Fermentative l-lactic acid production from pretreated whole slurry of oil palm trunk treated by hydrothermolysis and subsequent enzymatic hydrolysis

Efficient production of polyhydroxybutyrate using lignocellulosic biomass derived from oil palm trunks by the inhibitor-tolerant strain Burkholderia ambifaria E5-3

Lignocellulosic biomass is a valuable, renewable substrate for the synthesis of polyhydroxybutyrate (PHB), an ecofriendly biopolymer. In this study, bacterial strain E5-3 was isolated from soil in Japan; it was identified as Burkholderia ambifaria strain E5-3 by 16 S rRNA gene sequencing. The strain showed optimal growth at 37 °C with an initial pH of 9. It demonstrated diverse metabolic ability, processing a broad range of carbon substrates, including xylose, glucose, sucrose, glycerol, cellobiose, and, notably, palm oil. Palm oil induced the highest cellular growth, with a PHB content of 65% wt. The strain exhibited inherent tolerance to potential fermentation inhibitors derived from lignocellulosic hydrolysate, withstanding 3 g/L 5-hydroxymethylfurfural and 1.25 g/L acetic acid. Employing a fed-batch fermentation strategy with a combination of glucose, xylose, and cellobiose resulted in PHB production 2.7-times that in traditional batch fermentation. The use of oil palm trunk hydrolysate, without inhibitor pretreatment, in a fed-batch fermentation setup led to significant cell growth with a PHB content of 45% wt, equivalent to 10 g/L. The physicochemical attributes of xylose-derived PHB produced by strain E5-3 included a molecular weight of 722 kDa, a number-average molecular weight of 191 kDa, and a polydispersity index of 3.78. The amorphous structure of this PHB displayed a glass transition temperature of 4.59 °C, while its crystalline counterpart had a melting point of 171.03 °C. This research highlights the potential of lignocellulosic feedstocks, especially oil palm trunk hydrolysate, for PHB production through fed-batch fermentation by B. ambifaria strain E5-3, which has high inhibitor tolerance.

Biotechnological enhancement of lactic acid conversion from palm kernel cake by immobilized Actinobacillus succinogenes 130Z.. [DOI: 10.21203/rs.3.rs-2469941/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The aim of this study was to establish an improved pretreatment and fermentation method i.e. immobilized cells for high recovery of fermentable sugars from PKC and its effects on fermentability performance by Actinobacillus succinogenes 130Z in the conversion of lactic acid. The effects of oxalic acid concentrations (1–6% w/v) and residence times (1–5 h) on the sugar recovery were initially investigated and it was found that the highest mannose concentration was 25.1 g/L at the optimum hydrolysis conditions of 4 h and 3% (w/v) oxalic acid. The subsequent enzymatic saccharification of the pretreated PKC afforded the highest enzymatic digestibility with the recovered sugars amounting to 25.18 g/L and 9.14 g/L of mannose and glucose, respectively. Subsequently, the fermentability performance of PKC hydrolysate was evaluated and compared in terms of cultivation phases (i.e. mono and dual-phases), carbonate loadings (i.e. magnesium and sodium carbonates), and types of sugars (i.e. glucose and mannose). The highest titer of 19.4 g/L lactic acid was obtained from the fermentation involving A. succinogenes 130Z in dual-phase cultivation supplemented with 30 g/L of magnesium carbonate. Lactic acid production was further enhanced by using immobilized cells with coconut shell-activated carbon (CSAC) of different sizes (A, B, C, and D) in the repeated batch cultivation of dual-phase fermentation producing 31.64 g/L of lactic acid. This work sheds light on the possibilities to enhance the utilization of PKC for lactic acid production via immobilized A. succinogenes 130Z.

An integrated biorefinery strategy for the utilization of palm-oil wastes

Each year, the palm oil industry generates a significant amount of biomass residue and effluent waste; both have been identified as significant sources of greenhouse gas (GHG) emissions. This issue poses a severe environmental challenge for the industry due to the possibility of long-term negative effects on human well-being. The palm-oil industry must invest significantly in the technology that is required to resolve these issues and to increase the industry's sustainability. However, current technologies for converting wastes such as lignocellulosic components and effluents into biochemical products are insufficient for optimal utilization. This review discusses the geographical availability of palm-oil biomass, its current utilization routes, and then recommends the development of technology for converting palm-oil biomass into value-added products through an integrated biorefinery strategy. Additionally, this review summarizes the palm oil industry's contribution to achieving sustainable development goals (SDGs) through a circular bioeconomy concept.

