Plasma-mediated enhancement of enzyme secretion in Aspergillus oryzae

Brilacidin, a host defense peptide mimetic, potentiates ibrexafungerp antifungal activity against the human pathogenic fungus Aspergillus fumigatus

Aspergillus fumigatus is the primary etiological agent of aspergillosis. Here, we show that the host defense peptide mimetic brilacidin (BRI) can potentiate ibrexafungerp (IBX) against clinical isolates of A. fumigatus. BRI + IBX can inhibit the growth of A. fumigatus voriconazole- and caspofungin-resistant clinical isolates. BRI is a small molecule host defense peptide mimetic that has previously exhibited broad-spectrum immunomodulatory/anti-inflammatory activity against viruses, bacteria, and fungi. In vitro, combination of BRI + IBX plays a fungicidal role, increases the fungal cell permeability, decreases the fungal survival in the presence of A549 epithelial cells, and appears as a promising antifungal therapeutic alternative against A. fumigatus.

IMPORTANCE

Invasive fungal infections have a high mortality rate causing more deaths annually than tuberculosis or malaria. Aspergillus fumigatus causes a series of distinct invasive fungal infections have a high mortality rate causing more deaths annually than tuberculosis or malaria. A. fumigatus causes a spectrum of distinct clinical entities named aspergillosis, which the most severe form is the invasive pulmonary aspergillosis. There are few therapeutic options for treating aspergillosis and searching for new antifungal agents against this disease is very important. Here, we present brilacidin (BRI) as a synergizer o fibrexafungerp (IBX) against A. fumigatus. BRI is a small molecule host defense peptide mimetic that has previously exhibited broad-spectrum immunomodulatory/anti-inflammatory activity against bacteria and viruses. We propose the combination of BRI and IBX as a new antifungal combinatorial treatment against aspergillosis.

Brilacidin, a host defense peptide mimetic, potentiates ibrexafungerp antifungal activity against the human pathogenic fungus Aspergillus fumigatus

Aspergillus fumigatus is the primary etiological agent of aspergillosis. Here, we show that the host defense peptide mimetic, brilacidin (BRI) can potentiate ibrexafungerp (IBX) against clinical isolates of A. fumigatus. CAS-resistant strains with mutations in fks1 that encodes the 1,3-β-D-glucan synthase are not IBX-resistant and BRI+IBX can inhibit their growth. The combination of BRI+IBX plays a fungicidal role, increases the fungal cell permeability and decreases the fungal survival in the presence of A549 epithelial cells.

The Effect of Plasma-Treated Water on Microbial Growth and Biosynthesis of Gamma-Decalactones by Yarrowia lipolytica Yeast

In recent years, the production of plasma-treated water (PTW) by low-temperature low-pressure glow plasma (LPGP) has been increasingly gaining in popularity. LPGP-treated water changes its physical and physiochemical properties compared to standard distilled water. In this study, a non-conventional lipolytic yeast species Yarrowia lipolytica was cultivated in culture media based on Nantes plasma water with heightened singlet oxygen content (Nantes PW) or in water treated with low-temperature, low-pressure glow plasma while in contact with air (PWTA) or nitrogen (PWTN). The research aimed to assess the influence of culture conditions on castor oil biotransformation to gamma-decalactone (GDL) and other secondary metabolites in media based on nanowater. The Nantes plasma water-based medium attained the highest concentration of gamma-decalactone (4.81 ± 0.51 g/L at 144 h of culture), maximum biomass concentration and biomass yield from the substrate. The amplified activity of lipases in the nanowater-based medium, in comparison to the control medium, is encouraging from the perspective of GDL biosynthesis, relying on the biotransformation of ricinoleic acid, which is the primary component of castor oil. Although lipid hydrolysis was enhanced, this step seemed not crucial for GDL concentration. Interestingly, the study validates the significance of oxygen in β-oxidation enzymes and its role in the bioconversion of ricinoleic acid to GDL and other lactones. Specifically, media with higher oxygen content (WPTA) and Nantes plasma water resulted in remarkably high concentrations of four lactones: gamma-decalactone, 3-hydroxy-gamma-decalactone, dec-2-en-4-olide and dec-3-en-4-olide.

A host defense peptide mimetic, brilacidin, potentiates caspofungin antifungal activity against human pathogenic fungi

Fungal infections cause more than 1.5 million deaths a year. Due to emerging antifungal drug resistance, novel strategies are urgently needed to combat life-threatening fungal diseases. Here, we identify the host defense peptide mimetic, brilacidin (BRI) as a synergizer with caspofungin (CAS) against CAS-sensitive and CAS-resistant isolates of Aspergillus fumigatus, Candida albicans, C. auris, and CAS-intrinsically resistant Cryptococcus neoformans. BRI also potentiates azoles against A. fumigatus and several Mucorales fungi. BRI acts in A. fumigatus by affecting cell wall integrity pathway and cell membrane potential. BRI combined with CAS significantly clears A. fumigatus lung infection in an immunosuppressed murine model of invasive pulmonary aspergillosis. BRI alone also decreases A. fumigatus fungal burden and ablates disease development in a murine model of fungal keratitis. Our results indicate that combinations of BRI and antifungal drugs in clinical use are likely to improve the treatment outcome of aspergillosis and other fungal infections.

