Aspergillus Colonies Research Articles

An Unusual Case of Early Cytomegalovirus Retinitis with UTI, Invasive Pulmonary Aspergillosis, Klebsiella Pneumonia in a Renal Allograft Recipient

Cytomegalovirus (CMV) remains the most common opportunistic infection after a kidney transplant. CMV retinitis is a rare manifestation of CMV invasive disease and is potentially threatening to vision in immunocompromised individuals. Invasive aspergillosis (IA) is one of the major causes of invasive fungal infection in kidney transplant recipients. Posttransplant CMV significantly increases the risk of IA in solid organ transplants. However, simultaneous or superadded opportunistic infections are rare and often delay the diagnosis. We report a case of early CMV retinitis in a renal transplant recipient, who initially developed extended-spectrum beta-lactamase-positive Escherichia coli cystitis at 2 weeks posttransplant. At 4 weeks posttransplant, he developed CMV retinitis managed with intravenous and intravitreal ganciclovir. At around 6 weeks, he developed persistent low-grade fever and pancytopenia without any specific systemic symptoms with initial sterile cultures sterile and normal imaging except for high-resolution computed tomography chest, which was suggestive of fungal pneumonia. Bronchoscopy and bronchoalveolar lavage were done, which came positive for aspergillus colonies. The patient improved with Amphotericin B, which was later changed to oral voriconazole. A few days later, the patient again deteriorated with new-onset fever, cough, and expectoration, which were diagnosed with Klebsiella pneumonia by imaging supported by sputum culture, which was managed by appropriate antibiotics. CMV and IA are both uncommon opportunistic infections and simultaneous or superadded infection with bacterial pneumonia is very rare. In the presence of persistent symptoms, early suspicion of another infection is crucial for patient management and long-term prognosis.

Altered Pseudomonas Strategies to Inhibit Surface Aspergillus Colonies.

Pseudomonas aeruginosa and Aspergillus fumigatus infections frequently co-localize in lungs of immunocompromised patients and individuals with cystic fibrosis (CF). The antifungal activity of P. aeruginosa has been described for its filtrates. Pyoverdine and pyocyanin are the principal antifungal P. aeruginosa molecules active against A. fumigatus biofilm metabolism present in iron-limited or iron-replete planktonic P. aeruginosa culture filtrates, respectively. Using various P. aeruginosa laboratory wild-type strains (PA14, PAO1, PAK), we found antifungal activity against Aspergillus colonies on agar. Comparing 36 PA14 and 7 PAO1 mutants, we found that mutants lacking both major siderophores, pyoverdine and pyochelin, display higher antifungal activity on agar than their wild types, while quorum sensing mutants lost antifungal activity. Addition of ferric iron, but not calcium or magnesium, reduced the antifungal effects of P. aeruginosa on agar, whereas iron-poor agar enhanced antifungal effects. Antifungal activity on agar was mediated by PQS and HHQ, via MvfR. Among the MvfR downstream factors, rhamnolipids and elastase were produced in larger quantities by pyoverdine–pyochelin double mutants and showed antifungal activity on agar. In summary, antifungal factors produced by P. aeruginosa on agar differ from those produced by bacteria grown in liquid cultures, are dependent on quorum sensing, and are downregulated by the availability of ferric iron. Rhamnolipids and elastase seem to be major mediators of Pseudomonas’ antifungal activity on a solid surface.

Aspergillus flavus as a surprise space occupying lesion in an immunocompetent pediatric patient

BackgroundFungal infections of the CNS are almost always a clinical surprise. Aspergillus species although ubiquitous are more frequently observed in immuno-compromised individuals upon inhalation of conidia. Most of the fungal infections which happen in humans are opportunistic, mostly due to immunocompromised host.Case descriptionWe present the case of a 14-year-old boy who presented to the Emergency Department of Aga Khan University Hospital, Karachi, with complaints of right-sided weakness of the body. This was a rapid-onset condition which was associated with gait disturbances and multiple episodes of vomiting. MRI head showed encapsulated Space Occupying Lesion with puss in the left frontal lobe with surrounding edema. The patient was planned for a craniotomy to remove an intracerebral abscess. Histopathology report revealed the presence of chronic granulomatous inflammation with necrosis and numerous septate hyphae. A fungus culture was run which confirmed the presence of heavy colonies of Aspergillus flavus.ConclusionFungal infections of the central nervous system are almost always a clinical surprise, have a subtle presentation and mistaken often as meningitis, brain abscess, or tumor. Any suspected lesion once removed should be sent for biopsy to rule out the presence of any fungal infection.

