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Background Wood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining. Results We recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden (https://doi.org/10.5061/dryad.gtht76hrd). These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome-wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole-tree-biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees. Conclusions The simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks.

Aims The present study aimed to specifically transform stevioside (ST) into rubusoside (RS) through bioconversion with high efficiency, seeking to endow steviol glycosides (SGs) with subtle flavours for commercial acceptability. Methods and Results An endophytic bacterium named Lelliottia LST-1 was screened and confirmed to specifically convert ST into RS, reaching a conversion rate of 75.4% after response surface optimization. Phylogenetic analysis combined with complete genome sequencing demonstrated that LST-1 was also presumed to be a new species. To further explore the principle and process of biological transformation, the potential beta-glucosidases GH3-1, GH3-2, GH3-3 and GH3-4 were expressed, purified and reacted with SGs. High-performance liquid chromatography revealed that all enzymes hydrolysed ST and generated RS, but substrate specificity analysis indicated that GH3-2 had the highest substrate specificity towards STs and the highest enzyme activity. Conclusion The potential β-glucosidase GH3-2 in Lelliottia sp. LST-1 was found to specifically and efficiently convert ST to RS. Significance and Impact of Study The efficient biotransformation of ST into RS will be beneficial to its large-scale production and extensive application in the food and pharmaceutical industries.

Black soldier fly larvae (BSFL) are widely used in recycling and upcycling of nutrients in agri-food by-products, but low and inconsistent BSFL rearing performance (i.e. larval growth, bioconversion rate, and substrate reduction) has been identified as a key challenge. The aims of this research were two-fold: (1) validate an existing closed rearing system design; and (2) assess whether a microbial inoculum derived from the rearing residue increases rearing performance. In controlled bench-scale experiments, BSFL were reared on tomato pomace (TP) and white wine pomace (WWP), along with food waste as control substrate. The two aims were assessed based on the following response variables: larval mass, substrate reduction, residue properties (i.e. pH, temperature, moisture content), and larval intestinal and residue microbiota. Higher BSFL mass (by 5.1 mg dry mass) at harvest on WWP and substrate reduction on TP (by 11.7% dry mass) in the closed system compared to the open system confirmed the potential of closed systems for rearing performance improvements of agri-food by-products. The rearing system also affected the residual moisture content and temperature, but only had a small effect on microbiota. Performance improvements by the closed rearing system design may be outweighed by insufficient aeration with pasty substrates and higher operational efforts for aeration and larval separation from the high-moisture residues. In contrast to the rearing system design, addition of the residue-derived microbial inoculum did not result in improved performance, nor did it alter intestinal and residue microbiota. Missing performance improvements could have been due to absent or low numbers of probiotic bacteria. The success of microbial substrate supplementation could be improved by studying effects of larval-associated microbes and developing cultivation methods that selectively amplify the beneficial (yet unknown) members of the microbial community. Our investigations aimed to increase the valorisation of low-value agri-food by-products in BSFL rearing.

Black soldier fly larvae (BSFL) treatment is promising for organic waste valorisation in the circular economy; however, waste variability impacts the process performance and quality of produced larvae. Specifically, variation in the carbohydrate profile of treated wastes has been suggested to have a significant impact on BSFL treatment performance and quality of produced larvae, with particular carbohydrates either positively or negatively influencing these variables. This study examines the hypothesis that the types of carbohydrates within the substrate can have significant influence on larval survival, waste reduction, bioconversion, and waste conversion efficiency, as well as the crude lipid content and fatty acid profiles of the produced larvae. The carbohydrates explored were D glucose, sucrose, D (−) fructose, corn and wheat starch, D (+) galactose, D (+) mannose, D (+) xylose, D (−) arabinose and xylan from beechwood. Young larvae were grown for 9 days on chicken feed-based diets containing various carbohydrate additives each at 20 dry mass %. Treatments containing hemicellulose constituents galactose and arabinose produced the most adverse effects on process performance relative to the benchmark. Xylan was significantly detrimental to bioconversion (−14.7 ± 3.8%) and waste conversion efficiencies (−19.0 ± 4.4%). There were minimal significant effects on performance from mono- and di-saccharides and starch additives. Larvae crude lipid contents were significantly increased by wheat starch (+12.6 ± 3.0%) and decreased by galactose (−15.0 ± 1.4%) and xylan additives (−27.5 ± 3.4%), however fatty acid profiles were largely unaffected and were dominated by lauric acid. These results indicate that despite an otherwise balanced and nutritious substrate, the carbohydrate profile of organic waste should be an important consideration in BSFL treatment when ensuring process performance and larval lipid contents. The consequences of these results for BSFL treatment of real wastes are discussed. Large scale treatment facilities should formulate substrates accordingly and identify methods to mitigate the anti-nutritional effects of poor carbohydrate profiles, particularly those high in hemicelluloses and their constituents.

Stevia rebaudiana is a sweet herbaceous perennial plant, which is frequently used in the preparation of plant‐based sweeteners. The demand for such sweeteners continues to increase due to purposeful nutrition and modern‐day metabolic syndromes. More than 20 types of steviol glycosides provide a sweet taste, which are more than 300 times sweeter than sucrose. They are formed of two main components, namely stevioside and rebaudioside A. Only a handful of studies have dealt with Stevia rebaudiana leaf extracts, the conversion of pure stevioside into the preferred rebaudioside A is more common. The aim of this study was to enrich the rebaudioside A content of Stevia rebaudiana leaf extract using enzymatic bioconversion by applying fermented cyclodextrin glycosyltransferase from Bacillus licheniformis DSM13. Two differently processed plant materials, namely dried and lyophilized Stevia rebaudiana plants, were extracted and compared. Following the bioconversion, the rebaudioside A content was on average doubled. The maximum increase was fivefold with a 70–80% conversion of the stevioside.

Ectoine, a cyclic amino acid derivative is produced by some moderately halophilic microorganisms. It is widely used in the field of medicine and cosmetics; however its high cost, low yield and complicated production process restrict its use in an industry. The present study was carried out to construct an engineered Escherichia coli for the heterologous ectoine production. Firstly, the ectoine synthesis cluster (ectABC genes) from Halomonas elongata were introduced into E. coli for the ectoine production in heterologous system. Secondly, the effect of deletion for lysA and thrA on producing ectoine was investigated. Thirdly, the bioconversion conditions for synthesizing ectoine were optimized. In this study, nine strains of E.coli BW25113 were constructed, and an engineering strain ABC (∆lysA)/BW25113 with ectoine synthesis ability was screened out. An improved yield of ectoine was obtained with optimized conditions like 100 mmol/L sodium aspartate, 100 mmol/L glycerol, 80 mmol/L glucose and 120 mmol/L KCl at temperature 30°C, and the pH 7.0. A yield 2.08 g/L of ectoine was obtained. After preliminary optimization, the ABC (∆lysA)/BW25113 catalytic synthesis of ectoine increased by 2 times, indicating that optimized reaction conditions can increase the yield of ectoine. Here, we successfully constructed an engineered Escherichia coli for the heterologous production of ectoine. Our study herein provides a feasible and valuable biosynthesis pathway of ectoine with a potential for large-scale industrial production using simple and cheap feedstocks.

