Cell Wall Disruption Research Articles

Green and Efficient Extraction of Taraxacum kok-saghyz Natural Rubber and Its Structural Analysis

Natural rubber (NR) is in high demand due to its excellent elasticity and physical and mechanical properties, but production is limited and NR is in short supply. There is an urgent need to find new alternative rubber sources. Taraxacum kok-saghyz (TKS), as a green, renewable, widely planted and high content rubber producing plant, has shown broad application prospects. The extraction process is the key to developing efficient, green, and high-purity Taraxacum kok-saghyz Natural Rubber (TKNR) to replace NR in various applications. In this study, TKS roots were processed through repeated boiling to remove inulin, followed by alkaline treatment with potassium hydroxide (KOH) to isolate lignin and facilitate cell wall disruption. Subsequent enzymatic hydrolysis using pectinase and cellulase enabled the dissolution of root-structure carbohydrates, thereby obtained TKNR. Structural characterization of TKNR was conducted and compared with that of NR. The results showed that the combined alkaline and enzymatic extraction methodology effectively isolates TKNR from TKS roots. Structural analysis reveals that TKNR closely resembles NR, having comparable molecular weight and distribution, crystallinity, and crosslinking networks, with both polymers primarily consisting of cis-1,4-polyisoprene.

Natural peptides and their synthetic congeners acting against Acinetobacter baumannii through the membrane and cell wall: latest progress.

Acinetobacter baumannii is one of the deadliest Gram-negative bacteria (GNB), responsible for 2-10% of hospital-acquired infections. Several antibiotics are used to control the growth of A. baumannii. However, in recent decades, the abuse and misuse of antibiotics to treat non-microbial diseases have led to the emergence of multidrug-resistant A. baumannii strains. A. baumannii possesses a complex cell wall structure. Cell wall-targeting agents remain the center of antibiotic drug discovery. Notably, the antibacterial drug discovery intends to target the membrane of the bacteria, offering several advantages over antibiotics targeting intracellular systems, as membrane-targeting agents do not have to travel through the plasma membrane to reach the cytoplasmic targets. Microorganisms, insects, and mammals produce antimicrobial peptides as their first line of defense to protect themselves from pathogens and predators. Importantly, antimicrobial peptides are considered potential alternatives to antibiotics. This communication summarises the recently identified peptides of natural origin and their synthetic congeners acting against the A. baumannii membrane by cell wall disruption.

Disruption of cell wall and membrane integrity as antioomycete and antifungal mode of action by fusaric and 9,10-dehydrofusaric acids from endophytic fungus Fusarium lactis strain SME13-2.

This study aimed to assess the mode of action of fusaric and 9,10-dehydrofusaric acids on cell respiration by measuring the hyphal oxygen consumption rate, and the effects on cell membrane integrity by determining the electrical conductivity of the mycelium. Bioactivity-directed fractionation of the active culture medium and mycelium organic extracts from the Fusarium lactis strain SME13-2 isolated from Sapium macrocarpum, led to the isolation of two known alkylpicolinic acid derivatives: fusaric acid and 9,10-dehydrofusaric acid, along with the known polyketide bikaverin. Fusaric acid and 9,10-dehydrofusaric acid exhibited antioomycete and antifungal activities, significantly inhibiting the radial growth of Phytophthora capsici, Pythium aphanidermatum, Alternaria alternata and Fusarium oxysporum. Additionally, they induced changes in colony morphology and negative effects on the ultrastructure of their hyphae. To date, the antimicrobial mode of action of fusaric acid and other alkylpicolinic acid derivatives is not thoroughly understood. Therefore, we investigated their effect on cellular respiration by measuring the oxygen consumption rate of the hyphae and their impact on cell membrane integrity by determining the electrical conductivity of the mycelium. Fusaric and 9,10-dehydrofusaric acids inhibited the respiration of the mycelium and altered the permeability of the cell membrane in the tested phytopathogenic microorganisms in a concentration and exposure time-dependent manner, exerting a greater effect on oomycetes. The disruption of cell membrane integrity resulted in the leakage of cytoplasmic electrolytes into the extracellular medium, which, coupled with the respiratory inhibition, could lead to cell death. Fusaric and 9,10-dehydrofusaric acids show potential for the development of new fungicides and anti-oomycetes agents.

