Enhanced Production of Mycophenolic Acid from Penicillium brevicompactum via Optimized Fermentation Strategy

Recent advances in the application of CRISPR/Cas-based gene editing technology in Filamentous Fungi

Filamentous fungi are essential industrial microorganisms that can serve as sources of enzymes, organic acids, terpenoids, and other bioactive compounds with significant applications in food, medicine, and agriculture. However, the underdevelopment of gene editing tools limits the full exploitation of filamentous fungi, which still present numerous untapped potential applications. In recent years, the CRISPR/Cas (clustered regularly interspaced short palindromic repeats) system, a versatile genome-editing tool, has advanced significantly and been widely applied in filamentous fungi, showcasing considerable research potential. This review examines the development and mechanisms of genome-editing tools in filamentous fungi, and contrasts the CRISPR/Cas9 and CRISPR/Cpf1 systems. The transformation and delivery strategies of the CRISPR/Cas system in filamentous fungi are also examined. Additionally, recent applications of CRISPR/Cas systems in filamentous fungi are summarized, such as gene disruption, base editing, and gene regulation. Strategies to enhance editing efficiency and reduce off-target effects are also highlighted, with the aim of providing insights for the future construction and optimization of CRISPR/Cas systems in filamentous fungi.

Isolation, Identification, and Fermentation Optimization of Phytase-Producing Bacteria and Their Effects on Soybean Seedlings

Phosphorus in soil mostly exists in complex compounds such as phytic acid, which reduces the effectiveness of phosphorus and limits agricultural production. Phytase has the activity of hydrolyzing phytate into phosphate. The mineralization of phytate in soil by phytase secreted by microorganisms is an effective way to improve the utilization rate of phytate. This study isolated a high-yield phytase strain, identified as Pseudomonas by 16S rDNA and named Pseudomonas sp. S3-10. The fermentation medium composition and conditions were optimized using the single-factor method, Plackett-Burman design (PBD), and response surface methodology (RSM). The results showed that cane molasses, MgCl2, and temperature significantly affected the fermentation biomass of the bacterium. The optimal fermentation conditions were cane molasses and MgCl2 concentrations of 61.80 g/L and 5.94 g/L, respectively, at 34.4 °C. Compared with the unoptimized fermentation conditions, the maximum biomass increased by 160.17 ± 6.26% under the optimized fermentation conditions, reaching 9.13 ± 0.09 × 109 CFU/mL. The pot experiment results showed that Pseudomonas sp. S3-10 has a significant promoting effect on soybean growth. The strain increased the fresh weight and length of soybean seedlings by 112.92 ± 28.41% and 74.02 ± 3.24%, respectively, and increased the phytase activity in the soil and available phosphorus concentration in the plant rhizosphere by 388.15 ± 24.24% and 365.05 ± 91.96%, respectively. This study provided a high-yield phytase strain and its optimal fermentation conditions. The bacterium has significant plant growth-promoting effects and can be used as a new type of biological fertilizer, which is of great significance for reducing phosphorus fertilizer usage, improving phosphorus utilization efficiency, and protecting the ecological environment in agricultural production.

Low-cost solid-state fermentation to improve mycophenolic acid synthesis

Mycophenolic acid (MPA) is an immunosuppressive/antibiotic drug, biologically produced by the fermentation of Penicillium brevicompactum as its secondary metabolite using submerged (SmF) and solid-state (SSF) fermentation processes. In this study, the SSF of P. brevicompactum (MTCC 1999) was done in optimised conditions to enhance MPA yield. Substrates including basmati and non-basmati rice, barley, oats, cornflakes, rice bran, and wheat bran were 80% moistened and sterilised. The active-spore suspension was inoculated and incubated for 30 days. Wheat bran has been shown to produce the highest MPA yield in bench-scale studies. Therefore, wheat bran was subjected to large-scale MPA production. The indigenous fermentation bags were used in the large-scale SSF process. The MPA production was increased from 0.02 mg/g in bench-scale SSF to 9.5 mg/g in large-scale SSF in 15 days of incubation. The MPA increase is nearly 9.48 mg/g. This paper presents an improved SSF process for enhanced MPA production.

