Chlorine dioxide inactivation of bacterial threat agents

Aims: To evaluate the efficacy of chlorine dioxide (ClO₂) against seven species of bacterial threat (BT) agents in water. Methods and Results: Two strains of Bacillus anthracis spores, Yersinia pestis, Francisella tularensis, Burkholderia pseudomallei, Burkholderia mallei and Brucella species were each inoculated into a ClO₂ solution with an initial concentration of 2·0 (spores only) and 0·25 mg l^?1 (all other bacteria) at pH 7 or 8, 5 or 25°C. At 0·25 mg l^?1 in potable water, six species were inactivated by at least three orders of magnitude within 10 min. Bacillus anthracis spores required up to 7 h at 5°C for the same inactivation with 2·0 mg l^?1 ClO₂. Conclusions: Typical ClO₂ doses used in water treatment facilities would be effective against all bacteria tested except B. anthracis spores that would require up to 7 h with the largest allowable dose of 2 mg l^?1 ClO₂. Other water treatment processes may be required in addition to ClO₂ disinfection for effective spore removal or inactivation. Significance and Impact of Study: The data obtained from this study provide valuable information for water treatment facilities and public health officials in the event that a potable water supply is contaminated with these BT agents.     

The influence of local environment on the aging and mortality ofAedes aegypti (L.): Case study in Fortaleza‐CE,Brazil

It is generally assumed that the daily probability of survival of mosquitoes is independent of age. To test this assumption we have conducted a three‐year experimental fieldwork study (2005–2007) at Fortaleza‐CE in Brazil, determining daily survival rates of the dengue vector Aedes aegypti (L.). Survival rates of adult Ae. aegypti may be age‐dependent and the statistical analysis is a sensitive approach for comparing patterns of mosquito survival. The mosquito survival data were better fit by a Weibull survival function than by the more traditionally used Gompertz or logistic survival functions. Gompertz, Weibull, or logistic survival functions often fit the survival, and the tails of the survival curves usually appear to fall between the values predicted by the three functions. We corroborate that the mortality of Ae. aegypti in semi‐natural conditions may no more be considered as a constant phenomenon during the life of adult mosquitoes but varies according to the age and environmental conditions under a tropical climate. This study estimates the variability in the survival rate of Ae. aegypti and environmental factors that are related to such variability. The statistical analysis shows that the fitting ability, concerning the hazard function, was in decreasing order: Seasonal Cox, the three‐parameter Gompertz, and the three‐parameter Weibull, that was similar to the three‐parameter logistic. The advantage of using the Cox model is that it is convenient for exploring the relationship between survival and several explanatory variables. The Cox model has the advantage of preserving the variable in its original quantitative form and of using a maximum of information. The survival analyses indicate that mosquito mortality is both age‐ and environment‐dependent.     

Ueber die AscomycetengattungenCeratostomella Sacc.,Ophiostoma Syd. undRostrella Zimmermann

Summary Ceratostomella Sacc. is a member of theDiaporthaceae (sensuMiller 1949) and is closely related toPhomatospora Sacc., ifCeratostomella vestita Sacc. [=C. cirrhosa (Pers.) Sacc.] is regarded as type of the genus. This species has perithecia with a rather thick membrane, consisting of several layers of slightly compressed, dark cells. The neck is long cylindrical, lined with periphyses. The asci are cylindrical, with an refractive ring in the thickened tip. When young, the spores are continuous, hyaline, with two or four oildrops, when old they often develop one or three pseudosepta. A list of synonyms of this species is given. Some species, which have been described asCeratostomella belong toOphiostoma Sydow (1919); this genus belongs to thePlectascales (Nannfeldt 1932, 1934).Rostrella coffeae Zimmerm. is also anOphiostoma and must be namedO. coffeae (Zimmerm.) comb. nov. The nameRostrella Zimmermann (1900) is older thanOphiostoma, but must be rejected, as an ascomycetous genusRostrella Fabre exists, described in 1878. Several other species, described asCeratostomella, Endoconidiophora andGrosmannia are transferred toOphiostoma. A list of synonyms of the genus is given.      

