Category Archives: Aspergillus

Research – The effect of royal jelly and propolis alone and in combination on inhibition of Aspergillus parasiticus growth, aflatoxin production, and aflR gene expression

Posted on August 22, 2020 by | Leave a comment

Wiley Online

The objective of this study was to determine the inhibitory effect of royal jelly (RJ) and propolis on growth, aflatoxin production and aflR gene expression in Aspergillus parasiticus . Inhibitory effect of RJ and propolis against a standard strain of A. parasiticus (ATCC 15517) was determined alone and in combination in accordance with the CLSI M38‐A2 and checkerboard methods, respectively. The aflatoxin concentrations in the control and treated media were determined by HPLC. Also, the quantitative changes in the aflR gene expression were analyzed. The minimum inhibitory concentrations (MIC) of RJ and propolis alone were 3,200 and 100μg/ml, respectively. Also, the MICs of RJ and propolis in combination were 200 and 25μg/ml, respectively. When combined, a synergistic interaction was observed with a FICI of 0.312. Total levels of aflatoxin decreased from 386.1ppm to 8.72, 3.01 and 1.75ppm at 1,600μg/ml of RJ, 50μg/ml of propolis and 100+12.5μg/ml of RJ and propolis, respectively. In addition, the level of afIR gene expression was significantly decreased after treatment with RJ and propolis extracts alone and with their combination. The findings reveal that RJ and propolis extracts, either alone or in combination, have a significant inhibitory effect on aflR gene expression in aflatoxin production.

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Posted in Aflatoxin, Aspergillus, Food Microbiology Research, Food Technology, Food Toxin, Mould Toxin, Mycotoxin, Research, Uncategorized

Research – Quantitative microbial spoilage risk assessment (QMSRA) of pasteurized strawberry purees by Aspergillus fischeri (teleomorph Neosartorya fischeri)

Posted on August 22, 2020 by | Leave a comment

Science Direct

Aspergillus fischeri ascospores are known as potential spoilage microorganisms of pasteurized fruit products due to their high incidence in fruits, the ability to survive pasteurization and to grow in acidic conditions. This study aimed to develop a quantitative microbial spoilage risk assessment (QMSRA) model approach to estimate the spoilage risk of packaged strawberry purees due to A. fischeri under various scenarios regarding product formulation, processing and storage conditions. The development of the risk assessment comprised three steps: (1) initial contamination level of raw material by ascospores (N0), (2) inactivation of ascospores during thermal processing (Np) and (3) determination of the number of ascospores which are able to survive thermal processing and develop visible mycelia (D = 2 mm) during storage (Nf). Data of visible growth (tv, days) comprised distributions previously obtained as function of water activity (aw) (0.860–0.985), oxygen (0–21%), temperature (8–30 °C) and pasteurization (95–105 °C/15 s). The simulations were performed in triplicate with 100,000 iterations using the software R. The outcome “spoilage risk” was defined as the probability of having at least one ascospore (Nf) capable of forming visible colonies in 100 g-pack strawberry puree within the typical use-by dates. Overall, high probabilities of spoilage were estimated for purees pasteurized at milder treatments at 85 °C/15–60 s (67%) and 90 °C/15–60 s (≥40%) stored at ambient temperature (22 °C). The spoilage risk was only effectively reduced (0.02%) by increasing pasteurization conditions to 95 °C for at least 45 s. Moreover, the microbial stability of such purees, i.e., spoilage risk <0.001% (=less than 1 spoilage pack out of 105 produced units) was predicted to occur for purees treated at 100 °C/15 s or stored at chilled conditions (≤8 °C) or at strict anaerobic conditions or produced as concentrates (aw ≤ 0.860). Based on the outcomes obtained, a set of specifications for Heat-Resistant Moulds (HRMs) in raw material and pasteurized purees aimed to be used as an ingredient was suggested. Furthermore, the results can be used to support risk management decisions in identifying and quantifying the impact of possible interventions during formulation, processing and storage conditions of fruit purees to effectively reduce this risk.

