study not only advances caproic acid production but contributes a versatile ML-driven strategy applicable to bioprocess optimizations, potentially transformative for sustainable and economically viable bioproduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • M. elsdenii enhanced lactic acid conversion to H 2 in the strain mixtures. • M. elsdenii itself achieved up to 3-fold higher H 2 than Clostridium strains. • The addition of pretreated sludge boosted H 2 production in the strain mixtures. • The optimal mixture ratio of M. elsdenii and Clostridium produced 1739 mL H 2 /L. Lactic acid has been applied as a precursor for hydrogen (H 2) production from substrates rich in lactic acid bacteria (LAB), focusing on microbial interactions between producing and consuming LAB tested with model substrates. Therefore, this study evaluated the effect of single and combined lactic acid-consuming bacteria on mesophilic H 2 production in batch tests from lactic acid from fermented food waste (FW). Megasphaera elsdenii , Clostridium beijerinckii , and Clostridium butyricum were inoculated at different ratios (v/v). Additionally, thermal pretreated sludge (TPS) was added to the strain mixtures. The highest production was obtained with M. elsdenii , C. beijerinckii , and C. butyricum (17:66:17 ratio), obtaining 1629.0 mL/L reactor. The optimal mixture (68:32:0 of M. elsdenii and C. beijerinckii) enriched with TPS reached 1739.3 ± 98.6 mL H 2 /L reactor , consuming 98 % of lactic acid added. M. elsdenii and Clostridium strains enhance H 2 production from lactic acid as they persist in a microbial community initially dominated by LAB. [ABSTRACT FROM AUTHOR]

[Display omitted] • L-lactate dehydrogenase gene was disrupted in Lactiplantibacillus pentosus PeL. • PeL fermented hydrolyzed lignocellulosic materials to D-lactic acid at high yields. • D-lactic acid production of PeL from wood chips was 915.9 ± 4.4 mg/g at ton scale. • High-purity D-lactic acid (up to 95.0%) was achieved at both 100-L and ton scales. • Sustainable and industrialized D-lactic acid production was accomplished. Worsening environmental conditions make lactic acid a sustainable alternative to petroleum-based plastics. This study created a genetically-engineered strain Lactiplantibacillus pentosus PeL containing a disrupted L-lactate dehydrogenase gene to produce high yield and optically pure D-lactic acid. Cellobiose was identified as the optimal sugar in the single carbon source test, yielding the highest lactic acid. In 5-L fermentation tests, pretreated wood chips hydrolysate was the best lignocellulosic substrate for PeL, resulting in a D-lactic acid yield of 900.7 ± 141.4 mg/g of consumed sugars with an optical purity of 99.8 ± 0.0 %. Gradually scaled-up fermentations using this substrate were achieved in 100-, and 9,000-L fermenters; PeL produced remarkably high D-lactic acid yields of 836.3 ± 11.9 and 915.9 ± 4.4 mg/g of consumed sugars, with optical purities of 95.0 ± 0.0 % and 93.8 ± 0.2 %, respectively. This study is the pioneer in demonstrating economical and sustainable ton-scale production of D-lactic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Insect residues can be biotransformed by lactic acid bacteria without a carbon source. • Deproteinization of 29 % achieved after 120 h of incubation by L. brevis. • Lactic acid bacteria biomass increased by 2 log 10 CFU/mL in only 48 h. • Biotransformation led to the formation of peptides with antioxidant activity. Processing of edible insects typically involves fractionating into high-value food ingredients, which results in by-products containing chitin and insoluble proteins. This study examined the effectiveness of lactic acid bacteria (LAB) in removing proteins from chitin in insect processing residues. Lesser mealworm processing residues were biologically treated for 48 and 120 h using LAB strains without added carbon sources. Results showed partial deproteinization, up to 29 % with Levilactobacillus brevis after 120 h. Most LAB grew up to 2 log 10 colony-forming units/mL in the first 48 h. Confocal microscopy and Fourier-transform infrared spectra indicated that some protein remained attached to chitin. The molecular weight of solubilized proteins was affected by strain and time of incubation, with antioxidant activity increasing significantly after 120 h with Lacticaseibacillus paracasei. The biological treatment of insect processing streams can be a sustainable approach to producing high amounts of LAB biomass with subsequent protein solubilization and chitin release. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZVI addition boosted caproic acid production by 186% in co-culture experiments. • Co-culturing A. woodii and M. hexanoica optimized carbon flux towards caproic acid. • 3 g/L ZVI maximized CA yield while balancing biomass and carbon flux. • Automated bioreactor validation confirmed stable caproic acid production with ZVI. • ZVI as an electron donor enhanced lactate oxidation and chain elongation processes. Acetobacterium woodii and Megasphaera hexanoica were co-cultured for caproic acid (CA) production from lactic acid (LA) and CO 2. Also, various concentrations (1 g/L, 3 g/L, 5 g/L, and 10 g/L) of Zero Valent Iron (ZVI) were supplied to study its impact on the co-culture system. In flask experiments, 10 g/L LA and 1.0 bar CO 2 produced 0.6 g/L CA with some biomass growth. ZVI increased LA consumption and CA production. Indeed, 3 g/L ZVI boosted CA production by 186 % and biomass accumulation by 103 %, suggesting that ZVI controls the carbon flux. Subsequent automated bioreactor studies showed that 3 g/L ZVI produced 1.842 g/L CA at stable pH, compared to 0.969 g/L without ZVI (control). Further, metabolic activity showed that both bacteria could directly use H 2 , generated by ZVI (3 g/L), as electron donor. Higher ZVI concentrations (10 g/L) resulted in Fe2+ causing excessive oxidation pressure on M. hexanoica , with its carbon flux flowing preferentially towards biomass. Enzyme assays confirmed that A. woodii preferred 10 g/L ZVI while M. hexanoica preferred 3 g/L for optimal bioconversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LA yield of FW fermentation reached 0.91 g LA/g total sugar with 1 % ITs addition. • The mechanism analysis of ITs promoting LA fermentation of FW was demonstrated. • Pyruvate to LA conversion was facilitated by 1 % ITs with a high NADH/NAD+ ratio. • Lactococcus and Lactobacillus were more abundant with ITs addition. • LAB of FW fermentation system can partially remove heavy metals from ITs. In this study, the feasibility of promoting the lactic acid (LA) fermentation of food waste (FW) with iron tailings (ITs) addition was explored. The best LA yield was 0.91 g LA/g total sugar when 1 % ITs were added into the system. The mechanisms for promoting LA production were acidification alleviation effects and reduction equivalent supply of ITs. Furthermore, the addition of ITs promoted carbohydrate hydrolysis, and the carbohydrates digestibility reached 88.85 % in the 1 % ITs group. The ITs also affected the microbial communities, Lactococcus gradually replaced Streptococcus as the dominant genus, and results suggested that Lactococcus had a positive correlation with LA production and carbohydrate digestibility. Finally, the complex LAB in FW had significant effects on heavy metal removal from ITs, and the removal efficiency Cr, As, Pb, Cd, and Hg can reach 50.84 %, 26.72 %, 59.65 %, 49.75 % and 78.87 % in the 1 % ITs group, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • SM and AW fermentation for LA production via enzyme pretreatment was investigated. • High LA level of 42.70 g/L was observed at enzyme loading of 300 U/g VS substrate. • Enzymatic pretreatment boosted SM and AW solubilization and hydrolysis. • Lactobacillus for LA production was enriched by enzymatic pretreatment. Anaerobic co-fermentation of swine manure (SM) and apple waste (AW) restricts by the slow hydrolysis of substrates with complex structures, which subsequently leads to low