Relationship between spirometry results and colonisation of Aspergillus species in allergic asthma.

Exposure to fungi in patients with asthma leads to the release of various fungal antigens, which can increase the severity of asthma. Regarding this, the present study was conducted to evaluate the relationship between the colonisation of Aspergillus species and spirometry results in allergic asthma. Two hundred sixteen patients with mild to severe asthma and 30 healthy controls were included. All participants underwent pulmonary function tests. Furthermore, sputum samples were collected from each subject. Each sputum sample was subjected to direct microscopic examination and fungal culture. All cultured Aspergillus colonies were identified at species level by molecular methods. Finally, all available data from sputum culture and spirometry test were analysed. Out of 216 sputum samples, 145 (67.1%) were positive for fungal growth. Furthermore, out of 264 grown fungal colonies, 137 (51.9%) were Aspergillus species. Among the Aspergillus isolates, A. flavus (29.2%) was the most prevalent species, followed by A. fumigatus (27.7%). The mean forced expiratory volume in one second (FEV1) in the mild, moderate and severe asthmatic patients with a positive sputum culture for fungi were obtained as 90.0±11.1, 71.1±15.9 and 54.9±16.4, respectively. In general, Aspergillus species colonisation had no statistically significant effect on spirometry results of study patients. Our results showed that there is no difference in the FEV1 and forced vital capacity between Aspergillus positive and negative patients in any asthma severity group.

Hygiene behavior assessment of a hazelnut processing plant

PurposeThe purpose of this paper is to evaluate the possible microbiological contamination in terms of total counts and representative microbial groups found in the hazelnuts as well as in work areas and on the working surfaces of a hazelnut processing plant.Design/methodology/approachSome microbiological parameters related to the manufacturing process (e.g. aerobic colony count yeast and fungi) were evaluated. Indoor air samples were tested in order to evaluate the possible contamination of fungal strains (i.e. mycotoxin producing fungi).FindingsThe results showed that the highest values (>of 500 CFU/m3) for bacteria and fungi were only observed in the shelling and sorting areas. Some species such as Aspergillus and Penicillium (potential mycotoxin-producers) as well as some noxious colonies ofAspergillus fumigatuswere detected along the processing line. No occurrence of aflatoxins was observed in the finished product. Microbial loads obtained through surface analyses were in accordance to the reference data.Originality/valueThe aim of this study was to monitor and improve the procedures currently used in a hazelnut processing plant.

Fungal sinusitis among patients with chronic rhinosinusitis who underwent endoscopic sinus surgery.

Fungal paranasal sinusitis can be either invasive or non-invasive. Saprophytic infections, fungus balls (FB) and allergic fungal rhinosinusitis are non-invasive (AFR). The present study examined 521 patients who underwent endoscopic sinus surgery between January 2016 and April 2017 due to chronic paranasal sinusitis at the Department of Laryngology and Laryngological Oncology of the Upper Silesian Medical Centre in Katowice. The aim of the study was to analyse the histopathological and microbiological material collected intraoperatively and to determine the incidence and type of fungal infections among patients treated for chronic sinusitis. Chronic fungal sinusitis was confirmed in 10 of 521 operated patients. The study group consisted of 9 females and 1 male. Histopathological examination revealed dead mycelium in 5 patients and colonies of Aspergillus spp. in 4, while microbiological examination revealed Candida albicans infection in 1 case. Allergy to inhalant allergens of fungal spores of Alternaria and Penicillinum was confirmed in a 73-year-old patient, which, based on the whole clinical presentation, enabled to diagnose chronic allergic fungal sinusitis. The most common location of mycelium was the maxillary sinus, followed by the sphenoid sinus. The most common form of non-invasive fungal sinusitis is the so-called fungus ball, which was also confirmed in our report (95% of the test subjects). AFRS is more likely to occur in warm, moist climates that favour the growth of fungi.

