Enzyme Production Potential of Penicillium oxalicum M1816 and Its Application in Ferulic Acid Production

Recent advances in genetic engineering to enhance plant-polysaccharide-degrading enzyme expression in Penicillium oxalicum: A brief review

With the depletion of non-renewable fossil fuels, there has been an increasing emphasis on renewable biomass. Penicillium oxalicum is notable for its exceptional capacity to secrete a diverse array of enzymes that degrade plant polysaccharides into monosaccharides. These valuable monosaccharides can be harnessed in the production of bioethanol and other sustainable forms of energy. By enhancing the production of plant-polysaccharide-degrading enzymes (PPDEs) in P. oxalicum, we can optimize the utilization of plant biomass. This paper presents recent advances in augmenting PPDE expression in P. oxalicum through genetic engineering strategies involving protoplast preparation, transformation, and factors influencing PPDE gene expression.

Fermentation biotechnology applied to wheat bran for the degradation of cell wall fiber and its potential health benefits: A review

Consumption of wheat bran is associated with health benefits. However, the insoluble cell layer fiber and considerable levels of anti-nutritional factors limit bioavailability of wheat bran, which can be effectively improved through fermentation. To comprehensively elucidate the precise biotransformation and health benefits mechanisms underlying wheat bran fermentation. This review investigates current fermentation biotechnology for wheat bran, nutritional effects of fermented wheat bran, mechanisms by which fermented wheat bran induces health benefits, and the application of fermented wheat bran in food systems. The potential strategies to improve fermented wheat bran and existing limitations on its application are also covered. Current findings support that microorganisms produce enzymes that degrade the cell wall fiber of wheat bran during the fermentation, releasing nutrients and producing new active substances while degrading anti-nutrient factors in order to effectively improve nutrient bioavailability, enhance antioxidant activity, and regulate gut microbes for health effects. Fermentation has been an effective way to degrade cell wall fiber, thereby improving nutrition and quality of whole grain or bran-rich food products. Currently, there is a lack of standardization in fermentation and human intervention studies. In conclusion, understanding effects of fermentation on wheat bran should guide the development and application of bran-rich products.

Screening, identification, and mechanism analysis of starch-degrading bacteria during curing process in tobacco leaf

Tobacco, a vital economic crop, had its quality post-curing significantly influenced by starch content. Nonetheless, the existing process parameters during curing were inadequate to satisfy the starch degradation requirements. Microorganisms exhibit inherent advantages in starch degradation, offering significant potential in the tobacco curing process. Our study concentrated on the microbial populations on the surface of tobacco leaves and in the rhizosphere soil. A strain capable of starch degradation, designated as BS3, was successfully isolated and identified as Bacillus subtilis by phylogenetic tree analysis based on 16SrDNA sequence. The application of BS3 on tobacco significantly enhanced enzyme activity and accelerated starch degradation during the curing process. Furthermore, analyses of the metagenome, transcriptome, and metabolome indicated that the BS3 strain facilitated starch degradation by regulating surface microbiota composition and affecting genes related to starch hydrolyzed protein and key metabolites in tobacco leaves. This study offered new strategies for efficiently improving the quality of tobacco leaves.

Simple phenylpropanoids: recent advances in biological activities, biosynthetic pathways, and microbial production

Covering: 2000 to 2023Simple phenylpropanoids are a large group of natural products with primary C6-C3 skeletons. They are not only important biomolecules for plant growth but also crucial chemicals for high-value industries, including fragrances, nutraceuticals, biomaterials, and pharmaceuticals. However, with the growing global demand for simple phenylpropanoids, direct plant extraction or chemical synthesis often struggles to meet current needs in terms of yield, titre, cost, and environmental impact. Benefiting from the rapid development of metabolic engineering and synthetic biology, microbial production of natural products from inexpensive and renewable sources provides a feasible solution for sustainable supply. This review outlines the biological activities of simple phenylpropanoids, compares their biosynthetic pathways in different species (plants, bacteria, and fungi), and summarises key research on the microbial production of simple phenylpropanoids over the last decade, with a focus on engineering strategies that seem to hold most potential for further development. Moreover, constructive solutions to the current challenges and future perspectives for industrial production of phenylpropanoids are presented.

