Utilization of straw-based phenolic acids as a biofugicide for a green agricultural production

Trade-off between pathogen control and seed viability: Engineering hydrothermal wastewater towards agricultural sustainable development and food security

Ensuring the balance between pathogen control and seed viability is critical for advancing sustainable agricultural practices. Hydrothermal liquefaction aqueous phase (HTL-AP), a renewable byproduct of biomass processing, exhibits promising antifungal properties but poses challenges due to its concentration-dependent phytotoxicity. Here we report trade-off and tailored protocol for simultaneously efficient antifungal and seed growth via engineering HTL-AP based disinfectant. Employing wheat and cabbage seeds contaminated with pathogenic fungi as representative crop seeds, HTL-AP achieved complete inhibition of fungal growth at a concentration of 4.8 %, whereas seed viability was negatively impacted by HTL-AP at low dilution ratios (i.e., × 1, × 2). Customized disinfection protocols were developed tailored to different seeds, involving adjustments of HTL-AP concentration, exposure time, and wash post-treatment, in order to achieve the optimal trade off, comparable to that of conventional disinfectants. The multifaceted disinfection mechanisms of HTL-AP were discussed, including cell membrane disruption, metabolic pathways interference, and enzyme system damage. This study underscores the significance for a customized strategy in both pathogen reduction and the promotion of plant health. By engineering a renewable HTL-AP reagent, this research advances sustainable agricultural practices and bolsters global food security.

Magnolol from Magnolia officinalis inhibits Neopestalotiopsis ellipsospora by damaging the cell membrane

Tea gray blight disease is a significant threat to the tea industry. In this study, a biological activity approach was utilized to investigate the efficacy of green fungicides from Magnolia officinalis stem bark against Neopestalotiopsis ellipsospora. The active compounds were isolated and purified, and their structures were elucidated. In vitro and in vivo activity screenings revealed that the n-hexane extract, which contained magnolol and honokiol, exhibited strong activity against N. ellipsospora, showing complete inhibition at 100 mg/L. The EC50 values of magnolol and honokiol were 5.11 and 6.09 mg/L, respectively. Mechanistically, magnolol was found to disrupt N. ellipsospora invasion by damaging the cell membrane, increasing permeability, and causing leakage of intracellular substances. Transcriptome analysis revealed that magnolol treatment downregulates membrane-related genes and leads to the enrichment of lipid metabolism pathway genes. This study revealed that magnolol inhibits N. ellipsospora growth by affecting lipid metabolism and compromising cell membrane integrity.

Influence of Different Pretreatment Steps on the Ratio of Phenolic Compounds to Saccharides in Soluble Polysaccharides Derived from Rice Straw and Their Effect on Ethanol Fermentation

The complex structure of rice straw is such that its bioconversion requires multiple physical and chemical pretreatment steps. In this study, it was found that a large amount of soluble polysaccharides (SPs) are formed during the pretreatment of straw. The yield of NaOH-based SPs (4.8%) was much larger than that of ball-milled SPs (1.5%) and H₂SO₄-based SPs (1.1%). For all the pretreatments, the ratio of phenolic compounds to saccharides (P/S) for each type of SPs increased upon increasing the concentration of ethanol in the order of 90% > 70% > 50%. The yield of NaOH-based SPs was much higher than that of acid-based and ball-milled SPs. The changes in the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power assay (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) of SPs follow the same rule, i.e., the higher the P/S ratio, the higher the antioxidant values of the SPs. The flow cytometry and laser scanning microscopy results show that the P/S ratio can significantly influence the effect of SPs on microbial growth and cell membrane permeability. Upon varying the ethanol concentration in the range of 50-90%, the P/S ratio increased from 0.02 to 0.17, resulting in an increase in the promoting effects of the SPs on yeast cell growth. Furthermore, H₂O₂, NAD⁺/NADH, and NADP⁺/NADPH assays indicate that SPs with a high P/S ratio can reduce intracellular H₂O₂ and change the intracellular redox status.

Understand the antibacterial behavior and mechanism of hydrothermal wastewater

Unlocking the antibacterial potential is an emerging strategy to valorizing the toxic wastewater from hydrothermal liquefaction (HTL). Here, we investigated the response and biological mechanism of antibacterial properties of HTL wastewater. Four different biowastes i.e. microalgae, cornstalk, cow manure and swine manure were used as the feedstock of HTL to create wastewater with diverse molecule spectrum, whereas ten strains i.e. five gram-positive strains and five gram-negative strains were employed to represent typical pathogenic microorganism. HTL wastewater exhibited antibacterial potential and obvious reduction on cell viability at high inclusion ratio, although the minimum inhibitory concentration (MIC) and cell response intensity varied depending on different HTL feedstocks and strain species. The decreased ATP generation and increased H₂O₂ accumulation in treated cells further confirmed the inhibition of HTL wastewater on the cell metabolism. The antibacterial mechanism of HTL wastewater was confirmed, including damage to biomolecules or membranes, depletion of crucial components, disruption of metabolic circuits and imbalance of creation of redox cofactor. The complex compounds in HTL wastewater were probably attributed to the multiple inhibition pathways and the relationship among those multiple pathways was speculated. The present study contributes to the mechanism analysis of complex compound mixture and bactericide characteristics of HTL wastewater.

Antibacterial Effect of Phenolic Acids Derived from Rice Straw and in Combination with Antibiotics Against Escherichia coli

Many studies have demonstrated that natural plant extracts have inhibitory effects on microorganisms. The purpose of this study was to investigate the inhibitory effect of phenolic acids from rice straw (PAs) on Escherichia coli and their synergistic effect in combination with antibiotics. PAs can inhibit the growth of E. coli effectively by inducing the formation of H₂O₂; PA-treated cells had a tenfold greater intracellular H₂O₂ concentration than the control group. The synergistic effect caused by the interaction of PAs and antibiotics on inhibiting the growth of E. coli was significant. This effect may be caused by a PA-induced change in the permeability of E. coli cell membrane. The treatment with PAs made the extracellular K⁺ concentration reached 15 mg/L within 30 min, while the K⁺ concentration in the control group was very low and did not change significantly over time. Similarly to the extracellular K⁺, the extracellular protein concentration exceeded 150 mg/L in the PA treatment group, while it remained very low in the control group. Due to the increased cell permeability, more antibiotics can enter the cell. Hence, this study may provide a novel method of improving the safe use of antibiotics.

Ultrasound, infrared and its assisted technology, a promising tool in physical food processing: A review of recent developments

Traditional food processing techniques can no longer meet the ever increasing demand for high quality food across the globe due to its low process efficiency, high energy consumption and low product yield. This review article is focused on the mechanism and application of Infrared (IR) and ultrasound (US) technologies in physical processing of food. We herein present the individual use of IR and US (both mono-frequency and multi-frequency levels) as well as IR and US supported with other thermal and non-thermal technologies to improve their food processing performance. IR and US are recent thermal and non-thermal technologies which have now been successfully used in food industries to solve the demerits of conventional processing technologies. These environmentally-friendly technologies are characterized by low energy consumption, reduced processing time, high mass-transfer rates, better nutrient retention, better product quality, less mechanical damage and improved shelf life. This work could be, with no doubt, useful to the scientific world and food industries by providing insights on recent advances in the use of US and IR technology, which can be applied to improve food processing technologies for better quality and safer products.