Aspergillus Osteomyelitis Of Metatarsal

Aspergillus osteomyelitis is a rare disease and involving metatarsal is the rarest one. Here we present a case of middle aged diabetic male person complaining of pain and swelling of right foot since one year. On X-ray and MRI studies, a lytic lesion was observed at the base of 4 th metatarsal of right foot. Clinical diagnosis of chronic osteomyelitis was made. He underwent surgical curettage of the lesion and the necrotic material that obtained was sent for histopathological examination. H-E stain along with special stain PAS and GMS showed granulomatous inflammation with fungal colonies of Aspergillus. The patient was put on antifungal drugs and has been regularly followed-up. This study concluded that a clinical suspicion of aspergillus ostomyelitis should always be made on the symptoms of pain and swelling of lower extremities if associated with diabetes or any immunosupressed condition. Management of aspergillus ostomyelitis include both surgical modalities and antifungal drugs with regular follow up. DOI: 10.21276/APALM.1513

Fungal Stress Database (FSD)--a repository of fungal stress physiological data.

The construction of the Fungal Stress Database (FSD) was initiated and fueled by two major goals. At first, some outstandingly important groups of filamentous fungi including the aspergilli possess remarkable capabilities to adapt to a wide spectrum of environmental stress conditions but the underlying mechanisms of this stress tolerance have remained yet to be elucidated. Furthermore, the lack of any satisfactory interlaboratory standardization of stress assays, e.g. the widely used stress agar plate experiments, often hinders the direct comparison and discussion of stress physiological data gained for various fungal species by different research groups. In order to overcome these difficulties and to promote multilevel, e.g. combined comparative physiology-based and comparative genomics-based, stress research in filamentous fungi, we constructed FSD, which currently stores 1412 photos taken on Aspergillus colonies grown under precisely defined stress conditions. This study involved altogether 18 Aspergillus strains representing 17 species with two different strains for Aspergillus niger and covered six different stress conditions. Stress treatments were selected considering the frequency of various stress tolerance studies published in the last decade in the aspergilli and included oxidative (H2O2, menadione sodium bisulphite), high-osmolarity (NaCl, sorbitol), cell wall integrity (Congo Red) and heavy metal (CdCl2) stress exposures. In the future, we would like to expand this database to accommodate further fungal species and stress treatments.URL: http://www.fung-stress.org/

Distribution of indigenous strains of atoxigenic and toxigenic Aspergillus flavus and Aspergillus parasiticus in maize and peanuts agro-ecological zones of Kenya

Grains of important food and export crops in Africa are susceptible to contamination by toxin-producing moulds. Aflatoxins are mycotoxins associated with liver damage and cancer in humans and animals. These toxic substances are produced by fungi (such as Aspergillus flavus and Aspergillus parasiticus) in food and feed exposed to poor conditions during crop cultivation, storage or processing of harvest. The presence of aflatoxins in especially maize and peanuts in Kenya is of great concern. Recent developments in the application of atoxigenic strains of these fungi as biological control agents against toxigenic strains could be a solution to the problem. The objective of this study was to isolate, identify and characterize atoxigenic and toxigenic strains of A. flavus and A. parasiticus in Kenya, and investigate possible application of atoxigenic strains in control of aflatoxin levels in maize and peanuts. Fungal communities in soils of maize and peanut fields were examined to determine the distributions of aflatoxin-producing Aspergillus species and to identify endemic atoxigenic strains. 220 isolates belonging to A. flavus and A. parasiticus were collected randomly from soils of maize and peanuts fields in seven agro-ecological zones and characterized using morphological and physiological examination. Aspergillus section Flavi was detected in all the 57 soil samples collected in Kenya. Members of Aspergillus section Flavi L strain was the most common (54 %), followed by S-strains (35 %). Among Aspergillus, A. flavus was the most predominant (63.2 %), followed by A. parasiticus (27.7 %), A. tamari (5.5 %) and A. nomius (2.7 %). The mean CFU of the Aspergillus colonies per gram of soil was highly variable among the districts, ranging from 3.0 × 103 to 1.72 × 106 (p 0.05). The results also showed that A. flavus was detected in all the zones examined. Each of the regions had atoxigenic strains of potential value which can be employed as biological control agents in the management of aflatoxicoses.

Aspergillus colonization in patients with chronic obstructive pulmonary disease.

