The radiation resistance of ascospores and sclerotia of Pyronema domesticum

The Food and Drug Administration has become aware of several instances where supposedly sterile medical surgical products made of Chinese cotton have been found to contain viable Pyronema domesticum. The aim of this research was to determine the gamma and electron beam radiation resistance values for the two dormant phases (ascospores and sclerotia) of P. domesticum. The resistance values were obtained by developing a standardized system to cultivate, purify, and harvest biological indicators containing sclerotia or ascospores. Ascospores were more resistant to radiation than sclerotia. The D ₁₀ values for sclerotia were 0.79 and 1.09 kGy for strains 32030 and 14881, respectively. The resistance value for wild type ascospores was 2.83 kGy. The current standard for assuring radiation sterilization of medical devices is ISO 11137. This standard was developed to address the propensity for highly radiation-resistant organisms such as P. domesticum. Prior to the standard, biological indicators such as Bacillus pumilus, having a nominal D ₁₀ value or 1.7 kGy, were used to determine the sterility of many medical devices. Journal of Industrial Microbiology & Biotechnology (2002) 29, 51–54 doi:10.1038/sj.jim.7000267 Received 09 October 2001/ Accepted in revised form 08 April 2002     

The ascigerous state of Candida chodatii

In Candida chodatii, a mycelial yeast having denticulate conidiogenous cells, the asci are formed by conjugating budding cells (conidia) and usually contain 2 hat-shaped, small ascospores. It is classified in Hyphopichia, a new genus of the Ascoideaceae. A key to the genera of the Ascoideaceae is given.     

Entomopathogenic potential of fungi isolated from intertidal environments against the cabbage aphid Brevicoryne brassicae (Hemiptera: aphididae)

The use of biopesticides formulated from entomopathogenic fungi is a strategy utilised in integrated pest management programmes. The microorganisms used in these biopesticides are isolated from terrestrial organisms and ecosystems. However, bioprospecting in marine environments may lead to the discovery of promising fungi for pest control. In this study, marine fungi were identified and evaluated for the control of Brevicoryne brassicae. The effects of the most virulent isolate so identified on the mortality of aphids were compared to the effects of bioinsecticides that were formulated from fungal strains of Beauveria bassiana (Bovemax®) and Metarhizium anisopliae (Methamax®). Moreover, lethal and sublethal effects of this isolate on B. brassicae biological parameters were also examined. The isolates were identified as Aspergillus versicolor, Aspergillus sydowii (isolates 1 and 2), Penicillium dipodomyicola, and Trichoderma harzianum. The fungal strain A. versicolor was the most virulent fungal species, causing 85.9% mortality in B. brassicae at 24 h. The mortality rate caused by A. versicolor was similar to that caused by Bovemax® and Methamax® at concentrations of 10⁵ conidia mL^?1, and superior to that caused by Methamax® at a concentration of 10⁹ conidia mL^?1. The exposure of B. brassicae to CL₂₅ (0.32 × 10³) of A. versicolor did not affect the net reproductive rate (R_o), average generation time (T), intrinsic rate of population growth (r_m), and finite rate of population increase (λ). This is the first study to demonstrate that A. versicolor isolated from a marine environment is a promising candidate for the biological control of agricultural pests.     

Studies on Enzymatic Production of ATP

A study of the microflora of radurized Vienna sausages which did not contain preservatives revealed gram-negative diplococci and paired short rods. These radio-resistant isolates were the main residual flora in radurized viennas. The cultures were aerobic, oxidase positive and non-motile, and sugars were oxidized or not attacked at all. The population at the low temperature incubation from 0 to 10°C was abundant and these isolates may be psychrophilic bacteria. The cultures are also capable of growing in media supplemented with 7.5% sodium chloride. The present study has demonstrated that all of these organisms should be tentatively classified as an Intermediate type of Moraxella and Acinetobacter.

D₁₀ values of typical isolates ranged from 44 to 54 krad when irradiated in 0.067 m phosphate buffer, pH 7.0, and were about 4 times larger than that of Acinetobacter calcoaceticus.     