Rational design and synthesis of novel phenyltriazole derivatives targeting MRSA cell wall biosynthesis.

Antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) is a major global health challenge. This study reports the design and synthesis of novel phenyltriazole derivatives as potential anti-MRSA agents. The new scaffold replaces the thiazole core with a 1,2,3-triazole ring, enhancing antimicrobial efficacy and physicochemical properties. A series of derivatives were synthesized and evaluated, with four compounds (20, 23, 29 and 30) showing significant activity against MRSA (MIC ≤ 4 μg mL-1). Compound 29 emerged as the most promising candidate, showing rapid bactericidal activity and superior performance over vancomycin in time-kill assays. It exhibited selective toxicity against bacterial cells, minimal cytotoxicity in human cell lines and low hemolytic activity. Mechanistic studies showed that compound 29 targets the bacterial cell wall by binding to penicillin-binding protein 2a (PBP2a), disrupting cell wall integrity. Additionally, it showed strong anti-biofilm activity and reduced MRSA biofilms by up to 40%. Preliminary pharmacokinetic profiles suggested a favorable profile, including a prolonged plasma half-life and good oral bioavailability. These results suggest that compound 29 is a promising lead for further development in the fight against MRSA.

Release of Biopolymers from Saccharomyces cerevisiae Biomass Through Thermal and Non-Thermal Technologies.

Components of yeast cell walls, such as β-glucans and mannoproteins, show promise for developing sustainable biopolymers for food packaging. Efficient extraction, however, is challenging due to the complexity of the yeast cell wall. This study explored high-pressure homogenisation (HPH) and pulsed electric fields (PEFs), alone and with heat treatment (TT), on bakery yeast (BY) and brewery spent yeast (BSY) biomasses. In the treated samples we assessed carbohydrates, proteins, β-glucans, and mannoproteins and evaluated cell wall disruption microscopically. HPH caused complete cell disintegration, enhancing intracellular release, while PEF primarily permeabilised the membranes. Combined HPH and PEF treatments significantly increased cell wall stress, leading to partial disintegration. Notably, the β-glucans released reached 3.90 g/100 g dry matter in BY and 10.44 g/100 g dry matter in BSY, demonstrating significant extraction improvements. These findings highlight the potential of HPH and PEF for enhancing β-glucan recovery from yeast biomass, offering a promising route for sustainable biopolymer production for food packaging.

The novel peptide adjuvants potentiate antimicrobial properties of melittin against methicillin-resistant Staphylococcus aureus and their efficacy as potential food preservatives

Melittin, a notable antimicrobial peptide (AMP), shows great potential in food preservation due to its robust antimicrobial properties, especially when facing multidrug-resistant (MDR) bacteria. However, developing melittin as a food preservative is limited by its poor cell selectively, necessitating innovative strategies are needed to address the application bottleneck of melittin. Here, we characterize two linear peptide adjuvants (3-WP and 9-RP), which exhibited obvious synergistic effects with melittin against common Gram-positive bacteria. Their synergistic effects potentiated antimicrobial efficacy of melittin against methicillin-resistant Staphylococcus aureus (MRSA), while reduced the required dose of melittin for antimicrobial activity, which is contributed to improving the cell selectively of melittin. Mechanistically, 3-WP disrupted cell wall membrane permeability, induced reactive oxygen species (ROS) production, and inhibited energy metabolism. The 3-WP/melittin combination exhibited favorable antimicrobial effects in food storage contexts. Our findings highlighted the great potential of 3-WP as a peptide adjuvant of melittin for combating MDR-associated foodborne diseases and developing safe and effective peptide-based bio-preservatives.

Synthesis, Characterization and Antibacterial Activity Evaluation of CuO NPs and B-CuO NPs Obtained from Livistona Chinensis Leaf Extract.

