Penicillium Citrinum Research Articles

Fungicidal Potentials of Leaf and Bark Extracts of Bryophyllum pinnatum on Cowpea (Vigna unguiculata L.) Seed Fungi

In Nigeria, Cowpea (Vigna unguiculata [L.] Walp) is an important grain legume which besides being a food crop serves as a major source of income for rural households. The action of pathogens on stored seeds causes huge post-harvest and economic losses to cowpea farmers in Nigeria. This research was aimed at isolating and identifying the spoilage pathogens of cowpea seed and testing the potentiality of ethanol extracts of Bryophyllum pinnatum on the isolates. Spoilt cowpea seed samples were purchased from different markets in Anambra State. They were transported to Alpha Research Laboratory, Awka in sterile polythene bags for microbial isolation. The spoilage organisms were isolated from the seeds through microbial culture. The media used for the isolation were Sabouraud Dextrose Agar and Potato Dextrose Agar. Pathogenic fungi were isolated from the spoilt cowpea seeds. The findings indicated that Aspergillus aculeatus, Fusarium solani, Penicillium citrinum, Rhizopus stolonifer, and Aspergillus flavus were present. The pathogenicity test also showed that the above organisms were responsible for cowpea spoilage. These isolates were tested for their in-vitro antifungal activity against the leaf and bark extracts of Bryophyllum Pinnatum. The antifungal activity ethanol extracts of Bryophyllum pinnatum on the isolated microorganisms were investigated using the disc method. Three different concentrations (25%, 50%, 100%) of extracts were used for the test. Fusarium solani showed the highest percentage of inhibition with antifungal medication while Penicillium citrinum showed the least percentage of inhibition with antifungal medication. The antifungal potential of Bryophyllum pinnatum extract on spoilage pathogens of stored cocoyam corms encourages more research on the active ingredient of the plant for easy use by farmers as alternative to commercial/ synthetic fungicides.

Insights into the antifungal activity and mechanisms of cinnamon components against Aspergillus flavus and Penicillium citrinum

Fungal spoilage of food and the excessive use of chemical disinfectants serves potential adverse effects on human health and the environment. Consequently, there is a growing interest in exploring natural alternatives, particularly plant-derived antimicrobial preservatives. Cinnamon extracts are known for their antifungal activity, but most research has focused on essential oils, rarely on other bioactive components. This study assessed the antifungal activity and underlying mechanisms of four components—trans-cinnamaldehyde, cis-2-methoxycinnamic acid, coumarin, and o-methoxycinnamaldehyde—extracted from Cinnamomum cassia Presl (cinnamon) against Aspergillus flavus and Penicillium citrinum. These cinnamon components can inhibit the two fungi strains at the minimum inhibitory concentration ranged from 0.30 to 8.55 mmol/L. These components can disrupt fungal cell membranes by enhancing relative electrical conductivity and cytoplasmic content leakage, reducing ergosterol content, and increasing malondialdehyde level. Additionally, they can affect fungal cell wall integrity, leading to the leakage of alkaline phosphatase and alterations in the contents of β-1,3-glucan and chitin. Moreover, the cinnamon components influenced the activities of malate dehydrogenase, succinate dehydrogenase, as well as adenosine triphosphate levels. The observed suppression of fungal contamination in A. flavus and P. citrinum suggests that these cinnamon components as potential natural antifungal agents.

Combating vibriosis in Penaeus monodon culture system by administration of endophytic Penicillium citrinum SW171 extract that confers better growth and protection