lactic acid (LA) production. Therefore, a novel strategy based on enzymatic pretreatment for improving LA production from anaerobic co-fermentation of SM and AW was proposed in this study. The results indicated that the maximal LA concentration increased from 35.89 ± 1.84 to 42.70 ± 2.18 g/L with the increase of enzyme loading from 0 to 300 U/g VS substrate. Mechanism exploration indicated that enzymatic pretreatment significantly promoted the release and hydrolysis of insoluble organic matter from fermentation substrate, thus providing an abundance of reaction intermediates that were directly available for LA production. Additionally, bacteria analysis revealed that the high concentration of LA was associated with the prevalence of Lactobacillus. This study offered an environmental-friendly strategy for promoting SM and AW hydrolysis and provided a viable approach for recovering valuable products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-produced crude lactic acid was used to pretreat wheat straw. • Pretreatment by 2.0% crude lactic acid achieved 95.5% cellulose recovery rate. • Enzymatic hydrolysis was accomplished with glucose yield of 99.7%. • Pretreatment liquor was recycled three times without impaired capacity. • Lactic acid pretreatment improved the accessibility of cellulase to cellulose. The purpose of this study was to investigate an environmentally friendly and recyclable pretreatment approach that would enhance the enzymatic digestibility of wheat straw. Wheat straw was pretreated using self-produced crude lactic acid obtained from enzymatic hydrolysate fermentation by Bacillus coagulans. Experimentally, crude lactic acid at low concentration could achieve a pretreatment effect comparable to that of commercial lactic acid. After pretreatment at 180 °C for 60 min with 2.0 % crude lactic acid, hemicellulose could be effectively separated and high recovery of cellulose was ensured, achieving cellulose recovery rate of 95.5 % and hemicellulose removal rate of 92.7 %. Excellent enzymatic hydrolysis was accomplished with a glucose yield of 99.7 %. Moreover, the crude lactic acid demonstrated acceptable pretreatment and enzymatic hydrolysis performance even after three repeated cycles. This not only effectively utilizes the pretreatment solution, but also offers insights into biomass pretreatment using other fermentable acids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Red mud acted as both a detoxifying and neutralizing agent for the hydrolysate. • Detoxification of hydrolysate by red mud doubled the lactic acid productivity. • Red mud replaced CaCO 3 as a cheap neutralizer in lactic acid fermentation. • Simultaneous leaching of valuable metals in lactic acid fermentation was realized. • A dealkalization efficiency up to 92.2% was achieved for red mud. The cost of detoxification and neutralization poses certain challenges to the development of an economically viable lactic acid biorefinery with lignocellulosic biomass as feedstock. Herein, red mud, an alkaline waste, was explored as both a detoxifying agent and a neutralizer. Red mud treatment of lignocellulosic hydrolysate effectively removed the inhibitors generated in dilute acid pretreatment, improving the lactic acid productivity from 1.0 g/L·h−1 to 1.9 g/L·h−1 in later fermentation. In addition, red mud could replace CaCO 3 as a neutralizer in lactic acid fermentation, which in turn enabled simultaneous bioleaching of valuable metals (Sc, Y, Nd, and Al) from red mud. The neutralization of alkali in red mud by acids retained in lignocellulosic hydrolysate and lactic acid produced from fermentation led to effective dealkalization, rendering a maximum alkali removal efficiency of 92.2 %. Overall, this study offered a win–win strategy for the valorization of both lignocellulosic biomass and red mud. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1. UV–vis responsive Fe@C additives promote hydrogen production in photofermentation. • Introduction of TEOA in Fe@C hydrogen photofermentation system increased by 129%. • Dynamic regulation of fermentation environment and metabolites of R. sphaeroides. • Rapid electron transfer and microenvironment pH stability in ternary systems. This study investigated the mediating effect of Triethanolamine on Fe@C- Rhodobacter sphaeroides hybrid photosynthetic system to achieve efficient biohydrogen production. The biocompatible Fe@C generates excited electrons upon exposure to light, releasing ferrum for nitrogenase synthesis, and regulating the pH of the fermentation environment. Triethanolamine was introduced to optimize the electron transfer chain, thereby improving system stability, prolonging electron lifespan, and facilitating ferrum corrosion. This, in turn, stimulated the lactic acid synthetic metabolic pathway of Rhodobacter sphaeroides , resulting in increased reducing power in the biohybrid system. The ternary coupling system was analyzed through the regulation of concentration, initial pH, and light intensity. The system achieved the highest total H 2 production of 5410.9 mL/L, 1.29 times higher than the control (2360.5 mL/L). This research provides a valuable strategy for constructing ferrum-carbon-based composite-cellular biohybrid systems for photo-fermentation H 2 production. [ABSTRACT FROM AUTHOR]

Biobased L-lactic acid (L-LA) appeals to industries; however, existing technologies are plagued by limited productivity and high energy consumption. This study established an integrated process for producing macroalgae-based L-LA from Eucheuma denticulatum phycocolloid (EDP). Dilute acid-assisted microbubbles-mediated ozonolysis (DAMMO) was selected for the ozonolysis of EDP to optimize D-galactose recovery. Through single-factor optimization of DAMMO treatment, a maximum D-galactose recovery efficiency (59.10 %) was achieved using 0.15 M H 2 SO 4 at 80 °C for 75 min. Fermentation with 3 % (w/v) mixed microbial cells (Bacillus coagulans ATCC 7050 and Lactobacillus acidophilus-14) and fermented residues achieved a 97.67 % L-LA yield. Additionally, this culture approach was further evaluated in repeated-batch fermentation and showed an average L-LA yield of 93.30 %, providing a feasible concept for macroalgae-based L-LA production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

[Display omitted] • A novel osmotic-tolerant strain was generated by heavy ion mutagenesis. • The osmotic-tolerant strain had enhanced osmotic pressure tolerance ability. • The engineered strain had improved L-lactic acid production performance. Open unsterile fermentation of the low-cost non-food crop, sweet sorghum, is an economically feasible lactic acid biosynthesis process. However, hyperosmotic stress inhibits microbial metabolism and lactic acid biosynthesis, and engineering strains with high osmotic tolerance is challenging. Herein, heavy ion mutagenesis combined with osmotic pressure enrichment was used to engineer a hyperosmotic-tolerant Bacillus coagulans for L-lactic acid production. The engineered strain had higher osmotic pressure tolerance, when compared with the parental strain, primarily owing to its improved properties such as cell viability, cellular antioxidant capacity, and NADH supply. In a pilot-scale open unsterile fermentation using sweet sorghum juice as a feedstock, the engineered strain produced 94 g/L L-lactic acid with a yield of 91 % and productivity of 6.7 g/L/h, and optical purity of L-lactic acid at the end of fermentation was 99.8 %. In short, this study provided effective and low-cost approach to produce polymer-grade L-lactic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructed microbial consortia-based strategy enhanced caproic acid production. • Clostridium sensu stricto 1 and Caproiciproducers were key genera. • Lactate platform could contribute to product upgrading in acidogenic fermentation. • EDBM enabled phase separation of caproic acid with a purity of 82.58%. A constructed microbial consortia-based strategy to enhance caproic acid production from one-stage mixed-fermentation of glucose was developed, which incubated with acidogens (Clostridium sensu stricto 1 , 11 dominated) and chain elongators (including Clostridium sensu stricto 12 , Sporanaerobacter, and Caproiciproducens) acclimated from anaerobic sludge. Significant product upgrading toward caproic acid (8.31 g‧L−1) and improved substrate degradation was achieved, which can be greatly attributed to the lactic acid platform. Whereas, a small amount of caproic acid was observed in the control incubating with acidogens, with an average concentration of 2.09 g‧L−1. The strategy accelerated the shape and cooperation of the specific microbial community dominated by Clostridium sensu stricto and Caproiciproducens , which thereby contributed to caproic acid production via the fatty acid biosynthesis pathway. Moreover, the tailored electrodialysis with bipolar membrane enabled progressive up-concentration and acidification, allowing selective separation of caproic acid as an immiscible product with a purity of 82.58 % from the mixture. [ABSTRACT FROM AUTHOR]

