Efficient conversion of Hubrid Pennisetum to glucose by oxygen-aqueous alkaline ionic liquid media pretreatment under benign conditions

Response of soil microbial community structure to temperature and nitrogen fertilizer in three different provenances of Pennisetum alopecuroides

Soil microorganisms are key indicators of soil health, and it is crucial to investigate the structure and interactions of soil microbial communities among three different provenances of Pennisetum alopecuroides under varying nitrogen fertilizer and temperature levels in Northwest China. This study aims to provide theoretical support for the sustainable use of artificial grassland in this region. Employing a two-factor pot-control experiment with three nitrogen fertilizer treatments and three temperature treatments, a total of all treatments was utilized to examine the composition and abundance of soil microbial communities associated with Pennisetum alopecuroides using high-throughput sequencing, PCR technology, and molecular ecological network analysis. The results revealed that Proteobacteria was the dominant bacterial phylum while Ascomycota was the dominant fungal phylum in the soil samples from three provenances of Pennisetum. Specifically, Proteobacteria exhibited higher abundance in the N3T2 treatment compared to other treatments under N3T2 (25-30°C, 3 g/pot) treatment conditions in Shaanxi and Gansu provinces; similarly, Proteobacteria was more abundant in the N1T2 (25-30°C, 1 g/pot) treatment in Inner Mongolia under N1T2. Moreover, Ascomycota displayed higher abundance than other treatments in both Inner Mongolia and Gansu provinces. Additionally, Pennisetum Ascomycota demonstrated greater prevalence under (25-30°C, 3 g/pot) treatment compared to other treatments; furthermore, Shaanxi's Pennisetum Ascomycota exhibited increased prevalence under N3T1 (18-23°C, 3 g/pot) treatment compared to other treatments. The richness and diversity of soil microbial communities were significantly influenced by nitrogen fertilizer and temperature changes, leading to notable alterations in their structure. Molecular ecological network analyses revealed strong collaborative relationships among microbial species in Shaanxi Pennisetum and Inner Mongolia Pennisetum under high nitrogen and high temperature treatments, while competitive relationships were observed among microbial species in Gansu Pennisetum under similar conditions. Redundancy analysis indicated that soil pH, total potassium, and total phosphorus were the primary environmental factors influencing microorganisms. In summary, this study offers a theoretical foundation for assessing the sustainable utilization of Pennisetum artificial grasslands in Northwest China by investigating the shifts in soil microbial communities and the driving factors under varying nitrogen fertilizer and temperature levels.

Transcriptome analysis of Pennisetum americanum × Pennisetum purpureum and Pennisetum americanum leaves in response to high-phosphorus stress

Excessive phosphorus (P) levels can disrupt nutrient balance in plants, adversely affecting growth. The molecular responses of Pennisetum species to high phosphorus stress remain poorly understood. This study examined two Pennisetum species, Pennisetum americanum × Pennisetum purpureum and Pennisetum americanum, under varying P concentrations (200, 600 and 1000 µmol·L- 1 KH2PO4) to elucidate transcriptomic alterations under high-P conditions. Our findings revealed that P. americanum exhibited stronger adaption to high-P stress compared to P. americanum× P. purpureum. Both species showed an increase in plant height and leaf P content under elevated P levels, with P. americanum demonstrating greater height and higher P content than P. americanum× P. purpureum. Transcriptomic analysis identified significant up- and down-regulation of key genes (e.g. SAUR, GH3, AHP, PIF4, PYL, GST, GPX, GSR, CAT, SOD1, CHS, ANR, P5CS and PsbO) involved in plant hormone signal transduction, glutathione metabolism, peroxisomes, flavonoid biosynthesis, amino acid biosynthesis and photosynthesis pathways. Compared with P. americanum× P. purpureum, P. americanum has more key genes in the KEGG pathway, and some genes have higher expression levels. These results contribute valuable insights into the molecular mechanisms governing high-P stress in Pennisetum species and offer implications for broader plant stress research.

Effects of Mulberry Leaves and Pennisetum Hybrid Mix-Silage on Fermentation Parameters and Bacterial Community