Optimization of fermentation conditions for physcion production of Aspergillus chevalieri BYST01 by response surface methodology

This study aimed to optimize the culture conditions of the termite-derived fungus Aspergillus chevalieri BYST01 for the production of physcion, a characteristic component of the traditional herb rhubarb, which has been commercially approved as a botanical fungicide in China. First, potato dextrose broth was screened as the suitable basal medium for further optimization, with an initial yield of 28.0 mg/L. Then, the suitable carbon source, fermentation time, temperature, pH value, and the rotary shaker speed for physcion production were determined using the one-variable-at-a-time method. Based on the results of single factors experiments, the variables with statistically significant effects on physcion production were further confirmed using the Plackett-Burman design (PBD). Among the five variables, temperature, initial pH, and rotary shaker speed were identified as significant factors (P < 0.05) for physcion productivity in the PDB and were further analyzed by response surface methodology (RSM). Finally, we found that the maximum physcion production (82.0 mg/L) was achieved under the following optimized conditions:initial pH 6.6, rotary shaker speed of 177 rpm, temperature of 28 °C, and glucose concentration of 30 g/L in PDB medium after 11 d of fermentation. The yield of physcion under the optimized culture conditions was approximately threefold higher than that obtained using the basal culture medium. Furthermore, the optimum fermentation conditions in the 5-L bioreactor achieved a maximal physcion yield of 85.2 mg/L within 8 d of fermentation. Hence, response surface methodology proved to be a powerful tool for optimizing physcion production by A. chevalieri BYST01. This study may be helpful in promoting the application of physcion produced by A. chevalieri BYST01 to manage plant diseases.

Approaches Towards Better Immunosuppressive Agents

Several classes of compounds are applied in clinics due to their immunosuppressive properties in transplantology and the treatment of autoimmune diseases. Derivatives of mycophenolic acid, corticosteroids and chemotherapeutics bearing heterocyclic moieties like methotrexate, azathioprine, mizoribine, and ruxolitinib are active substances with investigated mechanisms of action. However, improved synthetic approaches of known drugs and novel derivatives are still being reported to attempt better accessibility and therapeutic properties. In this review article, we present the synthesis of the designed chemical structures based on recent literature reports concerning novel compounds as promising immunosuppressive drugs. Moreover, some of the discussed derivers revealed also other types of activities with prospective medicinal potential.

PrlaeA Affects the Production of Roquefortine C, Mycophenolic Acid, and Andrastin A in Penicillium roqueforti, but It Has Little Impact on Asexual Development

The regulation of fungal specialized metabolism is a complex process involving various regulators. Among these regulators, LaeA, a methyltransferase protein originally discovered in Aspergillus spp., plays a crucial role. Although the role of LaeA in specialized metabolism has been studied in different fungi, its function in Penicillium roqueforti remains unknown. In this study, we employed CRISPR-Cas9 technology to disrupt the laeA gene in P. roqueforti (PrlaeA) aiming to investigate its impact on the production of the specialized metabolites roquefortine C, mycophenolic acid, and andrastin A, as well as on asexual development, because they are processes that occur in the same temporal stages within the physiology of the fungus. Our results demonstrate a substantial reduction in the production of the three metabolites upon disruption of PrlaeA, suggesting a positive regulatory role of LaeA in their biosynthesis. These findings were further supported by qRT-PCR analysis, which revealed significant downregulation in the expression of genes associated with the biosynthetic gene clusters (BGCs) responsible for producing roquefortine C, mycophenolic acid, and andrastin A in the ΔPrlaeA strains compared with the wild-type P. roqueforti. Regarding asexual development, the disruption of PrlaeA led to a slight decrease in colony growth rate, while conidiation and conidial germination remained unaffected. Taken together, our results suggest that LaeA positively regulates the expression of the analyzed BGCs and the production of their corresponding metabolites in P. roqueforti, but it has little impact on asexual development.