Pretreatment of lignocellulosic biomass is crucial for the release of biofermentable sugars for biofuels production, which could greatly alleviate the burgeoning environment and energy crisis caused by the massive usage of traditional fossil fuels. Pyrolysis is a cost-saving pretreatment process that can readily decompose biomass into levoglucosan, a promising anhydrosugar; however, many undesired toxic compounds inhibitory to downstream microbial fermentation are also generated during the pyrolysis, immensely impeding the bioconversion of levoglucosan-containing pyrolysate. Here, we took the first insight into the proteomic responses of a levoglucosan-utilizing and ethanol-producing Escherichia coli to three representative biomass-derived inhibitors, identifying large amounts of differentially expressed proteins (DEPs) that could guide the downstream metabolic engineering for the development of inhibitor-resistant strains. Fifteen up- and eight down-regulated DEPs were further identified as the biomarker stress-responsive proteins candidate for cellular tolerance to multiple inhibitors. Among these biomarker proteins, YcfR exhibiting the highest expression fold-change level was chosen as the target of overexpression to validate proteomics results and develop robust strains with enhanced inhibitor tolerance and fermentation performance. Finally, based on four plasmid-borne genes encoding the levoglucosan kinase, pyruvate decarboxylase, alcohol dehydrogenase, and protein YcfR, a new recombinant strain E. coli LGE-ycfR was successfully created, showing much higher acetic acid-, furfural-, and phenol-tolerance levels compared to the control without overexpression of ycfR. The specific growth rate, final cell density, ethanol concentration, ethanol productivity, and levoglucosan consumption rate of the recombinant were also remarkably improved. From the proteomics-guided metabolic engineering and phenotypic observations, we for the first time corroborated that YcfR is a stress-induced protein responsive to multiple biomass-derived inhibitors, and also developed an inhibitors-resistant strain that could produce bioethanol from levoglucosan in the presence of inhibitors of relatively high concentration. The newly developed E. coli LGE-ycfR strain that could eliminate the commonly-used costly detoxicification processes, is of great potential for the in situ cost-effective bioethanol production from the biomass-derived pyrolytic substrates.

Alpha-amylase is one of the most employed enzymes in the food industry because of its capacity to degrade starch, improving the organoleptic and nutritional properties of food products. Thus, it is very important to develop novel industrial production processes for its production. A submerged fermentation process using Aspergillus oryzae was optimised to modulate the most important factors affecting alpha-amylase production. Flour mill waste, an abundant worldwide agro-industrial residue, was used as substrate due to its starch-rich composition. This residue was able to avoid catabolite repression during the fermentation, acting as a slow-release substrate. The process optimization led to a maximum yield of alpha-amylase production of 14076 ± 2346 U/L. The secretome of the fungi in the tested conditions was analysed by LC-MS, showing that two isoforms of alpha-amylase (amy-1 and amy-3) were produced. Finally, a two-step process was developed to purify alpha-amylase, consisting of fractional precipitation using (NH4)2SO4 followed by hydrophobic interaction chromatography. The purification allowed a four-time concentration of alpha-amylase, with an eleven-time purification factor and 65 % recovery and a reduction of the proteolytic activity to 14%.

This study developed postbiotics with whey bioconversion product produced by Enterococcus faecalis M157 KACC 81148BP, and mixed whey bioconversion products produced by E. faecalis M157 KACC 81148BP and Lactococcus lactis ssp. lactis CAU2013 KACC 81152BP to alleviate periodontitis (PD) and to improve gut health. The powdered whey bioconversion product (EF) produced by E. faecalis M157 KACC 81148BP, mixed whey bioconversion products (EF+LL) from E. faecalis M157 KACC 81148BP and L. lactis CAU2013 KACC 81152BP, and phosphate-buffered saline (PBS; control) were administered orally to PD-induced rats for 8 wk. Infiltration of inflammatory cells and epithelial proliferation in periodontal tissue were found in control, but the lesions were reduced in PD+EF group (administration of EF to PD-induced rats), and no lesions were observed in PD+EF+LL group (administration of EF+LL to PD-induced rats). The bone loss volumes in PD+EF and PD+EF+LL groups were lower than in control. Cytokine production levels related to inflammation were lower and antioxidative stress markers were higher in PD+EF and PD+EF+LL groups than in control for both periodontal tissue and gut. The ratios of Lactobacillus spp. in gut microbiome of PD+EF and PD+EF+LL groups were higher than in control. These results indicate that the whey bioconversion product produced by E. faecalis M157 KACC 81148BP, and mixed whey bioconversion products produced by E. faecalis M157 KACC 81148BP and L. lactis CAU2013 KACC 81152BP are effective on relieving periodontitis and improving the gut health.

Vine shoots (Vitis vinifera L.) constitute an abundant lignocellulosic source which is frequently underutilised. Alkaline and acidic pretreatments (with and without washing steps) were compared and optimised to release fermentable sugars from vine shoots. An acidic pretreatment using 1.72% H2SO4 at 134 °C for 17 min (with 10% w/w solid biomass), followed by an enzymatic hydrolysis, offered the most cost-effective results, releasing 40.21 g/L sugars. Three thermotolerant strains, namely, Bacillus coagulans DSM 2314, Geobacillus stearothermophilus DSM 2313, and G. stearothermophilus DSM 494, were assessed to produce lactic acid from vine-shoot hydrolysates under aerobic and non-sterile conditions, without the need of detoxification steps. In addition, wine lees were satisfactorily employed as nitrogen sources for the fermentation, providing similar results to yeast extract and being the only nutrient added to vine-shoot hydrolysates. Under optimal conditions, B. coagulans DSM 2314 produced 29.21 ± 0.23 g/L lactic acid in 24 h, with a sugar consumption of 98.74 ± 0.07% and a yield of 96.38 ± 0.76%, when supplemented with red wine lees. The purity of the isomer L( +) reached 97.59 ± 1.35% of the total lactic acid produced. Although G. stearothermophilus was able to transform the hexoses from vine-shoot hydrolysates into lactic acid, it proved to be inefficient for metabolising pentoses, thus obtaining lower lactic acid values (16–18 g/L).