Enhancement of Fungal Enzyme Production by Radio-Frequency Electromagnetic Fields

Enzyme production by microorganisms on an industrial scale has demonstrated technical bottlenecks, such as low efficiency in enzyme expression and extracellular secretion. In this study, as a potential tool for overcoming these technical limits, radio-frequency electromagnetic field (RF-EMF) exposure was examined for its possibility to enhance production of an enzyme, α-amylase, in a filamentous fungus, Aspergillus oryzae. The RF-EMF perfectly resonated at 2 GHz with directivity radiation pattern and peak gain of 0.5 dB (0.01 Watt). Total protein concentration and activity of α-amylase measured in media were about 1.5-3-fold higher in the RF-EMF exposed (10 min) sample than control (no RF-EMF) during incubation (the highest increase after 16 h). The level of α-amylase mRNA in cells was approximately 2-8-fold increased 16 and 24 h after RF-EMF exposure for 10 min. An increase in vesicle accumulation within fungal hyphae and the transcription of some genes involved in protein cellular trafficking was observed in RF-EMF-exposed samples. Membrane potential was not changed, but the intracellular Ca2+ level was elevated after RF-EMF exposure. Our results suggest that RF-EMF can increase the extracellular level of fungal total proteins and α-amylase activity and the intracellular level of Ca2+.

Effects of non-thermal atmospheric plasma on protein

Currently, the advancement in non-thermal atmospheric plasma technology enables plasma treatments on some heat-sensitive targets, including biological substances, without unspecific damage caused by thermal effect. The significant effects of non-thermal atmospheric plasma modulating biological events have been demonstrated by considerable studies. Protein, one of the most important biomolecules, participates in the majority of the life-sustaining activities in all organisms, whose functions are derived from the diverse biochemical properties of amino acid compositions and four-tiered protein structure hierarchy. Therefore, the knowledge of how non-thermal atmospheric plasma affects protein greatly benefits the understanding and application of the non-thermal atmospheric plasma's effect in biological area. In this review, we summarize recent research progress on the effects of non-thermal atmospheric plasma, particularly its reactive species, on biochemical and biophysical characteristics of proteins at different structural levels that leads to their functional changes. Moreover, the physiological effects of non-thermal atmospheric plasma at cellular or organism level driven by the manipulations on protein and their relative application prospects are reviewed. Despite the exceptional application potential, the exploration of the non-thermal atmospheric plasma's effect on protein still confronts with difficulties due to the limited knowledge of the underlying mechanisms and the complexity of non-thermal atmospheric plasma operation systems, which requires further studies and standardization of non-thermal atmospheric plasma treatments.

Nonthermal Plasma Effects on Fungi: Applications, Fungal Responses, and Future Perspectives

The kingdom of Fungi is rich in species that live in various environments and exhibit different lifestyles. Many are beneficial and indispensable for the environment and industries, but some can threaten plants, animals, and humans as pathogens. Various strategies have been applied to eliminate fungal pathogens by relying on chemical and nonchemical antifungal agents and tools. Nonthermal plasma (NTP) is a potential tool to inactivate pathogenic and food-contaminating fungi and genetically improve fungal strains used in industry as enzyme and metabolite producers. The NTP mode of action is due to many highly reactive species and their interactions with biological molecules. The interaction of the NTP with living cells is believed to be synergistic yet not well understood. This review aims to summarize the current NTP designs, applications, and challenges that involve fungi, as well as provide brief descriptions of underlying mechanisms employed by fungi in interactions with the NTP components.

Plasma Promotes Fungal Cellulase Production by Regulating the Levels of Intracellular NO and Ca2

For the industrial-scale production of useful enzymes by microorganisms, technological development is required for overcoming a technical bottleneck represented by poor efficiency in the induction of enzyme gene expression and secretion. In this study, we evaluated the potential of a non-thermal atmospheric pressure plasma jet to improve the production efficiency of cellulolytic enzymes in Neurospora crassa, a filamentous fungus. The total activity of cellulolytic enzymes and protein concentration were significantly increased (1.1~1.2 times) in media containing Avicel 24–72 h after 2 and 5 min of plasma treatment. The mRNA levels of four cellulolytic enzymes in fungal hyphae grown in media with Avicel were significantly increased (1.3~17 times) 2–4 h after a 5 min of plasma treatment. The levels of intracellular NO and Ca²⁺ were increased in plasma-treated fungal hyphae grown in Avicel media after 48 h, and the removal of intracellular NO decreased the activity of cellulolytic enzymes in media and the level of vesicles in fungal hyphae. Our data suggest that plasma treatment can promote the transcription and secretion of cellulolytic enzymes into the culture media in the presence of Avicel (induction condition) by enhancing the intracellular level of NO and Ca²⁺.

