Regulation of the external mycoflora of the giant Madagascar hissing-cockroach,gromphadorhina portentosa, by its mite associate,gromphadorholaelaps schaeferi, and its implications on human health

The giant Madagascar hissing-cockroach,Gromphadorhina portentosa, and its mite associate,Gromphadorholaelaps schaeferi, constitute an intimate commensalistic symbiosis. While the mite’s very survival is dependent by feeding on cockroach saliva and associated organic debris, the degree that the cockroach benefits from this association is unclear. We investigated the mite’s potential role at regulating surface fungi on the exoskeletons of this insect. Numbers of fungal isolates that resulted were compared between captive-bred cockroaches with and without mites. The mycoflora of both groups consisted of common molds (Alternaria sp.,Aspergillus sp.,Cladosporium sp.,Geotrichum sp.,Mucor sp.,Penicillium sp.,Rhizopus sp.,Trichoderma sp.). The presence of mites reduced the number of isolates by 1/2 in mature females, 1/3 in males, and 1/4 in sixth (final) instar nymphs. Fungus levels continued to drop when mite-free cockroaches were artificially supplemented with mites. A direct correlation was detected between mites and the reduction in the quantity of surface molds up to 20 mites per cockroach. The addition of more mites above 20 per cockroach, even 4x more, had a minimal, but still reducing, effect. Mites regulated all types of fungi, not just a select few taxa. We propose that mites reduce the mycoflora not because they consume fungi, but because mites and molds compete for the same resources in an ecological niche, saliva and organic debris that accumulate in between cockroach’s legs. Cockroaches reared in captivity do not apparently benefit by the removal of surface molds by mites, lending support for a commensalistic symbiosis. This cockroach species has been linked to severe allergic reactions in children, in part, because it harbors antagonistic molds. GivenG. schaeferi’s regulatory role at suppressing fungi, these mites could conceivably impose a small indirect, albeit beneficial role to humans by reducing the amount of fungal inoculum (conidia) that might otherwise be inhaled.     

Studies on seed-borne fungi of wheat in seed health testing programme

Seed mycoflora associated with wheat was studied on different media with a particular reference to Blotter and potato dextrose agar (PDA) procedures of ISTA. Seed-borne fungi, viz. Fusarium moniliforme, Rhizopus spp., Mucor spp., Alternaria alternata, Aspergillus niger, Aspergillus flavus, Curvularia lunata, Drechslera spp, Alternaria spp. and Penicillium spp., were isolated from the variety HD264. Blotter method was found to be the best media for the isolation of mycoflora whether borne externally or internally. Total number and frequency of occurrence of fungi were recorded. The effect of seed treatment with different chemicals and eco-friendly botanicals was analysed on germination, and growth, better percentage of seed germination and reduction in fungal pathogen were due to biochemical seed treatment.     

A survey of outdoor and indoor airborne fungal spora in the Redemption City, Ogun State, south-western Nigeria

The concentration and biodiversity of airborne fungi of the Redemption City, an immense campground for Christian faithful and the temporary site of the Redeemer’s University in south-western Nigeria, was studied between February and May 2011 using the culture plate method. The study was undertaken to assess the concentrations of fungal spores and their health implication in this ever-busy environment. Fifteen different sites classified as closed or open were selected. During the experiment, a total of 228 colonies were counted, and 29 fungal species belonging to 26 genera were isolated which include the following: Aspergillus flavus, Aspergillus niger, Bipolaris spp., Chrysosporium spp., Cladosporium spp., Coniothyrium corda, Curvularia spp., Diplodia spp., Fusarium spp., Gliocladium spp., Monilia spp., Mucor spp., Mucor plumbeus, Penicillium spp., Phycomyces spp., Phytophthora spp., Pilobolus spp., Pyrenochaeta spp., Rhizopus stolonifer, Torula spp., Trichoderma spp. and Trichophyton spp. The most frequently occurring fungi were A. niger, C. corda and M. plumbeus, while the least recorded were Torula and Trichophyton species. Majority of the fungi isolated are known allergens; they could also be opportunistic causing various diseases in man. There is therefore a dire need for good sanitation practices within the studied areas of the camp.     

Qualitative microbiological changes during decomposition of plant material in a sandy sierozem soil

The successive qualitative microbial changes during the decomposition of bajra stalk in a sandy sierozem soil were studied.Alternaria spp.,Aspergillus spp.,Cladosporium spp.,Fusarium spp.Gliocladium spp.,Mucor spp. andRhizopus spp. were most common fungi. The bacteria observed wereAchromobacter, Arthrobacter, Bacillus, Micrococcus, Pseudomonas andXanthomonas. Cellvibrio andCellulomonas were also observed.     