Background and Purpose:Chronic obstructive pulmonary disease (COPD) has been recognized as a risk factor for invasive aspergillosis. Airway colonization by Aspergillus species is a common feature of chronic pulmonary diseases. Nowadays, the incidence of COPD has increased in critically ill patients. The aim of the present study was to isolate and identify Aspergillus colonies in the respiratory tract of COPD patients.Materials and Methods:This study was performed on 50 COPD patients, who were aged above 18 years, and were in intensive care units of three hospitals in Sari, Iran, for at least six days. All the samples obtained from sputum, bronchoalveolar lavage, and tracheal aspirates were cultured for fungi each week. According to the conventional techniques, Aspergillus isolates were initially based on growth and standard morphological characteristics. To confirm the identification of grown Aspergillus, the partial beta-tubulin gene was sequenced using specific primers. Results:A total of 50 patients, who met our inclusion criteria, were enrolled in the study during 2012-14. The results showed that 27 (54%) and 23 (46%) of the participants were male and female, respectively. The majority of the patients developed dyspnea followed by hemoptysis, chest pain, and high fever. Corticosteroids and broad-spectrum antibacterial agents were administered to 75% and 80% of the patients, respectively. Based on the conventional and molecular approaches, A. fumigatus (seven cases; 43.7%), A. flavus (five cases; 31.2%), A. niger (one case; 6.2%), A. terreus (one case; 6.2%), A. orezea (one case; 6.2%), and A. tubingensis (one case; 6.2%) were recovered.Conclusion:Recovery of Aspergillus species from the respiratory tract of COPD patients with pneumonia indicates two possibilities: either colonization or invasive aspergillosis.

Exposition domiciliaire aux moisissures : quel impact sur le statut aspergillaire du patient atteint de mucoviscidose ?

The sources of exposure during diseases due to Aspergillus fungi in cystic fibrosis patients are still poorly explored. We assessed home fungal exposure in patients suffering from cystic fibrosis and analysed its impact on the presence of Aspergillus biological markers, the colonisation of airways, as well as the sensitization and Aspergillus serology. Between March 2012 and August 2012, 34 patients benefited from a visit performed by a home environment medical adviser including sampling for mycological analysis. The number of colonies of Aspergillus was not significantly different in the various sampling sites (P=0.251), but the number of non-Aspergillus colonies was much higher in the kitchen (P=0.0045). Subsequently, home fungal exposure was compared between the groups "absence of Aspergillus-related markers" and "presence of Aspergillus-related markers". Home exposure to Aspergillus (P=0.453) and non-Aspergillus (P=0.972) flora was not significant between the 2 groups. Within this series of 34 patients that should be expanded, we note an absence of clear relationship between home exposure and the Aspergillus-linked markers in patients suffering from cystic fibrosis. This result should be taken into account regarding too restrictive hygiene advices provided to families, given the fact that fungal exposure can also results from activities performed away from home.

EVALUATING FUNGI INDOOR PRESENCE IN HOMES THROUGH VIABLE AND NON-VIABLE SAMPLING

Moulds are common and important allergens. They are more abundant outdoors but patients affected by mould allergy stay indoors much longer than outdoors. So, indoor sampling could help to assess the influence of the concentration of allergens in allergic symptoms. The aim of this study was to assess the relative efficiencies of two air sampling methods, viable and non viable, for the quantification of airborne indoor fungi in the homes of patients sensitized to Alternaria. Furthermore, outdoor sampling was carried out to compare results. Samples were taken over six months in Badajoz (SW Spain). Two houses were selected according to the presence of allergic patients to Alternaria. They were sampled once a month using both viable and non viable personal samplers at solar noon. A Burkard personal sampler was used to record spores and a Sampl’air AES Chemunex sampler was used for colonies. Three rooms were selected in each home: living room, kitchen and bathroom. Temperature and relative humidity were registered at each sample. Outdoor sampling was performed one day per week at the Faculty of Science, using a seven day Burkard sampler for spores and the same personal sampler for colonies. On average, 200-300 CFU/ m3 were found from more than 40 taxa identified. The highest number of colonies was recorded in the kitchen, then in the bathroom and finally in the living room. Nevertheless, there were minor differences between rooms. The houses studied showed a similar temporal pattern, with maximum values in December and minimum in January. Cladosporium colonies showed statistical differences between homes, but these differences were not found with Alternaria, Aspergillus or Penicillium colonies. Differences between rooms appeared for Alternaria colonies and Cladosporium herbarium spores. Temperature was positively correlated in most cases and relative humidity negatively with Alternaria spores. The number of spores collected was as twice as that of colonies, with an average concentration between 600-700 colonies/m3 , and nearly 1400 spores/m3 as maximum concentration. The temporal pattern of spores was similar to that found for colonies. Comparing colonies to spores, Alternaria and AspergillusPenicillium showed similar values. Notwithstanding, Cladosporium spores were nearly five times more abundant than colonies. The advantage of viable methods is the identification to species level, but they have the disadvantage that spores from some ubiquitous species, as Cladosporium, do not always grow in those media, which raises the interest to use additional non-viable methods.