Electrochemical biomass upgrading: degradation of glucose to lactic acid on a copper(ii) electrode

Biomass upgrading - the conversion of biomass waste into value-added products - provides a possible solution to reduce global dependency on nonrenewable resources. This study investigates the possibility of green biomass upgrading for lactic acid production by electrochemically-driven degradation of glucose. Herein we report an electrooxidized copper(ii) electrode which exhibits a turnover frequency of 5.04 s^-1 for glucose conversion. Chronoamperometry experiments under varied potentials, alkalinity, and electrode preparation achieved a maximum lactic acid yield of 23.3 ± 1.2% and selectivity of 31.1 ± 1.9% (1.46 V vs. RHE, 1.0 M NaOH) for a room temperature and open-to-atmosphere reaction. Comparison between reaction conditions revealed lactic acid yield depends on alkalinity and applied potential, while pre-oxidation of the copper had a negligible effect on yield. Post-reaction cyclic voltammetry studies indicated no loss in reactivity for copper(ii) electrodes after a 30 hour reaction. Finally, a mechanism dependent on solvated Cu²⁺ species is proposed as evidenced by similar product distributions in electrocatalytic and thermocatalytic systems.

High-Titer Lactic Acid Production by Pediococcus acidilactici PA204 from Corn Stover through Fed-Batch Simultaneous Saccharification and Fermentation

Lignocellulose comprised of cellulose and hemicellulose is one of the most abundant renewable feedstocks. Lactic acid bacteria have the ability to ferment sugar derived from lignocellulose. In this study, Pediococcus acidilactici PA204 is a lactic acid bacterium with a high tolerance of temperature and high-efficiency utilization of xylose. We developed a fed-batch simultaneous saccharification and fermentation (SSF) process at 37 °C (pH 6.0) using the 30 FPU (filter paper units)/g cellulase and 20 g/L corn steep powder in a 5 L bioreactor to produce lactic acid (LA). The titer, yield, and productivity of LA produced from 12% (w/w) NaOH-pretreated and washed stover were 92.01 g/L, 0.77 g/g stover, and 1.28 g/L/h, respectively, and those from 15% NaOH-pretreated and washed stover were 104.11 g/L, 0.69 g/g stover, and 1.24 g/L/h, respectively. This study develops a feasible fed-batch SSF process for LA production from corn stover and provides a promising candidate strain for high-titer and -yield lignocellulose-derived LA production.

POLYMERIC BIOMATERIALS FOR SCAFFOLD-BASED BONE REGENERATIVE ENGINEERING

Reconstruction of large bone defects resulting from trauma, neoplasm, or infection is a challenging problem in reconstructive surgery. The need for bone grafting has been increasing steadily partly because of our enhanced capability to salvage limbs after major bone loss. Engineered bone graft substitutes can have advantages such as lack of antigenicity, high availability, and varying properties depending on the applications chosen for use. These favorable attributes have contributed to the rise of scaffold-based polymeric tissue regeneration. Critical components in the scaffold-based polymeric regenerative engineering approach often include 1. The existence of biodegradable polymeric porous structures with properties selected to promote tissue regeneration and while providing appropriate mechanical support during tissue regeneration. 2. Cellular populations that can influence and enhance regeneration. 3. The use of growth and morphogenetic factors which can influence cellular migration, differentiation and tissue regeneration in vivo. Biodegradable polymers constitute an attractive class of biomaterials for the development of scaffolds due to their flexibility in chemistry and their ability to produce biocompatible degradation products. This paper presents an overview of polymeric scaffold-based bone tissue regeneration and reviews approaches as well as the particular roles of biodegradable polymers currently in use.

Production of 5-aminovaleric acid in recombinant Corynebacterium glutamicum strains from a Miscanthus hydrolysate solution prepared by a newly developed Miscanthus hydrolysis process

This study examined nine expired industrial Corynebacterium glutamicum strains with high lysine producing capability for enhanced production of 5-AVA. C. glutamicum KCTC 1857 exhibiting the highest lysine production was transformed with either original Pseudomonas putida davBA genes, encoding the 5-AVA biosynthesis pathway, or C. glutamicum codon-optimized davBA genes. C. glutamicum KCTC 1857 expressing the original genes had superior cell viability and 5-AVA production capability compared to the other strain. This strain produced 39.93g/L of 5-AVA, which is the highest titer reported to date in fed-batch fermentation from glucose. Indeed, Miscanthus hydrolysate solution prepared from a novel process, comprising pretreatment, hydrolysis, purification, and concentration, was used as feedstock for 5-AVA production. A total of 12.51g/L 5-AVA was produced from the Miscanthus hydrolysate; this value is 34.7% higher than that obtained from glucose in batch fermentation.