Survival analysis of three clones of Brachionus plicatilis (Rotifera)

Age-specific survival schedules of females from three genetically different clones of Brachionus plicatilis were analyzed at several environmental conditions in the laboratory.Lifespan showed the expected decrease with increasing temperature, but a general trend with salinity or genotype was not observed. Probability of death increased with age, as tested by polynomial regression analysis of the survival curve and using theoretical mortality distributions. Three two-parameter models (linear-exponential model, Weibull model, and Gompertz model) were fitted to the survival data. Fitting of these models to data was rather poor, but the Gompertz model and, to a lesser extent, the Weibull model fitted the data better than the linear-exponential model. Parameters obtained from the survival curve analyses were related to other demographic parameters. A significant relationship between the shape parameter of the Gompertz model and the cohort generation time was detected, suggesting, but not proving, an effect of reproductive effort on aging.     

Influence of the surface temperature of packaging specimens on the inactivation of Bacillus spores by means of gaseous H(2) O(2)

Aims: To determine the influence of condensation as a function of the surface temperature of aseptic packaging, on the inactivation of Bacillus spores [Bacillus subtilis (DSM 347), B. subtilis SA22, Bacillus atrophaeus] having different surface properties by means of vaporized H₂O₂. Methods and Results: The packaging specimens inoculated with Bacillus spores were tempered and subsequently exposed to H₂O₂‐vapour. During the exposure, surface temperature curves were measured and the spore survival was determined. Results showed that decreasing the initial surface temperature of the packaging specimens had a positive effect on the sporicidal activity of H₂O₂‐vapour, where the effect was less pronounced for less hydrophilic spores. The surfaces of spores were characterized by means of the water contact angle. Conclusions: For starting surface temperatures below the dew point temperature of the sterilant gas, the condensation of highly concentrated liquid H₂O₂ on the packaging surface accelerates the killing of the spores, while the inferior wettability of more hydrophobic spores compared to more hydrophilic ones diminishes the effect. Significance and Impact of the Study: Regarding industrial packaging sterilization, a mixed microflora has to be inactivated. Promoting the condensation of H₂O₂ improves in general the killing of different species of spores, however, at various degrees depending on the wettability of spores.     

Use of Brassica callus culture to induce sporulation in Alternaria brassicae (Berk.) Sacc.

A non-sporulating isolate of Alternaria brassicae, inoculated on callus culture of Brassica juncea cv. Kranti, colonized the callus and produced spores. When captafol, a fungicide, was added (100 mg/l) to the callus culture medium, if effectively checked fungal contamination and saprophytic growth of A. brassicae on culture medium, without adversely affecting callus growth or establishment of dual culture.     

Mycotoxigenic isolates and toxin production on buckwheat and rice hulls used as bedding materials

Summary A pre-evaluation of the samples of both buckwheat and rice hulls, planned for use as pillow fill-materials, showed the presence ofAspergillus flavus, A glaucus, andPenicillium spp. Buckwheat- and rice-hull media (BHM and RHM) inoculated withA. flavus both supported the production of aflatoxins (AFB₁ and AFG₁) in the parts per million (ppm) range; BHM yielded approximately twice the quantity of both AFB₁ and AFG₁ than did RHM. Both BHM and RHM inoculated withFusarium tricinctum yielded trichothecenes (T-2 toxins) in the ppm range, with the BHM producing approximately three times more T-2 toxins than the RHM. Also,F. tricinctum grown on both media produced several metabolites which included HT-2, 3-OH T-2, neosolariol, T-2 triol, and T-2 tetraol. The BHM yielded all of the above, while the RHM failed to support the production of the 3-OH T-2 toxin. In addition, neither medium inoculated withMyrothecium roridum yielded any detectable levels of macrocyclic trichothecenes. The results indicated that these materials have the potential to become contaminated with mycotoxins.     