The black tiger shrimp, Penaeus monodon, has been a key species in the development and expansion of intensive shrimp aquaculture worldwide. The problem of disease susceptibility in P. monodon, particularly vibriosis caused by Vibrio harveyi, poses a significant threat and leads to substantial economic losses. To combat bacterial infections, researchers are exploring the antimicrobial potential of microbes from unique environments, like algicolous endophytes. In this study, we investigated the in vivo exclusion of Vibrio in P. monodon post-larvae using an extract from the endophytic fungus Penicillium citrinum SW171 (PCE), evaluating its impact on disease resistance, growth, and survival. Crude endophytic extract was administered both via feed and rearing water for 28 days before the challenge with V. harveyi. Treatment with PCE improved the water quality of rearing water by significantly reducing ammonia and nitrate levels compared to the control. This treatment notably decreased Vibrio colonies without substantial alteration in the overall microbial load of the rearing water. Moreover, the endophytic extract not only inhibited pathogens but also enhanced productivity, as evidenced by improved growth rates (1272 ± 20.8 and 1109.02 ± 28.4mg) compared to the control (1026.02 ± 33.8mg). Transcript levels of the immune-related genes i.e., anti-lipopolysaccharide factor (ALF), crustin, penaeidin, prophenoloxidase-activating enzyme (PPA), phagocytosis-activating protein (PAP), lysozyme-like, ferritin, haemocyanin, lectin, and survivin, were assessed in post-larvae using qRT-PCR. Extract treatment led to significant up-regulation of all genes except PPA, survivin and ALF. The cumulative survival rate of the group orally treated with PCE was 66.9%, while that of water treatment was 64.5%, significantly higher than that of the control group. The higher growth rate and post-challenge survival of P. monodon larvae point towards the immunostimulatory and antibacterial properties of endophytic P. citrinum extract which can be exploited in aquaculture for better production.

Penicitrisochromans A-C, new isochromans from the marine-derived fungus Penicillium citrinum PSU-MF100.

Three new isochroman derivatives, penicitrisochromans A-C (1-3), together with 25 known polyketides were isolated from the marine-derived fungus Penicillium citrinum PSU-MF100. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of 1 and 2 were established by comparison of specific rotations and electronic circular dichroism (ECD) data with those of the known co-metabolite whereas those of 3 were assigned based on the ECD calculation and biosynthetic consideration. Among the isolated polyketides, three known anthraquinone derivatives, ω-hydroxyemodin, penicillanthranin A and emodin, displayed moderate to strong antibacterial activity against methicillin-resistant Staphylococcus aureus with MIC values of 32, 16 and 4 µg/mL, respectively. For antifungal activity, two known benzopyranones, coniochaetones A and C, exhibited moderate antifungal activity against Candida albicans NCPF3153 and Cryptococcus neoformans ATCC90112 with the respective MIC values of 16 and 64 µg/mL.

Dicitrinols A-C: Citrinin Derivatives from Hydrothermal Vent-Associated Fungus Penicillium citrinum TW132-59.

Three new unusual citrinin derivatives with a unique 6/5/7/5 core, dicitrinols A-C (1-3, respectively), were isolated via the fermentation of hydrothermal vent-associated fungus Penicillium citrinum TW132-59. Their structures were unambiguously determined by nuclear magnetic resonance, mass spectrometry, and electronic circular dichroism calculations. Dicitrinols A-C represent a novel cage carbon skeleton with a decahydro-5,9,4-(epipropane[1,1,3]triyl)cycloocta[b]furan ring system. Dicitrinols A-C showed moderate antifungal activity against Candida albicans, Cryptococcus neoformans, and Fusarium oxysporum and antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii with minimum inhibitory concentrations ranging from 4 to 16 μg/mL.