Fungi associated with eggs and first-instar larvae of the European corn borer

Fungi isolated from field-collected egg masses of the European corn borer, Ostrinia nubilalis, were identified as Alternaria spp., A. porri, Fusarium spp., Fusarium oxysporum, Beauveria bassiana, Mucor spp., and an unidentified yeast. Most fungi were associated with predator injury to the egg mass. Bioassay of fungi on egg masses, however, showed that Alternaria spp. and A. porri reduced the hatch of both injured and uninjured egg masses, and Mucor sp. reduced the hatch only when the egg mass was injured.     

Peanut-pod mycoflora and kernel infection

Summary The mycoflora in soil clinging to dry pods of peanuts of the Spanish variety Argentine was sampled in 2 experiments by serially washing pods for increasing periods in changes of sterile water. Of the 9 principal fungi found,Aspergillus niger, A. flavus, A. terreus, Rhizopus spp. andSclerotium bataticola were present initially in relatively small numbers and decreased rapidly in subsequent dilutions. This decrease paralleled a decrease in weight of suspended material and in percentage of soil and organic particles greater than 0.016 mm in size.Penicillium funiculosum, P. rubrum, P. citrinum, andFusarium spp. were found in large numbers and increased or slowly decreased in numbers in subsequent dilutions. In some instances variations in numbers followed trends of percentages of soil and organic particles less than 0.016 mm in size.When dry pods with this known mycoflora were allowed to hydrate over a 6-day period at 26°, 32°, or 38°C, there was extensive pod penetration and kernel infection byA. niger, A. flavus, S. bataticola andRhizopus spp. but not by other fungi. The degree ofA. flavus andA. niger infection increased with increasing temperatures.Approved by the Director as Journal Series Paper No. 135.     

Performance of Rhizopus,Rhizomucor, and Mucor in ethanol production from glucose,xylose, and wood hydrolyzates

In searching for ethanol producing microorganisms also capable of fermenting pentoses, nine zygomycetes strains including three strains of Rhizopus oryzae, Mucor corticolous, M. hiemalis, M. indicus, Rhizomucor pusillus, R. miehei, and zygomycete IT were examined. Each strain was cultivated on glucose, xylose or dilute-acid hydrolyzate (DAH) as carbon sources, and the production of ethanol, lactic acid, glycerol, xylitol, and succinic acid were investigated. Great similarities but also conspicuous differences were seen between the species, to some extent linked to the genera. All strains were capable of growing on glucose or xylose as single carbon source. With the exception of the two Rhizomucor strains, all produced ethanol. All the strains produced glycerol as by-product, while Rhizopus and Rhizomucor but not Mucor produced lactic acid in significant amounts. All Mucor and Rhizopus strains and one strain of Rhizomucor produced xylitol in the xylose medium, but no xylitol was detected after growth on DAH. All Mucor and two R. oryzae strains were capable of growing on DAH. Two Mucor species, M. hiemalis and M. indicus showed greater ethanol production than the other strains. The ethanol yields by M. hiemalis on glucose, xylose, and DAH were 0.39, 0.18, and 0.44 g/g, respectively, whereas the corresponding results for M. indicus were 0.39, 0.22, and 0.44 g/g. The strains also rapidly consumed hydroxymethyl furfural present in DAH.     

Separation of Fungal Propagules by Partition in Aqueous Polymer Two-Phase Systems

Conidia of Penicillium chrysogenum and Penicillium frequentans and sporangiospores of Rhizopus rhizopodiformis, Rhizomucor pusillus, and Mucor racemosus were subjected to partition in aqueous polymer two-phase systems. The partition behavior differed drastically between the conidia of the two Penicillium species and the sporangiospores of the three species of phycomycetes. This difference in partition behavior can be used for purification of fungi belonging to different taxonomical groups. P. frequentans was completely separated from M. racemosus by two extractions, whereas four extractions were needed to purify M. racemosus. This method was used on an air sample from a locality where wood fuel chips are handled. The conidia of the fungi Trichoderma viride and Rhizopus rhizopodiformis were removed completely by only two extractions.     

The influence of berries infected with Botrytis cinerea on the enzymic breakdown of sulphited strawberries

Endo-polygalacturonase produced by Botrytis cinerea is rapidly inactivated in infected strawberry tissue both by the naturally occurring fruit phenolics and also by those oxidised compounds formed as a result of polyphenol oxidase activity in the infected tissue. In contrast, the endo-polygalacturonases of Mucor piriformis, Rhizopus sexualis and R. stolonifer are more resistant to inactivation by the fruit phenolics and no polyphenol oxidase was detected in tissue infected by these fungi. The presence of Botrytis-infected berries in sulphited fruit containing tissue infected with Mucor or Rhizopus resulted in more rapid inactivation of the endopolygalacturonases from the latter fungi, and hence reduced the amount of softening and breakdown of the fruit. This inactivation is considered to be due largely to the oxidised phenolics present in Botrytis-infected tissue.     