The current research demonstrates the biotechnological economization of accumulated and inefficiently used agro-industrial orange peel wastes to generate amylase, endoglucanase, exoglucanase, pectinase, and xylanase, industrially essential enzymes with growing demands in enzyme markets, from three Cladosporium isolates. In submerged fermentation (SmF) at 10°C, the isolate AUMC 10865 produced the highest level of amylase (4164 IU/gram dry substrate). Endoglucanase, exoglucanase and xylanase had development peaks (923 IU/gds, 2280 IU/gds, and 1646 IU/gds, respectively in case of Cladosporium sp. AUMC 11366. Pectinase produced the most (7840 IU/gds) in the strain AUMC 11340. At 30°C, the strain AUMC 11340 secretes the most amylase (4120 IU/gds), endoglucanase (2700 IU/gds) and xylanase (3220 IU/gds). Exoglucanase development reached the peak (8750 IU/gds) in the isolate AUMC 10865. The overall production (5570 IU/gds) was instead enhanced by pectinase in the AUMC 11366 isolate. In solid-state fermentation (SSF) at 10°C, the isolate AUMC 10865 outperformed the other two isolates producing 640.0 IU/gds amylase, 763.3 IU/gds endoglucanase, 771.0 IU/gds exoglucanase, 1273.23 IU/gds pectinase and 1062.0 IU/gds xylanase, while the isolate AUMC 11366 produced the least amount of 399.7 IU/gds, 410.0 IU/gds, 413.3 IU/gds, 558.7 IU/gds, and 548.0 IU/gds, respectively. At 30°C, the isolate AUMC 11340 was superiorly producing higher levels of amylase (973.3 IU/gds), endoglucanase (746.0 IU/gds), exoglucanase (1052.0 IU/gds), pectinase (1685.3 IU/gds) and xylanase (1340.0 IU/gds), whereas isolate AUMC 10865 generated the least amounts of amylase (556.7 IU/gds) and exoglucanase (452.7 IU/gfs), and the isolate AUMC 11366 produced the least endoglucanase (256.3 IU/gds), pectinase (857.7 IU/gfs) and xylanase (436.3 IU/gds) amounts.

The combined cross-linked enzyme aggregates (combi-CLEAs) containing galactitol dehydrogenase (Gdh) and NADH oxidase (Nox) were prepared for l-tagatose synthesis. To prevent the excess consumption of cofactor, Nox in the combi-CLEAs was used to in situ regenerate NAD+. In the immobilization process, ammonia sulfate and glutaraldehyde were used as the precipitant and cross-linking reagent, respectively. The preparation conditions were optimized as follows: 60% ammonium sulfate, 1:1 (molar ratio) of Gdh to Nox, 20:1 (molar ratio) of protein to glutaraldehyde, and 6 h of cross-linking time at 35 °C. Under these conditions, the activity of the combi-CLEAs was 210 U g−1. The combi-CLEAs exhibited higher thermostability and preserved 51.5% of the original activity after eight cycles of reuses at 45 °C. The combi-CLEAs were utilized for the preparation of l-tagatose without by-products. Therefore, the combi-CLEAs have the industrial potential for the bioconversion of galactitol to l-tagatose.

Prenyl groups increase the lipophilicity of flavonoids, endowing them with a special activity, selectivity, and pharmacological properties by prenylation. Herein, a novel prenyltransferase (ShFPT) gene from Streptomyces sp. NT11 was expressed in Escherichia coli, and its biochemical characteristics were determined. ShFPT exhibited high selectivity to prenylate naringenin at C-6 to generate 6-prenylnaringenin. The optimal activity was observed at pH 6.0 and 55 °C. The Kcat and Km for naringenin were 0.0095 s-1 and 0.20 mM, respectively. Several promiscuous kinase and isopentenyl phosphate kinase genes were screened to develop the most efficient dimethylallyl diphosphate (DMAPP) synthesis pathway for 6-prenylnaringenin synthesis in E. coli. The 6-prenylnaringenin production was improved by changing the induction strategies and optimizing the bioconversion conditions. Finally, 6-prenylnaringenin production reached the highest yield of 69.9 mg/L with average productivity of 4.0 mg/L/h after 16 h incubation, which is the highest yield for any prenylated flavonoid reported to date in E. coli. Therefore, this study provides an efficient method for 6-prenylnaringenin production and reveals the DMAPP synthesis pathway.

Background Lignocellulosic biomass is an attractive and sustainable alternative to petroleum-based feedstock for the production of a range of biochemicals, and pretreatment is generally regarded as indispensable for its biorefinery. However, various inhibitors that severely hinder the growth and fermentation of microorganisms are inevitably produced during the pretreatment of lignocellulose. Presently, there are few reports on a single microorganism that can detoxify or tolerate toxic mixtures of pretreated lignocellulose hydrolysate while effectively transforming sugar components into valuable compounds. Alternatively, microbial coculture provides a simpler and more efficacious way to realize this goal by distributing metabolic functions among different specialized strains. Results In this study, a novel synthetic microbial consortium, which is composed of a responsible for detoxification bacterium engineered Pseudomonas putida KT2440 and a lactic acid production specialist Bacillus coagulans NL01, was developed to directly produce lactic acid from highly toxic lignocellulosic hydrolysate. The engineered P. putida with deletion of the sugar metabolism pathway was unable to consume the major fermentable sugars of lignocellulosic hydrolysate but exhibited great tolerance to 10 g/L sodium acetate, 5 g/L levulinic acid, 10 mM furfural and HMF as well as 2 g/L monophenol compound. In addition, the engineered strain rapidly removed diverse inhibitors of real hydrolysate. The degradation rate of organic acids (acetate, levulinic acid) and the conversion rate of furan aldehyde were both 100%, and the removal rate of most monoaromatic compounds remained at approximately 90%. With detoxification using engineered P. putida for 24 h, the 30% (v/v) hydrolysate was fermented to 35.8 g/L lactic acid by B. coagulans with a lactic acid yield of 0.8 g/g total sugars. Compared with that of the single culture of B. coagulans without lactic acid production, the fermentation performance of microbial coculture was significantly improved. Conclusions The microbial coculture system constructed in this study demonstrated the strong potential of the process for the biosynthesis of valuable products from lignocellulosic hydrolysates containing high concentrations of complex inhibitors by specifically recruiting consortia of robust microorganisms with desirable characteristics and also provided a feasible and attractive method for the bioconversion of lignocellulosic biomass to other value-added biochemicals.