Fungal communities in three root herbs: Insights and implications

The roots of Astragali Radix (AM), Dioscoreae Rhizome (DR), and Codonopsis Radix (CR) are frequently used in classical tonic formulations and dietary supplements. Given the extended exposure of rhizomes to complex biological environments, it is necessary to investigate the fungal composition of their surface. In this study, the fungal communities in the three root herbs were analyzed by DNA metabarcoding, and an extensive comparison of the fungal diversity at each taxonomic level was carried out. Furthermore, we examined the effects of species, collection site, and processing method on the fungal community. In Astragali Radix and Codonopsis Radix samples, Cladosporium was the predominant genus, with relative abundances of 1.98 %-76.81 % and 1.69 %-85.59 %, respectively. Aspergillus (0.08 %–99.92 %) was the prevailing genus in Dioscoreae Rhizome samples. Meanwhile, a total of 12 potential toxigenic fungi were identified, including Aspergillus restrictus, Fusarium oxysporum, and Penicillium citrinum. Moreover, the variations in fungal diversity and community composition from different collection sites and processing approaches were observed. Linear discriminant analysis effect size indicated significant differences in the relative abundance of genera among the three root herbs. Gibberella and Mucor genera were significantly enriched in Astragali Radix samples, while Yarrowia and Cladosporium genera exhibited significant enrichment in Dioscoreae Rhizome and Codonopsis Radix samples, respectively (p≤0.001). This study presents novel insights into the fungal profiles of three root herbs, thereby providing references for their safe utilization and quality improvement.

Safety evaluation of the food enzyme endonuclease from the non-genetically modified Penicillium citrinum strain NP 11-15.

The food enzyme endonuclease (Aspergillus nuclease S1; EC 3.1.30.1) is produced with the non-genetically modified Penicillium citrinum strain NP 11-15 by Shin Nihon Chemical Co., Ltd. The food enzyme is free from viable cells of the production organism. It is intended to be used in the processing of yeast and yeast products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.006 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1010 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 168,333. A search for homology of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, especially for individuals allergic to Penicillium. However, the likelihood of such reactions will not exceed the likelihood of allergic reactions to Penicillium. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Biodegradation potential of Low-Density Polyethylene (LDPE) by soil-inhabiting ascomycetous microfungi isolated from urban dumpsites

ABSTRACT Urban dumpsites are excellent sources of microbes which can biodegrade numerous materials present in waste. This study focused on the assessment of the mycodegradation potential of LDPE (Low-Density Polyethylene) by ascomycetous microfungi from urban dumpsites in Sri Lanka. Out of the collection obtained from five localities in Sri Lanka, eight species of ascomycetes, viz. Talaromyces purpureogenus (GF85), T. beijingensis (GGF03), Penicillium citrinum (GF89), Purpureocillium lilacinum (GF99), Aspergillus flavus (GF94), Aspergillus sp. (GF82), A. terreus (MMF08), and Fusarium falciforme (GF77), demonstrated mycodegradation potential based on the primary screening. All the isolates were accurately identified based on morphology, Sanger sequencing, and phylogenetic analysis of nuclear internal transcribed spacer region with 5.8 s ribosomal DNA (ITS). Among the isolates, T. purpureogenus GF85 showed a 13–17% weight reduction of LDPE. The same fungus showed evidence of remarkable ability to cause biodeterioration of LDPE by Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). This study highlights the significance of extensive sampling, morphological, molecular characterisation, and comparative analysis of fungi from unexplored habitats towards developing sustainable solutions for the polyethylene waste crisis.

Ethyl Acetate Extracts Endophytic Fungi from the Medicinal Tree Fern Cyathea Contaminans (Hook) Copel with Antimicrobial Activity