[Display omitted] • An acid-tolerant yeast, I. orientalis , was engineered for organic acid production. • Engineered I. orientalis , SD108XL, can consume xylose and produce lactic acid. • Without pH regulation, SD108XL had difficulty in producing lactic acid. • A self-buffering strategy helps produce lactic acid by reducing pH regulation. This study presents a cost-effective strategy for producing organic acids from glucose and xylose using the acid-tolerant yeast, Issatchenkia orientalis. I. orientalis was engineered to produce lactic acid from xylose, and the resulting strain, SD108XL, successfully converted sorghum hydrolysates into lactic acid. In order to enable low-pH fermentation, a self-buffering strategy, where the lactic acid generated by the SD108XL strain during fermentation served as a buffer, was developed. As a result, the SD108 strain produced 67 g/L of lactic acid from 73 g/L of glucose and 40 g/L of xylose, simulating a sugar composition of sorghum biomass hydrolysates. Moreover, techno-economic analysis underscored the efficiency of the self-buffering strategy in streamlining the downstream process, thereby reducing production costs. These results demonstrate the potential of I. orientalis as a platform strain for the cost-effective production of organic acids from cellulosic hydrolysates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Structures of DESs affected the pretreatment efficiency and ethanol fermentation. • Lactic acid/guanidine hydrochloride effectively removed lignin and xylan. • The hydrolysates of various DES pulps had impressive ethanol yields. • 302.75 g ethanol and 118.98 g lignin were harvested from 1 kg dried biomass. Deep eutectic solvents (DESs) offer a potential opportunity in biomass utilization industries. This work emphasized the impact of hydrogen bond donors (HBD) and acceptors (HBA) on deconstruction and valorization of rice straw. Acidity, alkyl chain length, hydrogen bonding ability and functional groups of HBD and HBA appeared to be important factors affecting the fractionated pulps and lignins, which further influenced ethanol fermentation. Among the candidate DESs, lactic acid/guanidine hydrochloride (LGH) was proved to be the most suitable one due to the excellent delignification and xylan removal. For the downstream fermentation process, 0.47 g g−1 of bioethanol with 0.55 g/L h−1 of productivity can be obtained from the LGH pulp's hydrolysate. Mass balance showed 302.8 g bioethanol and 119.0 g technical lignin can be co-generated from 1 kg dried rice straw. This "green" valorization strategy offers a promising scheme in biorefinery of lignocelluloses. [ABSTRACT FROM AUTHOR]

[Display omitted] • The efficient D-lactic acid production from G. amansii hydrolysate was achieved. • P. acicilactici fermented the mixed sugars of galactose, glucose and xylose without CCR. • SSCF of the pretreated and biodetoxified G. amansii was conducted using P. acidilactici. • A record high of D-lactic acid (41.4 g/L) from macroalgae biomass was obtained. Macroalgae biomass has been considered as a promising renewable feedstock for lactic acid production owing to its lignin-free, high carbohydrate content and high productivity. Herein, the D-lactic acid production from red macroalgae Gelidium amansii by Pediococcus acidilactici was investigated. The fermentable sugars in G. amansii acid-prehydrolysate were mainly galactose and glucose with a small amounts of xylose. P. acidilactici could simultaneously ferment the mixed sugars of galactose, glucose and xylose into D-lactic acid at high yield (0.90 g/g), without carbon catabolite repression (CCR). The assimilating pathways of these sugars in P. acidilactici were proposed based on the whole genome sequences. Simultaneous saccharification and co-fermentation (SSCF) of the pretreated and biodetoxified G. amansii was also conducted , a record high of D-lactic acid (41.4 g/L) from macroalgae biomass with the yield of 0.34 g/g dry feedstock was achieved. This study provided an important biorefinery strain for D-lactic acid production from macroalgae biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • LAFL was preferred as external carbon source on N removal in wastewater treatment. • Adding LAFL render a more robust structure of microbial community than using NaAc. • Functional species ascribe to heterotrophic nitrifiers/denitrifiers were enhanced. • Excess sludge production reduced by 109% with adding LAFL relative to adding NaAc. Lactic acid-rich fermentation liquid (LAFL) of food waste is found to act as a promising alternative carbon source for nitrogen removal in wastewater treatment. Here, LAFL was employed to investigate its impacts on nitrogen removal during raw municipal wastewater treatment with a comparison to sodium acetate (NaAc). Results indicated that nitrogen removals were comparable when incorporated with LAFL and NaAc (92.89 % v.s. 91.23 %). Unlike the utilization of NaAc, using LAFL could avoid suppressing the relative abundance of the nitrification genes and thus pose a negative risk to nitrogen removal during prolonged operation. The introduction of LAFL increased the stability and robustness of the functional microbial community and effectively reduced excess activated sludge (AS) generation by 109 % compared to NaAc addition, consequently enhancing nitrogen removal but diminishing the treatment cost. In general, LAFL exhibits prospective engineering application potentials and economic advantages in improving nitrogen removal by AS process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed a dynamic regulation strategy for glycolate production. • Enhanced glycolate titer via cofactor engineering. • Achieved glucose and xylose co-utilization through sugar transport engineering. • Utilized corn stover hydrolysate as glycolate production substrate. Glycolic acid is widely employed in chemical cleaning, the production of polyglycolic acid-lactic acid, and polyglycolic acid. Currently, the bottleneck of glycolate biosynthesis lies on the imbalance of metabolic flux and the deficiency of NADPH. In this study, a dynamic regulation system was developed and optimized to enhance the metabolic flux from glucose to glycolate. Additionally, the knockout of transhydrogenase (sthA), along with the overexpression of pyridine nucleotide transhydrogenase (pntAB) and the implementation of the Entner-Doudoroff pathway, were performed to further increase the production of the NADPH, thereby increasing the titer of glycolate to 5.6 g/L. To produce glycolate from corn stover hydrolysate, carbon catabolite repression was alleviated and glucose utilization was accelerated. The final strain, E. coli Mgly10-245, is inducer-free, achieving a glycolate titer of 46.1 g/L using corn stover hydrolysate (77.1 % of theoretical yield). These findings will contribute to the advancement of industrial glycolate production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Brewers' spent grain (BSG) was valorized for enzymes and