Molds on house walls and the effect of their chloroform-extractable metabolites on the respiratory cilia movement of one-day-old chicksin vitro

The ciliostatic activity of the chloroform-extractable endo- and exometabolites of 5 strains of filamentous fungi—Alternaria sp.,Aspergillus glaucus group,Aspergillus versicolor, Cladosporium sphœrospermum, Penicillium sp. andUlocladium sp.—isolated from molded walls of a dwelling—on tracheal cilia from 1-d-old chicksin vitro was evaluated. Endometabolites ofAlternaria sp. andA. versicolor and exometabolites ofUlocladium sp. were the most active, these extracts stopped the ciliary movement within 1 d. The results are discussed in relation to the health status of people living in “moldy” dwellings.     

Sedimentation of DNA of Dictyostelium discoideum lysed on alkaline sucrose gradients: role of single-strand breaks in gamma ray lethality of sensitive and resistant strains

The nuclear and mitochondrial DNA of the amoebae of the cellular slime mold Dictyostelium discoideum have been labeled with [methyl-³H]thymidine by allowing them to grow on Escherichia coli 15T^? containing this label in its DNA. Neutral CsCl gradients were used to identify the labeled molecules. Alkaline sucrose sedimentation profiles of cells lysed directly on the gradients revealed two high molecular weight species, one of about 90 S (single-strand mol wt = 1.4 × 10⁸) identified by alkaline CsCl rebanding as nuclear DNA, and another of 43 S (single-strand mol wt = 2.3 × 10⁷), identified as mitochondrial DNA. These alkaline sucrose gradients were used to study the production of single-strand breaks and their rejoining in DNA of a gamma ray-resistant strain (NC-4; 10% survival dose for cell proliferation, D₁₀ = 300 krad) and in two radiation-sensitive daughter mutants (γs-18, D₁₀ = 75 krad; γs-13, D₁₀ = 4 krad). With ⁶⁰Co gamma rays, breaks were produced in nuclear and mitochondrial DNA at an efficiency of one break per 33 eV in all three strains. At doses up to about 100 krad, these single-strand breaks were closed equally well during post-irradiation incubation of NC-4, γs-18 and γs-13, even though their survivals were widely different, indicating no apparent correlation between parental strand rejoining and survival in the sensitive strains. At higher doses, post-irradiation treatment with 1 mg caffeine/ml sensitized NC-4 and retarded strand-rejoining, suggesting that lethality in this resistant strain may be related to strand breaks. It is concluded that single-strand rejoining is a necessary, but not sufficient, condition for radiation survival in this organism. The nature of the apparently unrepaired lesions leading to lethality in the sensitive strains is not known.     

Studies on the Metabolites of Aspergillus versicolor (Vuillemin) Tiraboschi

Three new pigments, named versicolorins A, Band C, as metabolites from the mycelium of Aspergillus versicolor have been isolated. Versicolorin A, C₁₈H₁₀O₇, is fine orange yellow needles, m.p. 289°C (decomp.), [α]_D^-354°. It is an anthraquinoid pigment having three hydroxyl groups and a vinyl ether system contained in a five-membered ring. Versicolorin A trimethyl ether was hydrogenated to a dihydro-derivative, and by oxidation gave 3,5-dimethoxyphthalic acid and a hydroxy acid which may be 1,6,8-trirnethoxy-3-hydroxy anthraquinone-2-carboxylic acid. These chemical behavior and NMR data show that versicolorin A probably has the structure of (I). Versicolorin B, C₁₈H₁₂O₇, is fine orange yellow needles, m.p., 298°C (decomp.), [α]_D^-223° Its trimethyl ether is identical with that of dihydroversicolorin A. Therefore, the structure (II) could be assigned to versicolorin B. Versicolorin C, C₁₈H₁₂O₇, is orange red needles, m.p.>310°C, [α]_D O° Comparison of optical properties, IR and NMR spectra of versicolorin B and its methyl ether with those of versicolorin C and its methyl ether indicates that versicolorin C is very probably a racemate of versicolorin B.     