A survey on distribution and toxigenicity of Aspergillus flavus from indoor and outdoor hospital environments

In the present study, genetic diversity and mycotoxin profiles of Aspergillus flavus isolated from air (indoors and outdoors), levels (surfaces), and soils of five hospitals in Southwest Iran were examined. From a total of 146 Aspergillus colonies, 63 isolates were finally identified as A. flavus by a combination of colony morphology, microscopic criteria, and mycotoxin profiles. No Aspergillus parasiticus was isolated from examined samples. Chromatographic analyses of A. flavus isolates cultured on yeast extract-sucrose broth by tip culture method showed that approximately 10% and 45% of the isolates were able to produce aflatoxin B(1) (AFB(1)) and cyclopiazonic acid (CPA), respectively. Around 40% of the isolates produced sclerotia on Czapek-Dox agar. The isolates were classified into four chemotypes based on the ability to produce AF and CPA that majority of them (55.5%) belonged to chemotype IV comprising non-mycotoxigenic isolates. Random amplified polymorphic DNA (RAPD) profiles generated by a combination of four selected primers were used to assess genetic relatedness of 16 selected toxigenic and non-toxigenic isolates. The resulting dendrogram demonstrated the formation of two separate clusters for the A. flavus comprised both mycotoxigenic and non-toxigenic isolates in a random distribution. The obtained results in this study showed that RAPD profiling is a promising and efficient tool to determine intra-specific genetic variation among A. flavus populations from hospital environments. A. flavus isolates, either toxigenic or non-toxigenic, should be considered as potential threats for hospitalized patients due to their obvious role in the etiology of nosocomial aspergillosis.

Management of voriconazole hepatotoxicity in a lung transplant patient

Lung allograft airway colonization by Aspergillus species is common among lung transplant recipients. We report the case of a 46-year-old female lung transplant outpatient diagnosed with persistent pulmonary Aspergillus colonization (>50 colonies of Aspergillus terreus) 3 months after lung transplantation. Oral voriconazole 200 mg twice a day (b.i.d) was initiated shortly after diagnosis. Two days after voriconazole initiation, alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) were normal or slightly elevated (79, 37, and 21 UI/L, respectively). Ten days after the first voriconazole administration, these values started to increase. Maximum levels were reached after 20 days for ALP (369 UI/L) and at around 30 days for ALT and AST (223 and 188 UI/L, respectively). Instead of discontinuing antifungal therapy, it was decided to reduce the voriconazole dose to 100 mg b.i.d. This asymptomatic progressive cholestatic hepatitis resolved, and 10 days after dose reduction ALP, ALT, AST were at 136, 53, and 28 UI/L, respectively. Finally, therapeutic drug monitoring revealed adequate voriconazole plasma trough concentrations (0.98 mg/L) 30 days after dose reduction and no more colonies of Aspergillus were observed. Voriconazole-induced hepatotoxicity is a well known dose-dependent adverse drug reaction. This experience confirms the appropriateness of voriconazole dose reduction instead of therapy interruption in dose-dependent moderate liver toxicity. Voriconazole therapeutic drug monitoring before and after dose reduction may help to avoid drug accumulation and inappropriately low drug exposure, respectively.