Nanoparticles (NPs) exhibit fascinating size-dependent chemical and physical characteristics that make them useful for a variety of applications. The present paper reports the green synthesis of CuO NPs and B-doped CuO NPs (B-CuO NPs) from Livistona chinensis leaf extract. Not much work has been reported on the use of the plant extract for the fabrication of NPs, particularly those of Cu and its doped counterparts. Various spectroscopic techniques were used to characterize the synthesized NPs. In the FT-IR spectra, peaks obtained at 504 cm-1 to 600 cm-1 were due to Cu-O vibrations. The energy dispersive X-ray analysis (EDX) spectra confirmed the CuO NPs' composition and B's presence inside the NPs. The peak pattern in the X-ray diffraction (XRD) spectrum confirmed the crystalline and monoclinic phases of the NPs. The average crystalline size of CuO NPs and B-CuO NPs was 19.56 nm and 17.30 nm respectively. The CuO and B-CuO NPs were tested against three Gram-positive bacterial strains namely Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus and three Gram-negative Escherichia coli, Salmonella abony, and Pseudomonas aeruginosa through Agar well diffusion method and it was found that CuO NPs showed higher activity than B-CuO NPs. Gentamicin was used as the positive control. The antibacterial activity may be due to the cell wall disruption by induction of innate and adaptive host immune response, generating toxic reactive oxygen species (ROS), and stimulating intracellular effects.

Antibacterial activity of cell-free supernatant produced by Lactobacillus coryniformis 7841 against Vibrio parahaemolyticus and its potential application in salmon preservation

In this study, a strain of lactic acid bacteria, whose cell-free supernatant (CFS) exhibited strong antibacterial activity against Vibrio parahaemolyticus, was isolated from traditional Chinese fermented vegetables and identified as Lactobacillus coryniformis 7841 (LC7841) based on morphological, biochemical, and molecular characteristics. The minimum bactericidal concentration and minimum inhibitory concentration of the 10-fold cell-free supernatant concentrate (CFSC) were both 10 μL/mL against V. parahaemolyticus. CFSC caused cell wall and membrane disruption of V. parahaemolyticus validated by the increasing leakages of intracellular substances (nucleic acids, proteins, and β-galactosidase), alkaline phosphatase and the accumulation of malondialdehyde. In further, scanning electron microscopy, transmission electron microscopy, and live-dead cell observation by confocal laser scanning microscope revealed that CFSC caused cell wall and membrane damages in V. parahaemolyticus in a concentration-dependent manner. The composite films incorporating CFSC in chitosan-gelatin based films were applied for salmon preservation. The composite films significantly inhibited the propagation of V. parahaemolyticus, decreased the decay rate, and prolonged the shelf-life of salmon. Consequently, these results indicated that CFC of LC7841 may have potential applications as biopreservatives against Vibrio-related contamination in seafood.

Multi-omics analysis of metabolic differences in rape bee pollen fermented by single and mixed lactic acid bacterial strains

Bee pollen is a nutrient-rich granule, but its hard cell wall limits the absorption of its nutrients by the human body. Fermenting bee pollen with lactic acid bacteria breaks down its cell wall and enhances its metabolite profile, improving nutrient availability. However, the differences in metabolites and cell wall disruption effects between mixed and single-strain fermentation have not been clarified. This study aimed to analyze the metabolites of Lactobacillus plantarum comprehensively fermented bee pollen (LPFP), Lactobacillus acidophilus fermented bee pollen (LAFP), and L. plantarum and L. acidophilus mixed fermented bee pollen (LMFP) using targeted and untargeted metabolomics as well as lipidomics, to explore the key metabolic pathways of LMFP. The results showed that under scanning electron microscopy (SEM), the cell wall of LMFP was more thoroughly disrupted. Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) and metabolic pathway enrichment analysis indicated that the degradation of flavonoids in LMFP was reduced, while the contents of total phenols, total flavonoids, rutin, and other polyphenols were significantly increased. Meanwhile, the metabolism of sucrose and amino acids in LMFP was enhanced, which might have contributed to the production of flavor compounds. Additionally, compared to LAFP and LPFP, triglycerides (TG) in LMFP increased by 8.14% and 9.85%, respectively, while the proportion of phosphatidylcholine (PC) decreased by 0.62% and 2.88%. Overall, this study presents a comprehensive metabolic profile of LAFP, LPFP, and LMFP, demonstrating how fermentation strategies affect cell wall disruption and metabolite diversity, laying a foundation for enhancing bee pollen's nutritional and functional properties.