Cheap and renewable feedstocks such as the one-carbon substrate formate are emerging for sustainable production in a growing chemical industry. We investigated the acetogen Acetobacterium woodii as a potential host for bioproduction from formate alone and together with autotrophic and heterotrophic co-substrates by quantitatively analyzing physiology, transcriptome, and proteome in chemostat cultivations in combination with computational analyses. Continuous cultivations with a specific growth rate of 0.05 h−1 on formate showed high specific substrate uptake rates (47 mmol g−1 h−1). Co-utilization of formate with H2, CO, CO2 or fructose was achieved without catabolite repression and with acetate as the sole metabolic product. A transcriptomic comparison of all growth conditions revealed a distinct adaptation of A. woodii to growth on formate as 570 genes were changed in their transcript level. Transcriptome and proteome showed higher expression of the Wood-Ljungdahl pathway during growth on formate and gaseous substrates, underlining its function during utilization of one-carbon substrates. Flux balance analysis showed varying flux levels for the WLP (0.7–16.4 mmol g−1 h−1) and major differences in redox and energy metabolism. Growth on formate, H2/CO2, and formate + H2/CO2 resulted in low energy availability (0.20–0.22 ATP/acetate) which was increased during co-utilization with CO or fructose (0.31 ATP/acetate for formate + H2/CO/CO2, 0.75 ATP/acetate for formate + fructose). Unitrophic and mixotrophic conversion of all substrates was further characterized by high energetic efficiencies. In silico analysis of bioproduction of ethanol and lactate from formate and autotrophic and heterotrophic co-substrates showed promising energetic efficiencies (70–92%). Collectively, our findings reveal A. woodii as a promising host for flexible and simultaneous bioconversion of multiple substrates, underline the potential of substrate co-utilization to improve the energy availability of acetogens and encourage metabolic engineering of acetogenic bacteria for the efficient synthesis of bulk chemicals and fuels from sustainable one carbon substrates.

Summary Whole‐cell bioconversion of technical lignins using Pseudomonas putida strains overexpressing amine transaminases (ATAs) has the potential to become an eco‐efficient route to produce phenolic amines. Here, a novel cell growth‐based screening method to evaluate the in vivo activity of recombinant ATAs towards vanillylamine in P. putida KT2440 was developed. It allowed the identification of the native enzyme Pp‐SpuC‐II and ATA from Chromobacterium violaceum (Cv‐ATA) as highly active towards vanillylamine in vivo. Overexpression of Pp‐SpuC‐II and Cv‐ATA in the strain GN442ΔPP_2426, previously engineered for reduced vanillin assimilation, resulted in 94‐ and 92‐fold increased specific transaminase activity, respectively. Whole‐cell bioconversion of vanillin yielded 0.70 ± 0.20 mM and 0.92 ± 0.30 mM vanillylamine, for Pp‐SpuC‐II and Cv‐ATA, respectively. Still, amine production was limited by a substantial re‐assimilation of the product and formation of the by‐products vanillic acid and vanillyl alcohol. Concomitant overexpression of Cv‐ATA and alanine dehydrogenase from Bacillus subtilis increased the production of vanillylamine with ammonium as the only nitrogen source and a reduction in the amount of amine product re‐assimilation. Identification and deletion of additional native genes encoding oxidoreductases acting on vanillin are crucial engineering targets for further improvement., In this study, Pseudomonas putida was engineered for whole‐cell conversion of ferulic acid and vanillin to vanillylamine with ammonium as nitrogen source. Furthermore, a novel growth‐based screening method to select for recombinant vanillin transaminases was developed and used to identify SpuC‐II and Cv‐ATA as suitable enzymes for in vivo biocatalysis with P. putida.

Two genes encoding lytic polysaccharide monooxygenases (LPMOs) CsLPMO9A and CsLPMO9B were cloned from the white-rot fungus Ceriporiopsis subvermispora and successfully expressed in Komagataella phaffii. The oxidative degradation of phosphoric acid swollen cellulose by the LPMOs was conducted using ascorbic acid as an electron donor. Analysis with high performance anion-exchange chromatography and matrix assisted laser desorption/ionization-time-of-flight mass spectrometry indicated that the two enzymes cleaved the polysaccharides by oxidization of the C1 carbon atom of the glucose unit. Synergistic effects between CsLPMO9A or CsLPMO9B and a commercial cellulase cocktail from Trichoderma reesei were observed in the saccharification of delignified wheat straw. The amounts of glucose, cellobiose and xylose released from the substrate by the combined enzymes were increased by 83 %, 16 % and 47 % (for CsLPMO9A), or 79 %, 52 % and 81 % (for CsLPMO9B), compared to the cellulase alone, respectively. The two new enzymes displayed promising potential in industrial bioconversion of lignocellulosic biomass.

In this study, the optimisation of a process for producing medium-chain-length polyhydroxyalkanoate (mcl-PHA) by Pseudomonas putida KT2440 when fed with a polyethene (PE)-derived fatty acid mixture was investigated. The PE was pyrolysed to produce a hydrocarbon wax that was subsequently oxidised to produce a mixture of fatty acids, purified, and used as a PHA substrate for the growth and selection of microorganisms. Based on the shaken flask screening, a production strain, i.e., Pseudomonas putida KT2440, was selected for conducting bioreactor studies. Feeding PE-derived fatty acids in a 20-L setup resulted in high mcl-PHA yields (83.0 g L−1 CDW with 65% PHA in 25 h). Furthermore, life-cycle assessment (LCA) was conducted to determine the environmental advantages of the proposed process and its impacts compared to those of other technologies for treating PE-derived waste streams. We conclude that processing waste PE into PHA, rather than incineration, produces biodegradable material while also reducing the additional emissions that arise from traditional PE waste treatment processes, such as incineration to gain energy.

Abeliophyllum distichum Nakai is a deciduous shrub that belongs to Oleaceae Abeliophyllum and grows only in Korea. In this study, the antioxidative activity, cytotoxicity, anti-aging activity, and levels of acteoside and isoacteoside were compared between non-fermented and fermented (using Lactobacillus plantarum and Lactobacillus brevis) extracts of A. distichum Nakai. The cytotoxicity of these extracts, along with their ability to inhibit elastase activity and Matrix metalloproteinase-1 (MMP-1) expression, and their ability to promote type I procollagen synthesis were investigated in human dermal fibroblasts cells. These tests revealed that the fermented extract possessed higher antioxidant and anti-aging activities compared with the non-fermented extract. The levels of acteoside and isoacteoside were about 1.25 and 1.05 times higher in the fermented extract than in the non-fermented extract. It was speculated that they were converted from acteoside glucosides and isoacteoside glucosides via bioconversion by the fermentation strains. Together, these findings indicate that extracts of A. distichum Nakai show good potential as antioxidative and anti-aging cosmetic materials. Key words: Abeliophyllum distichum Nakai, Lactobacillus plantarum, Lactobacillus brevis, fermentation, antioxidative activity, anti-aging activity.

Bioconversion of acetate, a byproduct generated in industrial processes, into microbial lipids using oleaginous yeasts offers a promising alternative for the economic utilization of acetate-containing waste streams. However, high acetate concentrations will inhibit microbial growth and metabolism. In this study, the acetate utilization capability of Yarrowia lipolytica PO1f was successively improved by overexpressing the key enzyme of acetyl-CoA synthetase (ACS), which resulted in an accumulation of 9.2% microbial lipids from acetate in shake flask fermentation. By further overexpressing the second key enzymes of acetyl-CoA carboxylase (ACC1) and fatty acid synthase (FAS) in Y. lipolytica, the lipid content was increased to 25.7% from acetate. Finally, the maximum OD600 of 29.2 and a lipid content of 41.7% were obtained with the engineered strain by the adoption of cosubstrate (glycerol and acetate) fed-batch fermentation, which corresponded to an increase of 68 and 95%, respectively. These results presented a promising strategy for economic and efficient microbial lipid production from the waste acetate.