Study of Mycological Examination Methods in Clinical Laboratories

We performed a comparative study of the effects of centrifugation, large amounts of inoculum and incubation temperature with regard to recovery of Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus from fungal suspensions in order to identify optimal processing methods for mycological examination of clinical specimens. The number of fungal colonies, except for Candida spp., isolated from respiratory specimens, and the duration of incubation needed to isolate pathogenic fungi from clinical specimens were also analyzed retrospectively. There was a difference in the number of recovered colonies, with or without centrifugation, between inoculum sizes of 10 microl and 50 microl, but no differences were observed in the results obtained under two sets of centrifugation conditions: 2,000 x g for 15 minutes and 3,000 x g for 20 minutes. Candida albicans and Aspergillus fumigatus developed more rapidly at 35 degrees C than at 27 degrees C in the first 24 hours of incubation, while Cryptococcus neoformans formed a larger colony at 27 degrees C than at 35 degrees C. One to three colonies of Aspergillus spp. and Cryptococcus spp. were isolated from respiratory specimens in 73% and 50% of cases, respectively. The required incubation period was six days for isolation of 65 Aspergillus spp. strains from respiratory specimens, while 14 days was needed for isolation of 46 dermatophyte strains. Based on these results, we recommend a pretreatment of centrifugation and a large quantity of inoculum for respiratory specimen processing, as well as an incubation period of at least 7 days and 21 days for internal and dermatological specimens, respectively.

Host specificity of Eupenicillium ochrosalmoneum, E. cinnamopurpureum and two Penicillium species associated with the conidial heads of Aspergillus

The genus Penicillium comprises species that mostly colonize plant matter. However early reports suggest that several species are capable of parasitizing Aspergillus and sporulating on the conidial heads of the host. More recently Eupenicillium ochrosalmoneum and E. cinnamopurpureum, both with Penicillium anamorphs, have been observed sporulating on the heads of Aspergillus species belonging to section Flavi during the colonization of peanut seeds. Little is known about the host specificity underlying these Aspergillus-Penicillium associations. In this study Aspergillus species representing nine taxonomic sections were paired in culture with E. ochrosalmoneum, E. cinnamopurpureum and two unnamed Penicillium species. Eupenicillium ochrosalmoneum, E. cinnamopurpureum and Penicillium sp. 1 sporulated predominantly on the heads of section Flavi species. In contrast Penicillium sp. 2 was restricted to the heads of section Nigri species. All species spread across Aspergillus colonies by means of aerial hyphae that grew from head to head. Additional studies are required to clarify whether Eupenicillium and Penicillium species are parasitic or simply epibiotic on their hosts.

Host specificity of Eupenicillium ochrosalmoneum, E. cinnamopurpureum and two Penicillium species associated with the conidial heads of Aspergillus

The genus Penicillium comprises species that mostly colonize plant matter. However early reports suggest that several species are capable of parasitizing Aspergillus and sporulating on the conidial heads of the host. More recently Eupenicillium ochrosalmoneum and E. cinnamopurpureum, both with Penicillium anamorphs, have been observed sporulating on the heads of Aspergillus species belonging to section Flavi during the colonization of peanut seeds. Little is known about the host specificity underlying these Aspergillus-Penicillium associations. In this study Aspergillus species representing nine taxonomic sections were paired in culture with E. ochrosalmoneum, E. cinnamopurpureum and two unnamed Penicillium species. Eupenicillium ochrosalmoneum, E. cinnamopurpureum and Penicillium sp. 1 sporulated predominantly on the heads of section Flavi species. In contrast Penicillium sp. 2 was restricted to the heads of section Nigri species. All species spread across Aspergillus colonies by means of aerial hyphae that grew from head to head. Additional studies are required to clarify whether Eupenicillium and Penicillium species are parasitic or simply epibiotic on their hosts.

Aspergillus Volatiles Regulate Aflatoxin Synthesis and Asexual Sporulation in Aspergillus parasiticus