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Posted in Aspergillus, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Poisoning, microbial contamination, Microbiology, Mould Toxin, Moulds, Research, Uncategorized

Research – Commercial green tea from Portugal: Comprehensive microbiologic analyses

Posted on August 16, 2020 by | Leave a comment

Science Direct

In recent times green tea (GT) consumption has increased, due to the numerous studies that indicate a wide variety of health benefits following its regular consumption. The aim of this study was to assess the bioburden (bacteria and fungi) of bulk and bags of GT marketed in Lisbon and to obtain a more refined fungal burden characterization, including azole resistance profile. The bacteriota in tea bags before boiling ranged from lower than the detection limit to 1770 CFU.g−1, whereas in brew samples ranged from lower than the detection limit to 54.55 CFU.mL−1. In bulk samples before boiling ranged from lower than the detection limit to 2636 CFU.g−1, while after boiling ranged from lower than the detection limit to 72.73 CFU.mL−1. Fungal contamination on tea bags before boiling ranged from lower than the detection limit to 66.67 CFU.g−1 and after boiling, all samples presented results lower than the detection limit. Concerning bulk samples before boiling ranged from lower than the detection limit to 96.97 CFU.g−1, whereas after boiling ranged from lower the detection limit to 30.3 CFU.mL−1. Before boiling, the most common fungal species in the bagged tea (90.91 CFU.g−1; 45.45%) and bulk samples (66.67 CFU.g−1; 91.67%) was Aspergillus section Nigri. Fungal diversity was higher on bulk samples than in tea bags. Aspergillus section Nigri and Rhizopus sp. growth was observed mostly on itraconazole-supplemented Sabouraud dextrose agar media, which require further investigation. Aspergillus sections Fumigati and Nidulantes were detected by using real time PCR, but not in the GT samples in which they were identified through culture-based methods. A significantly reduction of bacterial contamination after boiling was observed, however fungal contamination with toxigenic potential was observed before and after boiling. Future research work needs to characterize in detail the mycotoxins contamination to allow a risk-benefit assessment to estimate the human health benefits and risks following tea consumption and to support policy-actions, if and when needed. The results also suggest that the conditions how tea is packed can influence the fungal diversity and this variable should be further investigated.

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Posted in Aspergillus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, Uncategorized

Research – Aspergillus mycotoxins and their effect on the host

Posted on July 25, 2020 by | Leave a comment

Pub Med

Abstract

Aspergillus fumigatus is known to produce various immunosuppressive mycotoxins including gliotoxin. However, none of these mycotoxins has been confirmed as being directly related to the pathogenesis of aspergilli. Recent studies have made substantial progress in the determination of mycotoxins as virulence factors. Gliotoxin was found to be produced much faster than previously believed under certain culture conditions, such as at 37 degrees C and under high oxygen content, which is close to the environment in the host. Gliotoxin was also found to be detectable in the sera of aspergillosis mice and of aspergillosis patients. Based on these findings, it is becoming evident that gliotoxin is produced in the infected organs of patients of aspergillosis at a significant level. In addition to these known mycotoxins, A. fumigatus produces many mycotoxins apparently different from known toxins. From the aspect of gene analysis, the deletion of laeA was found to block the expression of metabolic gene clusters such as sterigmatocystin, and the gene is also expected to be related to the production of gliotoxin. The significance of mycotoxins as virulence factors will hopefully be clarified in the near future.

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Posted in Aspergillus, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Poisoning, Food Safety, Food Testing, Food Toxin, Mould Toxin, Mycotoxin, Uncategorized

Research – Evaluation of eight essential oils for postharvest control of Aspergillus carbonarius in grapes

Posted on May 11, 2020 by | Leave a comment

Journal of Food Protection

A wide range of fungal species is associated with post-harvest spoilage of grapes. However, Aspergillus carbonarius is the primary fungus responsible for the contamination of grapes with ochratoxin A, a mycotoxin causing several confirmed health effects to humans and animals. Aiming to find a method, safe for the consumers, to prevent post-harvest decay and ochratoxin A contamination of grapes, the potential use of essential oils as preservatives was investigated. Essential oils of Origanum dictamnus (dittany) , Origanum onites (oregano) , Origanum microphyllum (marjoram) , Thymbra capitata (thyme) , Satureja thymbra (savory) , Rosmarinus officinalis (rosemary) , Laurus nobilis (laurel) and Salvia officinalis (sage) were tested. The essential oil components were identified by GC/MS analysis. A first evaluation of the effectiveness of essential oils was performed in vitro , at a range of concentrations up to 300 μL L -1 . Based on the results of the in vitro tests, the four most effective essential oils ( O. dictamnus , O. onites , T. capitata and S. thymbra ) were tested on Sultana grapes, during post-harvest storage. The four essential oils tested, having the carvacrol and/or thymol as a common component, at a high concentration, significantly reduced, or even completely inhibited the growth of the fungus, in all treatments. As revealed from the results, the essential oils of O. dictamnus , O. onites and S. thymbra were the most effective, causing total inhibition on the growth of the fungus with a minimum concentration of 100 μL L -1 , followed by the essential oil of T. capitata , total effective with a minimum concentration of 200 μL L -1 . Essential oils of O. microphyllum , L. nobilis , S. officinalis and R. officinalis , although they had a significant effect on the growth of A. carbonarius , failed to inhibit its growth completely at any of the concentrations tested.