Improvement of the color of potato chips from cold-stored tubers by pretreatment with ultrasonication.

Low-temperature sweetening is a crucial aspect in the potato chips industry because of the initiation of browning. The present study aimed to investigate the effect of ultrasonication on the concentrations of reducing sugars, sucrose, asparagine and chip color on tubers with different characteristics. Therefore, samples of the cultivars (cvs.) Nicola, Laura and Golden Wonder were used in this study. The tubers were initially stored at 4 °C and a relative humidity of 90% for 18 weeks. Ultrasonication was applied at 25 and 50 °C for 10, 20 and 30 min. The results showed that ultrasonication contributed to improve the color of the chips produced from the chip cultivar (cv. Golden Wonder), as well as the non-chip cultivars (cvs. Nicola and Laura). The concentration of reducing sugars and sucrose is the main factor for the color development of the chips. Increased temperature and extended ultrasonication duration correlate with more pronounced cell wall disruption. The present study revealed that ultrasonication could be considered as a pretreatment for production of chips from cold-stored tubers. However, it is necessary to validate the feasibility of this application in an upscaled process. © 2024 Society of Chemical Industry.

Preparation and characterization of moringin-loaded chitosan-coated liposomes and their antibacterial activity against Staphylococcus aureus

This study aimed to improve the stability of moringin and clarify the inhibitory mechanisms of moringin-loaded chitosan-coated liposomes (MR-CS-LPs) against Staphylococcus aureus. Optimisation of MR-CS-LPs was conducted using the response surface methodology, and extensive characterization was performed. The anti-bacterial activity of MR-CS-LPs was assessed by determining the minimum inhibitory concentration (MIC) and conducting growth curve analyses. The effects of MR-CS-LPs on S. aureus cell wall and membrane integrity were investigated using techniques such as scanning electron microscopy and physical and chemical analyses. Apoptotic effects were evaluated by examining oxidative stress parameters, and the impact on S. aureus biofilm formation was explored. An LC–MS/MS analysis provided insights into the inhibitory mechanism of MR-CS-LPs against S. aureus. The results indicated that MR-CS-LPs achieved an encapsulation rate of 69.02 %. Furthermore, they demonstrated potent anti-bacterial activity against S. aureus, with an MIC of 0.125 mg/mL. MR-CS-LPs disrupted cell wall and membrane integrity, resulting in macromolecule leakage, induced oxidative stress–mediated apoptosis and effectively suppressed biofilm formation, ultimately leading to bacterial death. Metabolomics analysis revealed that MR-CS-LPs inhibit S. aureus by regulating pyruvate pathways. These findings affirm that MR-CS-LPs possess significant anti-microbial properties, underscoring their potential as effective anti-microbial agents against S. aureus.

Antifungal activity and mechanism of mefentrifluconazole against Magnaporthe grisea causing rice blast

Rice blast, caused by Magnaporthe grisea, is one of the most destructive diseases of rice worldwide. Mefentrifluconazole, a novel isopropanol triazole fungicide, exhibits excellent bioactivity to a wide range of fungi. However, its antifungal activity against M. grisea is not well studied. In this study, the sensitivity of 103 M. oryzae strains to mefentrifluconazole was determined by mycelial growth rate method, and the effect of mefentrifluconazole on the biochemical and physiological characteristers was examined. The results indicated that mefentrifluconazole exhibited excellent inhibitory activity against M. oryzae with EC50 values of 103 M. oryzae strains tested ranging from 0.363 to 1.576 μg/mL, and the average EC50 value of 0.958 ± 0.298 μg/mL. After mefentrifluconazole treatment, the apical branches of M. oryzae mycelia increased and the mycelia became distorted, twisted and ruptured. In addition, mefentrifluconazole increased relative conductivity, disrupted cell wall and membrane integrity, and significantly reduced ergosterol content. The expression levels of demethylation inhibitor resistance-associated genes Cyp51A, ABC6 and MFS1 were all significantly upregulated, suggesting an adaption response to mefentrifluconazole of M. oryzae. Furthermore, the results of pot experiment showed that mefentrifluconazole provided >70 % control efficacy against rice blast at 300 μg/mL, surpassing the performance of carbendazim, prochloraz and azoxystrobin at the same concentration. Overall, this study demonstrated the strong inhibitory activity of mefentrifluconazole against M. oryzae and the excellent efficacy in controlling rice blast, thus providing new sights into rice blast control as well as the practical application of mefentrifluconazole.