lactic acid production. • Trichoderma sp. could effectively produce cellulase and β-glucosidase from BSG. • Successive solid-state and submerged fermentation most promoted enzyme production. • Fungal enzyme cocktail could be used for low-cost lactic acid production from BSG. • This approach may also be applicable to other similar agro-industrial wastes. This study aimed to increase the value of brewers' spent grain (BSG) by using it as feedstock to produce lignocellulolytic enzymes and lactic acid (LA). Twenty-two fungal strains were screened for lignocellulolytic enzyme production from BSG. Among them, Trichoderma sp. showed the highest cellulase activity (35.84 ± 0.27 U/g-BSG) and considerably high activities of xylanase (599.61 ± 23.09 U/g-BSG) and β-glucosidase (16.97 ± 0.77 U/g-BSG) under successive solid-state and submerged fermentation. The processes were successfully scaled up in a bioreactor. The enzyme cocktail was recovered and characterized. The maximum cellulase and xylanase activities were found at pH 5.0 and 50 °C, and the activities were highly stable at pH 4–8 and 30–50 °C. The enzyme cocktail was applied in simultaneous saccharification and fermentation of acid-pretreated BSG for LA production. The maximum LA obtained was 59.3 ± 1.0 g/L. This study has shown the efficient biovalorization of BSG, and this approach may also be applicable to other agro-industrial wastes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigating the potential of rice husk (RH) as the biorefinery feed crop. • Combined alkali-HPAC pretreatment enhances the removal of lignin and silica from RH. • The hydrolysis process was optimized using the Box–Behnken experimental design. • The hydrolysis efficiency was 87.9% at 11% (wt) substrate concentration. • High efficiency co-production of bioethanol, lactic acid and D-psicose from RH. Rice husk, rich carbon content, is an agricultural waste produced globally at an amount of 120 million tons annually, and it has high potential as a biorefinery feedstock. Herein, we investigated the feasibility of producing various products as D-psicose, bioethanol and lactic acid from rice husk (RH) through a biorefinery process. Alkali-hydrogen peroxide-acetic acid pretreatment of RH effectively removed lignin and silica, resulting in enzymatic hydrolysis yield of approximately 86.3% under optimal hydrolysis conditions. By using xylose isomerase as well as D-psicose-3-epimerase with borate, glucose present in the RH hydrolysate was converted into D-psicose with a 40.6% conversion yield in the presence of borate. Furthermore, bioethanol (85.4%) and lactic acid (92.5%) were successfully produced from the RH hydrolysate. This study confirmed the high potential of RH as a biorefinery feedstock, and it is expected that various platform chemicals and value-added products can be produced using RH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The waste combustion ash from dry biorefinery contained high amount of CaCO 3. • The waste ash was efficiently recycled as neutralizer in biorefining chain. • No negative effects when 100% of CaCO 3 and 40% of Ca(OH) 2 was replaced by ash. • The cellulosic L-lactic acid titer reached 102.4 ± 3.6 g/L with waste ash recycling. One of the major end-products of lignocellulosic biorefining chain is the solid residues containing various compounds. The present approach to solid residues treatment is combustion for generation of heat and electricity. This study investigated the potential for recycling of the combustion ash from the solid residues after lignocellulosic dry biorefining process. A range of characterizations showed that the combustion ash contained a high amount of calcium carbonate. By recycling the ash as the neutralizer in biorefining process, the waste calcium carbonate in the ash was efficiently utilized for pretreated biomass neutralization and can replace 40 % of calcium hydroxide for lactic acid production. The chiral L-lactic acid titer reached 102.4 ± 3.6 g/L from 20 % (w/w) solids loading of wheat straw. Three feasible strategies of ash recycling for the investigated biorefinery concept were further proposed base on the rigorous calcium mass calculation, which can efficiently reduce the consumption of neutralizers. [ABSTRACT FROM AUTHOR]

Here, Baijiu distillers' grains (BDGs) were employed in biorefinery development to generate value-added co-products and bioethanol. Through ethyl acetate extraction at a 1:6 solid-liquid ratio for 10 h, significant results were achieved, including 100 % lactic acid and 92 % phenolics recovery. The remaining BDGs also achieved 99 % glucan recovery and 81 % glucan-to-glucose conversion. Simultaneous saccharification and fermentation of remaining BDGs at 30 % loading resulted in 78.5 g bioethanol/L with a yield of 94 %. The minimum selling price of bioethanol varies from $0.149-$0.836/kg, contingent on the co-product market prices. The biorefinery processing of one ton of BDGs caused a 60 % reduction in greenhouse gas emissions compared to that of the traditional production of 88 kg corn-lactic acid, 70 kg antioxidant phenolics, 234 kg soybean protein, and 225 kg corn-bioethanol, along with emissions from BDG landfilling. The biorefinery demonstrated a synergistic model of cost-effective bioethanol production and low-carbon emission BDGs treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

[Display omitted] • A ternary DES was prepared, explored and compared with binary ones. • Microwave-assisted DES pretreatment was applied for lignin processing. • Lignin has been improved such as purity, dispersity and thermal stability. • The interaction between ternary DES and lignin was analyzed by MD simulation. • Dissolution mechanism of microwave-assisted ternary DES on lignin was proposed. Lignin is the most abundant natural aromatic macromolecule in the nature, but its high value-added utilization has been seriously hindered by the highly random and branched structures and the high difficulty in separation and purification. A microwave-assisted ternary deep eutectic solvent (DES) composed by formic acid, lactic acid and choline chloride was developed for lignin pretreatment. The effects of three types of DES on main characteristics of lignin were investigated, and the corresponding dissolution mechanism was proposed. The results showed that, the microwave-assisted ternary DES pretreatment showed an obvious improvement on main characteristics of regenerated lignin, e.g., a higher purity, lower molecular weight with reduced dispersity, improved thermal stability, higher phenolic hydroxyl content, and increased antioxidative activity in comparison with control. It is expected that the lignin macromolecular can be facile regulated and upgraded by the proposed ternary DES. [ABSTRACT FROM AUTHOR]

[Display omitted] • Engineered G. thermoglucosidasius produces polymer-grade lactic acid at 60 °C. • Rational and semi-rational design strategies are used to reprogram the chassis. • Potential genetic targets are revealed to improve the production performance. • The highest lactic acid production is achieved in thermophile strains over 55 °C. The production and application of biodegradable polylactic acid are still severely hindered by the cost of its polymer-grade lactic acid monomers. High-temperature biomanufacturing has emerged as an increasingly attractive approach to enable low-cost and high-efficiency bulk chemical production. In this study, thermophilic Geobacillus thermoglucosidasius was reprogrammed to obtain optically pure l -lactic acid- and d -lactic acid-producing strains, G. thermoglucosidasius GTD17 and GTD7, by using rational metabolic engineering strategies including pathway construction, by-product elimination, and production enhancing. Moreover, semi-rational adaptive evolution was carried out to further improve their lactic acid synthesis performance. The final strains GTD17-55 and GTD7-144 produce 151.1 g/L of l -lactic acid and 153.1 g/L of d -lactic acid at 60 °C, respectively. In consideration of the high