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Posted in Aspergillus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Mould Toxin, Moulds, Mycotoxin, Research, Technology, Uncategorized

Research – Effects of coating pistachio kernels with mixtures of whey protein and selected herbal plant extracts on growth inhibition of Aspergillus flavus and prevention of aflatoxin during storage

Posted on February 17, 2020 by | Leave a comment

Wiley Online

Whey protein concentrate (WPC) mixed with various concentrations of Shirazi thyme (ST), sage, and cumin seed (CS) extracts separately. Then pistachio kernels (PK) contaminated with Aspergillus flavus (Af) were coated with each extract and the Af mycelium and generated aflatoxins measured after 3, 5, and 7‐days at 20°C. The ST, sage, and CS had two major antioxidants of thymol (~27%) and carvacrol (~41%), α‐thujone (~28%) and camphor (~14%), and cumin‐aldehyde (~21%) and safranal (~20%), respectively. While the Af mycelium diameter on PK without extract became >90 mm within 3 days, it was shrunk after 7 days when the WPC‐coated PK had 4,000 ppm ST extract. When ST concentrations increased in WPC‐coated PK linearly, the Af growth and aflatoxins production decreased logarithmically. No aflatoxins (B1, B2, G1, and G2) detected in PK after 9 days when the extract concentrations of ST, sage, and CS in WPC reached, respectively to 5,000, 4,500, and 6,500 ppm. Sage extract had significantly (p < .01) the highest TPC (lowest IC50) and preventing power for aflatoxin generation in comparison with ST and CS extracts. The PK will be safe and healthy if the extract concentration of sage, ST, and CS exceed 950, 1,400, and 1,700 mg/kg, respectively.

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Posted in Aflatoxin, Aspergillus, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Food Toxin, microbial contamination, Microbiology, Mould Toxin, Mycotoxin, Research, Uncategorized

Research – Effects of edible coating containing Williopsis saturnus var. saturnus on fungal growth and aflatoxin production by Aspergillus flavus in peanuts

Posted on December 28, 2019 by | Leave a comment

Wiley Online

Abstract

Production of aflatoxin by Aspergillus flavus in peanuts is both a health hazard and major problem. This study investigated the ability of a whey protein concentrate (WPC)‐based edible coating containing Williopsis saturnus var. saturnus to prevent growth of A. flavus and aflatoxin production in peanuts. WPC with/without W. saturnus (7 log colony‐forming unit [CFU]/g) or W. saturnus alone was sprayed on peanuts inoculated with A. flavus (3 log CFU/g) and stored for 84 days at 25°C. Application of coating with W. saturnus reduced both growth of A. flavus and aflatoxin level by 82 and 69.5% compared with the control, respectively. Thiobarbituric acid values were around 60% lower in peanuts coated with WPC compared with the control. Sensory and chemical properties of peanuts were not significantly affected by coating treatment (p < .05). Based on results, coating with W. saturnus appears useful in preventing both growth of A. flavus and aflatoxin production in peanuts.

Practical Applications

Improved WPC based coating containing W. saturnus can be applied on surface of roasted peanuts to prevent growth of A. flavus and aflatoxin production.