A bifunctional glycoside hydrolase GH78 from the ascomycete Xylaria polymorpha (XpoGH78) possesses catalytic versatility towards both glycosides and esters, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of XpoGH78 to the conversion of lignocellulosic materials without any chemical pretreatment to release the water-soluble aromatic fragments, carbohydrates, and methanol was studied. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolases and phenoloxidases. The considerable changes in low (3 kDa), medium (30 kDa), and high (> 200 kDa) aromatic fragments were observed after the treatment with XpoGH78 alone or with this potent cocktail. Synergistic conversion of rape straw also resulted in a release of 17.3 mg of total carbohydrates (e.g., arabinose, galactose, glucose, mannose, xylose) per gram of substrate after incubating for 72 h. Moreover, the treatment of rape straw with XpoGH78 led to a marginal methanol release of approximately 17 μg/g and improved to 270 μg/g by cooperation with the above accessory enzymes. In the case of beech wood conversion, the combined catalysis by XpoGH78 and laccase caused an effect comparable with that of fungal strain X. polymorpha in woody cultures concerning the liberation of aromatic lignocellulose fragments.

Debaryomyces hansenii has been employed to study, initially, the influence of the oxygen availability on D-xylose to xylitol fermentation, as this parameter is considered as one of the most critical variables for this bio alcohol accumulation. Apart from the air supplied in the fermentation process through the stirring vortex (0.0 v/v/min), additional aeration rates (0.1-2.0 v/v/min) effects were discussed. Furthermore, a change in the fermentative medium composition as well as a comparative analysis of D. hansenii behavior with respect to fermentation of D-glucose and D-xylose mixtures solutions, with the aim of producing both xylitol and ethanol bioproducts, were performed. For these purposes, specific growth rates, biomass productivities, specific substrate-uptake rates, overall biomass yields, specific xylitol formation rates and overall xylitol yields values have been calculated, applying a differential method to the kinetic data. Aeration influence was clearly evinced since a faster D-xylose metabolism, for aeration values close to 1.0 v/v/min, was noted. This yeast exhibited a sequential substrate consumption, firstly D-glucose and then D-xylose. The maximum xylitol yield (0.32 kg kg- 1) was obtained for 0.5 v/v/min airflow, remarking a significant reduction of this parameter for both above and below the quoted air supply value.

Many soil Actinobacteria are potent producers of extracellular enzymes decomposing lignocellulose. Four strains of Actinobacteria with a high potential to hydrolyse cellulose and hemicellulose were identified among environmental isolates. The strains were grown on raw lignocellulosic substrates (olive pomace, oat flakes, sawdust, and wheat straw) under submerged fermentation in a laboratory scale. Modified Melin Norkrans Medium amended with raw lignocellulosic substrates as carbon sources (0.5%) was used to enhance lignocellulosic biomass decomposition. Three strains belonged to the genus Streptomyces and one strain to the genus Mycobacterium. Annotation of genomes showed high proportion of genes encoding for carbohydrate-active enzymes in Streptomyces sp. GESEQ-4 (537, i.e. 6% of 8404 genes), Streptomyces sp. GESEQ-13 (351 (5%) of 6705 genes), Streptomyces sp. GESEQ-35 (608 (6%) of 9788 genes), and Mycolicibacterium fortuitum subsp. fortuitum GESEQ-9 (222 (3%) of 6405 genes). These included plant cell wall-degrading enzymes belonging to the families GH1, GH2, GH3, GH5, GH6, GH9, GH10, GH12, GH16, GH26, GH30, GH39, GH48, GH51, and GH74, of which GH1, GH2, GH3, GH5, GH6, and GH16 were found in all four genomes. Assays for cellulose and hemicellulose degrading extracellular enzymes confirmed the ability of the isolates to decompose cellulose and hemicellulose. The highest endo-cleaving enzyme activities were produced by the strain Steptomyces sp. GESEQ-4 DSM 106287. Our results provide new perspectives into the enzymatic array by which the Actinobacteria break down complex lignocellulosic biomass. It is crucial to assess the genome to determine enzyme function as well as the enzyme families responsible for the degradation process in Actinobacteria. The potential degradation functions for these actinobacterial strains were validated by testing their cellulolytic and hemicellulolytic activities with various lignocellulosic substrates.

In the production of natural sausage casings, three layers of serosa, muscular, and mucosa are removed from gastro-intestinal wall of sheep as waste materials. The submocusa layer is taken for further processing. There is no report about generating added value out of these wastes. In this study, a novel approach was introduced for bioconversion of waste gastro-intestinal wall (WGW) to a value-added product. Alkaline hydrolysis of WGW was investigated and the hydrolysate was utilized for cultivation of Dunaliella salina, a value-added biomass. The hydrolysate that contained the highest total soluble protein was used for three sets of cultivations on different medium compositions, i.e., (1) cultivations on the modified Johnson’s medium enriched with different percentage of hydrolysate (0.5, 1, 2.5, 5, and 10 (%v/v)), (2) cultivations on modified Johnson’s medium which was free of nitrogen and carbon sources and enriched with different percentage of hydrolysate (0.5, 1, 2.5, 5, and 10 (%v/v), and (3) cultivation on modified Johnson’s medium which was free of nitrogen source and enriched with 2.5% hydrolysate. The results showed that WGW contained 60.7, 8.4, 15.8, and 15.2% protein, lipid, moisture, and ash, respectively and the enrichment of the medium with the hydrolysate (2.5%) increased biomass productivity by 20%. Additionally, substitution of 2.5% hydrolysate for nitrogen source (KNO3) resulted in the same biomass productivity. The results of this study revealed the potential of the hydrolysate as an alternative for KNO3 in cultivation of D. salina. Overall, this work proposed a novel approach for converting waste gastro-intestinal wall to value.

Poly(ethylene terephthalate) (PET) is a widely used plastic in bottles and fibers; its waste products pollute the environment owing to its remarkable durability. Recently, Ideonella sakaiensis 201-F6 was isolated as a unique bacterium that can degrade and assimilate PET, thus paving the way for the bioremediation and bioconversion of PET waste. We found that this strain harbors a poly(hydroxyalkanoate) (PHA) synthesis gene cluster, which is highly homologous with that of Cupriavidus necator, an efficient PHA producer. Cells grown on PET accumulated intracellular PHA at high levels. Collectively, our findings in this study demonstrate that I. sakaiensis can mediate the direct conversion of non-biodegradable PET into environment-friendly plastic, providing a new approach for PET recycling.