Vesicular-arbuscular mycorrhizal fungi in coastal dune plant communities I. Spore formation ofGlomus spp. predominates under a patch ofElymus mollis

Vesicular-arbuscular (VA) mycorrhizal fungi in pure patches of coastal dune plantsElymus mollis, Wedelia prostrata andZoysia macrostachya were examined for frequency of occurrence and number of spores of VA mycorrhizal fungi over one year. Six species in three genera of VA mycorrhizal fungi were recovered. Under a patch ofE. mollis, spores ofAcaulospora sp. 1,Glomus tortuosum, Glomus sp. 1,Glomus sp. 2 andScutellospora gregaria were recovered. Spores ofGlomus spp. were most common. In patches ofW. prostrata andZ. macrostachya spores ofAcaulospora sp. 1,G. tortuosum, Glomus sp. 1,Glomus sp. 2,S. gregaria andScutellospora sp. 1 were found.Contribution No. 112, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Inactivation and mechanisms of chlorine dioxide on Nosema bombycis

Biological tests demonstrated that the inactivation of Nosema bombycis (N. bombycis) spores by chlorine dioxide (ClO₂) occurs very fast and is highly sensitive. The lowest effective inactivation dosage and time was 15 mg/mL for 30 min. The inactivation of spores was additionally verified by using double color fluorescence stain and spore germination testing. A series of biological changes, including a large number of substrates that were leaked out from the spores included proteins, DNA, polysaccharide, K⁺, and Ca²⁺, occurred a short time after N. bombycis spores were treated with ClO₂. In addition, the lipid of spores was disrupted and ATPase activity was inhibited, which resulted in the destruction of the inner structure of the spores.     

Effect of low-concentration chlorine dioxide gas against bacteria and viruses on a glass surface in wet environments

Aims: To evaluate the efficacy of low‐concentration chlorine dioxide (ClO₂) gas against model microbes in the wet state on a glass surface. Methods and Results: We set up a test room (39 m³) and the ClO₂ gas was produced by a ClO₂ gas generator that continuously releases a constant low‐concentration ClO₂ gas. Influenza A virus (Flu‐A), feline calicivirus (FCV), Staphylococcus aureus and Escherichia coli were chosen as the model microbes. The low‐concentration ClO₂ gas (mean 0·05 ppmv, 0·14 mg m^?3) inactivated Flu‐A and E. coli (>5 log₁₀ reductions) and FCV and S. aureus (>2 log₁₀ reductions) in the wet state on glass dishes within 5 h. Conclusions: The treatment of wet environments in the presence of human activity such as kitchens and bathrooms with the low‐concentration ClO₂ gas would be useful for reducing the risk of infection by bacteria and viruses residing on the environmental hard surfaces without adverse effects. Significance and Impact of the Study: This study demonstrates that the low‐concentration ClO₂ gas (mean 0·05 ppmv) inactivates various kinds of microbes such as Gram‐positive and Gram‐negative bacteria, enveloped and nonenveloped viruses in the wet state.     

Development of methane conversion factor models for Zebu beef cattle fed low‐quality crop residues and by‐products in tropical regions

The enteric methane conversion factor (Y_m) is an important country‐specific value for the provision of precise enteric methane emissions inventory reports. The objectives of this meta‐analysis were to develop and evaluate the empirical Y_m models for the national level and the farm level for tropical developing countries according to the IPCC's categorization. We used datasets derived from 18 in vivo feeding experiments from 1999 to 2015 of Zebu beef cattle breeds fed low‐quality crop residues and by‐products. We found that the observed Y_m value was 8.2% gross energy (GE) intake (~120 g methane emission head^?1 day^?1) and ranged from 4.8% to 13.7% GE intake. The IPCC default model (tier 2, Y_m = 6.5% ± 1.0% GE intake) underestimated the Y_m values by up to 26.1% compared with its refinement of 8.4% ± 0.4% GE intake for the national‐level estimate. Both the IPCC default model and the refined model performed worse in predicting Y_m trends at the farm level (root mean square prediction error [MSPE] = 15.1%–23.1%, concordance correlation coefficient [CCC] = 0.16–0.18, R² = .32). Seven of the extant Y_m models based on a linear regression approach also showed inaccurately estimated Y_m values (root MSPE = 16.2%–36.0%, CCC = 0.02–0.27, R² < .37). However, one of the developed models, which related to the complexity of the energy use efficiencies of the diet consumed to Y_m, showed adequate accuracy at the farm level (root MSPE = 9.1%, CCC = 0.75, R² = .67). Our results thus suggest a new Y_m model and future challenges for estimating Zebu beef cattle production in tropical developing countries.     