Medicinal plants are a rich source of naturally occurring substances utilized in treating a wide range of diseases; as a result, they serve as the basis for discovering new drugs. Research has focused on the relationship between endophytic microorganisms and host plants, as they produce a variety of secondary metabolites with significant biological functions. This study aimed to extract the endophytic fungi from various plant parts, including the roots, barks, and leaves of the Cyathea contaminans (Hook) Copel, which was collected from Kerinci, Jambi, Indonesia. By employing direct planting and pouring techniques with fungal culture media, the fungi were separated from the roots, stems, hairs, and leaves of C. contaminans and grown on rice media. The secondary metabolite of the fungus was extracted using ethyl acetate. The extracts were then tested for antimicrobial activity using a disk diffusion assay against microbial pathogens Staphylococcus aureus ATCC29213, Escherichia coli ATCC25922, and Methicillin-Resistant Staphylococcus aureus (MRSA). This research yielded 19 endophyte fungi. In the antibacterial activity screening results, four fungal strains (CBK3, CDK1, CDK4, and CAK2) were active against S. aureus, MRSA, and E. coli, with an inhibition zone in the range of 15.08 ± 0.854 to 23.52 ± 0.87 mm. All active fungal isolates were identified molecularly. CBK3 and CDK1 were Paecilomyces subglobosus PP510226 and Penicillium citrinum PP510227, respectively, while CDK4 and CAK2 were comparable to Aspergillus terreus PP510229 and Aspergillus terreus PP510228. The four endophytic fungi of Cyathea contaminans may be a new source of antibacterial compounds. HIGHLIGHTS This is the 1st report of endophytic fungi isolated from medicinal tree fern Cyathea contaminans origin from Sungai Bungkal, Jambi, Indonesia. The four potential endophytic fungi that were successful in purification namely, Paecilomyces subglobosus, Penicillium citrinum, and Aspergillus tereus, which were reported as the source of bioactive compounds Endophytic fungi isolated from medicinal tree fern Cyathea contaminans showed good activity on some pathogenic bacteria: Staphylococcus aureus, Escherichia coli, and Methicillin-Resistant Staphylococcus aureus (MRSA) GRAPHICAL ABSTRACT

Licuri (Syagrus coronata) Oil Cake as a Substrate for Collagenolytic Protease Production by Submerged Fermentation Using a Novel Strain of Penicillium citrinum Isolated from the Brazilian Caatinga

Licuri (Syagrus coronata) Oil Cake as a Substrate for Collagenolytic Protease Production by Submerged Fermentation Using a Novel Strain of Penicillium citrinum Isolated from the Brazilian Caatinga

Multi-metal tolerant Porostereum umbrinoalutaceum isolated from Pleurotus ostreatus fruit body showing root colonization, growth promotion of chilli (Capsicum annuum L.) plant and antagonism against fungal pathogens.

Mushroom associated microbes could be utilized to improve crop productivity providing nutrients, plant growth promoting substances, production of hydrolytic enzymes and protecting plant from biotic and abiotic stress. An endophyte designated as KUFC101 was isolated from fruit body of Pleurotus ostreatus and identified as Porostereum umbrinoalutaceum based on nuclear-rRNA gene sequence analysis. Growth in different culture media, metal tolerance, biochemical characterization and effect on chilli plant growth promotion were studied. The isolate showed best growth in Malt extract medium and least growth in synthetic media. It could tolerate toxic metals (Mg, Ca, Fe, Cu, Mn, Zn and Cd each at 100ppm concentration). It produced amylase, cellulase, chitinase, pectinase, catecholate type of siderophore and indole acetic acid, and inhibited growth of Alternaria solani and Penicillium citrinum. It could colonize in the rhizosphere of chilli plant and influence growth of chilli plant by improving biomass and metabolite content. Porostereum umbrinoalutaceum KUFC101 could be utilized in formulation of biofertiliser under sustainable agricultural system.

Limited Effectiveness of Penicillium camemberti in Preventing the Invasion of Contaminating Molds in Camembert Cheese.

Mold-ripened cheese acquires a distinctive aroma and texture from mold cultures that mature on a fresh cheese wheel. Owing to its high moisture content (aw = 0.95) and pliability, soft cheese is prone to contamination. Many contaminating mold species are unable to grow at colder temperatures, and the lactic acid produced by the cheese bacteria inhibits further infiltration. Thus, Camembert cheese is generally well protected against contamination by a wide range of species. In this study, cocultures of Penicillium camemberti and widely distributed mycotoxin-producing mold species were incubated on different types of agars, and purchased Camembert samples were deliberately contaminated with mycotoxin-producing mold species capable of growing at both 25 °C and 4 °C. The production of mycotoxins was then monitored by the extraction of the metabolites and their subsequent measurement by means of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) based targeted metabolite profiling approach. The production of cyclopiazonic acid (CPA) was highly dependent on the species cocultivated with Penicillium camemberti, the temperature and the substrate. Contamination of Camembert cheese with Penicillium chrysogenum, Mucor hiemalis, or Penicillium glabrum induced CPA production at 25 °C. Although mold growth on cheese was not always evident on biofilms for certain cultures, except for Penicillium citrinum, which stained the monosaccharide agar yellow, mycotoxins were detected in many agar and cheese samples, as in all monosaccharide agar samples. In conclusion, cheese should be immediately discarded upon the first appearance of mold.