Due to the expansion in the global population, there is an increase in animal protein demand and waste generation. Currently, food waste derived from supermarkets, etc., which is used to produce biogas, is collected separately and can contain (micro)plastics deriving from food packaging, imposing potential risks to the environment. A possible solution to address protein, waste and plastic concerns can potentially be achieved by rearing black soldier fly (BSF) larvae on such substrates. In this study, we investigated the effect of polyvinyl chloride (PVC) (micro)plastics on the growth, survival, and bioconversion of BSF larvae. On the other hand, the impact of the larvae on the polymer structure and degradation was also assessed. This was carried out by rearing BSF larvae on artificial food waste spiked with micro-, meso-, and macroplastics, while measuring larval growth, survival, and bioconversion parameters. The remaining plastics were collected and analysed upon changes and degradation of their polymer structure. Generally, BSF larvae were not affected in terms of growth performance (179.9–210.4 mg), survival (77.1–87.3%), and bioconversion (FCR: 4.65–5.53) by the presence of (micro)plastics in the substrates. Furthermore, the larvae were also unable to significantly alter the polymer structure of the used plastic.

The research evaluated the changes in degradability of some agro-forest wastes such as poplar sawdust, wheat straw, date palm wastes, and sugarcane bagasse during the cultivation of T. versicolor (turkey tail) to better understand the nutritional needs, evaluation of chemical and lignocellulosic changes of substrates, and physicochemical traits of mushroom. In addition, the possibility of spent wastes as soil amendment was evaluated. The substrates were studied for pH, EC, moisture, ash, cellulose, hemicellulose, lignin, macro-(C, N, P, K, Ca, and Mg), and microelements (Cu, Zn, Fe, and Mn), at nine substrate formulations during growing stages. Moreover, the effect of agro-wastes on mushroom fresh and dry weight, spawn run time, pinhead formation time, precocity time, some minerals (N, K, and Ca), and total polysaccharides was assessed. Among the nine formulations, the S1 (80% poplar sawdust + 20% wheat straw) exhibited maximum quantitative and qualitative yield. No relationship was found between the turkey tail yield and the nutritional composition or lignocellulosic account of the growing substrates. This indicates that the turkey tail mushroom needs moderate nutrition. In addition, in spent substrates (SS) the macro-(N, P, K, and Mg) and microelements (Zn and Fe) content was generally higher than initial substrates (IS), but carbon (C) content, lignocellulosic composition, and pH reduced in all SSs. The results suggest that the tested isolate has a suitable bioconversion capability and can be used to make agro-wastes to soil fertilizer. Furthermore, S1 substrate may be recommended as an appropriate substrate for T. versicolor cultivation.

As the bioconversion of methane becomes increasingly important for bio-industrial and environmental applications, methanotrophs have received much attention for their ability to convert methane under ambient conditions. This includes the extensive reporting of methanotroph engineering for the conversion of methane to biochemicals. To further increase methane usability, we demonstrated a highly flexible and efficient modular approach based on a synthetic consortium of methanotrophs and heterotrophs mimicking the natural methane ecosystem to produce mevalonate (MVA) from methane. In the methane-conversion module, we used Methylococcus capsulatus Bath as a highly efficient methane biocatalyst and optimized the culture conditions for the production of high amounts of organic acids. In the MVA-synthesis module, we used Escherichia coli SBA01, an evolved strain with high organic acid tolerance and utilization ability, to convert organic acids to MVA. Using recombinant E. coli SBA01 possessing genes for the MVA pathway, 61 mg/L (0.4 mM) of MVA was successfully produced in 48 h without any addition of nutrients except methane. Our platform exhibited high stability and reproducibility with regard to cell growth and MVA production. We believe that this versatile system can be easily extended to many other value-added processes and has a variety of potential applications.

Microalgal carbohydrate is considered one of the potential feedstock for biofuel produced via the bioconversion process. However, the current cultivation process using commercial medium exhibited low biomass production and its carbohydrate productivity which become a bottleneck for sustainable microalgal-carbohydrate-based biofuel production. Thus, the objective of this study is to assess the utilization of industrial waste including molasses and glycerol on the Halochlorella rubescens and Tetraselmis suecica growth as well as its carbohydrate content under different cultivation modes such as autotrophic, heterotrophic and photoheterotrophic conditions. From this study, the highest maximum biomass of H. rubenscens and T. suecica of 0.653 ± 0.009 and 0.669 ± 0.01gL−1 were obtained when the cultivation was performed under photoheterotrophic using molasses. High carbohydrate content of H. rubescens and T. seucica of 56.81 ± 0.39% and 71.52 ± 0.03% with glucose represent the dominant sugar was observed under this condition. The growth kinetic model of the analysis indicated that Huang and Gompertz Models described well the growth of H. rubescens and T. suecica under photoheteroptroph condition with a high significant R2 of 0.99. The information generated could be beneficial for the future development of low-cost microalgal cultivation media formulation for future microalgal carbohydrate-based products such as bioethanol.

Biological technology has presented a promising application for phosphine (PH3) purification; however, the degradation characteristics and microbial community of PH3 biopurification systems have ra...

Objective: The present study is aimed at optimization of concentration of substrate (pomegranate peel extract) for the production of Ellagic acid using Aspergillus niger and Rhizopus oryzae. Methods: Test organisms were isolated and identified using standard microbiological techniques. Collected pomegranate peels were dried, grained and used as the substrate for solid-state fermentation. Prepared spore suspension of the test organisms was inoculated and incubated at room temperature. At regular intervals of 24 h, samples were drawn and subjected to analysis of reducing sugar, soluble proteins, hydrolysable tannins and production of extracellular tannase using standard methods. Results: The results of the present investigation demonstrated the optimum substrate concentration for the active conversion of ellagitannins to ellagic was 15g of A. niger, 20g for R. oryzae and 15g for mixed culture. Conclusion: From the current work, it was concluded that solid-state bioprocessing of fruit substrates and fruit wastes using fungi has shown to enrich phenolic antioxidants and improve phytochemical consistency.

Accepted article, BACKGROUND 2-Phenylethanol (2-PE) is an aromatic alcohol with delicate fragrance of rose petals, widely used in perfumes, cosmetics, foods, beverages, and pharmaceutical industries. The yeast Yarrowia can produce 2-PE through L-Phenylalanine (L-Phe) biotransformation. However, it is poorly explored in this field, despite its interesting characteristics for this process, such as the Crabtree negative trait. RESULTS This study explored the potential of different Yarrowia species (Y. lipolytica W29, CH 1/5 and CH 3/4 and Y. divulgata M 445/4) for 2-PE production. It was observed that all strains were inhibited by 2-PE concentrations above 2gL1, but only Y. lipolytica W29 was inhibited by 15gL1 L-Phe. It was also confirmed that all strains were able to produce 2-PE, with concentrations ranging from 1 to 2.2gL1. Afterwards, crude glycerol was used as an alternative carbon source for 2-PE production. All strains grew and produce 2-PE on this carbon source, but CH 1/5 strain was selected for further studies since it allowed the highest 2-PE throughput. The production of 2-PE with CH 1/5 was further studied in bioreactor batch cultures, where a low accumulation of 2-PE was observed. However, a step-wise fed-batch culture allowed to increase the production of 2-PE to 3.2gL1. CONCLUSION To the best of the author's knowledge, this value corresponds to the highest titer of 2-PE obtained to date with Y. lipolytica. In this study, Y. lipolytica CH 1/5 is for the first time described as a good natural producer for 2-PE., Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/ BIO/04469/2020 unit and BioTecNorte operation (NORTE-01-0145- FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors thank Dr. D.Q. Nguyen and Dr. E.Nagy from Szent István University, Budapest, Hungary, for kindly providing Y. lipolytica CH 1/5, CH 3/4, and Y. divulgata M445/4 strains. The authors also want to express their gratitude to Prio Energy – Prio Biocombustíveis, SA for providing the glycerol used in this experimental work, info:eu-repo/semantics/publishedVersion

