Starch-based antifungal edible coatings to control sour rot caused by Geotrichum citri-aurantii and maintain postharvest quality of 'Fino' lemon.

BACKGROUND: Two edible coating (EC) emulsions based on potato starch (F6 and F10) alone or formulated with sodium benzoate (SB, 2% w/w) (F6/SB and F10/SB) were evaluated to maintain postharvest quality of cold-stored 'Fino' lemons and control sour rot on lemons artificially inoculated with Geotrichum citri-aurantii. Previous research showed the potential of these ECs to improve the storability of 'Orri' mandarins and reduce citrus green and blue molds caused by Penicillum digitatum and Penicillium italicum, respectively. RESULTS: The coatings F6/SB and F10/SB significantly reduced sour rot incidence and severity compared to uncoated control samples on lemons incubated at 28 °C for 4 and 7 days. The F6/SB coating reduced weight loss and gas exchange compared to uncoated fruit after 2 and 4 weeks of storage at 12 °C plus a shelf life of 1 week at 20 °C, without adversely affecting the lemon physicochemical quality. CONCLUSION: Overall, the F6/SB coating formulation, composed of pregelatinized potato starch, glyceryl monostearate, glycerol, emulsifiers and SB, with a total solid content of 5.5%, showed the best results in reducing citrus sour rot and maintaining the postharvest quality of cold-stored 'Fino' lemons. Therefore, it showed potential as a new cost-effective postharvest treatment suitable to be included in integrated disease management programs for citrus international markets with zero tolerance to chemical residues. © 2021 Society of Chemical Industry.

Determination of metabolites of Geotrichum citri-aurantii treated with peppermint oil using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

Sour rot is a leading disease of citrus fruit caused by the postharvest pathogen Geotrichum citri-aurantii. It has been reported that essential oils can be used as substitutes for synthetic fungicides to control the pathogen. In this study, changes in metabolites and antifungal effects of G. citri-aurantii treated with peppermint oil (PO) were investigated. The inhibition rate of the mycelial growth increased as the PO concentration increased, and 6 µl PO/disk resulted in a radial growth inhibition of 79.2%. The electrical conductivity of G. citri-aurantii treated with PO increased compared to the control. By comparing the metabolic profiles of treated and untreated G. citri-aurantii cells, a total of 53 distinct metabolites 9 were up-regulated and 44 were down-regulated were found, including 16 lipid metabolites, 6 carbohydrate metabolites, 2 amino acid metabolites, 5 alcohols, 2 glycoside metabolites, and 3 ketone metabolites, etc, and these metabolites are involved in 25 major metabolic pathways. PRACTICAL APPLICATIONS: Chemical fungicides can effectively control G. citri-aurantii during fruit postharvest period. However, synthetic chemical fungicides have gradually led to buildup of resistance of fungil, which seriously causes the frequent of food-borne diseases. PO extracted from natural plants can be used as natural additive in many foods due to their antioxidant, antibacterial, and antifungal properties. Therefore, PO can be considered as a promising bacteriostatic agent for the defense of G. citri-aurantii during fruit postharvest period.

Antifungal efficiency of wild plants against human-opportunistic pathogens.

BACKGROUND: Fungal infection with opportunistic fungi can cause a serious problem for immunocompromised persons such as organ-transplant recipients, cancer, and HIV/AIDS patients. Control of these organisms using natural products is an interesting strategy to avoid the use of heavy chemotherapy in patients. OBJECTIVE: This study aimed to use the extract of Forsskaolea tenacissima L. and Xanthium spinosum L. to suppress the growth of Candida albicans and Geotrichum candidum and to investigate their potential mode of action. MATERIALS AND METHODS: Different plant extracts were tested for their antifungal activity using disc diffusion method and their mode of action was explored using the scanning electron microscopy (SEM) and gas chromatography-mass spectrometry (GC-MS). RESULTS: The results showed that chloroform extract of X. spinosum was the most effective against G. candidum, inhibiting its growth at very low concentration (38µg/mL). Chloroform extract of F. tenacissima was the most effective against C. albicans, with a minimum inhibitory concentration of 39µg/mL. SEM demonstrated the fungitoxicity of the plant extracts against both pathogens. C. albicans treated with plant extract were invaginated and ruptured and the treated mycelia of G. candidum were distorted and squashed. GC-MS analysis showed that the chloroform extract of both plants had 13 different compounds. CONCLUSION: Due to these promising results, these extracts should be further investigated and tested on different strains of C. albicans and G. candidum towards validation of their efficacy as a natural drug.