Growth and mortality of larval Myctophum affine (Myctophidae,Teleostei)

The growth and mortality rates of Myctophum affine larvae were analysed based on samples collected during the austral summer and winter of 2002 from south‐eastern Brazilian waters. The larvae ranged in size from 2·75 to 14·00 mm standard length (L_S). Daily increment counts from 82 sagittal otoliths showed that the age of M. affine ranged from 2 to 28 days. Three models were applied to estimate the growth rate: linear regression, exponential model and Laird–Gompertz model. The exponential model best fitted the data, and L₀ values from exponential and Laird–Gompertz models were close to the smallest larva reported in the literature (c. 2·5 mm L_S). The average growth rate (0·33 mm day^?1) was intermediate among lanternfishes. The mortality rate (12%) during the larval period was below average compared with other marine fish species but similar to some epipelagic fishes that occur in the area.     

Modelling and predicting the effect of temperature,water activity and pH on growth of Streptococcus iniae in Tilapia

Aims: To evaluate and model the growth of Streptococcus iniae affect by temperatures (10–45°C), water activity (A_w; 0·995–0·957), and pH (5–8). Methods and Results: Temperatures, A_w, and pH were adjusted. The behaviour of S. iniae was studied and modelled. Growth curves were fitted by using logistic, Gompertz, and Baranyi models. The maximum growth rates obtained from the primary model were then modelled as a function of temperature, A_w, and pH using the Belehradek‐type models for secondary model. The optimum values for growth were found to be in the range of 35–40°C, A_w 0.995–1, and pH 6–7. The statistical characteristics of the models were validated by r², mean square error, bias, and accuracy factors. The results of validation indicated that Baranyi model performed the best. Conclusions: The effect of temperature, A_w/NaCl, pH control of S. iniae in tilapia could be satisfactorily predicted under current experimental conditions, and the proposed models could serve as a tool for this purpose. Significance and Impact of the Study: The suggested predictive model can be used for risk assessment concerning S. iniae in tilapia.     

Coremiella cuboidea (Sacc. et Ell.) Cif. et Car. n. comb. isolata da feci umane

Riassunto Sono studiati nelle loro caratteristiche morfo-culturali e biologiche quattro ceppi omogenei diCoremiella isolati da feci umane. Questo genera è simile aGeotrichum ma oltre a cellule miceliche clamidosporo-simili presenta formazione apicali miceliche di tipo coremioide reptante.L'artrosporulazione è un processo endogeno come inGeotrichum, e come inGeorichum si hanno artrospore clamidosporioidi fertili opache e artrospore usuali non fertili e jaline, ma meno differenziate.I ceppi vengono riferiti aC. ulmariae e le caratteristiche vengono paragonate anche con le culture su legno diSpirea ulmaria.Il primo esemplare diCoremiella è stato pubblicato comeOospora cuboidea Sacc. etEll. come è stato accertato studiando l'esemplare autentico diEllis.In conclusione il genereCoremiella Bub. etKrieg. è stato emendato ed è stata creata la combinazioneC. cuboidea (Sacc. etEll.).

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Summary Four homogeneous strains ofCoremiella from human feces were studied from morpho-cultural and biological standpoint. This genus is likeGeotrichum, but in addition to some mycelial, chlamydospore-like cells, coremioid mycelial, reptant strands are formed.The arthrosporulation is an endogeneous process, and, likeGeotrichum, there are usual hyaline and duller chlamydosporioid, fertile arthrospores, but less differentiated.The strains are referred toC. ulmariae, and the characteristics were compared also on timber and woody European Meadowsweet cultures. But the first binomial ofCoremiella has been published asOospora cuboidea Ell. etSacc., as ascertained by the study of the authenticEllis specimen.In conclusion, the genusCoremiella Bub. etKrieg. has been emended, and the combinationC. cuboidea (Sacc. etEll.) established.