Torrubiella pruinosa,a teliomorph of an entomopathogenic fungus Hirsutella versicolor of mango hopper (Idioscopus clypealis) from India

Torrubeilla pruinosa, a teliomorph of an anamorphic entomopathogenic fungus Hirsutella versicolor on mango hopper (Idioscopus clypealis) was observed. On the infected mango hopper, tiny pin head signs of ascomata were observed. Ascomata of T. pruinosa is pale brown or tawny brown, crowded, immersed in stroma, wall dark golden brown, 260–320?×?230–260?μm, asci clavate, hyaline and thin walled. The ascospores of T. pruinosa are fusiform, distoseptate with a faint tint of pigmentation, 17.5–25.0?×?5.0–7.5?μm. The anamorph stage of H. versicolor fungal hyphae is hyaline, septate and profusely branched, and conidiogenous (phialides) cells are hyaline, pear-shaped and smooth-walled with single or double sterigmata and rarely, multiple sterigmata. Each sterigmata bears single conidia which are hyaline, oval to pear-shaped.     

Nuclear and Mitochondrial DNA Synthesis in Gamma Ray-Resistant and -Sensitive Slime Mold Amebas

Uptake of [methyl-³H]thymidine label from Escherichia coli 15T^- into the DNA of Dictyostelium discoideum has been measured in control and [⁶⁰Co]-gamma-irradiated cells of the resistant strain NC-4 (D₁₀, colony-forming survival = 300 krad) and two sensitive daughter strains, γs-18 (D₁₀ = 75 krad) and γs-13 (D₁₀ = 4 krad). Nuclear (n) and mitochondrial (m) DNA were resolved by isopycnic CsCl gradients. The uptake of label into n-DNA during the immediate postirradiation period was selectively inhibited by irradiation, compared with uptake into m-DNA. For all three strains, the gamma ray dose to reduce the uptake into n-DNA to 37% of the control during the first hour after irradiation was 3 krad, whereas for uptake into m-DNA it was 75 krad. After the initial dose- and strain-dependent lag, uptake into n-DNA resumed. γs-18 showed longer lags in n-DNA synthesis and cell division than did NC-4. γs-13 resumed n-DNA synthesis and cell division after slightly shorter lags than for NC-4. The early postlag uptake into n-DNA in this strain was almost at the control rate and was accompanied by division until the cell number had nearly doubled. The rate of label uptake then declined, division stopped, and gradual cell lysis ensued. The postdelay response of γs-13 was almost independent of dose in the range of 10-100 krad. The response of γs-18 in these and earlier experiments is consistent with the view-point that it is sensitive because of a decreased rate of repair of DNA damage. However, the basis for the sensitivity of γs-13 seems to be more complex. This strain undergoes a premature but short-lived burst of n-DNA synthesis and division for what appears to be about one round of replication. Replication then ceases, even at very low doses, leading to greatly reduced probability of survival.     

Sensitivity of the conidia of plant pathogenic fungi to Gamma-rays,electron particles and X-ray (Bremsstrahlung) irradiation

Twelve species of plant pathogenic fungi were exposed to high-energy irradiation and their sensitivities compared by the irradiation (termed D ₁₀) required to decrease the viability of conidia by 10%. The D ₁₀ of conidia in 0.06 Mxxx phosphate buffer and irradiated with gamma-rays at 32 to 35°C ranged from 0.16 to 0.71 kGy. When conidia were mixed with trehalose and vacuum dried, their sensitivity towards gamma-rays doubled. There was no identifiable trend in the response of dry conidia towards irradiation by gamma-rays, electron particles or X-rays.M. LebaiJuri and N. Yusof are with the Nuclear Energy Unit, PUSPATI Complex, Bangi, 43000 Kajang, Malaysia; M. Omar is with the Department of Microbiology, Universiti Kebangsaan Malaysia 43600 Ukm Bangi, Malaysia.     