Recent advances in the development of Aspergillus for protein production

Aspergillus had been widely used in the industrial production of recombinant proteins. In addition to the safety and broad substrate utilization spectrum, its efficient post-translational modification and strong protein secretion capacity have significant advantages for developing an excellent protein-producing cell factory in industrial production. However, the difficulties in genetic manipulation of Aspergillus and varying expression levels of different heterologous proteins hampered its further development and application. Recently, the development of CRISPR genome editing and high-throughput screening platforms has facilitated the Aspergillus development of a wide range of modifications and applications. Meanwhile, multi-omics analysis and multiplexed genetic engineering have promoted effective knowledge mining. This paper provides a comprehensive and updated review of these advances, including high-throughput screening, genome editing, protein expression modules, and fermentation optimization. It also highlights and discusses the latest significant progress, aiming to provide a practical guide for implementing Aspergillus as an efficient protein-producing cell factory.

Application of Non-Thermal Plasma to Fungal Resources

In addition to being key pathogens in plants, animals, and humans, fungi are also valuable resources in agriculture, food, medicine, industry, and the environment. The elimination of pathogenic fungi and the functional enhancement of beneficial fungi have been the major topics investigated by researchers. Non-thermal plasma (NTP) is a potential tool to inactivate pathogenic and food-spoiling fungi and functionally enhance beneficial fungi. In this review, we summarize and discuss research performed over the last decade on the use of NTP to treat both harmful and beneficial yeast- and filamentous-type fungi. NTP can efficiently inactivate fungal spores and eliminate fungal contaminants from seeds, fresh agricultural produce, food, and human skin. Studies have also demonstrated that NTP can improve the production of valuable enzymes and metabolites in fungi. Further studies are still needed to establish NTP as a method that can be used as an alternative to the conventional methods of fungal inactivation and activation.

Membrane Traffic in Aspergillus oryzae and Related Filamentous Fungi

The industrially important filamentous fungus Aspergillus oryzae, known as the yellow Koji mold and also designated the Japanese National fungus, has been investigated for understanding the intracellular membrane trafficking machinery due to the great ability of valuable enzyme production. The underlying molecular mechanisms of the secretory pathway delineate the main secretion route from the hyphal tip via the vesicle cluster Spitzenkörper, but also there is a growing body of evidence that septum-directed and unconventional secretion occurs in A. oryzae hyphal cells. Moreover, not only the secretory pathway but also the endocytic pathway is crucial for protein secretion, especially having a role in apical endocytic recycling. As a hallmark of multicellular filamentous fungal cells, endocytic organelles early endosome and vacuole are quite dynamic: the former exhibits constant long-range motility through the hyphal cells and the latter displays pleiomorphic structures in each hyphal region. These characteristics are thought to have physiological roles, such as supporting protein secretion and transporting nutrients. This review summarizes molecular and physiological mechanisms of membrane traffic, i.e., secretory and endocytic pathways, in A. oryzae and related filamentous fungi and describes the further potential for industrial applications.

Influence of Non-Thermal Atmospheric Pressure Plasma Jet on Extracellular Activity of α-Amylase in Aspergillus oryzae

In a previous study, we found that plasma can enhance spore germination and α-amylase secretion in A. oryzae, a beneficial fungus used in fermentation. To confirm this, in the current study, we investigated the effects of plasma on development and α-amylase secretion using an enlarged sample size and a different plasma source: a plasma jet. There was a ~10% (p < 0.01) increase in spore germination upon non-thermal atmospheric pressure plasma jet (NTAPPJ) treatment for 5 min and 10 min, as compared with the control (no plasma treatment). The activity of α-amylase detected in potato dextrose broth (PDB) media during incubation was significantly elevated in plasma-treated samples, with a more obvious increase upon 10 min and 15 min treatments and 24–96 h incubation periods. The levels of the oxidation reduction potential (ORP) and NOX (nitrogen oxide species) were higher in the plasma-treated samples than in the control samples, suggesting that these two variables could serve as standard indicators for enhancing α-amylase activity after plasma treatment. Genome sequencing analysis showed approximately 0.0016–0.0017% variations (changes in 596–655 base pairs out of a total of 37,912,014 base pairs) in the genomic DNA sequence of A. oryzae after plasma treatment. Our results suggest that NATPPJ can enhance the spore germination and extracellular activity of α-amylase, probably by increasing the levels of ORP and NOX to an optimum level.