Ionic strength regulates IFT in microemulsion for extraction of botanical natural products

Microemulsion, an emerging environmentally friendly medium, has demonstrated significant potential in botanical natural products (BNP) extraction. We found suitable ionic strength could enhance the BNP extraction capability of microemulsion. However, this mechanism remains unclear. Elucidating this mechanism will help to develop extraction strategies to increase BNP yields. Therefore, this mechanism was explored through scanning electron microscope, 2D NOESY, and molecular dynamics simulation. Ionic strength was quantified by Na+ concentration. BNP was represented by acteoside, hyperoside, luteolin and apigenin in Rehmannia glutinosa Libosch. Leaves. The results revealed the position of coordination ring shift forward when ionic strength regulated IFT. This reduced the electrostatic repulsion among surfactants’ head groups. Head groups are thus closely arranged at interface. This improves the pool capacity, hydrogen bonding interaction between head group and cellulose, as well as the interaction between head group and BNP. These provide guarantees for effective microemulsion-mediated cell wall disruption and BNP extraction.

Disruption to de novo uridine biosynthesis alters β-1,3-glucan masking in Candida albicans.

The uridine derivatives UDP-glucose and UDP-N-acetylglucosamine are important for cell wall construction as they are the precursors for the synthesis of β-1,3-glucan and chitin, respectively. Previous studies have demonstrated attenuated virulence of uridine auxotrophs in mice, which has been attributed to insufficient uridine levels for growth in the host. We have discovered that uridine deprivation in the uridine auxotroph ura3ΔΔ disrupts cell wall architecture by increasing surface mannans, exposing β-1,3-glucan and chitin, and decreasing UDP-sugar levels. Cell wall architecture and UDP-sugars can be rescued with uridine supplementation. The cell wall architectural disruptions in the ura3ΔΔ mutant also impact immune activation since the mutant elicited greater TNFα secretion from RAW264.7 macrophages than wild type. To determine if cell wall defects contributed to decreased virulence in the ura3ΔΔ mutant, we used a murine model of systemic infection. Mice infected with the ura3ΔΔ mutant exhibited increased survival and reduced kidney fungal burden compared with mice infected with wild type. However, suppression of the immune response with cyclophosphamide did not rescue virulence in mice infected with the ura3ΔΔ mutant, indicating the attenuation in virulence of uridine auxotrophs can be attributed to decreased growth in the host but not increased exposure of β-1,3-glucan. Moreover, the ura3ΔΔ mutant is unable to grow on ex vivo kidney agar, which demonstrates its inability to colonize the kidneys due to poor growth. Thus, although uridine auxotrophy elicits changes to cell wall architecture that increase the exposure of immunogenic polymers, metabolic fitness costs more strongly drive the observed virulence attenuation.IMPORTANCECandida albicans is a common cause of bloodstream infections (candidemia). Treatment of these bloodstream infections is made difficult because of increasing antifungal resistance and drug toxicity. Thus, new tactics are needed for antifungal drug development, with immunotherapy being of particular interest. The cell wall of C. albicans is composed of highly immunogenic polymers, particularly β-1,3-glucan. However, β-1,3-glucan is naturally masked by an outer layer of mannoproteins, which hampers the detection of the fungus by the host immune system. Alteration in cell wall components has been shown to increase β-1,3-glucan exposure; however, it is unknown how the inability to synthesize precursors to cell wall components affects unmasking. Here, we demonstrate how cell wall architecture is altered in response to a deficit in precursors for cell wall synthesis and how uridine is a crucial component of these precursors.