Determination of culturable indoor airborne fungi during normal and dust event days in Ahvaz, Iran

The first purpose of our study was to determine culturable indoor airborne fungi in different places in Ahvaz during normal and dust event days. Ahvaz is the biggest city in southwest of Iran which has suffered from dust storms in recent decade. To minimize personal exposure to polluted air, governmental and private sectors excluding critical places such as hospitals, fire department and security organization are closed during dust event days. Therefore, the second objective of this survey was to see whether this plan (forced shutdown) is in place. Samples were collected from July 2010 to March 2011 by using quick take 30 equipped with a single-stage sampler. Fungal population was measured in school, university and hospital during normal and dust event days. Five dominant fungi genera in three sampling stations were Cladosporium, Alternaria, Aspergillus, Penicillium and Rhizopus the concentrations (CFU/m³) of which were higher during dust events than normal days. Airborne fungi such as Aspergillus, Mucor and Rhizopus are opportunistic fungi which can cause aspergillusis and mucormycosis infections in immunodeficiency individuals, vulnerable groups as well as healthy people. The results of this study confirmed the measure of forced shutdown in Ahvaz city due to increased concentration of fungi during dust event days.     

Effect of pre-harvest fungicides on the spoilage of soft fruit after harvest

In the 1972 season, Elvaron and Benlate reduced the count of Botrytis cinerea, Cladosporium spp., Penicillium spp. and Aureobasidiutn pullulans on strawberry and raspberry fruits during the first 2 wk of the season, but not subsequently. No such reduction was recorded for Hainesia lythri (strawberries only), Phoma state of Didymella applanata (raspberries only), Mucor spp., and Rhizopus spp. Similar results were obtained in 1973. In the first half of either season, both fungicides decreased the rate of fungal spoilage of stored fruit (except for Benlate in the 1973 season), although in the latter part of the season, there was little difference in the incidence of fungal spoilage between sprayed and unsprayed fruit. Both fungicides, however, reduced the development of B. cinerea (and Cladosporium spp. on raspberries) on stored fruit irrespective of season or harvest date except for Benlate in the 1973 season where Benlate-resistant strains of the fungi developed on the fruit. The failure of either fungicide to reduce fungal spoilage in the latter part of the harvesting season was due to the development of Phycomycetes, particularly Mucor mucedo and to a lesser extent Rhizopus stolonifer and R. sexualis, except where Benlate-resistant strains of B. cinerea and Cladosporium spp. were present.     

Susceptibility of cockroaches (Gromphadorhina portentosa,Nauphoeta cinerea and Blaptica dubia) exposed to entomopathogenic nematodes

Cockroaches are major pests, vectors of pathogenic bacteria and induce allergies. Current control methods use chemical pesticides, but they can be ineffective and costly and there are reports of resistance in the field; hence new control methods are needed. There are conflicting reports about the susceptibility of cockroaches to entomopathogenic nematodes (EPNs); so we investigated if EPNs could kill several diverse cockroach species, including the Madagascan hissing roach (Gromphadorhina portentosa), the Lobster roach (Nauphoeta cinerea) and Blaptica dubia. Female adult cockroaches were exposed to either commercial products containing Steinernema kraussei or a combination of Heterorhabditis spp. and Steinernema spp. at 50 and 150 nematodes per cm² for 21 days. We also monitored feeding and the numbers of infective juveniles that were produced from each cockroach corpse. We found that S. kraussei were harmless to all cockroach species (at both doses) but when exposed to a mixture of Heterorhabditis spp. and Steinernema spp. B. dubia died after 6 days and its feeding was strongly inhibited. We also found that the mixture of Heterorhabditis spp. and Steinernema spp. could proliferate in the cadavers of B. dubia whilst S. kraussei could only reproduce in G. portentosa and B. dubia but not N. cinerea. In conclusion, S. kraussei was harmless to all three cockroach species but B. dubia was killed when exposed to Heterorhabditis spp. and Steinernema spp., highlighting the differences in the host range of EPNs.     