Microbially-driven alkaline regulation: Organic acid secretion behavior of Penicillium oxalicum and charge neutralization in bauxite residue

Microbially-driven alkaline neutralization in bauxite residue by functional microorganisms is a promising approach for the ecological rehabilitation on alkaline disposal areas. However, the alkali resistance and acid secretion mechanism of functional microorganisms are still unknown, which limits their application. Here, saline-alkaline resistance, acid production performance, and differentially expressed genes of Penicillium oxalicum (P. oxalicum, a functional fungus screened from a typical disposal area) were investigated and its bio-neutralization efficiency was evaluated. This fungus exhibited high tolerance to alkalinity (pH 12), and salinity (NaCl 2.0 M), and produced a large amount of oxalic acid to reduce the medium pH to 2.0. Transcriptome showed that alkali stress induced the overexpression of genes related to antioxidant and stress-resistant enzymes (GST, KatE) and glycolytic pathway rate-limiting enzymes (HK). The rate of glycolysis and other organic acid metabolism processes was increased with higher stress resistance of P. oxalicum. The integrated application of P. oxalicum and maize straw accelerated the dissolved organic carbon content and stabilized the leachate pH of bauxite residue at about 7.4. 3DEEM and BIOSEM analysis indicated that P. oxalicum maintained high activity in the residue leachate and continuously decomposed the maize straw for their metabolism. P. oxalicum showed strong alkaline resistance, biomass degradation capacity, and alkaline regulation potential, which should be beneficial for microbial-driven alkaline regulation in bauxite residue.

A High-Quality Genome Sequence of the Penicillium oxalicum 5-18 Strain Isolated from a Poplar Plantation Provides Insights into Its Lignocellulose Degradation

Studies on the degradation of plant cell wall polysaccharides by fungal extracellular enzymes have attracted recent attention from researchers. Xylan, abundant in hemicellulose, that play great role in connection between cellulose and lignin, has seen interest in its hydrolytic enzymatic complex. In this study, dozens of fungus species spanning genera were isolated from rotting leaves based on their ability to decompose xylan. Among these isolates, a strain with strong xylanase-producing ability was selected for further investigation by genome sequencing. Based on phylogenetic analysis of ITS (rDNA internal transcribed spacer) and LSU (Large subunit 28S rDNA) regions, the isolate was identified as Penicillium oxalicum. Morphological analysis also supported this finding. Xylanase activity of this isolated P. oxalicum 5-18 strain was recorded to be 30.83 U/mL using the 3,5-dinitro-salicylic acid (DNS) method. Further genome sequencing reveals that sequenced reads were assembled into a 30.78 Mb genome containing 10,074 predicted protein-encoding genes. In total, 439 carbohydrate-active enzymes (CAZymes) encoding genes were predicted, many of which were associated with cellulose, hemicellulose, pectin, chitin and starch degradation. Further analysis and comparison showed that the isolate P. oxalicum 5-18 contains a diverse set of CAZyme genes involved in degradation of plant cell wall components, particularly cellulose and hemicellulose. These findings provide us with valuable genetic information about the plant biomass-degrading enzyme system of P. oxalicum, facilitating a further exploration of the repertoire of industrially relevant lignocellulolytic enzymes of P. oxalicum 5-18.

Isolation and Molecular Characterization of Indigenous Penicillium chrysogenum/rubens Strain Portfolio for Penicillin V Production

Beta (β)-lactam antibiotic is an industrially important molecule produced by Penicillium chrysogenum/rubens. Penicillin is a building block for 6-aminopenicillanic acid (6-APA), an important active pharmaceutical intermediate (API) used for semi-synthetic antibiotics biosynthesis. In this investigation, we isolated and identified Penicillium chrysogenum, P. rubens, P. brocae, P. citrinum, Aspergillus fumigatus, A. sydowii, Talaromyces tratensis, Scopulariopsis brevicaulis, P. oxalicum, and P. dipodomyicola using the internal transcribed spacer (ITS) region and the β-tubulin (BenA) gene for precise species identification from Indian origin. Furthermore, the BenA gene distinguished between complex species of P. chrysogenum and P. rubens to a certain extent which partially failed by the ITS region. In addition, these species were distinguished by metabolic markers profiled by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Secalonic acid, Meleagrin, and Roquefortine C were absent in P. rubens. The crude extract evaluated for PenV production by antibacterial activities by well diffusion method against Staphylococcus aureus NCIM-2079. A high-performance liquid chromatography (HPLC) method was developed for simultaneous detection of 6-APA, phenoxymethyl penicillin (PenV), and phenoxyacetic acid (POA). The pivotal objective was the development of an indigenous strain portfolio for PenV production. Here, a library of 80 strains of P. chrysogenum/rubens was screened for PenV production. Results showed 28 strains capable of producing PenV in a range from 10 to 120 mg/L when 80 strains were screened for its production. In addition, fermentation parameters, precursor concentration, incubation period, inoculum size, pH, and temperature were monitored for the improved PenV production using promising P. rubens strain BIONCL P45. In conclusion, P. chrysogenum/rubens strains can be explored for the industrial-scale PenV production.