Antagonism of rhizosphere Trichoderma brevicompactum DTN19 against the pathogenic fungi causing corm rot in saffron (Crocus sativus L.) in vitro.

Corm rot in saffron (Crocus sativus L.) significantly impacts yield and quality. Non-toxic fungi, particularly Trichoderma species, are valuable for biological control due to their production of diverse and biologically active secondary metabolites. This study aimed to isolate an effective antagonistic fungus against the pathogenic fungi causing corm rot in saffron. Four pathogenic fungi (Fusarium oxysporum, Fusarium solani, Penicillium citreosulfuratum, and Penicillium citrinum) were isolated from diseased saffron bulbs in Chongming. Initial screening through dual culture with these pathogens re-screening from rhizosphere soil samples of C. sativus based on its inhibitory effects through volatile, nonvolatile, and fermentation broth metabolites. The inhibitory effect of biocontrol fungi on pathogenic fungi in vitro was evaluated by morphological observation and molecular biology methods. Antagonistic fungi were identified as Trichoderma brevicompactum DTN19. F. oxysporum was identified as the most severe pathogen. SEM (scanning electron microscope) and TEM (transmission electron microscope) observations revealed that T. brevicompactum DTN19 significantly inhibited the growth and development of F. oxysporum mycelium, disrupting its physiological structure and spore formation. Additionally, T. brevicompactum DTN19 demonstrated nitrogen fixation and production of cellulase, IAA (Indole acetic acid), and siderophores. Whole-genome sequencing of strain DTN19 revealed genes encoding protease, cellulase, chitinase, β-glucosidase, siderophore, nitrogen cycle, and sulfate transporter-related proteins. T. brevicompactum DTN19 may inhibit the propagation of pathogenic fungi by destroying their cell walls or producing antibiotics. It can also produce IAA and iron carriers, which have the potential to promote plant growth. Overall, T. brevicompactum DTN19 showed the development prospect of biological agents.

Isolation and Identification of Postharvest Rot Pathogens in Citrus × tangelo and Their Potential Inhibition with Acidic Electrolyzed Water.

This study focused on the identification of rot-causing fungi in Citrus × tangelo (tangelo) with a particular emphasis on investigating the inhibitory effects of acidic electrolyzed water on the identified pathogens. The dominant strains responsible for postharvest decay were isolated from infected tangelo fruits and characterized through morphological observation, molecular identification, and pathogenicity detection. Two strains were isolated from postharvest diseased tangelo fruits, cultured and morphologically characterized, and had their gene fragments amplified using primers ITS1 and ITS4. The results revealed the rDNA-ITS sequence of two dominant pathogens were 100% homologous with those of Penicillium citrinum and Aspergillus sydowii. These isolated fungi were confirmed to induce tangelo disease, and subsequent re-isolation validated their consistency with the inoculum. Antifungal tests demonstrated that acidic electrolyzed water (AEW) exhibited a potent inhibitory effect on P. citrinum and A. sydowii, with EC50 values of 85.4μg/mL and 60.12μg/mL, respectively. The inhibition zones of 150μg/mL AEW to 2 kinds of pathogenic fungi were over 75mm in diameter. Furthermore, treatment with AEW resulted in morphological changes such as bending and shrinking of the fungal hyphae surface. In addition, extracellular pH, conductivity, and absorbance at 260nm of the fungi hypha significantly increased post-treatment with AEW. Pathogenic morphology and IST sequencing analysis confirmed P. citrinum and A. sydowii as the primary pathogenic fungi, with their growth effectively inhibited by AEW.