Breakthrough infection of Geotrichum capitatum during empirical caspofungin therapy after umbilical cord blood transplantation.

We experienced a breakthrough fungal infection caused by Geotrichum capitatum during empirical therapy with caspofungin. A 68-year-old male patient with refractory acute lymphoblastic leukemia had received umbilical cord blood transplantation after two courses of induction therapy. Empirical therapy with caspofungin was initiated 5 days before transplantation. Tacrolimus was continuously infused to prevent graft-versus-host disease. A minidose of methotrexate was intravenously administered on days 1 and 3 post-transplantation, which was changed to prednisolone from day 7 due to severe mucositis. During a recurrence of fever on day 11, blood cultures were found to be positive for a yeast-like organism, which was later confirmed by mass spectrometry to be G. capitatum. The serum levels of beta-D-glucan were elevated to 747 pg/mL. Caspofungin was switched to liposomal amphotericin B; however, radiological findings revealed pulmonary, splenic, and central nervous system involvement. Progressive renal and hepatic dysfunction subsequently developed. The patient died on day 25 post-transplantation secondary to the development of hemophagocytic syndrome and respiratory failure. We emphasize that recurrent febrile episodes, prolonged neutropenia, and underlying gastrointestinal mucosal damage require extreme caution due to the possibility of breakthrough infection caused by new fungal pathogens during empirical therapy with caspofungin.

Use of Cistus aqueous extracts as botanical fungicides in the control of Citrus sour rot.

In this work, we investigated the in vitro and in vivo antifungal activity of aqueous extracts obtained from eight Cistus plant species against the development of Geotrichum citri-aurantii, the causal agent of citrus sour rot. The results demonstrate the in vitro effectiveness of all tested Cistus species aqueous extracts against G. citri-aurantii, the inhibition of mycelial growth ranged between 80 and 100%. Furthermore, Cistus aqueous extracts totally inhibited germination of G. citri-aurantii arthrospores at a concentration of 5 mg/mL. Among the plant species tested, C. laurifolius, C. salviifolius, C. monspeliensis, C. ladanifer and C. populifolius displayed the best fungistatic activity since the minimum inhibitory concentration (MIC) was <0.625 mg/mL. Under in vivo conditions, incidence of sour rot was lowered to 8.33% when fruits were treated with aqueous extracts of C. populifolius and C. creticus compared to 100% in the control. Disease severity was lowered to 3.74, 4.47 and 5.13% when fruits were treated with C. creticus, C. ladanifer and C. populifolius aqueous extracts, respectively. Using such these biopesticides in a replacement for synthetic fungicides or in combination with other established disease management practices could help control citrus postharvest decay in a more sustainable and eco-friendly way.

Ellagitannins from Raspberry (Rubus idaeus L.) Fruit as Natural Inhibitors of Geotrichum candidum.

The paper presents the chemical characteristics of ellagitannins isolated from raspberry (Rubus idaeus L.) fruit and their in vitro and in situ antifungal activity against Geotrichum candidum LOCK 0511. The study investigated a complex preparation containing various raspberry ellagitannins at a concentration of 86% w/w, as well as pure lambertianin C and sanguiin H-6. The ellagitannin preparation was obtained by extracting raspberry press cake and purifying the extract using Amberlite XAD resin, while individual compounds were isolated by means of preparative HPLC. The complex preparation was analyzed for the content of ellagitannins, anthocyanins, and flavan-3-ols using HPLC and LC-MS. The antifungal activity of the complex ellagitannin preparation and the isolated ellagitannins was determined for the strain Geotrichum candidum. The MIC and MFC values (10.0 mg/mL and 30.0 mg/mL, respectively) were found to be the same for lambertianin C, sanguiin H-6, and the complex ellagitannin preparation. The fungistatic activity of the studied ellagitannin preparation at a concentration of 10 mg/mL, as determined by the poisoned medium method, was 65.2% following 6 day incubation of Geotrichum candidum, with the linear growth rate of only 16.2 mm/day. The corresponding parameters for the control sample were 0% and 56 mm/day, respectively. The study demonstrated both in vitro and in situ antifungal activity of raspberry ellagitannins against Geotrichum candidum.