Strategic enhancement of antimicrobial activity of zinc phosphate conversion coatings through effective integration of P-doped MoS2 nanoparticles for marine applications

The present study proposes a strategic enhancement in biocorrosion resistance and barrier protection characteristics of steel surfaces through the development of P-doped MoS2 based composite phosphate conversion coatings. The tuning of composition of the nanoparticles additive in the composite coating brings desirable surface reformation to the composite coating, to achieve favorable structure, morphology, composition, and topography to fight against a diverse group of bacterial species. The tuned composite coating (0.3–PMS coating) exhibits the least bacterial survivability percentage in all the bacterial cultures chosen for the study, such as culture-1 (gram-negative bacterial culture: 24.67 %), culture-2 (gram-positive bacterial culture: 26.95 %), and culture-3 (marine mixed bacterial culture: 18.41 %), as compared to the other developed coatings. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) analyses of the 0.3–PMS coating after exposure to different bacterial culture confirms the extinction of bacterial cells on the coating surface, responsible for the reduced bacterial survivability values. The chemical nature and reactive oxygen species (ROS) generation ability of the composite coatings in conjunction with the influence of their morphological/topographical features results in cell wall disruption and bacterial death. Hence, the effectiveness of the composite coating to offer a combined action of biocorrosion resistance, barrier protection characteristics and long-term stability towards different bacterial cultures indicate their usefulness for marine and coastal applications.

Exploration of Metal-Doped Iron Oxide Nanoparticles as an Antimicrobial Agent: A Comprehensive Review.

Over the past two decades, nanotechnology has captured significant interest, especially in the medical field, where the unique characteristics of nanoscale particles offer substantial advantages. The family of nanosized materials, specifically iron oxide nanoparticles (IONPs), has emerged as promising due to their magnetic properties, biocompatibility, and substantial surface area for therapeutic molecule attachment. The review explores various strategies to enhance the antibacterial properties of IONPs, such as metal doping, which modifies their physicochemical, biological, electrical, and optical properties. Metal-doped IONPs, including those with nickel, copper, zinc, selenium, molybdenum, gold, and others, have shown that they effectively eradicate viruses and bacteria. The mechanisms behind their enhanced antibacterial activity involve generating reactive oxygen species (ROS), inhibiting antibiotic-resistant genes, disrupting cell walls and DNA, dysfunction of efflux pumps, and internalizing nanoparticles. The review also addresses the potential toxicity of IONPs, highlighting factors such as their dimension, form, and outermost layers, which change how they affect the overall condition of cellular structures. Surface coatings using polymers and essential oils are among the strategies being investigated as potential ways to reduce toxicity. This review additionally looks into IONPs' drug delivery potential for antibiotics and antifungals. The integration of IONPs with various pharmaceutical compounds and their controlled release mechanisms are also detailed. The review concludes by offering a positive outlook on the potential enhancements and prospects of IONPs. Challenges in synthesis technologies, size tuning, and surface alteration are acknowledged, emphasizing the need for continued research to fully harness the capabilities of IONPs in biomedical applications.

Prenylated Flavonoids Isolated from the Root of Sophora flavescens as Potent Antifungal Agents against Botrytis cinerea.

Sophora flavescens, a traditional Chinese herb, produces a wide range of secondary metabolites with a broad spectrum of biological activities. In this study, we isolated six isopentenyl flavonoids (1-6) from the roots of S. flavescens and evaluated their activities against phytopathogenic fungi. In vitro activities showed that kurarinone and sophoraflavanone G displayed broad spectrum and superior activities, among which sophoraflavanone G displayed excellent activity against tested fungi, with EC50 values ranging from 4.76 to 13.94 μg/mL. Notably, kurarinone was easily purified and showed potential activity against Rhizoctonia solani, Botrytis cinerea, and Fusarium graminearum with EC50 values of 16.12, 16.55, and 16.99 μg/mL, respectively. Consequently, we initially investigated the mechanism of kurarinone against B. cinerea. It was found that kurarinone disrupted cell wall components, impaired cell membrane integrity, increased cell membrane permeability, and affected cellular energy metabolism, thereby exerting its effect against B. cinerea. Therefore, kurarinone is expected to be a potential candidate for the development of plant fungicides.