Characterization of antifungal activity of the GH-46 subclass III chitosanase from Bacillus circulans MH-K1

We characterized the antifungal activity of the Bacillus circulans subclass III MH-K1 chitosanase (MH-K1 chitosanase), which is one of the most intensively studied glycoside hydrolases (GHs) that belong to GH family 46. MH-K1 chitosanase inhibited the growth of zygomycetes fungi, Rhizopus and Mucor, even at 10 pmol (0.3 μg)/ml culture probably via its fungistatic effect. The amino acid substitution E37Q abolished the antifungal activity of MH-K1 chitosanase, but retained binding to chitotriose. The E37Q mutant was fused with green fluorescent protein (GFP) at its N-terminus and proved to act as a chitosan probe in combination with wheat-germ agglutinin (WGA), which is a chitin-specific binding lectin. The GFP-fused MH-K1 chitosanase mutant E37Q (GFP-E37Q) bound clearly to the hyphae of the Rhizopus and Mucor strains, indicating the presence of chitosan. In contrast, Cy5-labelled WGA (Cy5-WGA), but not GFP-E37Q, stained the hyphae of non-zygomycetes species, i.e. Fusarium oxysporum, Penicillium expansum, and Aspergillus awamori. When the mycelia of Rhizopus oryzae were treated with wild type MH-K1 chitosanase, they could not bind to GFP-E37Q but were stained instead by Cy5-WGA. We conclude that chitin is covered by chitosan in the cell walls of R. oryzae.     

Polyphasic approach to the taxonomy of the Rhizopus stolonifer group

Phylogenetic analysis of Rhizopus strains based on the D1/D2 region of LSU rDNA sequences yielded a phylogram with four well-supported clades. The R. microsporus clade concurs with classification obtained by traditional methods. The R. oryzae group was found to include species of the genus Amylomyces. The traditional R. stolonifer group was divided into two well-supported clades in the phylogram, with one clade comprising R. stolonifer var. stolonifer, R. sexualis var. sexualis, and R. sexualis var. americanus and the other clade comprising taxa with recurved sporangiophores; R. reflexus, R. stolonifer var. lyococcus, and R. circinans, identifying recurved sporangiophores as an important taxonomic character. The molecular data supported the recognition of this clade at the species level: R. lyococcus (basionym: Sporotrichum lyococcum).     

Formation of antigenic extracellular polysaccharides by selected strains ofMucor spp.,Rhizopus spp.,Rhizomucor spp.,Absidia corymbifera andSyncephalastrum racemosum

In this study, polyclonal IgG antibodies raised against extracellular polysaccharides (EPS) ofMucor racemosus were characterised as almost specific for moulds belonging to the order of Mucorales. Cross-reactivity in the ELISA could be observed only towards the yeastPichia membranaefaciens. EPS were isolated from various cultures ofM. hiemalis growing on six different carbon sources and two nitrogen sources, with ratios varying from 0.13 to 0.44 relative to the amount of biomass. Other strains includingMucor spp.,Rhizopus spp.,Rhizomucor spp.,Absidia corymbifera andSyncephalastrum racemosum also excreted EPS, with ratios varying from 0.05 to 0.23. In all cases, the excreted EPS had similar antigenic properties as determined by ELISA. No enzymatic degradation of the antigenic parts of the polysaccharides could be observed upon prolonged incubation. Considering that all tested strains formed similar amounts of antigenic EPS there might be scope for the specific detection of biomass of Mucoralean moulds using ELISA techniques for example in food.     

Communication in the courtship of a madagascan hissing cockroach. I. Normal courtship

The hissing Madagascar cockroach, Gromphadorhina portentosa, has a prolonged and complex courtship involving signals in several sensory modalities. Courtship was described for 13 pairs of cockroaches and the frequencies and sequencing of 16 behavioural units were analysed. Particular attention was paid to the function and interactions of acoustic, chemical and tactile components. The results indicate that posturing and sound production by males, and antennation by both males and females, are important in courtship. They also suggest that courtship in G. portentosa, rather than depending on a rigid sequence of behaviour determined by a series of discrete releasers, is quite flexible, using ‘behavioural monologues’ by both sexes as a means of achieving transitions from one stage of courtship to the next.     

Rhizosphere and phyllosphere fungi of four fern plants growing in Saudi Arabia

Seventy-eight species in addition to 1 variety of A. flavus belonging to 31 genera were collected from the rhizosphere (55 species + 1 variety and 24 genera) and phyllosphere (59 species and 22 genera) of Adiantum capillus-veneris, Ceterach officinarum, Asplenium filare and Cheilanthes catanensis.In the rhizosphere, the most common genera were Aspergillus, Penicillium, Fusarium, Mucor and yeasts. In the phyllosphere, the most prevalent fungi were Cladosporium herbarum, C. sphaerospermum, Alternaria alternata, Drechslera spicifera, Aspergillus spp., Penicillium spp., Cephalosporium roseo-griseum, Myrothecium verrucaria, Mucor racemosus and yeasts.     