Comparison of high antioxidant ZnONPs produced from different fungi as alternative biomaterials

In this study, zinc oxide nanoparticles (ZnONPs), a promising alternative biomaterial, were synthesized using a non-toxic, cost-effective green synthesis approach using various fungal species (Penicillium citrinum, Fusarium solani, Aspergillus flavus and Aspergillus niger). The effect of different fungal species on the structural, optical, morphological and antimicrobial properties of ZnO nanoparticles (ZnONPs) was compared. ZnO nanoparticles (ZnONPs) crystallized in a hexagonal wurtzite structure with grain sizes ranging from 45 to 61 nm. Fungal species had a significant effect on the surface plasmon resonance (SPR) peak observed at 302 nm. ZnONPs were obtained in different morphologies such as nanodiscs, nanospheres, nanorchins and nanonuts, and it was determined that fungal species had a significant effect on these structures. The antibacterial activity of ZnONPs against Candida albicans, Streptococcus mutans, Pseudomonas aeruginosa, Eosinophilic pneumonia and Staphylococcus aureus was investigated. The effect of these nanoparticle shapes on antibacterial activity was evaluated. ZnONPs were found to have a significant antimicrobial effect especially on Candida albicans and Streptococcus mutans. ZnONPs produced only with Aspergillus niger fungus were found to have a strong antimicrobial effect especially on Staphylococcus aureus. Based on these results, the biosynthesis of ZnO nanoparticles (ZnONPs) using Penicillium citrinum, Fusarium solani, Aspergillus flavus and Aspergillus niger fungal species is proposed for the production of ZnONPs as a biomaterial with remarkable antibacterial properties and various morphologies.

Endophytic fungi of spurred mangrove, Ceriops tagal and its bioactivity potential: Predominance of Aspergillus species and its ecological significance

Fungal endophytes were isolated from the leaves of spurred mangrove, Ceriops tagal and the isolation frequency was found to be 11.66 %. The endophytes were identified by both morphological and molecular methods. A total of 106 endophytic fungi were isolated with the majority (96 %) belonging to the Ascomycota and Basidiomycota constituted only 4 % of the total isolates. Within Ascomycota, three classes (Sordariomycetes, Eurotiomycetes, and Saccharomycetes) and 4 orders were observed. In Basidiomycota only agaricomycetes was obtained. Aspergillus (58 %) was the dominant genus, followed by Penicillium (20 %), Colletotrichum (9 %), and Schizophyllum (6 %). Notably, Aspergillus sydowii (35 %) was the predominant endophytic fungus in C. tagal. The colonization frequency was highest for Aspergillus sydowii (4.1 %) followed by Penicillium citrinum (3 %) and Aspergillus flavus (2.3 %). In total, 11 endophytic fungal species were identified from C. tagal. The isolates exhibited noteworthy hydrolytic enzyme production and antimicrobial properties, suggesting their suitability for potential applications as bioremediators and antimicrobials in aquaculture and medicine.

Transcriptomic Insights into the Physiological Aspects of the Saprotrophic Fungus Penicillium citrinum During the Spoilage of Tobacco Leaves

Penicillium citrinum is one of the most prevalent tobacco spoilage fungi. However, the mechanisms underlying fungal growth on tobacco leaves remain largely unknown. In this study, transcriptomic analyses were performed to reveal the genome-wide expression profiles of P. citrinum growing on tobacco leaves. First, a comparative analysis was conducted between two sets of transcriptomic data from P. citrinum growing on chemically defined media and tobacco leaves. Enrichment analyses showed that differentially regulated genes were mainly associated with carbohydrate degradation (e.g., cellulose, pectin, and xylan) and the catabolism of fatty acids and aromatic compounds. Comparative transcriptomic analyses between different time points indicated that the fungal transcriptome varied dynamically during the spoilage process, and the enriched terms were associated with small-molecule degradation and fungal development. Enrichment analyses indicated that more up-regulated genes appeared in all enriched Gene Ontology terms. Notably, more organelles significantly contributed to further fungal growth on tobacco leaves. In conclusion, P. citrinum activates a comprehensive transcriptome that changes dynamically when causing tobacco mildew.