Research on the Cell Wall Breaking and Subcritical Extraction of Astaxanthin from Phaffia rhodozyma.

This study focused on developing an effective cell wall-breaking method for Phaffia rhodozyma, followed by utilizing subcritical fluid extraction to isolate, extract, and concentrate astaxanthin from the complex fermentation products of P. rhodozyma. A comprehensive comparison of seven distinct methods for disrupting cell walls, including dimethyl sulfoxide treatment, lactic acid treatment, sodium hydroxide treatment, β-glucanase enzymatic digestion, β-mannanase enzymatic digestion, and a combined enzymatic treatment involving both β-mannanase and β-glucanase was conducted. The results identified the lactic acid method as the most effective in disrupting the cell walls of P. rhodozyma. The software, Design Expert, was used in the process of extracting astaxanthin from cell lysates using a subcritical extraction method. Through fitting analysis and response surface optimization analysis by Design Expert, the optimal extraction conditions were determined as follows: an extraction temperature of 41 °C, extraction frequency of two times, and extraction time of 46 min. These parameters facilitated the efficient extraction, concentration, and enrichment of astaxanthin from P. rhodozyma, resulting in an astaxanthin concentration of 540.00 mg/L. This result can establish the foundation for its high-value applications.

Dual RNA sequencing during Trichoderma harzianum-Phytophthora capsici interaction reveals multiple biological processes involved in the inhibition and highlights the cell wall as a potential target.

Phytophthora capsici is a destructive oomycete pathogen, causing huge economic losses for agricultural production. The genus Trichoderma represents one of the most extensively researched categories of biocontrol agents, encompassing a diverse array of effective strains. The commercial biocontrol agent Trichoderma harzianum strain T-22 exhibits pronounced biocontrol effects against many plant pathogens, but its activity against P. capsici is not known. T. harzianum T-22 significantly inhibited the growth of P. capsici mycelia and the culture filtrate of T-22 induced lysis of P. capsici zoospores. Electron microscopic analyses indicated that T-22 significantly modulated the ultrastructural composition of P. capsici, with a severe impact on the cell wall integrity. Dual RNA sequencing revealed multiple biological processes involved in the inhibition during the interaction between these two microorganisms. In particular, a marked upregulation of genes was identified in T. harzianum that are implicated in cell wall degradation or disruption. Concurrently, the presence of T. harzianum appeared to potentiate the susceptibility of P. capsici to cell wall biosynthesis inhibitors such as mandipropamid and dimethomorph. Further investigations showed that mandipropamid and dimethomorph could strongly inhibit the growth and development of P. capsici but had no impact on T. harzianum even at high concentrations, demonstrating the feasibility of combining T. harzianum and these cell wall synthesis inhibitors to combat P. capsici. These findings provided enhanced insights into the biocontrol mechanisms against P. capsici with T. harzianum and evidenced compatibility between specific biological and chemical control strategies. © 2024 Society of Chemical Industry.

Inactivation effect and mechanism of Pediastrum by in-liquid pulsed discharge plasma

The issue of eutrophication in river and lake ecosystems is escalating, resulting in harmful algal blooms that adversely impact the aquatic environment. Thus, it is crucial to develop new technology that can effectively inactivate algae without causing secondary pollution to the water body. This work uses in-liquid pulsed discharge plasma technique to inactivate Pediastrum. The research investigates variations in inactivation ratios, chlorophyll-a concentrations, and the inactivation mechanisms under different discharge conditions. The results indicate that the optimal inactivation effect is achieved at a peak voltage of 30 kV, an electrode spacing of 7 mm, and a discharge duration of 20 min, resulting in a 90 % inactivation ratio and a reduction in chlorophyll-a concentration from 1.31 mg/L to 0.63 mg/L (on the fourth day of re-culturing). The discharge process generates strong shock waves, ultraviolet lights, and significant amounts of oxidizing agents, such as· O, H2O2, O3, leading to cell damage, cell wall disruption, and enzyme activity reduction, thereby achieving effective inactivation.