Antifungal properties of organic extracts of eight Cistus L. species against postharvest citrus sour rot.

UNLABELLED: The effectiveness of methanol and chloroform extracts of eight Cistaceae species to control citrus sour rot decay, caused by Geotrichum citri-aurantii, was investigated in both in vitro and in vivo conditions. Methanol extracts of these plant species exhibited more interesting activity against G. citri-aurantii, in both in vitro and in vivo conditions, compared with chloroforme extracts. Under in vitro trials, obtained results showed that methanol extracts of all tested plants revealed a highest significant antifungal activity with inhibition zones that ranged between 12·33 and 16·33 mm in diameter. All tested methanol extracts totally inhibited spore germination when tested at 10 mg ml(-1) . Incidence of sour rot was significantly lowered to 11·11% when fruits were treated with Cistus populifolius and Cistus ladanifer methanol extracts compared with 100% in the control. The disease severity was lowered to 5·19% and 6·04% when fruits were treated with the same methanol extracts respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: The methanol Cistus extracts had sufficient antifungal activities in vitro and in vivo against G. citri-aurantii to consider its use in the citrus industry after it has been tested under production and natural infection conditions. Such natural products therefore represent a viable alternative approaches for sour rot postharvest management of citrus.

Chenopodolin: a phytotoxic unrearranged ent-pimaradiene diterpene produced by Phoma chenopodicola, a fungal pathogen for Chenopodium album biocontrol.

A new phytotoxic unrearranged ent-pimaradiene diterpene, named chenopodolin, was isolated from the liquid culture of Phoma chenopodicola, a fungal pathogen proposed for the biological control of Chenopodium album, a common worldwide weed of arable crops such as sugar beet and maize. The structure of chenopodolin was established by spectroscopic, X-ray, and chemical methods as (1S,2S,3S,4S,5S,9R,10S,12S,13S)-1,12-acetoxy-2,3-hydroxy-6-oxopimara-7(8),15-dien-18-oic acid 2,18-lactone. At a concentration of 2 mg/mL, the toxin caused necrotic lesions on Mercurialis annua, Cirsium arvense, and Setaria viride. Five derivatives were prepared by chemical modification of chenopodolin functionalities, and some structure-activity relationships are discussed.

Antifungal activity of Moroccan medicinal plants against citrus sour rot agent Geotrichum candidum.

AIMS: The aim of this work was to find an alternative to the chemical fungicides currently used in the control of Geotrichum candidum, the causal agent of citrus sour rot. METHODS AND RESULTS: Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) were determined using agar dilution method. The methanol extracts of Cistus villosus, Ceratonia siliqua and Halimium umbellatum exhibited strong antifungal activity with MIC values ranged between 0.156 and 1.25 mg ml(-1), and MFC values ranged between 2.5 and 5 mg ml(-1). Incidence of sour rot was lowered to 0.00, 3.33 and 11.66% when mandarin fruit was treated with C. villosus, C. siliqua and H. umbellatum methanol extracts at 50 mg ml(-1), respectively, compared with 95% in the control. CONCLUSIONS: Cistus villosus, C. siliqua and H. umbellatum methanol extracts successfully reduced the disease incidence caused by G. candidum, and no phytotoxic effects were recorded on citrus fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings suggest that C. villosus, C. siliqua and H. umbellatum plants may be useful and effective agents for control of citrus sour rot. Such natural products therefore represent a sustainable alternative to the use of synthetic fungicides.

In vitro and in vivo antifungal activity of a water-dilutable cassia oil microemulsion against Geotrichum citri-aurantii.