Titer improvement of mycophenolic acid in the novel producer strain Penicillium arizonense and expression analysis of its biosynthetic genes

Mycophenolic acid (MPA) is the active ingredient in the most important immunosuppressive pharmaceuticals. It has antifungal, antibacterial, antiviral, anti-psoriasis, and antitumor activities. Therefore, its overproduction in addition to gene expression analysis was our main target. Through this study, we isolated a novel potent mycophenolic acid (MPA) producer strain of the genus Penicillium from the refrigerated Mozzarella cheese and it was identified with the molecular marker ITS and benA genes as P. arizonenseHEWt1. Three MPA overproducer mutants were isolated by exposing the wild type to different doses of gamma-rays, and the fermentation conditions for the highest production of MPA were optimized. The results indicated that MPA amounts produced by the mutants MT1, MT2, and MT3 were increased by 2.1, 1.7, and 1.6-fold, respectively, compared with the wild-type. The growth of both mutant and wild-type strains on PD broth, adjusted to pH 6 and incubated at 25 °C for 15 d, were the best conditions for maximum production of MPA. In a silico study, five orthologs genes of MPA biosynthesizing gene clusters in P. brevicompactum were predicted from the genome of P. arizonense. Sequencing and bioinformatic analyses proved the presence of five putative genes namely mpaA, mpaC, mpaF, mpaG, and mpaH in the P. arizonense HEWt1 genome. Gene expression analysis by qRT-PCR indicated an increase in the transcription value of all annotated genes in the three mutants over the wild type. A highly significant increase in the gene expression of mpaC, mpaF, and mpaH was observed in P. arizonense-MT1 compared with wild-type. These results confirmed the positive correlation of these genes in MPA biosynthesis and are the first report regarding the production of MPA by P. arizonense.Kew word.Mycophenolic acid, Penicillium arizonense, mutagenesis, gene expression.

Current advances for omics-guided process optimization of microbial manufacturing

Currently, microbial manufacturing is widely used in various fields, such as food, medicine and energy, for its advantages of greenness and sustainable development. Process optimization is the committed step enabling the commercialization of microbial manufacturing products. However, the present optimization processes mainly rely on experience or trial-and-error method ignoring the intrinsic connection between cellular physiological requirement and production performance, so in many cases the productivity of microbial manufacturing could not been fully exploited at economically feasible cost. Recently, the rapid development of omics technologies facilitates the comprehensive analysis of microbial metabolism and fermentation performance from multi-levels of molecules, cells and microenvironment. The use of omics technologies makes the process optimization more explicit, boosting microbial manufacturing performance and bringing significant economic benefits and social value. In this paper, the traditional and omics technologies-guided process optimization of microbial manufacturing are systematically reviewed, and the future trend of process optimization is prospected.

Anti-multidrug-resistant Staphylococcus aureus and anti-dermatophyte activities of secondary metabolites of the endophytic fungus Penicillium brevicompactum ANT13 associated with the Algerian endemic plant Abies numidica

This study aims to identify and assess the antimicrobial activity of endophytic fungi found in the endemic plant Abies numidica. Among all isolates, the ANT13 isolate demonstrated significant antimicrobial activity in the preliminary screening, particularly Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 1024, with inhibition zones of 22 and 21.5 mm, respectively. Based on its morphological and molecular features, this isolate was identified as Penicillium brevicompactum. The maximum activity was observed in the ethyl acetate extract, followed by the dichloromethane extract; however, the n-hexane extract exhibited no activity. The ethyl acetate extract demonstrated very significant activity against the five strains of multidrug-resistant Staphylococcus aureus used, with average zones of inhibition ranging from 21 to 26 mm, in contrast to more resistant Enterococcus faecalis ATCC 49452 and Bacillus cereus ATCC 10876. The ethyl acetate extract was also very active against dermatophytes, where the zones of inhibition for Candida albicans, Microsporum canis, Trichophyton mentagrophytes, Trichophyton rubrum, and Epidermophyton floccosum were 23.5, 31, 43, 47, and 53.5 mm, respectively. The MIC values for dermatophytes ranged between 100 and 3200 µg/mL. The wild isolate of Penicillium brevicompactum ANT13 discovered as an endophyte in Abies numidica may be a distinctive source of novel compounds and drug discovery to trait dermatophytes and multidrug-resistant Staphylococcus aureus infections.