temperature, productive performance of these strains is superior compared to the state-of-the-art industrial strains. This study lays the foundation for the low-cost and efficient production of biodegradable plastic polylactic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • E. limosum was able to survive in the open culture during a continuous process. • SCCA were produced from glycerol and further elongated to MCCA with lactate. • Presence of E. limosum in an open culture boosted chain elongation to valerate. • Caproiciproducens species were dominant in the caproate producing open culture. • Imaging flow cytometry with machine learning discriminated the Eubacterium cells. The objective was to investigate the impact of the bioaugmentation on chain elongation process using glycerol, lactate and lactose as substrates in an open culture fermentation. In the batch trials the highest selectivity for chain elongation product, i.e. caproate, was observed in trials inoculated with co-culture of Megasphaera elsdenii and Eubacterium limosum grown on glycerol (28.6%), and in non-bioaugmented open culture run on lactose + lactate (14.8%). The results showed that E. limosum , out of two bioaugmented strains, was able to survive in the open culture. A continuous open culture fermentation of glycerol led to caproate and 1,3-propanediol (1,3-PDO) formation, while lactate addition led to 1,3-PDO and short chain carboxylates production. Moving the process into batch mode triggered even-carbon chain elongation. Presence of E. limosum promoted odd-carbon chain elongation and valerate production. Imaging flow cytometry combined with machine learning enabled the discrimination of Eubacterium cells from other microbial strains during the process. [ABSTRACT FROM AUTHOR]

[Display omitted] • An in vitro bienzyme system consisting of SPase and DAE was first constructed. • Lactic acid in CM induced SPase to hydrolyze sucrose instead of glycosylation. • High titer of 2-O-α-GG and d -allulose were prepared from A-CM via bienzyme system. The efficient and economical conversion of agricultural waste into glycosides and rare sugars is challenging. Herein, an in vitro synthetic bienzyme system consisting of sucrose phosphorylase and d -allulose 3-epimerase was constructed to produce 2-O-α-glucosyl glycerol and d -allulose from cane molasses. Lactic acid in the cane molasses significantly induced sucrose phosphorylase to hydrolyze sucrose instead of glycosylation. Notably, lactic acid significantly inhibited the catalytic performance of d -allulose 3-epimerase only in the presence of Na+ and K+, with an inhibition rate of 75%. After removing lactic acid and metal ions, 116 g/L 2-O-α-glucosyl glycerol and 51 g/L d -allulose were synthesized from 500 mM sucrose in the treated cane molasses with a sucrose consumption rate of 97%. Our findings offer an economically efficient and environmentally friendly pathway for the industrial production of glycosides and rare sugars from food industry waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solid-state fermentation was scaled-up in a new home-designed bioreactor. • Solid-state bioreactor size would be much smaller than the one for the hydrolysis. • Similar amylase activities were obtained in flasks and bioreactors (58 U/g ds) • Pilot scale experiments produced a lactic acid yield of 0.68 g LA /g ds and 0.89 g LA /g s. • Lactic acid was successfully purified at pilot scale, recovering the 55% Pasta waste has previously been studied in a process to obtain lactic acid through a sequential hydrolysis and fermentation. The process was improved by using enzymes produced via solid-state fermentation of wheat bran in shake flasks. However, the scale-up of the solid-state fermentation is a complex task. In this study, amylase was produced in a home-designed tray bioreactor which allowed to carry out the hydrolysis and fermentation steps at the pilot scale. Due to the efficiency of the solid-state fermentation and the activity of the enzyme, only a small amount (100 g) of wheat bran was required to achieve high yields in a hydrolysis in a 72 L bioreactor (50 L working volume). Overall, the lactic acid yield was 0.68 g LA /g dS , and after the purification, the lactic acid recovered was 55 %, with a total ion concentration of 500 mg/L and an enantiomeric purity of 98.1 % L-LA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recombinant yeast strains effectively hydrolyse single-use bioplastic items. • rCLE1 is modified during yeast expression and resulted in increased hydrolysis. • rCLE1 preferentially hydrolyses specific polymers in bioplastic blends. • Bioplastic blends could be highly susceptible to enzymatic hydrolysis. • Enzyme adsorption and product inhibition are bottlenecks to hydrolysis. • Future work would integrate enzymatic hydrolysis in waste management settings. Single-use bioplastic items pose new challenges for a circular plastics economy as they require different processing than petroleum-based plastics items. Microbial and enzymatic recycling approaches could address some of the pitfalls created by the influx of bioplastic waste. In this study, the recombinant expression of a cutinase-like-enzyme (CLE1) was improved in the yeast Saccharomyces cerevisiae to efficiently hydrolyse several commercial single-use bioplastic items constituting blends of poly(lactic acid), poly(1,4-butylene adipate -co- terephthalate), poly(butylene succinate) and mineral fillers. The hydrolysis process was optimised in controlled bioreactor configurations to deliver substantial monomer concentrations and, ultimately, 29 to 78% weight loss. Product inhibition studies and molecular docking provided insights into potential bottlenecks of the enzymatic hydrolysis process, while FT-IR analysis showed the preferential breakdown of specific polymers in blended commercial bioplastic items. This work constitutes a step towards implementing enzymatic hydrolysis as a circular economy approach for the valorisation of end-of-life single-use bioplastic items. [ABSTRACT FROM AUTHOR]

Green biorefinery process was conducted to extract α-chitin and high-value co-products from shrimp shell waste through microbial fermentation using mature coconut water (MCW) as a sole nutrient source. Symbiotic co-lactic acid fermentation (Co-LAF) by Lactobacillus plantarum and Streptococcus thermophilus produced higher levels of lactic acid (LA) and protease activity than their mono-cultures, which led to greater demineralization (DM) and deproteinization (DP) of shrimp shell powder (SSP). After optimizing Co-LAF through Response Surface Methodology and successive fermentation by an acid-active proteolytic fungus Rhizopus oligosporus, the highest DM of 94.0 ± 0.91 % and DP of 86.7 ± 0.1 % were achieved. Based on FT-IR, XRD, and SEM analysis, the bio-extracted chitin had similar structural characteristics to commercial α-chitin but with better quality. These strategies not only contribute to environmentally-friendly and cost-effective extraction of α-chitin (303 ± 18 mg/g-SSP), but also co-produce LA (57.18 ± 0.89 g/L), acid protease (4.33 ± 0.5 U/mL), bio-calcium (277 ± 12 mg-CaSO 4 /g-SSP), protein hydrolysate (268 ± 5 mg/g-SSP), and pigments (28.78 ± 1.56 µg/g-SSP)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Graphical abstract Highlights • Moringa oleifera leaves (MOL) ensiled with LAB strains and stored at 15 °C, 30 °C. • LAB inoculants improved fermentation quality of MOL silage. • The bacterial diversity of MOL silage stored at 30 °C was greater than 15 °C. • Exiguobacterium , Pseudomonas and Acinetobacter were more abundant at 30 °C. • Lactobacillus dominated in MOL silage and was enhanced when stored at 15 °C. Abstract Four lactic acid bacteria strains (LP, LF, LL, W), isolated and selected from Moringa oleifera leaves (MOL) silage, were identified as Lactobacillus plantarum , L. farciminis , Lactococcus lactis , Weissella thailandensis , respectively. Fermentation quality and bacterial community of MOL ensiled without or with the four strains at 15 °C and 30 °C were investigated. Results showed that all the LAB strains decreased (P < 0.05) the pH and ammonia-N content of MOL silage. Silage stored at 30 °C showed higher (P < 0.05) DM loss, acetic acid and ammonia-N content, and lower LAB count than 15 °C. The environmental temperature also made a great influence on bacterial community of MOL silage. Bacterial diversity was lower and the abundance of Lactobacillus was higher in silages stored at 15 °C. In conclusion, LAB inoculants and a relatively low environmental temperature could be effective to improve the quality of MOL silage. [ABSTRACT FROM AUTHOR]