Microbial biodiesel production from oil palm biomass hydrolysate using marine Rhodococcus sp. YHY01

The effect of various biomass derived inhibitors (i.e. furfural, hydroxymethylfurfural (HMF), vanillin, 4-hydroxy benzaldehyde (4-HB) and acetate) was investigated for fatty acid accumulation in Rhodococcus sp. YHY 01. Rhodococcus sp. YHY01 was able to utilize acetate, vanillin, and 4-HB for biomass production and fatty acid accumulation. The IC₅₀ value for furfural (3.1mM), HMF (3.2mM), vanillin (2.0mM), 4-HB (2.7mM) and acetate (3.7mM) was calculated. HMF and vanillin affect fatty acid composition and increase saturated fatty acid content. Rhodococcus sp. YHY 01 cultured with empty fruit bunch hydrolysate (EFBH) as the main carbon source resulted in enhanced biomass (20%) and fatty acid productivity (37%), in compression to glucose as a carbon source. Overall, this study showed the beneficial effects of inhibitory molecules on growth and fatty acid production, and support the idea of biomass hydrolysate utilization for biodiesel production by avoiding complex efforts to remove inhibitory compounds.

Reducing sugar loss in enzymatic hydrolysis of ethylenediamine pretreated corn stover

In this study, the effect of ethylenediamine (EDA) on enzymatic hydrolysis with different cellulosic substrates and the approaches to reduce sugar loss in enzymatic hydrolysis were investigated. During enzymatic hydrolysis, xylose yield reduced 21.2%, 18.1% and 13.0% with 7.5mL/L EDA for AFEX pretreated corn stover (CS), washed EDA pretreated CS and CS cellulose. FTIR and GPC analysis demonstrated EDA reacted with sugar and produced high molecular weight (MW) compounds. EDA was prone to react with xylose other than glucose. H₂O₂ and Na₂SO₃ cannot prevent sugar loss in glucose/xylose-EDA mixture, although they inhibited the browning and high MW compounds formation. By decreasing temperature to 30°C, the loss of xylose yield reduced to only 3.8%, 3.6% and 4.2% with 7.5mL/L EDA in the enzymatic hydrolysis of AFEX pretreated CS, washed EDA pretreated CS and CS cellulose.

Medium engineering for enhanced production of undecylprodigiosin antibiotic in Streptomyces coelicolor using oil palm biomass hydrolysate as a carbon source

In this study, a biosugar obtained from empty fruit bunch (EFB) of oil palm by hot water treatment and subsequent enzymatic saccharification was used for undecylprodigiosin production, using Streptomyces coelicolor. Furfural is a major inhibitor present in EFB hydrolysate (EFBH), having a minimum inhibitory concentration (MIC) of 1.9mM, and it reduces utilization of glucose (27%), xylose (59%), inhibits mycelium formation, and affects antibiotic production. Interestingly, furfural was found to be a good activator of undecylprodigiosin production in S. coelicolor, which enhanced undecylprodigiosin production by up to 52%. Optimization by mixture analysis resulted in a synthetic medium containing glucose:furfural:ACN:DMSO (1%, 2mM, 0.2% and 0.3%, respectively). Finally, S. coelicolor was cultured in a fermenter in minimal medium with EFBH as a carbon source and addition of the components described above. This yielded 4.2μg/mgdcw undecylprodigiosin, which was 3.2-fold higher compared to that in un-optimized medium.

Recombinant Ralstonia eutropha engineered to utilize xylose and its use for the production of poly(3-hydroxybutyrate) from sunflower stalk hydrolysate solution

Background

Lignocellulosic raw materials have extensively been examined for the production of bio-based fuels, chemicals, and polymers using microbial platforms. Since xylose is one of the major components of the hydrolyzed lignocelluloses, it is being considered a promising substrate in lignocelluloses based fermentation process. Ralstonia eutropha, one of the most powerful and natural producers of polyhydroxyalkanoates (PHAs), has extensively been examined for the production of bio-based chemicals, fuels, and polymers. However, to the best of our knowledge, lignocellulosic feedstock has not been employed for R. eutropha probably due to its narrow spectrum of substrate utilization. Thus, R. eutropha engineered to utilize xylose should be useful in the development of microbial process for bio-based products from lignocellulosic feedstock.