Botryosphaeriaceae gene machinery: Correlation between diversity and virulence

The Botryosphaeriaceae family comprises numerous fungal pathogens capable of causing economically meaningful diseases in a wide range of crops. Many of its members can live as endophytes and turn into aggressive pathogens following the onset of environmental stress events. Their ability to cause disease may rely on the production of a broad set of effectors, such as cell wall-degrading enzymes, secondary metabolites, and peptidases. Here, we conducted comparative analyses of 41 genomes representing six Botryosphaeriaceae genera to provide insights into the genetic features linked to pathogenicity and virulence. We show that these Botryosphaeriaceae genomes possess a large diversity of carbohydrate-active enzymes (CAZymes; 128 families) and peptidases (45 families). Botryosphaeria, Neofusicoccum, and Lasiodiplodia presented the highest number of genes encoding CAZymes involved in the degradation of the plant cell wall components. The genus Botryosphaeria also exhibited the highest abundance of secreted CAZymes and peptidases. Generally, the secondary metabolites gene cluster profile was consistent in the Botryosphaeriaceae family, except for Diplodia and Neoscytalidium. At the strain level, Neofusicoccum parvum NpBt67 stood out among all the Botryosphaeriaceae genomes, presenting a higher number of secretome constituents. In contrast, the Diplodia strains showed the lowest richness of the pathogenicity- and virulence-related genes, which may correlate with their low virulence reported in previous studies. Overall, these results contribute to a better understanding of the mechanisms underlying pathogenicity and virulence in remarkable Botryosphaeriaceae species. Our results also support that Botryosphaeriaceae species could be used as an interesting biotechnological tool for lignocellulose fractionation and bioeconomy.

Complete genome sequence, metabolic model construction, and huangjiu application of Saccharopolyspora rosea A22, a thermophilic, high amylase and glucoamylase actinomycetes

Saccharopolyspora is an important microorganism in the fermentation process of wheat qu and huangjiu, yet the mechanisms by which it performs specific functions in huangjiu remain unclear. A strain with high amylase and glucoamylase activities was isolated from wheat qu and identified as Saccharopolyspora rosea (S. rosea) A22. We initially reported the whole genome sequence of S. rosea A22, which comprised a circular chromosome 6,562,638 bp in size with a GC content of 71.71%, and 6,118 protein-coding genes. A functional genomic analysis highlighted regulatory genes involved in adaptive mechanisms to harsh conditions, and in vitro experiments revealed that the growth of S. rosea A22 could be regulated in response to the stress condition. Based on whole-genome sequencing, the first genome-scale metabolic model of S. rosea A22 named iSR1310 was constructed to predict the growth ability on different media with 91% accuracy. Finally, S. rosea A22 was applied to huangjiu fermentation by inoculating raw wheat qu, and the results showed that the total higher alcohol content was reduced by 12.64% compared with the control group. This study has elucidated the tolerance mechanisms and enzyme-producing properties of S. rosea A22 at the genetic level, providing new insights into its application to huangjiu.

Three-Dimensional Genome Map of the Filamentous Fungus Penicillium oxalicum

Higher-order spatial organization of the chromatin in the nucleus plays crucial roles in the maintenance of cell functions and the regulation of gene expression. Three-dimensional (3D) genome sequencing has been used to great effect in mammal and plants, but the availability of 3D genomes of filamentous fungi is severely limited. Here, we performed a chromosome-level genome assembly of Penicillium oxalicum through single-molecule real-time sequencing (Pacific Biosciences) and chromatin interaction mapping (Hi-C), with a scaffold N50 of 4.07 Mb and a contig N50 of 3.81 Mb, and further elucidated the 3D genome architecture of P. oxalicum. High-frequency interchromosomal contacts occurred within the centromeres and telomeres, as well as within individual chromosomes. There were 12,203 cis-interactions and 7,884 trans-interactions detected at a resolution of 1 kb. Moreover, a total of 1,099 topologically associated domains (or globules) were found, ranging in size from 2.0 to 76.0 kb. Interestingly, transcription factor-bound motifs were enriched in the globule boundaries. All the cellulase and xylanase genes were discretely distributed in the 3D model of the P. oxalicum genome as a result of few cis- and trans-interactions. Our results from this study provide a global view of chromatin interactions in the P. oxalicum genome and will act as a resource for studying spatial regulation of gene expression in filamentous fungi. IMPORTANCE The spatial structure of chromatin plays important roles in normal cell functions and the regulation of gene expression. The three-dimensional (3D) architectures of the genomes of many mammals and plants have been elucidated, but corresponding studies on filamentous fungi, which play vital roles as decomposers of organic matter in the soil, are very limited. Penicillium oxalicum is one of the predominant cellulolytic aerobic fungi in subtropical and tropical forest soils and can secrete integrative cellulase and xylanase under integrated regulatory control, degrading plant biomass highly efficiently. In the present study, we employed Hi-C technology to construct the 3D genome model of P. oxalicum strain HP7-1 and to further investigate cellulase and xylanase as well as transcription factor genes in 3D genome. These results provide a resource to achieve a deeper understanding of cell function and the regulation of gene expression in filamentous fungi.