Antioxidant capacity of major royal jelly proteins of honeybee (Apis mellifera) royal jelly

Major royal jelly proteins (MRJPs) of honeybee royal jelly (RJ) exhibit antimicrobial and antioxidant activities. Although MRJPs of Apis mellifera RJ (AmMRJPs) responsible for antibacterial activity have been identified, AmMRJPs with antioxidant effects remain to be elucidated. Here we identified and compared the antioxidant activities of purified recombinant AmMRJPs 1–7, which are expressed in baculovirus-infected insect cells. Antioxidant assays of recombinant AmMRJPs 1–7 against H₂O₂ revealed that AmMRJPs reduce caspase-3 activity and oxidative stress-induced cell apoptosis and lead to increased cell viability. Consistent with these results, AmMRJPs 1–7 exhibit 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity and protect against oxidative DNA damage. These results indicate that AmMRJPs play a role as antioxidants in A. mellifera RJ.     

Synthesis of α-L-Mannopyranosyl-containing Disaccharides and Phenols as Substrates for the α-L-Mannosidase Activity of Commercial Naringinase

In order to clarify the substrate specificity of the α-L-mannosidase activity of naringinase (Sigma), the following disaccharides and phenol glycosides were freshly prepared: methyl 2-O-(α-L-mannopyranosyl)­β-D-glucoside (1), methyl 3-O-(α-L-mannopyranosyl)-α-D-glucoside (2), methyl 4-O-(α-L-mannopyranosyl)-α-D-glucoside (3), methyl 5-O-(α-L-mannopyranosyl)-β-D-glucoside (4), methyl 6-O-(α-L-mannopyranosyl)-α-D­glucoside (5), 6-O-(α-L-mannpyranosyl)-D-galactose (6), p-nitrophenyl α-L-mannoside (7), and 4-methyl umbelliferone α-L-mannoside (8).These compounds, except for 3 and 5, were hydrolyzed with naringinase.     

Structure and mating system of the graminicolous fungal epibiont Echinodothis tuberiformis (Clavicipitales)

The developmental morphology and mating system of the epibiont Echinodothis tuberiformis is investigated. The structure of conidial stromata, conidia, perithecial stromata, asci, and ascospores is documented. Crosses involving transfer of conidia between stromata resulted in formation of perithecia, indicating a heterothallic mating system. Comparisons are made to other members of the Clavicipitales that are presently classified in the tribe Balansieae. It is suggested that this epibiont bears a closer relationship to the grass endophytes classified in the genus Epichloë (Fr.) Tul. than to several other members of the Balansieae.     

The most heat-resistant conidia observed to date are formed by distinct strains of Paecilomyces variotii

Fungi colonize habitats by means of spores. These cells are stress-resistant compared with growing fungal cells. Fungal conidia, asexual spores, formed by cosmopolitan fungal genera like Penicillium, Aspergillus and Peacilomyces are dispersed by air. They are present in places where food products are stored and as a result, they cause food spoilage. Here, we determined the heterogeneity of heat resistance of conidia between and within strains of Paecilomyces variotii, a spoiler of foods such as margarine, fruit juices, canned fruits and non-carbonized sodas. Out of 108 strains, 31 isolates showed a conidial survival >10% after a 10-min-heat treatment at 59°C. Three strains with different conidial heat resistance were selected for further phenotyping. Conidia of DTO 212-C5 and DTO 032-I3 showed 0.3% and 2.6% survival in the screening respectively, while survival of DTO 217-A2 conidia was >10%. The decimal reduction times of these strains at 60°C (D₆₀ value) were 3.7 ± 0.08, 5.5 ± 0.35 and 22.9 ± 2.00 min respectively. Further in-depth analysis revealed that the three strains showed differences in morphology, spore size distributions, compatible solute compositions and growth under salt stress. Conidia of DTO 217-A2 are the most heat-resistant reported so far. The ecological consequences of this heterogeneity of resistance, including food spoilage, are discussed.     