     

Differential susceptibility of two locust pests to the microsporidium Paranosema (Antonospora) locustae at suboptimal rearing temperature

Paranosema (Antonospora) locustae (Canning) is a microsporidium with an extensive host range including >100 reported insect hosts from the order Orthoptera. The susceptibility of two species of locusts (Orthoptera: Acrididae) – the migratory locust, Locusta migratoria subsp. migratorioides (Fairmaire & Reiche), and the desert locust, Schistocerca gregaria Forsskål – to P. locustae was compared under laboratory conditions at a decreased temperature of 27 °C to enhance susceptibility to infection. Locusta migratoria was found highly vulnerable as infection percentages exceeded 70% at 10⁴, 10⁵, and 10⁶ spores per insect, and mortality increased with increasing dosage. Conversely, P. locustae spores were not found in S. gregaria throughout the experiment. Only at 10⁷ spores per insect, as many as 20% of S. gregaria were infected. This suggests that the desert locust is resistant to P. locustae infection, as opposed to the migratory locust. The laboratory models of these parasite–host systems may be useful for elucidating mechanisms of insect immunity to microsporidia.     

The possible role of two species of Orthoptera in the dissemination of a plant pathogenic fungus

The ability of the locusts, Locusta migratoria and Schistocerca gregaria, to disseminate Colletotrichum graminicola, the fungal pathogen of maize anthracnose, were studied. The insects were fed with the diseased plants and spores were recovered in viable condition from the faeces. The spores recovered were able to grow on artificial media and were still infectious to the host plant.     

Isolation and characterization of polymorphic tetranucleotide microsatellite loci in the chestnut-crowned babbler (Pomatostomus ruficeps)

We describe 18 microsatellite markers isolated in the cooperatively breeding chestnut‐crowned babbler (Pomatostomus ruficeps). The number of alleles ranged from seven to 16 per locus (mean N_a = 10.4 ± 0.54 SE) and the expected heterozygosity ranged from 0.732 to 0.889 (mean H_E = 0.836 ± 0.01 SE). Three of the 18 loci exhibited significant heterozygote deficiency, but the remaining 15 will be used to analyse population genetic structure and the mating system of this highly social species.     

Reduction of Bacillus cereus spores in sikhye, a traditional Korean rice beverage, by modified tyndallization processes with and without carbon dioxide injection

Aims: The objective of this study was to inactivate Bacillus cereus spores in sikhye using a modified tyndallization process involving injection with carbon dioxide (CO₂). Methods and Results: Heat tolerance of B. cereus spores in tryptic soy broth and sikhye was evaluated. The D_95°C values of the B. cereus spores were 2·8–4·9 min, dependent of type of heating medium or inoculum level. The lethality of conventional heat treatment and modified tyndallization with or without CO₂ injection against B. cereus spores in sikhye was determined. The order of effectiveness was modified tyndallization with CO₂ > modified tyndallization without CO₂ > conventional heat treatment. Modified tyndallization with CO₂ reduced the number of B. cereus spores in sikhye by 5·8 log CFU ml^?1. The increased CO₂ concentration and decreased pH of sikhye resulting from CO₂ injection rapidly reverted to near‐normal values after heat treatment. Conclusions: Modified tyndallization with CO₂ was more effective than conventional heat treatment or modified tyndallization without CO₂ in reducing B. cereus spores in sikhye. Significance and Impact of the Study: Results of this study will be useful when developing strategies to control B. cereus spores in sikhye and may have application to other beverages.     