Highlights • Lp A1 could enhance the ensilage process and enzymatic saccharification. • Pretreatment with Lp A1 could reduce the fiber content of corn stalk silage. • Cellulose + Lp A1 had better performance in reducing lignocellulose. • Lp A1 had better performance in reducing lignocellulose at 25 °C rather than 40 °C. Abstract The effects of Acremonium cellulase and L. plantarum A1 with ferulic acid esterase activity on corn stalk silage fermentation characteristics, carbohydrate composition and enzymatic saccharification were studied at 25 and 40 °C, respectively. Corn stalk was ensiled without additive (C), Acremonium cellulase (AC), L. plantarum A1 (Lp) and AC + Lp for 60 days. Pretreatment with Lp or AC + Lp promoted the better silage fermentation and the degradation of lignocellulose as indicated by high lactic acid and low pH and lignocellulose content compared to control silages at 25 °C. AC + Lp performed better in reducing lignocellulose and DM loss. In addition, Lp alone enhanced enzymatic saccharification of corn stalk silage. However, the influence of L. plantarum A1 on corn stalk silage was not obvious at 40 °C. Corn stalk ensiled with combined additive is a suitable pretreatment method for subsequent biofuel production at 25 °C, but addition of Acremonium cellulase alone at 40 °C may be a promising method. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A mechanism of high-rate hydrogen production of DMBR was proposed. • H 2 production increased with dynamic membrane development without immobilization. • Flux balance analysis revealed the increase of H 2 -producing acetegenesis in DM. • Sporolactobacillaceae would contribute the H 2 -producing acetogenic activity. Abstract This study aimed to investigate the relationship among dynamic membrane (DM) formation, metabolic flux, and microbial community population in dark fermentative hydrogen production. A continuously stirred tank reactor was equipped with an external submerged polyester screen mesh and inoculated with heat-treated anaerobic sludge without immobilization. DM was successfully developed on the polyester mesh and provided high-rate hydrogen production at 60.5 L H 2 /L.d and 2.39 mol H 2 /mol glucose added. DM formation was along with tightly bound extracellular polymeric substances. Flux balance analysis revealed that formation of DM altered the metabolic pathways for acetic acid production from homoacetogenesis to hydrogenesis. Bacterial community analysis suggested that Sporolactobacillaceae would contributed to this metabolic pathway shift. Nevertheless, lactic acid was not accumulated and assumed to be consumed by hydrogen producers including Clostridia. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Increase in carboxylates concentration was accompanied by a decline in lactate. • Lactate with ethanol promote lactate oxidation coupled to chain elongation. • Lactic acid strongly affects the chain elongation. • Ionic liquid are promising for liquid-liquid extraction of carboxylates. • It is possible to economically effective produce caproic acid. Abstract The objective of this study was to investigate the potential of supplementing ethanol and lactic acid as electron donors in reverse β-oxidation for short chain carboxylic acids chain elongation during anaerobic fermentation of acid whey. Best results were achieved when lactic acid was added at concentration of 300 mM. It resulted in medium chain carboxylic acids (MCCAs) concentration of 5.0 g/L. In the trials with ethanol addition, the overall yield was 20% lower. Subsequently liquid-liquid extraction with ionic liquids (ILs) was investigated as a potential purification method of caproic acid. The most promising, with respect to recovery of caproic acid, was piperazinium IL [C 1 C 1 C 10 Ppz][NTF 2 ], however, the selectivity was only 0.39. Less effective [C 1 C 1 C 6 Ppz][NTF 2 ] recovered 85.9% of caproic acid while reaching a higher selectivity of 0.53. Technoeconomic model revealed that to meet the conservative value of $2.25 per kg of caproic acid, the downstream processing should not exceed $0.65 per kg. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An efficient l -lactic acid (l -LA) production yeast strain was constructed. • Glucose and xylose were simultaneously consumed in l -LA production. • No accumulation of xylitol via co-fermentation of glucose and xylose. • 103.00 g/L l -LA was produced through corncob SSCF with economical nitrogen source. • The optical purity of produced l -LA was 99.5%. Abstract Lactic acid is an important industrial product and the production from inexpensive and renewable lignocellulose can reduce the cost and environmental pollution. In this study, a Kluyveromyces marxianus strain which produced lactic acid efficiently from corncob was constructed. Firstly, two of six different lactate dehydrogenases, which from Plasmodium falciparum and Bacillus subtilis , respectively, were proved to be effective for l -lactic acid production. Then, five single genetic modifications were conducted. The overexpression of Saccharomyces cerevisiae proton-coupled monocarboxylate transporter, K. marxianus 6-phosphofructokinase, or disruption of K. marxianus putative d -lactate dehydrogenase enhanced the l -lactic acid accumulation. Finally, the strain YKX071, obtained via combination of above effective genetic engineering, produced 103.00 g/L l -lactic acid at 42 °C with optical purity of 99.5% from corncob residue via simultaneous saccharification and co-fermentation. This study first developed an effective platform for high optical purity l -lactic acid production from lignocellulose using yeast with inexpensive nitrogen sources. [ABSTRACT FROM AUTHOR]

Highlights • Lactic acid is produced from xylose and glucose using a genetically modified strain. • The modified strain presents yields very close to the theoretical. • The process was simulated to develop a technical and economic analysis. • The scale of production has great influence on the distribution of costs. • The industrial implementation of the strain is possible due to its versatility. Abstract In this work, d -lactic acid production was evaluated from a simulated hydrolysate of corn stover (32 g/L xylose, 42 g/L glucose) with the metabolically engineered Escherichia coli strain JU15. Based on the experimental results, a technical and economic analysis of the entire process was performed using the Aspen Plus software. As a result, it was possible to show that the strain can efficiently produce lactic acid from both sugars, reaching a final concentration of 40 g/L and a yield of 0.6 g lactic acid/g sugars. The process is economically viable at higher scales of 1000 tons/day. The cost distribution is influenced by the scale of the process; on a larger scale, the cost of raw materials represents a higher percentage of total cost than it does on smaller scales. The use of a metabolically engineered strain allows a better use of the sugars obtained from agroindustrial residues. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • B. coagulans IPE22 had the ability to excrete amylase (29.47 mU/mg in DF). • One step open SLSF method was optimal for LA production by B. coagulans. • LA productivity was related to both LDH activity and glucose concentration. • Inedible cassava and sorghum flour were alternatives of refined starch. Abstract The aim of this study was to establish a simplified operational process for lactic acid (LA) production by Bacillus coagulans IPE22 from inedible starchy biomass with open fermentation method. First, 29.47 mU/mg specific amylase activity was detected in direct batch fermentation from soluble starch, but the activity of the produced amylase was too low for effective production of LA. Then seven batches from 72 g/L soluble starch were conducted without sterilization. It was found that one step simultaneous liquefaction, saccharification and fermentation (SLSF) with the addition of mesothermal α-amylase and glucoamylase was the optimal mode with LA concentration, yield and productivity of 68.72 g/L, 0.99 g/g and 1.72 g/L h respectively. Finally, inedible starchy biomass, cassava and sorghum flours, were proved to be alternatives to refined soluble starch. For the first time, one step open SLSF of inedible starchy biomass was reported for LA production by B. coagulans. [ABSTRACT FROM AUTHOR]