Aspergillus parasiticus is one primary source of aflatoxin contamination in economically important crops. To prevent the potential health and economic impacts of aflatoxin contamination, our goal is to develop practical strategies to reduce aflatoxin synthesis on susceptible crops. One focus is to identify biological and environmental factors that regulate aflatoxin synthesis and to manipulate these factors to control aflatoxin biosynthesis in the field or during crop storage. In the current study, we analyzed the effects of aspergillus volatiles on growth, development, aflatoxin biosynthesis, and promoter activity in the filamentous fungus A. parasiticus. When colonies of Aspergillus nidulans and A. parasiticus were incubated in the same growth chamber, we observed a significant reduction in aflatoxin synthesis and asexual sporulation by A. parasiticus. Analysis of the headspace gases demonstrated that A. nidulans produced much larger quantities of 2-buten-1-ol (CA) and 2-ethyl-1-hexanol (EH) than A. parasiticus. In its pure form, EH inhibited growth and increased aflatoxin accumulation in A. parasiticus at all doses tested; EH also stimulated aflatoxin transcript accumulation. In contrast, CA exerted dose-dependent up-regulatory or down-regulatory effects on aflatoxin accumulation, conidiation, and aflatoxin transcript accumulation. Experiments with reporter strains carrying nor-1 promoter deletions and mutations suggested that the differential effects of CA were mediated through separate regulatory regions in the nor-1 promoter. The potential efficacy of CA as a tool for analysis of transcriptional regulation of aflatoxin biosynthesis is discussed. We also identify a novel, rapid, and reliable method to assess norsolorinic acid accumulation in solid culture using a Chroma Meter CR-300 apparatus.

Competition with filamentous fungi and its implication for a gregarious lifestyle in insects living on ephemeral resources

Abstract. 1. Recent studies have demonstrated the existence of positive density dependence in the survival and development ofDrosophila(the so‐called Allee effect); however the underlying mechanisms of such Allee effects have remained elusive. Competition with filamentous fungi have often been suggested to be involved in causing high mortality at low larval density, but it has not yet been explicitly tested if the well known spatial aggregation of insect eggs yields a fitness benefit for the developing larvae in the presence of noxious moulds.2. UsingDrosophila melanogaster, the present study tested whether larval survival is greater in aggregations when confronted with various combinations of three representative mould species (Aspergillus,Alternaria, andPenicillium) and a head start for fungal development.3. High rates of fungal‐dependent mortality and significant positive density‐dependent larval survival (i.e. Allee effects) were observed when larvae were confronted with food resources containing established colonies ofAspergillusorAlternaria. Neither the simultaneous transfer ofAspergillusorAlternariaspores with larvae to food patches nor food infections withPenicilliumaffected insect larval development.4. Significant correlations between mould growth and larval survival could be identified, although the patterns that emerged were shown to be inconsistent when the effects were compared between fungal species and fungal priority. Because mould growth only partly explained larval survival, the influence of other fungal‐borne factors, e.g. mycotoxins, needs to be elucidated in order to understand the mechanistic basis of insect–mould interactions.5. These results are the first to argue convincingly for moulds being involved in mediating Allee effects for insects on ephemeral resources; however they also demonstrate an unexpected diversity in insect–mould interactions. Considering this diversity may be important in understanding insect spatial ecology.

Absorção de água e proliferação de fungos em madeira de Pinus usada como embalagem para hortaliças

A madeira é o material mais utilizado para embalagens de hortaliças no Brasil, principalmente por conta de seu baixo custo e alta resistência mecânica. Neste trabalho estimou-se a absorção e a perda progressiva de água de ripas de madeira de Pinus utilizadas na montagem de caixas do tipo "K" em três condições de umidade relativa e o crescimento de fungos em sua superfície. Trinta ripas novas de madeira de Pinus (52 x 6 x 0,6 cm) foram pesadas individualmente, imersas em água durante 1 h e pesadas novamente para avaliar a absorção de água. Em outro experimento, dez ripas foram incubadas ao acaso em cada uma das três câmaras úmidas (61%, 86% e 94% UR) mantidas a 25ºC (±2ºC). A perda progressiva de água foi avaliada por pesagens diárias das ripas individualmente e o desenvolvimento de fungos na madeira foi avaliado com uma escala de notas (0-3) durante oito dias. A madeira nova de Pinus pode absorver até 38% de seu peso em água, e permanecer úmida por vários dias de acordo com a condição de armazenamento. A umidade relativa do ambiente afetou a taxa de perda de água diária da madeira, sendo 4,7%, 2,5% e 1,0% respectivamente em 61% UR, 86% UR e 94% UR, e ao final de oito dias alcançou 37,5%, 19,9% e 7,9%, respectivamente. Os fungos predominantes foram Trichoderma harzianum e Rhizopus stolonifer, mas também observou-se crescimento de Aspergillus sp. e Penicillium sp. Para evitar a absorção de água pela madeira de Pinus e a proliferação de fungos em sua superfície, as hortaliças lavadas devem ser secadas ou submeter a madeira a um processo de impermeabilização.