The potential of Beauveria bassiana inoculum formulated into a polymeric matrix for a microbial control of spruce bark beetle

Two local strains of Beauveria bassiana originally isolated from naturally infected spruce bark beetles in Slovakia were tested for their virulence to Ips typographus (IT) and for their compatibility with a polymeric matrix composed of low-molecular polyethylene. Conidia could be homogenously immobilized in the low-molecular polyethylene matrix with no adverse effect on their viability and infectivity. At constant temperature (25°C), viability of immobilized conidial decreased only by 1–2% after 7 or 14 days when compared with non-formulated conidia. In field conditions, viability of conidia formulated in the matrix was even significantly higher than non-formulated conidia 35 days after their application in traps. Conidia incorporated into the polymeric matrix were infective to IT adults in laboratory bioassays. Mean values of LC₅₀ for native conidia (0.72–2.05?×?10⁶ conidia?ml^?1) and conidia immobilized in the polymeric matrix (0.64–1.03?×?10⁵ conidia?mm^?2) demonstrated high virulence. The efficacy of the local strains was significantly higher than that of B. bassiana strains from mycoinsecticides (Boverol^®, Botanigard^® ES and Naturalis-L^®). Results showed potential of this polymeric material for its use in microbial control of IT when mixed with conidia of B. bassiana.     

Antiapoptotic role of major royal jelly protein 8 of honeybee (Apis mellifera) venom

The dominant protein components of honeybee royal jelly (RJ) are major royal jelly proteins (MRJPs), which exhibit various biological properties. However, the biological basis of why bee venom contains MRJPs and what role MRJPs play in bee venom remains to be elucidated. This study reports the antiapoptotic role of MRJP 8 of Apis mellifera venom (AmMRJP 8) in melittin-treated mammalian cells. Recombinant AmMRJP 8 reduced caspase-3 activity and melittin-induced cell apoptosis. Additionally, recombinant AmMRJP 8 decreased the production levels of H₂O₂ and proinflammatory molecules. These results indicate that MRJP in bee venom plays a role in cell protection in bee venom-induced inflammatory responses.     

Filamentous fungi exposed to spaceflight stresses including known levels of ultraviolet irradiations

Chaetomium globosum ascospores andTrichophyton terrestre conidia were exposed to spaceflight parameters of Apollo 16 then returned to Earch for studies in hyphal grwoth dynamics as one of the postflight investigations. Selected phenotypic strains of each species appeared to show changes in growth according to specific ultraviolet irradiations in space.     

Ecophysiological Features of Polar Soil Unicellular Microalgae1

Due to their ecological, physiological, and molecular adaptations to low and varying temperatures, as well as varying seasonal irradiances, polar non-marine eukaryotic microalgae could be suitable for low-temperature biotechnology. Adaptations include the synthesis of compounds from different metabolic pathways that protect them against stress. Production of biological compounds and various biotechnological applications, for instance, water treatment technology, are of interest to humans. To select prospective strains for future low-temperature biotechnology in polar regions, temperature and irradiance of growth requirements (Q₁₀ and Ea of 10 polar soil unicellular strains) were evaluated. In terms of temperature, three groups of strains were recognized: (i) cold-preferring where temperature optima ranged between 10.1 and 18.4°C, growth rate 0.252 and 0.344 · d⁻¹, (ii) cold- and warm-tolerating with optima above 10°C and growth rate 0.162–0.341 · d⁻¹, and (iii) warm-preferring temperatures above 20°C and growth rate 0.249–0.357 · d⁻¹. Their light requirements were low. Mean values Q₁₀ for specific growth rate ranged from 0.7 to 3.1. The lowest Ea values were observed on cold-preferring and the highest in the warm-preferring strains. One strain from each temperature group was selected for P_N and R_D measurements. The P_N:R_D ratio of the warm-preferring strains was less affected by temperature similarly as Q₁₀ and Ea. For future biotechnological applications, the strains with broad temperature tolerance (i.e., the group of cold- and warm-tolerating and warm-preferring strains) will be most useful.     

Microascus cinereus (Émile-Weil & Gaudin) Curzi — a human pathogen?

Microascus cinereus is described accompanying Aspergillus fumigatus in human lung tissue. The tissue contained A. fumigatus conidiophores and conidia and M. cinereus perithecia, ascospores, annellophores and conidia. The pathogenicity of M. cinereus is discussed.