BACKGROUND: Recently, food-grade microemulsions have been of increasing interest to researchers and have shown great potential in industrial applications. In this study a food-grade water-dilutable microemulsion system with cassia oil as oil, ethanol as cosurfactant, Tween 20 as surfactant and water was developed and its antifungal activity in vitro and in vivo against Geotrichum citri-aurantii was assessed. RESULTS: The phase diagram results confirmed the feasibility of forming a water-dilutable microemulsion based on cassia oil. One microemulsion formulation, cassia oil/ethanol/Tween 20 = 1:3:6 (w/w/w), was selected with the capability to undergo full dilution with water. The average particle size was 6.3 nm. The in vitro antifungal experiments showed that the microemulsion inhibited fungal growth on solid medium and prevented arthroconidium germination in liquid medium and that cassia oil had stronger activity when encapsulated in the microemulsion. The in vivo antifungal experiments indicated that the water-dilutable microemulsion was effective in preventing postharvest diseases of citrus fruits caused by G. citri-aurantii. CONCLUSION: The results of this study suggest a promising utilisation of water-dilutable microemulsions based on essential oils for the control of postharvest diseases.

Enzymatic enrichment of polyunsaturated fatty acids using novel lipase preparations modified by combination of immobilization and fish oil treatment.

Novel modification methods for lipase biocatalysts effective in hydrolysis of fish oil for enrichment of polyunsaturated fatty acids (PUFAs) were described. Based on conventional immobilization in single aqueous medium, immobilization of lipase in two phase medium composed of buffer and octane was employed. Furthermore, immobilization (in single aqueous or in two phase medium) coupled to fish oil treatment was integrated. Among these, lipase immobilized in two phase medium coupled to fish oil treatment (IMLAOF) had advantages over other modified lipases in initial reaction rate and hydrolysis degree. The hydrolysis degree increased from 12% with the free lipase to 40% with IMLAOF. Strong polar and hydrophobic solvents had negative impact on immobilization-fish oil treatment lipases, while low polar solvents were helpful to maintain the modification effect of immobilization-fish oil treatment. After five cycles of usage, the immobilization-fish oil treatment lipases still maintained more than 80% of relative hydrolysis degree.

Antifungal activity of thyme oil against Geotrichum citri-aurantii in vitro and in vivo.

AIMS: To investigate antifungal effect of thyme oil on Geotrichum citri-aurantii arthroconidia germination and germ tube elongation, to reveal effects of thyme oil on morphological structures on fungal hyphae and arthroconidia and to assess potential bio-control capacities of thyme oil against disease suppression in vivo conditions. METHODS AND RESULTS: Thyme oil controlled the growth of G. citri-aurantii effectively. Arthroconidia germination and germ tube elongation in potato dextrose broth was greatly inhibited by thyme oil. At 600 microl l(-1), it inhibited the germination of about 94% of the arthroconidia and the germ tube length was only 4.32 +/- 0.28 microm. Observations using light microscope, scanning electron microscope and transmission electron microscope revealed ultrastructural modifications caused by thyme oil that included markedly shrivelled and crinkled hyphae and arthroconidia, plasma membrane disruption and mitochondrial disorganization. Thyme oil applied to 'Satsuma' mandarin oranges that had been artificially wounded and inoculated with G. citri-aurantii reduced sour rot from 78.1% among untreated control fruit to 14.1% after 5 days at 26 degrees C. Thyme oil applied to intact fruits reduced the decay from 76% among untreated control fruit to 35% after 30 days at 20 degrees C. Thyme oil treatment did not harm 'Satsuma' mandarin oranges when they were examined after treatment and storage at 20 degrees C for 30 days. CONCLUSIONS: Thyme oil may provide an alternative means of controlling postharvest sour rot on citrus fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of such essential oil may constitute an important alternative to synthetic fungicides. They can be exploited in commercial production and applied under storage and greenhouse conditions.

Combined therapies in a murine model of blastoschizomycosis.

In a murine model of blastoschizomycosis, amphotericin B combined with micafungin, flucytosine or voriconazole did not improve the efficacy of fluconazole. However, such combinations can constitute therapeutic options for those cases where fluconazole fails.

Effect of antifungal treatment in a murine model of blastoschizomycosis.

Blastoschizomyces capitatus is an emerging pathogenic fungus that can cause deep invasive diseases in neutropenic patients. We developed a model of disseminated blastoschizomycosis in immunosuppressed mice to evaluate the effectiveness of amphotericin B, flucytosine, fluconazole and voriconazole. High-dose fluconazole was the most effective drug at prolonging the survival of mice and at reducing fungal burden in the kidneys, spleen and liver.

Composition and Antimicrobial Activity of Anemopsis californica leaf oil.