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Posted in Aflatoxin, Aspergillus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Food Toxin, microbial contamination, Microbiology, Mould Toxin, Mycotoxin, Research, Technology, Uncategorized

Research – Prevalence and identification of Aspergillus and Penicillium species isolated from peanut kernels in central Myanmar

Posted on December 21, 2019 by | Leave a comment

Wiley Online

Abstract

The objective of the present study was to conduct a survey to evaluate the postharvest handling of peanuts at farm level and to screen and identify the strains of Aspergillus and Penicillium species from peanut kernels in central Myanmar. A total of 640 samples from the stores of farmers, collectors, and wholesalers were collected and seeded for growth, isolation, and characterization of fungi. Out of 85 isolates, Aspergillus flavus (38), A. niger (20), A. terreus (15), and Penicillium citrinum (12) were identified and confirmed by molecular techniques including DNA sequencing using internal transcribed spacer (ITS5/4) and beta‐tubulin (Bt2a/2b) primer sets. The study indicates different factors associated with fungal contamination at farm level peanut storage and warrants an immediate attention of food safety regulatory authorities to design and implement strategies for postharvest handling and storage practice in developing countries to minimize fungal contamination.

Practical applications

In developing countries like Myanmar, there are lack of food safety practices and policies regarding the food storage, handling, and farmer education. The current study indicates the different storage methods for peanut kernels at farm level and their influence on prevalence of fungi. The study will give a deep insight to the policy makers to design food safety practices at farm level and educate the farmers to adopt the better practices to assure the consumer health and satisfaction in developing countries.

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Posted in Aflatoxin, Aspergillus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Toxin, microbial contamination, Microbiology, Mould Toxin, Mycotoxin, Penicillium citrinium, Research, Uncategorized

Tanzania – Suspected aflatoxin outbreak reported in Tanzania

Posted on August 21, 2019 by | Leave a comment

Outbreak News Today

A suspected aflatoxicosis outbreak is being reported in Tanzania. The World Health Organization (WHO) was informed of the situation by the Ministry of Health in late June.

Since June 1, sporadic cases, presenting with symptoms and signs on abdominal distention, jaundice, vomiting, swelling of lower limbs, with a few cases of fever and headache, from Dodoma and Manyara Regions in Tanzania.

As of Aug. 11, a total of 53 cases and 8 deaths have been reported as from Chemba, Kondoa and Kiteto Districts. The situation is under investigation.

Aflatoxin is a potent toxin and a very serious health issue in many parts of the developing world. Major outbreaks have been seen in Africa, India, Malaysia and Taiwan over the years.

This mycotoxin is a natural toxin produced as a secondary metabolite to certain strains of the fungus Aspergillus, in particular Aspergillus flavus and Aspergillus parasiticus.

The toxin is then excreted onto plants or pre-processed foods, some intended for human consumption.

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Posted in Aflatoxin, Aspergillus, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Mycotoxin, Toxin, Uncategorized

Research – Antifungal Effect of Camellia Seed Cake Extract on Aspergillus flavus

Posted on February 27, 2019 by | Leave a comment

Journal of Food Protection

Aspergillus flavus is a well-known, widespread fungus that contaminates a great number of crops used for human and animal consumption, but previous study showed that camellia seed cake was not susceptible to A. flavus. This study was designed to evaluate the antifungal effect of the active substance in camellia seed cake on the growth and production of aflatoxins of A. flavus. Eighty percent methanol extracts of camellia seed cake showed greater activity than that of 80% ethanol, ethyl acetate, and pure water against A. flavus. The filtrate from the 80% methanol extract was extracted with ethyl acetate and saturated n-butanol; among the extracts, the n-butanol phase exhibited strong inhibitory activity against A. flavus. The inhibitory zone diameter increased from 15.25 mm at 25 mg/mL concentration up to 22.00 mm at 100 mg/mL concentration. The mycelial dry weight was reduced significantly from 0.16 g at 25 mg/mL to 0.11 g at 100 mg/mL, whereas the aqueous and ethyl acetate phases exhibited weak antifungal activity and no activity, respectively. In addition, the n-Butanol phase inhibited the production of aflatoxin B1 effectively, caused mycelia deformity, and reduced the production of conidia. n-Butanol extract of camellia seed cake exhibited apparent antagonistic effect on the growth and aflatoxin production of A. flavus. The concentration of 100 mg/mL worked best. This study provides a scientific basis for further study of its inhibiting mechanism.

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Posted in antifungal, Aspergillus, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, Food Safety, Food Spoilage, Food Technology, Food Testing, fungi, Mycotoxin, Uncategorized