Lethality of chlorine, chlorine dioxide, and a commercial fruit and vegetable sanitizer to vegetative cells and spores of Bacillus cereus and spores of Bacillus thuringiensis

Chlorine, chlorine dioxide (ClO₂), and a commercial raw fruit and vegetable sanitizer (Fit powder) were evaluated for their effectiveness in killing vegetative cells and spores of Bacillus cereus and spores of Bacillus thuringiensis. The ultimate goal was to use one or both species as a potential surrogate(s) for Bacillus anthracis in studies that focus on determining the efficacy of sanitizers in killing the pathogen on food contact surfaces and foods. Treatment with alkaline (pH 10.5–11.0) ClO₂ (200 mg/mL) produced by electrochemical technologies reduced populations of a five-strain mixture of vegetative cells and a five-strain mixture of spores of B. cereus by more than 5.4 and more than 6.4 log cfu/mL, respectively, within 5 min. This finding compares with respective reductions of 4.5 and 1.8 log cfu/mL resulting from treatment with 200 mg/mL chlorine. Treatment with a 1.5% acidified (pH 3.0) solution of Fit powder product was less effective, causing 2.5-log and 0.4-log cfu/mL reductions in the number of B. cereus cells and spores, respectively. Treatment with alkaline ClO₂ (85 mg/mL), acidified (pH 3.4) ClO₂ (85 mg/mL), and a mixture of ClO₂ (85 mg/mL) and Fit powder product (0.5%) (pH 3.5) caused reductions in vegetative cell/spore populations of more than 5.3/5.6, 5.3/5.7, and 5.3/6.0 log cfu/mL, respectively. Treatment of B. cereus and B. thuringiensis spores in a medium (3.4 mg/mL organic and inorganic solids) in which cells had grown and produced spores with an equal volume of alkaline (pH 12.1) ClO₂ (400 mg/mL) for 30 min reduced populations by 4.6 and 5.2 log cfu/mL, respectively, indicating high lethality in the presence of materials other than spores that would potentially react with and neutralize the sporicidal activity of ClO₂.Published by permission of the International Association for Food Protection: Journal of Food Protection (2004) 60:1702–1708This revised version was published online in April 2005 with corrections to the text and the section heading.In section Preparation of treatment solutions the phrase 22-28°C was replaced by 22±2°C.     

Inoculation of containerized Pseudotsuga menziesii and Pinus pinaster seedlings with spores of five species of ectomycorrhizal fungi

 Container-grown Pseudotsuga menziesii and Pinus pinaster seedlings were inoculated with water suspensions of spores of five ectomycorrhizal fungi commonly found in northeastern Spain. Pseudotsuga menziesii seedlings were inoculated with basidiospores of Melanogaster ambiguus, or Rhizopogon subareolatus, or with ascospores of Tuber maculatum. Pinus pinaster seedlings were inoculated with basidiospores of Melanogaster ambiguus, Rhizopogon roseolus or Scleroderma citrinum. The spore concentrations were 10²–10⁷ spores per seedling for Melanogaster ambiguus (in Pseu dotsuga menziesii) and Rhizopogon subareolatus, 10³–10⁷ for Melanogaster ambiguus (in Pinus pinaster), Rhizopogon roseolus, and Scleroderma citrinum, and 10²–10⁴ for Tuber maculatum. Melanogaster ambiguus colonized more short roots in a larger proportion of plants at 10⁷ spores per seedling than at any other rate. The highest colonization by Rhizopogon subareolatus was obtained at 10⁴ spores per seedling and higher, and all inoculated plants became infected at 10⁶ spores per seedling and higher. Tuber maculatum colonized a high percentage of short roots at all rates tested; the proportion of infected plants was over 80% at 10³–10⁴ spores per plant, decreasing to 50% at 10² spores per plant. Rhizopogon roseolus colonized the highest number of short roots on nearly all the inoculated plants when applied at 10⁵ spores per seedling and higher. Scleroderma citrinum colonized a high percentage of short roots on all inoculated plants when applied at 10⁵ spores per seedling and higher. The abundance of sporocarps of Melanogaster ambiguus, Rhizopogon subareolatus, R hizopogon roseolus and Scleroderma citrinum and their colonization ability at relatively low rates allows these spores to be used as ectomycorrhizal inocula on a large scale. Accepted: 27 February 1996