A Case of Rhinoorbital Mucormycosis in a Leukemic Patient with a Literature Review from Turkey

Mucormycosis (Zygomycosis) is a rare, invasive, opportunistic fungal infection of the paranasal sinuses, caused by a fungus of the order Mucorales. We report a case of rhinoorbital mucormycosis caused by Rhizopus oryzae in an acute lymphoblastic leukemia patient and review the 79 Mucormycosis cases reported in the last decade from Turkey. In our case, the diagnosis was made with endoscopic appearance, computerized tomography of the paranasal sinuses, and culture of the surgical materials. Following aggressive surgical debridement and parenteral amphotericin B therapy, the patient recovered completely. In Turkish literature, rhinocerebral manifestations were the most common form of the mucormycosis (64 cases), followed by pulmonary form (6 cases). The most common risk factor was hematologic malignancies (32 cases) and diabetes mellitus (32 cases), similar to those reported from the rest of the world. The etiologic agents responsible for the review cases were Rhizopus sp., Mucor spp., Rhizomucor spp., Rhizopus oryzae, Mucor circinelloides, and Lichtheimia corymbifera. Although various treatment modalities were used, amphotericin B was the mainstay of therapy. Mortality rate was found to be 49.4% in review cases. It seems that strong clinical suspicion and early diagnosis, along with aggressive antifungal therapy and endoscopic sinus surgery, have great importance for better prognosis in mucormycosis.     

Variations in amylase and protease activities amongRhizopus isolates

Summary Variations in amylase and protease activities among 16 local isolates ofRhizopus spp. were assessed.Rhizopus microsporus and theR. arrhizus isolates were consistently good producers of amylase. Good producers of protease wereR. microsporus and theR. oligosporus isolates. No amylase or protease activity was detected inR. stolonifer. The results also showed that

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Resumen Se evaluaron las variaciones en las actividades amilasa y proteasa de 16 aislados locales deRhizopus spp. Los aislados deR. microsporus y deR. arrhizus fueron buenos productores de amilasa en tanto que los aislados deR. microsporus y deR. oligosporus lo fueron de proteasa. No se detectó actividad amilasa ni proteasa enR. stolonifer. Los resultados mostraron además que la producción enzimática variaba entre las deferentes especies deRhizopus spp. aislados y tambien entre aislados de la misma especie. UnRhizopus spp. aislado de pan seco fue tan activo como varias cepas aisladas de tempeh.

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Résumé Les variations en activités amylolytique et protéolytique chez 16 souches isolées localement deRhizopus spp. ont été mesurées. Les souches deRhizopus microsporus et deR. arrhizus se sont avérées systématiquement bonnes productrices d'amylase. Les souches deR. microsporus et deR. oligosporus se sont avérées bonnes productrices de protéase. Ni amylase ni protéinase n'ont été détectées chezR. stolonifer. Les résultats ont également montré que la productivité enzymatique variait d'espèce chezRhizopus, et même parmi différentes souches de la même espèce. La souche deRhizopus isolée de pain bis était aussi active en production d'enzyme que certaines souches isolées de tempeh.

     

Growth Simulation and Discrimination of Botrytis cinerea,Rhizopus stolonifer and Colletotrichum acutatum Using Hyperspectral Reflectance Imaging

This research aimed to develop a rapid and nondestructive method to model the growth and discrimination of spoilage fungi, like Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum, based on hyperspectral imaging system (HIS). A hyperspectral imaging system was used to measure the spectral response of fungi inoculated on potato dextrose agar plates and stored at 28°C and 85% RH. The fungi were analyzed every 12 h over two days during growth, and optimal simulation models were built based on HIS parameters. The results showed that the coefficients of determination (R²) of simulation models for testing datasets were 0.7223 to 0.9914, and the sum square error (SSE) and root mean square error (RMSE) were in a range of 2.03–53.40×10⁻⁴ and 0.011–0.756, respectively. The correlation coefficients between the HIS parameters and colony forming units of fungi were high from 0.887 to 0.957. In addition, fungi species was discriminated by partial least squares discrimination analysis (PLSDA), with the classification accuracy of 97.5% for the test dataset at 36 h. The application of this method in real food has been addressed through the analysis of Botrytis cinerea, Rhizopus stolonifer and Colletotrichum acutatum inoculated in peaches, demonstrating that the HIS technique was effective for simulation of fungal infection in real food. This paper supplied a new technique and useful information for further study into modeling the growth of fungi and detecting fruit spoilage caused by fungi based on HIS.