Optimization, purification, and characterization of xylanase production by a newly isolated Trichoderma harzianum strain by a two-step statistical experimental design strategy

Establishing the green algae Chlamydomonas incerta as a platform for recombinant protein production

Chlamydomonas incerta, a genetically close relative of the model green alga Chlamydomonas reinhardtii, shows significant potential as a host for recombinant protein expression. Because of the close genetic relationship between C. incerta and C. reinhardtii, this species offers an additional reference point for advancing our understanding of photosynthetic organisms, and also provides a potential new candidate for biotechnological applications. This study investigates C. incerta's capacity to express three recombinant proteins: the fluorescent protein mCherry, the hemicellulose-degrading enzyme xylanase, and the plastic-degrading enzyme PHL7. We have also examined the capacity to target protein expression to various cellular compartments in this alga, including the cytosol, secretory pathway, cytoplasmic membrane, and cell wall. When compared directly with C. reinhardtii, C. incerta exhibited a distinct but notable capacity for recombinant protein production. Cellular transformation with a vector encoding mCherry revealed that C. incerta produced approximately 3.5 times higher fluorescence levels and a 3.7-fold increase in immunoblot intensity compared to C. reinhardtii. For xylanase expression and secretion, both C. incerta and C. reinhardtii showed similar secretion capacities and enzymatic activities, with comparable xylan degradation rates, highlighting the industrial applicability of xylanase expression in microalgae. Finally, C. incerta showed comparable PHL7 activity levels to C. reinhardtii, as demonstrated by the in vitro degradation of a polyester polyurethane suspension, Impranil® DLN. Finally, we also explored the potential of cellular fusion for the generation of genetic hybrids between C. incerta and C. reinhardtii as a means to enhance phenotypic diversity and augment genetic variation. We were able to generate genetic fusion that could exchange both the recombinant protein genes, as well as associated selectable marker genes into recombinant offspring. These findings emphasize C. incerta's potential as a robust platform for recombinant protein production, and as a powerful tool for gaining a better understanding of microalgal biology.

Genome Characteristics of the Endophytic Fungus Talaromyces sp. DC2 Isolated from Catharanthus roseus (L.) G. Don

Talaromyces sp. DC2 is an endophytic fungus that was isolated from the stem of Catharanthus roseus (L.) G. Don in Hanoi, Vietnam and is capable of producing vinca alkaloids. This study utilizes the PacBio Sequel technology to completely sequence the whole genome of Talaromyces sp. DC2The genome study revealed that DC2 contains a total of 34.58 Mb spanned by 156 contigs, with a GC content of 46.5%. The identification and prediction of functional protein-coding genes, tRNA, and rRNA were comprehensively predicted and highly annotated using various BLAST databases, including non-redundant (Nr) protein sequence, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Clusters of Orthologous Groups (COG), and Carbohydrate-Active Enzymes (CAZy) databases. The genome of DC2 has a total of 149, 227, 65, 153, 53, and 6 genes responsible for cellulose, hemicellulose, lignin, pectin, chitin, starch, and inulin degradation, respectively. The Antibiotics and Secondary Metabolites Analysis Shell (AntiSMASH) analyses revealed that strain DC2 possesses 20 biosynthetic gene clusters responsible for producing secondary metabolites. The strain DC2 has also been found to harbor the DDC gene encoding aromatic L-amino acid decarboxylase enzyme. Conclusively, this study has provided a comprehensive understanding of the processes involved in secondary metabolites and the ability of the Talaromyces sp. DC2 strain to degrade plant cell walls.

Successive process for efficient biovalorization of Brewers' spent grain to lignocellulolytic enzymes and lactic acid production through simultaneous saccharification and fermentation

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.