Cellulase has the biggest contribution to the high production costs of lignocellulose bioconversion and the substantial decrease of its production cost is the key to the commercialization of lignocellulosic biorefineries. Trichoderma reesei has the most robust cellulase among the candidates, which therefore is widely used for cellulase production in industry. This is not because of the size of its cellulase gene pool but its prodigious cargo of cellulase productivity. Still, T. reesei cellulase falls far short of perfection in real-world applications, especially for the composition. This review summarized the biotechnological advances in engineering T. reesei for enhanced cellulase production. Meanwhile, we proposed innovative ideas of systematically optimizing cellulase composition at the transcriptional level and improving cellulase production at the regulation level. Efficient genome editing is essential to achieving that target. Thus, the developments of the tools of multiple gene manipulations were discussed in detail here. This review provides ideas and/or inspirations to the future researches on T. reesei cellulase.

Rhodococcus spp. strains are widespread in diverse natural and anthropized environments thanks to their high metabolic versatility, biodegradation activities, and unique adaptation capacities to several stress conditions such as the presence of toxic compounds and environmental fluctuations. Additionally, the capability of Rhodococcus spp. strains to produce high value-added products has received considerable attention, mostly in relation to lipid accumulation. In relation with this, several works carried out omic studies and genome comparative analyses to investigate the genetic and genomic basis of these anabolic capacities, frequently in association with the bioconversion of renewable resources and low-cost substrates into triacylglycerols. This review is focused on these omic analyses and the genetic and metabolic approaches used to improve the biosynthetic and bioconversion performance of Rhodococcus. In particular, this review summarizes the works that applied heterologous expression of specific genes and adaptive laboratory evolution approaches to manipulate anabolic performance. Furthermore, recent molecular toolkits for targeted genome editing as well as genome-based metabolic models are described here as novel and promising strategies for genome-scaled rational design of Rhodococcus cells for efficient biosynthetic processes application.

The bioconversion of furfural to furfuryl alcohol is an attractive route in biomass valorization that could replace traditional contaminant methods. The use of whole cells has been explored for this purpose. Bacillus cereus without previous treatment with furanic compounds was used to selectively obtain furfuryl alcohol. Growing and resting cells were employed. Using growing cells of B. cereus, lower yields to alcohol were obtained because of furfural toxicity. However, employing resting cells it was possible to reach higher yields to furfuryl alcohol. Optimal operative conditions were studied: different concentrations of furfural, glucose and molybdenum, pH, and temperature. Thus, glucose (100 mM) and molybdenum (0.1 mM) were added to maintain cell biomass obtaining a yield to furfuryl alcohol close to 80% at 30 °C, pH 7.2 from 30 mM of furfural.

Bioconversion of food waste oil (FWO) into biodegradable plastic is a promising method for converting waste into high-value products. In this study, a strain (Pseudomonas sp. H3) was isolated for polyhydroxyalkanoate (PHA) synthesis from FWO. After 72 h of cultivation with 20 g/L of FWO, the high cell dry weight (CDW) of 3.6 g/L, PHA yield of 2.4 g/L, and PHA content of 65 wt% were obtained under the optimal temperature (25 °C) and inoculum amount (6% (v/v)). Fed-batch fermentation was conducted in a 5 L bioreactor with a maximum CDW of 16 g/L, PHA content of 54 wt%, and PHA productivity of 0.23 g/(L·h) after 36 h. The PHA had a molecular weight of 54 782 Da and a low polydispersity index of 1.41 with glass transition, melting, and degradation temperatures of −20 °C, 34 °C, and 210 °C, respectively. To further utilize the wastewater after PHA production, anaerobic digestion was employed for CH4 production, and the CH4 yield was 284 mL/g volatile solids. Microbial community analysis showed that the abundance of acetate-oxidizing bacteria and Methanobacterium significantly increased during anaerobic digestion. This study describes a new strain for the economical synthesis of biodegradable plastics and presents a novel framework for fully utilizing FWO with the production of PHA and CH4.

1,3-PDO (1,3-propanediol) is a high value-added platform chemical used widely in adhesives, laminates, and food additives. For the efficient production of 1,3-PDO, the sustainable and non-toxic regeneration of NADH is of great importance. ZVI (Zero-Valent Iron) can provide a reducing equivalent for 1,3-PDO synthesis from glycerol as an electron donor. Klebsiella pneumoniae has a 1,3-PDO conversion pathway from glycerol and has been studied as an electrochemically active strain that can exchange respiratory electrons through the cell membrane. In this study, 1,3-PDO was produced using an electrochemically active strain, K. pneumoniae L17, and ZVI as an electron donor. The production of 1,3-PDO with ZVI increased significantly to 24.2 ± 1.3 mM compared to the control (12.0 ± 0.1 mM). These results suggest that an external reducing agent, such as ZVI, can regulate the bioconversion of K. pneumoniae L17, and improve the conversion of glycerol to value-added platform chemicals.

Background As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays. Results In this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL−1 and 13.58 U mL−1 along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography–mass spectrometry (GC–MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions. Conclusions Our results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.

This study was aimed to grow the local isolates yeast Candida tropicalis on locally prepared sawdust powder hydrolysate as a basal medium and carbon source with respect to single cell protein (SCP) production. The saw dust powder was treated with 10% H2SO4 for one hour at 100 0C. After cooling the supernatant containing the isolated sugar separated from debris by filtration and used as a carbon source and basal medium for yeast growth and SCP production. A high amount of SCP was achieved after five days of incubation, the percentage of the produced SCP 39.05% of the biomass dry weight, which is equivalent to 3.07g/l. SCP formation biosynthesis was affected by the level of nitrogen present in the medium; a high amount of protein being achieved in fermentation medium containing 0.3% urea in which the percentage of the yielded SCP was increased to 42.54%, (3.71g/l) of the biomass dry weight. The effect of varying nitrogen sources on SCP accumulation was also assayed. Medium containing ammonium phosphate greatly stimulated protein production in which the produced SCP was increased to reach 5.90 g/l. The produced amount equivalent to (48.22%) of the biomass dry weight. Conversely, a medium containing sodium nitrate had a suppressive effect on SCP production. This evidence clearly suggests that the metabolic versatility of Candida tropicalis may be employed in the conversion of low-grade material into high SCP product.