Highlights • Production of fumaric, lactic and succinic acids by various immobilized cells. • Improvement of process parameters of organic acid production with immobilized cells. • Simultaneous saccharification of various raw materials sources to acids. • Efficient reuse of immobilized cells in organic acid production. Abstract The study was aimed at production of different organic acids (OA) (lactic, fumaric, or succinic) by various microbial cells (filamentous fungi Rhizopus oryzae (F-814, F-1127) and bacteria Actinobacillus succinogenes B-10111) immobilized into poly(vinyl alcohol) (PVA) cryogel from diverse renewable raw materials (wheat and rice straw, aspen and pine sawdust, Jerusalem artichoke stems and tubers, biomass of macro- and microalgae) under batch conditions. The process productivity, bulk output and OA concentrations were higher in case of using immobilized cells than in case of free cells under identical conditions. A higher OA productivity was reached via simultaneous enzymatic saccharification and microbial fermentation (SSF) of same raw materials as compared to their separate enzymatic hydrolysis and fermentation of accumulated reducing sugars (SHF). Maximal concentrations of all OAs studied were obtained for bioconversion of Jerusalem artichoke tubers. The immobilized cells were used in long-term conversion of various renewable materials to OAs in SSF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher than 200 g/L lactic acid was obtained from DLC-pretreated corn stover. • Cellulosic lactic acid fermentation was realized at 40% solid loading. • Cellulosic lactic acid fermentation was significantly improved by SSCF. • L. pentosus LB-1 can co-utilize glucose, xylose, arabinose, galactose and mannose. • No detoxify units are required for DLC pretreatment based biorefinery system. Lignocellulosic biomass is a reliable feedstock for lactic acid fermentation, low product titers hamper the scale production of cellulosic lactic acid. In this study, a Densifying Lignocellulosic biomass with Chemicals (sulfuric acid) pretreatment based cellulosic lactic acid biorefinery system was developed and demonstrated from multi-dimensions of producing bacteria, fermentation modes, corn stover solid loadings, fermentation vessels, and product purification. Results suggested that several lactic acid bacteria exhibited high fermentation activity in high solid loading corn stover hydrolysates. Remarkably, simultaneous saccharification co-fermentation performed in 100-mL flasks enabled 210.1 g/L lactic acid from 40% solid loading corn stover hydrolysate. When simultaneous saccharification co-fermentation was performed in 3-L bioreactors, 157.4 g/L lactic acid was obtained from 35% solid loading corn stover hydrolysate. These obtained lactic acid titers are the highest reports until now when lignocellulosic biomasses are used as substrates, making it efficient for scale production of cellulosic lactic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • It is the first time to use C.glutamicum to remove lactic acid from AW. • C.glutamicum mutants with enhanced lactate metabolic rate were isolated using ALE. • Best adapted strain reduced time required for lactic acid removal from AW by 50%. • The removal of lactic acid increased lactose yield of powder after spray drying. The presence of lactic acid and galactose makes spray drying of acid whey (AW) a significant challenge for the dairy industry. In this study, a novel approach is explored to remove these compounds, utilizing food-grade microorganisms. For removing lactic acid, Corynebacterium glutamicum was selected, which has an inherent ability to metabolize lactic acid but does so slowly. To accelerate lactic acid metabolism, a mutant strain G6006 was isolated through adaptive laboratory evolution, which metabolized all lactic acid from AW two times faster than its parent strain. To eliminate galactose, a lactose-negative mutant of Lactococcus lactis that cannot produce lactate was generated. This strain was then co-cultured with G6006 to maximize the removal of both lactic acid and galactose. The microbially "filtered" AW could readily be spray dried into a stable lactose powder. This study highlights the potential of utilizing food-grade microorganisms to process AW, which currently constitutes a global challenge. [ABSTRACT FROM AUTHOR]

[Display omitted] • A biobased, biodegradable, eco-friendly PLA/LA x carbon source was prepared. • High-molecular-weight PLA biodegraded better with slight ʟ-lactide. • Phylum unclassified_f__Rhodocyclaceae played a crucial role in denitrification. • Enriched Bacteroidota and Chloroflexi endow more biodegradability for PLA. • Mechanism of incorporating slight ʟ-lactide on PLA biodegradability was revealed. The utilization of wasted Poly(lactic acid) (PLA) as low-cost carbon sources in solid-phase denitrification is hindered by its low biodegradability, which can be attributed to its high molecular weight. This study presents a new approach by blending high-molecular-weight PLA with a small amount of ʟ-lactide (PLA/LA x) to treat nitrate-contaminated wastewater. The addition of ʟ-lactide enhanced the release of carbon from high-molecular-weight PLA. An impressive denitrification efficiency of 96.7% was achieved, accompanied by extremely low levels of accumulated NO 2 - - N (0.1 mg/L) and NH 4 + - N (0.4 mg/L). The quantity of ʟ-lactide used significantly impacted the bacterial community structure. A high abundance of the phyla Bacteroidota and Chloroflexi associated with polymer degradation was observed. The most dominant denitrifier was the genus unclassified_f__Rhodocyclaceae belonged to the phylum Proteobacteria. This study demonstrates that blending PLA with just 5 wt% lactide can transform it into a highly effective solid-phase carbon source to eliminate nitrates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of DGs and RS co-ensiling on methane production were studied. • The high amount of DGs enhanced lactic acid fermentation and the ensiling quality. • Low amounts of DGs enhance biodegradation but limit energy conversion. • High amounts of DGs significantly improve energy conversion and CH 4 yields. • Organic matter preservation of ensiling is essential for methane production. High organic matter preservation during ensiling promotes material conversion and energy output. In this study, the effects of co-ensiling distillers grains and rice straw on methane production was evaluated, as distillers grains are highly acidic. For co-ensiling, distillers grains and rice straw were mixed to produce methane at five carbon/nitrogen (C/N) ratios. RD20 (C/N20) and RD25 (C/N25) were defined as high-distillers-grain groups and other mixed groups as low-distillers-grain groups. The results showed that Lactobacillus was enriched in RD25, with the highest lactic acid content reaching 54.0 g/kg of dry matter. The pH and organic dry matter loss of RD25 were lower than those of low-distillers-grain groups, but the result for lignocellulose degradation rate was reversed. An 8.6% increase in methane yield and 7.9% increase in energy output were achieved in RD25. Ensiling-anaerobic digestion systems of C/N25 provide high organic matter preservation and energy output. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignin (47.1%) and xylan (44.6%) were removed at severity factor LogR 0 = 3.67. • Linear relations with saccharification relation were fitted. • The cellulase digestibility of Betaine:LA-treated SCB was 73.8%. • Comprehensive understanding of Betaine:LA pretreated SCB was explored. Green solvents, especially deep eutectic solvents (DESs), are widely applied to pretreat biomass for enhancing its enzymatic hydrolysis. In this work, lactic acid was selected as the hydrogen-bond-donor to prepare Betaine-base DES (Betaine:LA), The DES was utilized to pretreat sugarcane bagasse (SCB) at 160 ℃ for 80 min (severity factor LogR 0 = 3.67). The influences of Betaine:LA treatment on the chemical composition, crystal and microstructure structure of cellulose, and cellulase digestion were investigated. The results showed that the lignin (47.1%) and xylan (44.6%) were removed, the cellulase digestibility of Betaine:LA-treated SCB was 4.2 times that of the raw material. This improved efficiency was attributed to the enhanced accessibility of cellulose, the weakened surface area of lignin, the declined hydrophobicity, and the decreased crystallinity of cellulose. Several compelling linear correlations were fitted between enzymatic hydrolysis and these alterations of physicochemical features, comprehensively understanding enzymatic saccharification of Betaine:LA-pretreated SCB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel arginine-based DES pretreatment was proposed with fast microwave assistance. • Optimal delignification (84.8%) and saccharification (81.9%) were gained for LAA-3. • Supramolecular structures of crystalline cellulose greatly impact on bioconversion. • Lower viscosity and high α value of DES contribute to higher conversion yields. Development of amino acid-based natural deep eutectic solvents (DESs) pretreatment technology on lignocellulosic biomass is a promising approach to biorefinery. In this study, for arginine-based DESs with different molar ratios, the viscosity and Kamlet-Taft solvation parameters were quantified to evaluate the pretreatment performance on bamboo biomass. Further, microwave assisted DES pretreatment was eminent, evidenced by 84.8% lignin removal and increased saccharification yield (from 6.3% to 81.9%) in moso bamboo at 120 °C and ratio of 1:7 (arginine: lactic acid). Results showed degradation of lignin molecules together with release of phenolic hydroxyl units after DESs pretreatment, which is conducive to subsequent utilization. Meanwhile, DES-pretreated cellulose exhibited unique structural characteristics including destroyed crystalline region of cellulose (Crystallinity Index from 67.2% to 53.0%), decreased crystallite size (from 3.41 nm to 3.14 nm) and roughened fiber surface. Thus, arginine-based DES pretreatment has excellent potential in bamboo lignocellulose pretreatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • High solid loading of GG (1:7) reduced 40.8% byproduct from hemicellulose. • Carbon catabolite repression (CCR) reduced xylose conversion rate to 48.2%. • Semi-hydrolysis relieved CCR and restored xylose conversion rate to 85.7%. • Lactic acid yield of hemicellulose achieved to 0.49 g/g from GG hydrolysate. • High glucose induced ptsH and ccpA up-regulated and xylose genes down-regulated. Byproduct (acetate and ethanol) generation and carbon catabolite repression are two critical impediments to lactic acid production from the hemicellulose of lignocellulosic biomass. To reduce byproduct generations, acid pretreatment with high solid loading (solid–liquid ratio 1:7) of garden garbage was conducted. The byproduct yield was only 0.30 g/g during in the subsequent lactic acid fermentation from acid pretreatment liquid and 40.8% lower than that of low solid loading (0.48 g/g). Furthermore, semi-hydrolysis with low enzyme loading (10 FPU/g garden garbage cellulase) was conducted to regulate and reduce glucose concentration in the hydrolysate, thereby relieving carbon catabolite repression. During the lactic acid fermentation process, the xylose conversion rate was restored from 48.2% (glucose-oriented hydrolysis) to 85.7%, eventually achieving a 0.49 g/g lactic acid yield of hemicellulose. Additionally, RNA-seq revealed that semi-hydrolysis with low enzyme loading down-regulated the expression of ptsH and ccpA , thereby relieving carbon catabolite repression. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bacillus coagulans CC17B-1 can produce LA directly from corn cob hydrolysates. • CC17B-1 demonstrated a remarkable self-detoxification ability for hydrolysates. • Highly efficient phenolic acids degradation capacity was observed. • Phenolic aldehydes are converted to phenolic alcohols, which are further degraded. Here, an adapted Bacillus coagulans (Weizmannia coagulans) strain CC17B-1 was developed for lignocellulosic lactic acid production through a short and rapid adaptive laboratory evolution technique. Without any detoxification, two actual corn cob hydrolysates from the factory were effectively fermented to lactic acid within 60 h. Strain CC17B-1 is capable of degrading all nine determined phenolic compounds in the hydrolysate, with the only exception being vanillic acid. Notably, its tolerances for ferulic acid and p -coumaric acid are the highest doses reported in anaerobic microbes. A proposed degradation pathway showed that strain CC17B-1 could convert phenolic aldehydes to phenolic alcohol and then further degrade them completely. This work provides new ideas for the microbe phenolic degradation pathway and paves the way for industrial lactic acid production from lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Caproic acid (CA) production from food waste (FW) is a promising way for waste recycling, while the fermentation processes need further exploration. In this study, FW acidogenic fermentation under different pH (uncontrolled, 4, 5, 6) using indigenous microbiota was investigated. Result showed that substrate hydrolysis, carbohydrate degradation and acidogenesis increased with the increase of pH. Although various microbial communities were observed in FW, lactic acid bacteria (Lactobacillus and Limosilactobacillus) were enriched at pH lower than 6, resulting in lactic acid accumulation. CA (88.24 mM) was produced at pH 6 accounting for 31.23% of the total product carbon. The enriched lactic acid bacteria were directionally replaced by chain elongators (Caproicibacter, Clostridium&#95;sensu&#95;stricto, unclassified&#95;Ruminococcaceae) at pH 6, and carbohydrates in FW were firstly transformed into lactic acid, then to butyrate and CA through lactate-based chain elongation processes. This work provided a novel CA fermentation pathway and further enriched the FW valorization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this study, repeated-batch fermentation was used to convert fruit and vegetable waste to lactate and volatile fatty acids (VFAs), which are essential carbon sources for medium-chain fatty acids (MCFAs) production. The effect of cycle time and replacement ratio on acidification in long-term fermentation was investigated. The results showed that they had a significant impact on product yield, productivity, and type of products. Considering the yield, productivity, and lactate/VFAs ratio, a replacement ratio of 30% and a cycle time of 2 d may be more suitable for further production of MCFAs. Its productivity and lactate/VFAs ratio were 4.07 ± 0.24 g/(L·d) and 5 ± 0.6, respectively. The lactic acid bacteria, such as Enterococcus (63%) and Lactobacillus (33%), stabilized in the reactor, resulting in the generation of both lactate and VFAs by heterolactic fermentation. The present study demonstrated a new strategy with the potential to recover high-value products from organic waste streams., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)