Optimization of Xylooligosaccharides Production by Native and Recombinant Xylanase Hydrolysis of Chicken Feed Substrates

Poultry production faces several challenges, with feed efficiency being the main factor that can be influenced through the use of different nutritional strategies. Xylooligosaccharides (XOS) are functional feed additives that are attracting growing commercial interest due to their excellent ability to modulate the composition of the gut microbiota. The aim of the study was to apply crude and purified fungal xylanases, from Trichoderma harzianum, as well as a recombinant glycoside hydrolase family 10 xylanase, derived from Geobacillus stearothermophilus T6, as additives to locally produced chicken feeds. A Box-Behnken Design (BBD) was used to optimize the reducing sugar yield. Response surface methodology (RSM) revealed that reducing sugars were higher (8.05 mg/mL, 2.81 mg/mL and 2.98 mg/mL) for the starter feed treated with each of the three enzymes compared to the treatment with grower feed (3.11 mg/mL, 2.41 mg/mL and 2.62 mg/mL). The hydrolysis products were analysed by thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC) analysis and showed that the enzymes hydrolysed the chicken feeds, producing a range of monosaccharides (arabinose, mannose, glucose, and galactose) and XOS, with xylobiose being the predominant XOS. These results show promising data for future applications as additives to poultry feeds.

Purification and characterization of the low molecular weight xylanase from Bacillus cereus L-1

Xylanase is widely used in various industries such as food processing, paper, textiles, and leather tanning. In this study, Bacillus cereus L-1 strain was isolated and identified as capable of producing low molecular weight xylanase through 16 s rRNA sequencing. Maximum xylanase yield of 15.51 ± 2.08 U/mL was achieved under optimal fermentation conditions (5% inoculum, 20 g/L xylan, pH 6.0, for 24 h). After purification via ammonium sulfate precipitation and High-S ion exchange chromatography, electrophoretic purity xylanase was obtained with a 28-fold purification and specific activity of 244.97 U/mg. Xylanase had an optimal pH of 6.5 and temperature of 60 °C and displayed thermostability at 30 °C and 40 °C with 48.56% and 45.97% remaining activity after 180 min, respectively. The xylanase retained more than 82.97% of its activity after incubation for 24 h at pH 5.0 and was sensitive to metal ions, especially Mg2+ and Li+. Purified xylanase showed a molecular weight of 23 kDa on SDS-PAGE, and partial peptide sequencing revealed homology to the endo-1,4-beta-xylanase with a molecular weight of 23.3 kDa through LC/MS-MS (liquid chromatography-tandem mass spectrometry). This study suggests that the purified xylanase is easier to purify and enriches low molecular weight xylanases from bacteria source.

A glucose tolerant β-glucosidase from a newly isolated Neofusicoccum parvum strain F7: production, purification, and characterization

Cellulase-producing microorganisms produce low titres of β-glucosidases with low tolerance to glucose. This study aimed to improve production, purify, and characterize a β-glucosidase from a newly isolated Neofusicoccum parvum strain F7. β-Glucosidase production was significantly enhanced by a sequential statistical modelling approach from 1.5-fold in Plackett-Burman design to 2.5 U/ml in the Box-Behnken design compared to the preliminary one variable at a time experiments (1.6 U/ml). The optimal conditions for enzyme production by BBD were 12 days of fermentation at 20 °C, 175 rpm, 0.5% glycerol and 1.5% casein in pH 6.0 buffer. Three β-glucosidase isoforms referred to as Bgl1, Bgl2, Bgl3 were purified and characterized from the optimized crude extract displaying IC50 values of 2.6, 22.6 and 319.5 mM for glucose, respectively. Bgl3 with a molecular mass of approximately 65 kDa demonstrated the highest tolerance to glucose among the isoforms. The optimum activity and stability for Bgl3 was observed at pH 4.0 in 50 mM sodium acetate buffer with 80% β-glucosidase residual activity retained for three hours. This isoform also retained 60% residual activity at 65 °C for one hour which was then reduced to 40% which remained stable for another 90 min. The β-glucosidase activity of Bgl3 was not enhanced after the addition of metal ions in assay buffers. The Km and vmax for 4-nitrophenyl-β-D-glucopyranoside were 1.18 mM and 28.08 µmol/min, respectively indicating high affinity for the substrate. The ability to withstand the presence of glucose in conjunction with its thermophilic nature indicates promise for this enzyme in industrial application.