To obtain high yields of products through bioconversion processes, biomass must be pretreated to change its recalcitrant structures. The key goal of this analysis is to compare the findings in terms of total reducing sugar yield after organic solvents and hot water pretreatment on finger millet straw (FMS) using laboratory-scale equipment. Accordingly, the effect of two separate pretreatments, i.e., liquid hot water, and organic solvent (ethanol) at autoclave, and furnace temperatures, was investigated in this study to increase the enzymatic conversion of FMS under optimal conditions. The biomass recovery was found highest under the liquid hot water (autoclave; 9.477 ± 0.017%) pretreatment conditions. In addition, the cellulose content improved significantly with pretreatment, increasing from 41.7 ± 0.74 to 55.33 ± 0.89%, while the hemicellulose and lignin contents significantly decreased. The untreated sample having a lignin amount of around 6.42 ± 0.21% after different pretreatment methods dropped significantly (p = 0.00737**) and was found to have a 39.8 ± 1.84% delignification rate based on the ethanol autoclave method. The findings of the study revealed that the FMS is severely affected by liquid hot water and organic solvent pretreatment in the autoclave than the furnace. After the pretreatment procedure, the maximum amount of crystalline cellulose in biomass was transformed to the amorphous state, as shown by the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The pretreated cellulase blend enzyme sample was most active on the biomass treated with 1:20% (w/v) liquid hot water combined with autoclave heating at 121 °C, with 15 psi for 20 min, resulting in highest total reducing sugars; thus, results showed that the pretreated sample (0.75 g) contains 60.94 mg/g of fermentative sugars based on a 15% (w/v) ratio which claimed to be the fact that this is a better result than any other research by using FMS.

Bioconversion of food crops to bioethanol has generated numerous issues, necessitating the need for alternative feedstock. Pawpaw seeds (PS) were pretreated by different methods, dried and ground into flour. The flours were saccharified using crude amylase from Aspergillus niger and the reducing sugar produced was evaluated. Optimum conditions for ethanol production from the pawpaw seeds were determined. Seeds pretreated with sulphuric acid produced the highest amount of sugar (8.07 g/10 g PS), followed by seeds boiled in water (7.31 g/10 g PS). PS pretreated with sodium hydroxide produced 4.83 g/10 g PS. The optimum pH and temperature for amylase activity were 4.0 and 50 °C respectively, while the optimum substrate concentration for hydrolysis was 8 g/10 g PS flour. Increase in glucose concentration from 0.1 to 0.3 (g/100 ml) resulted in increase in the fermentable sugar production from 6.56 to 9.64 g/10g PS. The percentage yeast extract and peptone which gave the maximal fermentable sugar production from PS were 0.1% and 0.4%, respectively. The maximum ethanol concentration (4.33% v/v) produced by simultaneous saccharification and fermentation of pawpaw seed was obtained after 12 h of fermentation. These results indicate that pawpaw seeds, a food waste can be converted into ethanol within 12 h of fermentations through simultaneous saccharification and fermentation.

Enzymatic blends produced by fungal monocultures and consortia cultured in solid-state fermentation (SSF), using sugarcane bagasse (SB) and wheat bran as substrates (1:1, w/w), were evaluated for saccharification of sugarcane bagasse pretreated by autohydrolysis (hydrothermal pretreatment—HP) and alkaline delignification (HP-Soda). The highest glucose releases were obtained after saccharifications of SB pretreated by HP using enzyme cocktails produced by Aspergillus niger and by the consortium among A. fumigatus, Ganoderma lucidum and Trametes versicolor, with 10.8 and 9.8 g L−1, respectively. For SB pretreated by HP-Soda, the hydrolysate 10 (extract from A. niger, G. lucidum and Pleurotus ostreatus consortium) achieved maximal glucose concentration (11.92 g L−1). After alcoholic fermentation of the hydrolysates, the greatest ethanol yield in relation to the maximum theoretical yield (60.8%) was obtained in the fermentation of hydrolysate 1 (A. niger) obtained from SB pretreated by HP-Soda. These results demonstrated that on-site produced enzyme cocktails can be applied for saccharification of pretreated sugarcane bagasse and also contribute to cost reduction of bioconversion processes.

Introduction. Cellulose-containing parts of herbs are an excellent source of alternative energy and can be used to produce biological ethanol. The present research aims at improving this fundamental and promising area of biotechnology. It introduces a new consortium of microorganisms that can saccharify while fermenting the substrate. Study objects and methods. The research featured technical cellulose obtained from Miscanthus sinensis using hydrotropic delignification and oxidation with pertrifluoroacetic acid. The ethanol content in the culture liquid was determined using an Agilent 7890B gas chromatograph with a flame ionization detector. The biocompatibility of the strains was studied by growing a direct co-culture in a dense nutrient medium. Results and discussion. The research objective was to create a new microbial consortium for the single-step production of bioethanol from Miscanthus sinensis cellulose. A set of biocompatibility experiments and cultivation conditions made it possible to select the optimal producers. The two developed microbial consortia required optimal compositions of culture media, which were determined by varying the ratio of components and measuring the yield of ethanol in the resulting culture liquid. Conclusion. The best consortium for Miscanthus sinensis cellulose consisted of Pichia stipites Y7124, Candida shehatae NCL3501, Kluyveromyces marxianus Y-4290, and Zymomonas mobilis 113 at a ratio of 1:1:1:1. The optimal parameters of bioethanol production included: temperature = 35 ± 1°C, pH = 5.2, time = 16 ± 1 h. The most efficient culture medium had the following composition (g/l): glucose – 5.0; peptone – 5.0; yeast extract – 0.4; K2HPO4 – 1.5; (NH)2 HPO4 – 1.5; MgSO4 – 0.5.

In this article, we reviewed studies on the fruits of the jussara palm (Euterpe edulis Martius), an endangered Brazilian Atlantic Forest palm tree, also coined as "Superfruit." We summarized the chemical components of the pulp and observed biological activities in murine and humans, as well as the best practices involving the extraction of its target compounds, bioavailability, and stability of extracts. Jussara has shown a rich phenolic profile that justifies its antioxidant properties, in addition to a considerable lipidic and energetic value. As the main feature, the fruit possesses large amounts of anthocyanins that can be commercially explored as a food additive or cosmetic colorants. Recent studies emphasized jussara's antioxidant, anti-inflammatory, and cardioprotective capabilities via reshaping of the gut microbiota. Further knowledge is needed to establish bioavailability and optimal serving size, as many of its antioxidant compounds go under chemical bioconversion in the intestinal tract. While extraction of phenolic compounds, anthocyanins, and oils have interesting results, more studies are required in order to reduce the use of conventional organic solvents and improve their stability and shelf life when added to food products, an area in which nanotechnology seems promising.