Results

Recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes encoding xylose isomerase and xylulokinase respectively, was constructed and examined for the synthesis of poly(3-hydroxybutyrate) [P(3HB)] using xylose as a sole carbon source. It could produce 2.31 g/L of P(3HB) with a P(3HB) content of 30.95 wt% when it was cultured in a nitrogen limited chemically defined medium containing 20.18 g/L of xylose in a batch fermentation. Also, recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes produced 5.71 g/L of P(3HB) with a P(3HB) content of 78.11 wt% from a mixture of 10.05 g/L of glucose and 10.91 g/L of xylose in the same culture condition. The P(3HB) concentration and content could be increased to 8.79 g/L and 88.69 wt%, respectively, when it was cultured in the medium containing 16.74 g/L of glucose and 6.15 g/L of xylose. Further examination of recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes by fed-batch fermentation resulted in the production of 33.70 g/L of P(3HB) in 108 h with a P(3HB) content of 79.02 wt%. The concentration of xylose could be maintained as high as 6 g/L, which is similar to the initial concentration of xylose during the fed-batch fermentation suggesting that xylose consumption is not inhibited during fermentation. Finally, recombinant R. eutorpha NCIMB11599 expressing the E. coli xylAB gene was examined for the production of P(3HB) from the hydrolysate solution of sunflower stalk. The hydrolysate solution of sunflower stalk was prepared as a model lignocellulosic biomass, which contains 78.8 g/L of glucose, 26.9 g/L of xylose, and small amount of 4.8 g/L of galactose and mannose. When recombinant R. eutropha NCIMB11599 expressing the E. coli xylAB genes was cultured in a nitrogen limited chemically defined medium containing 23.1 g/L of hydrolysate solution of sunflower stalk, which corresponds to 16.8 g/L of glucose and 5.9 g/L of xylose, it completely consumed glucose and xylose in the sunflower stalk based medium resulting in the production of 7.86 g/L of P(3HB) with a P(3HB) content of 72.53 wt%.

Conclusions

Ralstonia eutropha was successfully engineered to utilize xylose as a sole carbon source as well as to co-utilize it in the presence of glucose for the synthesis of P(3HB). In addition, R. eutropha engineered to utilized xylose could synthesize P(3HB) from the sunflower stalk hydrolysate solution containing glucose and xylose as major sugars, which suggests that xylose utilizing R. eutropha developed in this study should be useful for development of lignocellulose based microbial processes.

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

The effects of pH, temperature and high organic loading rate (OLR) on lactic acid production from food waste without extra inoculum addition were investigated in this study. Using batch experiments, the results showed that although the hydrolysis rate increased with pH adjustment, the lactic acid concentration and productivity were highest at pH 6. High temperatures were suitable for solubilization but seriously restricted the acidification processes. The highest lactic acid yield (0.46g/g-TS) and productivity (278.1mg/Lh) were obtained at 37°C and pH 6. In addition, the lactic acid concentration gradually increased with the increase in OLR, and the semi-continuous reactor could be stably operated at an OLR of 18g-TS/Ld. However, system instability, low lactic acid yield and a decrease in VS removal were noticed at high OLRs (22g-TS/Ld). The concentrations of volatile fatty acids (VFAs) in the fermentation mixture were relatively low but slightly increased with OLR, and acetate was the predominant VFA component. Using high-throughput pyrosequencing, Lactobacillus from the raw food waste was found to selectively accumulate and become dominant in the semi-continuous reactor.

Biobutanediol-mediated liquefaction of empty fruit bunch saccharification residues to prepare lignin biopolyols

Saccharification residue from empty fruit bunch (EFB) was liquefied with bio-butanediol to produce lignin biopolyols for the preparation of biopolyurethane. To substitute petroleum-derived polyhydric alcohols, butanediol isomers (1,4-butanediol, levo-2,3-bio-butanediol, and meso-2,3-bio-butanediol) or PEG#400-blended butanediol isomers were used as liquefaction solvents in the presence of sulfuric acid catalyst. Lignin biopolyols with a conversion of 63.3%, a hydroxyl number of 582.7 mg KOH/g and an acid number of 21.7 mg KOH/g were obtained under the optimal condition consisting of 25% biomass loading, 3% acid loading, and a temperature of 150°C for 120 min when liquefied with 1,4-butanediol/PEG#400 blended solvent (9/1, w/w). When the levo-2,3-bio-butanediol solvent was used in the absence of PEG#400, the highest conversion, 68.9%, was obtained. Lignin biopolyol-based biopolyurethanes were synthesized with toluene diisocyanate. FT-IR analysis revealed that EFB lignin biopolyols liquefied with bio-butanediols were suitable monomers for the preparation of biopolyurethane.

High titer L-lactic acid production from corn stover with minimum wastewater generation and techno-economic evaluation based on Aspen plus modeling

Technological potentials of l-lactic acid production from corn stover feedstock were investigated by experimental and techno-economic studies. An optimal performance with 104.5 g/L in l-lactic acid titer and 71.5% in overall yield from cellulose in corn stover to l-lactic acid using an engineered Pediococcus acidilactici strain were obtained by overcoming several technical barriers. A rigorous Aspen plus model for l-lactic acid production starting from dry dilute acid pretreated and biodetoxified corn stover was developed. The techno-economic analysis shows that the minimum l-lactic acid selling price (MLSP) was $0.523 per kg, which was close to that of the commercial l-lactic acid produced from starch feedstock, and 24% less expensive than that of ethanol from corn stover, even though the xylose utilization was not considered. The study provided a prototype of industrial application and an evaluation model for high titer l-lactic acid production from lignocellulose feedstock.