The silage quality and bacterial community of hybrid Pennisetum (P. hydridum × P. americanum) with or without 30% and 50% mulberry leaves for 3, 7, 14, and 30 days were investigated. Results showed that compared with the 100% hybrid Pennisetum group, more lactic acid (40.71 vs. 80.81 g/kg dry matter (DM)), acetic acid (10.99 vs. 31.84 g/kg DM), lactic acid bacteria (8.46 vs. 8.51 log10 cfu/g fresh matter), water-soluble carbohydrates (2.41 vs. 4.41 g/100 g DM), crude protein (4.97 vs. 10.84 g/100 g DM), and true protein (3.91 vs. 8.52 g/100 g DM) content as well as less neutral detergent fiber (67.30 vs. 47.26 g/100 g DM), acid detergent fiber (33.85 vs. 25.38 g/100 g DM), and yeast counts (4.78 vs. 2.39 log10 cfu/g fresh matter) and an appropriate pH (3.77 vs. 4.06) were found in silages added with 50% mulberry leaves at 30 days of ensiling. Moreover, the addition of mulberry leaves also influenced the relative abundance of the bacterial community. The relative abundance of Firmicutes increased and Proteobacteria decreased when mulberry leaves were added. Weissella and Lactobacillus abundance also increased. To sum up the above, mixing with 50% mulberry leaves yielded the greatest fermentation quality in this study. In conclusion, mixing with mulberry leaves could be a reasonable way to improve the quality of hybrid Pennisetum silage.

Novel recyclable deep eutectic solvent boost biomass pretreatment for enzymatic hydrolysis

Deep eutectic solvent (DES) with protonic acid shows the great potential for biomass valorization. However, the acid corrosion and recycling are still severe challenges in biorefinery. Herein, a novel DES by coordinating FeCl₃ in choline chloride/glycerol DES was designed for effective and recyclable pretreatment. As compared to DESs with FeCl₂, ZnCl₂, AlCl₃ and CuCl₂, DES with FeCl₃ approvingly retained most of cellulose in pretreated Hybrid Pennisetum (95.2%). Meanwhile, the cellulose saccharification significantly increased to 99.5%, which was six-fold higher than that of raw biomass. The excellent pretreatment performance was mainly attributed to the high removal of lignin (78.88 wt%) and hemicelluloses (93.63 wt%) under the synergistic effect of Lewis acid and proper hydrogen-bond interaction of DES with FeCl₃. Furthermore, almost all cellulose still can be converted into glucose after five recycling process. Overall, the process demonstrated designed pretreatment was great potential for the low-cost biorefinery and boost the biofuel development.

Enhanced Enzymatic Hydrolysis of Pennisetum alopecuroides by Dilute Acid, Alkaline and Ferric Chloride Pretreatments

In this study, effects of different pretreatment methods on the enzymatic digestibility of Pennisetum alopecuroides, a ubiquitous wild grass in China, were investigated to evaluate its potential as a feedstock for biofuel production. The stalk samples were separately pretreated with H₂SO₄, NaOH and FeCl₃ solutions of different concentrations at 120 °C for 30 min, after which enzymatic hydrolysis was conducted to measure the digestibility of pretreated samples. Results demonstrated that different pretreatments were effective at removing hemicellulose, among which ferric chloride pretreatment (FCP) gave the highest soluble sugar recovery (200.2 mg/g raw stalk) from the pretreatment stage. In comparison with FCP and dilute acid pretreatment (DAP), dilute alkaline pretreatment (DALP) induced much higher delignification and stronger morphological changes of the biomass, making it more accessible to hydrolysis enzymes. As a result, DALP using 1.2% NaOH showed the highest total soluble sugar yield through the whole process from pretreatment to enzymatic hydrolysis (508.5 mg/g raw stalk). The present work indicates that DALP and FCP have the potential to enhance the effective bioconversion of lignocellulosic biomass like P. alopecuroides, hence making this material a valuable and promising energy plant.

Screening of potential IL-tolerant cellulases and their efficient saccharification of IL-pretreated lignocelluloses

Lignocellulosic biomass as one of the most abundant and renewable resources has great potential for biofuel production. The complete conversion of biomass to biofuel is achieved through the effective pretreatment process and the following enzyme saccharification. Ionic liquids (ILs) are considered as a green solvent for lignocellulose pretreatment. However, ILs exhibit an inhibitory effect on cellulase activity, leading to a subsequent decrease in the efficiency of saccharification. The screening of new potential IL-tolerant cellulases is important. In the current study, a fungal strain with a relatively high cellulase production was isolated and identified as Penicillium oxalicum HC6. The culture conditions were optimized using corn stover and peptone as the carbon source and nitrogen source at pH 4.0 and 30 °C with an inoculation size of 2% (v/v) for 8 days. It was found that P. oxalicum HC6 exhibited potential salt tolerance with the increase of the enzyme production at a salt concentration of 5.0% (w/v). In addition, high enzyme activities were obtained at pH 4.0–6.0 and 50–65 °C. The crude enzyme from P. oxalicum HC6 with good thermal stability was also stable in the presence of salt and ILs. Good yields of reducing sugar were obtained by the crude enzyme from P. oxalicum HC6 after the saccharification of corn stover that was pretreated by ILs. P. oxalicum HC6 with potentially salt-tolerant and IL-tolerant enzymes has great potential application in the enzymatic saccharification of lignocellulose.

Lignocellulosic biomass as one of the most abundant and renewable resources has great potential for biofuel production.