Draft genome sequence of Penicillium citrinum B9, a plant growth-promoting symbiont from barley rhizosphere.

Penicillium citrinum strain B9 is a plant growth-promoting fungus isolated from Barley (Hordeum vulgare) rhizosphere. We report the first draft genome of P. citrinum B9 assembled using single-molecule real-time sequencing and Illumina reads. The assembled genome spans 31.3 Mb comprising nine contigs and 10,106 protein-encoding genes.

Risk assessment of citrinin in Chinese dark tea and inhibitory effects of tea polyphenols on citrinin production

The fungus Penicillium citrinum (P. citrinum), which is found in Chinese dark tea, is involved in the production of citrinin (CIT), a secondary metabolite with renal toxicity. In this study, a rapid method was used to detect CIT in Chinese dark tea samples from different regions and years. Of the 216 samples tested, 5 were detected to have CIT contamination, with a concentration ranging from 272.43 ± 16.57 to 649.68 ± 62.16 μg kg−1. Risk assessment for consuming dark tea showed that four heavy intake consumer groups in the deterministic risk assessment had hazard quotients (HQ) > 1, and the HQ for the probabilistic risk assessment was significantly below the acceptable level of 1.0. Furthermore, we found that tea polyphenols (TPs) inhibited the growth of P. citrinum. Transcriptome results showed that there were 483 downregulated and 783 upregulated genes between the TPs and control groups. Of which, orf1 and ctnD were significantly downregulated, demonstrating that TPs can affect CIT biosynthesis. Our research indicates that CIT in dark tea is within an acceptable risk level, and provides new insights into the inhibition of CIT. Furthermore, this study suggests that the suppression of CIT in dark tea by polyphenols make the consumption of dark tea safe.

Evaluating the efficacy of probiotic bacterial strain Lactobacillus plantarum for inhibition of fungal strains associated with historical manuscript deterioration: An experimental study

The aim of this study is to develop safe biological methods for controlling fungal deterioration of historical manuscripts. Therefore, fifteen fungal isolates were obtained from paper sheets and leather skins of a deteriorated historical manuscript (dated back to the 13th century). Those isolates were identified using both traditional methods and ITS-sequencing analysis. Aspergillus niger accounted for seven strains, Penicillium citrinum for one strain, Aspergillus flavus for three, Aspergillus fumigatus for one, Aspergillus nidulans for one, and Penicillium chrysogenum for two of the fungal strains that were obtained. The ability of fungal strains for the secretion of cellulase, amylase, gelatinase, and pectinase as hydrolytic enzymes was evaluated. The capability of the probiotic-bacterial strain Lactobacillus plantarum DSM 20174 for inhibition of fungal strains that cause severe deterioration was studied using ethyl acetate-extract. The metabolic profile of the ethyl acetate-extract showed the presence of both high- and low-molecular-weight active compounds as revealed by GC-MS analysis. The safe dose to prevent fungal growth was determined by testing the ethyl acetate extract's biocompatibility against Wi38 and HFB4 as normal cell lines. The extract was found to have a concentration-dependent cytotoxic impact on Wi38 and HFB4, with IC50 values of 416 ± 4.5 and 349.7 ± 5.9 μg mL−1, respectively. It was suggested that 100 μg mL−1 as a safe concentration could be used for paper preservation. Whatman filter paper treated with ethyl acetate extract was used to cultivate the fungal strain Penicillium citrinum AX2. According to data analysis, fungal inhibition measurement, SEM, ATR-FT-IR, XRD, color change measurement, and mechanical property assessment, the recommended concentration of ethyl acetate extract was adequate to protect paper inoculated with the highest enzymatic producer fungi, P. citrinum AX2.