Isolation and characterization of leaf volatiles in Anemopsis californica (Nutt.) Hook. and Arn. (A. californica) was performed using steam distillation, solid-phase microextraction, and supercritical fluid extraction. Thirty-eight compounds were detected and identified by gas chromatography; elemicin was the major component of the leaf volatiles. While the composition of the leaf volatiles varied with method of extraction, alpha-pinene, sabinene, beta-phellandrene, 1,8-cineole, piperitone, methyl eugenol, (E)-caryophyllene, and elemicin were usually present in readily detectable amounts. Greenhouse-reared clones of a wild population of A. californica had an identical leaf volatile composition with the parent plants. Steam-distilled oil had antimicrobial properties against 3 (Staphylococcus aureus, Streptococcus pneumoniae, and Geotrichim candidum) of 11 microbial species tested. Some of this bioactivity could be accounted for by the alpha-pinene in the oil.

Purification, characterization, and sequencing of a novel type of antimicrobial peptides, Fa-AMP1 and Fa-AMP2, from seeds of buckwheat (Fagopyrum esculentum Moench.).

Novel antimicrobial peptides (AMP), designated Fa-AMP1 and Fa-AMP2, were purified from the seeds of buckwheat (Fagopyrum esculentum Moench.) by gel filtration on Sephadex G75, ion-exchange HPLC on SP COSMOGEL, and reverse-phase HPLC. They were basic peptides having isoelectric points of over 10. Fa-AMP1 and Fa-AMP2 had molecular masses of 3,879 Da and 3,906 Da on MALDI-TOF MS analysis, and their extinction coefficients in 1% aqueous solutions at 280 nm were 42.8 and 38.9, respectively. Half of all amino acid residues of Fa-AMP1 and Fa-AMP2 were cysteine and glycine, and they had continuous sequences of cysteine and glycine. The concentrations of peptides required for 50% inhibition (IC50) of the growth of plant pathogenic fungi, and Gram-positive and -negative bacteria were 11 to 36 microg/ml. The structural and antimicrobial characteristics of Fa-AMPs indicated that they are a novel type of antimicrobial peptides belonging to a plant defensin family.

Screening for antimycotic properties of 56 traditional Chinese drugs.

In the present study we screened extracts of 56 widely used dried Chinese medical plants or their parts (TCD) for their antimycotic properties against pathological phyla of Aspergillus fumigatus, Candida albicans, Geotrichum candidum and Rhodotorula rubra. The highest activity against Aspergillus fumigatus was shown by Carthamus tinctorius L. (flos) and Rheum palmatum L. (radix et rhizoma) and against Candida albicans, Scutellaria baicalensis Georgi (radix) had the highest activity. The highest activity against Geotrichum candidum was shown by Agastache rugosa (Fisch et Mey.) O. Ktze. Herba Menthae has moderate antimycotic properties.

Tributyrin specifically induces a lipase with a preference for the sn-2 position of triglyceride in Geotrichum sp. FO401B.

The extracellular Lipases A and C produced by Geotrichum sp. FO401B have a preference for the sn-1,3 and sn-2 positions of triglyceride, respectively. Total production of these lipases was increased by plant oils and tributyrin. Butyl Toyopearl column chromatography demonstrated that only Lipase C was produced in the presence of tributyrin. Lipase C hydrolysed natural fats except sardine oil preferentially at the sn-2 position, but it showed little stereoselectivity for triolein.

Lignans and sesquiterpene lactones from Artemisia sieversiana and Inula racemosa.

The aerial parts of Artemisia sieversiana afforded, in addition to beta-sitosterol, stigmasterol and daucosterol, two novel lignans as well as one known and three new guaianolides. The roots of Inula racemosa gave beta-sitosterol, daucosterol and isoalantolactone. The structures were determined by a combination of spectral methods (IR, EIMS, 1H and 13C NMR, DEPT, COSY, NOESY and HETCOR). All isolates were subjected to antifungal tests. Isoalantolactone, a major sesquiterpene lactone of I. racemosa, was found to be active against the human pathogenic fungi. Aspergillus flavus, A. niger, Geotrichum candidum, Candida tropicalis and C. albicans at concentrations of 50, 50, 25, 25 and 25 micrograms/ml, respectively. The taxonomic significance of the characterized constituents is discussed briefly.