Effect of ozone on spore germination,spore production and biomass production in two <Emphasis Type="Italic">Aspergillus</Emphasis> species

The ability of ozone gas to reduce food spoilage is relatively well documented, but the developmental effects of the gas on food spoilage fungi are not well known. In this study two model aspergilli, Aspergillus nidulans and Aspergillus ochraceus were used to study the effects of ozone on spore germination, sporulation and biomass production. These effects were examined under three levels of ozone; two high level ozone exposures (200 and 300 μmol mol⁻¹) and one low level exposure (0.2 μmol mol⁻¹). The two species behaved noticeably different to each other. Ozone was more effective in reducing growth from spore inocula than mycelia. No spore production could be detected in A. nidulans exposed to continuous low level O₃, whereas the same treatment reduced spores produced in A. ochraceus by 94%. Overall the work suggests that ozone exposure is an effective method to prevent spread of fungal spores in a food storage situation.     

Design,Synthesis, and Antifungal Activities of Novel 1,2,4‐Triazole Schiff Base Derivatives

With the aim to find new compounds with high antifungal activity, 21 4‐amino‐5‐substituted‐1,2,4‐triazole Schiff bases ( 2a  –  2g , 3a  –  3g , and 4a  –  4g ) were designed and synthesized. Their antifungal activities against Pythium solani, Gibberlla nicotiancola, Fusarium oxysporium f. sp. niveum, Gibberlla saubinetii, Alternaria iycopersici, Phytophthora capsici, Physalospora piricola, Cercospora arachidicola hori, and Fusarium oxysporium f. sp. cucumber were tested, parts of the compounds exhibited excellent antifungal activity. This research provides useful information for further study of antifungal agents.     

Gaseous ozone: A potent pest management strategy to control Callosobruchus maculatus (Coleoptera: Bruchidae) infesting green gram

Extending the storage life of legumes by protecting it from the Callosobruchus maculatus infestation is a major concern for the producers, processors and exporters. Legume processing industry requires “greener” alternatives to the conventional fumigants. Gaseous ozone has a great potential as an insect management strategy that is suited for this niche. Nevertheless, the efficacy of ozone against C. maculatus is yet unknown. A laboratory study was conducted to test the insecticidal effect of ozone in controlling the infestation of C. maculatus in green gram. We have determined the concentration of ozone exposure time–mortality relationship for all the stages of C. maculatus that were exposed to 500–1,500 ppmv ozone. The percentages of mortality for different stages of C. maculatus increased with the increase in ozone concentration and exposure time. It was documented that adult stage is least tolerant to ozone (500 ppmv for 274.40 min exposure required to kill 90%), whereas the most tolerant stage is pupa (500 ppmv for 1816.54 min is required to kill 90%). The results indicate that gaseous ozone is the attractive alternative to the synthetic fumigants.     

Impact of weather conditions,seasonality and moonlight on the use of artificial canopy bridges by nocturnal arboreal mammals

Natural and artificial canopy bridges can be used to mitigate the effects of habitat fragmentation. Understanding the ecological factors that influence bridge use is imperative to the effective design and placement of this potential conservation intervention. Moonlight, seasonality and weather may influence the cost and risk of using bridges, potentially reducing their effectiveness. We installed five artificial waterline bridges and, between 2017 and 2019, monitored via camera trapping their use by Javan palm civets Paradoxurus musanga javanicus and Javan slow lorises Nycticebus javanicus. We used a weather station to record microclimate data (temperature and relative humidity) and calculated the illumination percentage of the moon. We tested the influence of moon luminosity, relative humidity, seasonality (Julian day) and temperature on the frequency of bridge use via Generalised Additive Models. Camera traps captured 938 instances of bridge use by civets, which was significantly lower than the reference value at moon luminosity?>?90%, temperatures?>?20 °C, humidity?>?90%, and during the drier period (May–July). Camera traps captured 1036 instances of bridge use by lorises, which was significantly lower than the reference value during the drier period and higher than the reference value at temperatures?>?20 °C. Lorises showed peaks in bridge use close to sunset and sunrise whereas civets showed peaks around 2 h after sunset and 2 h before sunrise. Our study illustrates the utility of simple-to-construct bridges by two sympatric nocturnal mammals facing severe habitat loss, with bridge use differing between those species according to abiotic factors. In particular, less use by both taxa during the drier season could suggest modifying placement of bridges or providing another intervention during that time. Camera traps were an excellent mechanism to record these differences and to validate the importance of the bridges, including during inclement weather and dark nights, when observations would be more difficult for human observers. By understanding the influence that abiotic factors have on the use of artificial bridges, we can improve bridge placement and construction to encourage use by a variety of species, particularly those threatened by habitat fragmentation.

     

Growth and physiological responses to ozone and mild drought stress of tree species with different ecological requirements

An open-top chamber experiment was carried out in Curno (Northern Italy) in 2004 and 2005 on seedlings of Fagus sylvatica (FS), Quercus robur (QR), and an ozone-sensitive Populus (POP) clone, to investigate the role of two stress factors: tropospheric ozone and water shortage. Treatments were filtered air to achieve a 50% reduction in the environmental ozone concentrations (charcoal filtered, CF); and non-filtered air, with a 5% reduction in the environmental ozone concentrations (non-filtered, NF). Overall ozone exposure (AOT40) in open air (April–September) was 26,995 ppb h in 2004 and 25,166 ppb h in 2005. The plants were either watered (W) or not watered (dry, D). We investigated the above-ground biomass, tree-ring growth, stable carbon isotopes ratio, i.e. δ¹³C of tree rings, and the photosynthetic parameter Driving forces (DF_ABS), derived from chlorophyll a fluorescence analysis. Ozone-induced growth reduction (in terms of biomass) in POP, and that reduction was more pronounced in D plots. A synergistic effect of ozone and drought stress was evidenced by DF_ABS in POP and QR, but not in FS. The water availability was revealed as the main factor influencing the isotopic ratio δ¹³C. In drought-stressed seedlings, the increase in δ¹³C value was accompanied by the reduction in stomatal conductance and increased DF_ABS. Fast-growing plant species with high water requirements are more susceptible to ozone and drought stress.     

Interactive influences of ozone and climate on streamflow of forested watersheds

The capacity of forests to mitigate global climate change can be negatively influenced by tropospheric ozone that impairs both photosynthesis and stomatal control of plant transpiration, thus affecting ecosystem productivity and watershed hydrology. We have evaluated individual and interactive effects of ozone and climate on late season streamflow for six forested watersheds (38–970 000 ha) located in the Southeastern United States. Models were based on 18–26 year data records for each watershed and involved multivariate analysis of interannual variability of late season streamflow in response to physical and chemical climate during the growing season. In all cases, some combination of ozone variables significantly improved model performance over climate‐only models. Effects of ozone and ozone × climate interactions were also consistently negative and were proportional to variations in actual ozone exposures, both spatially across the region and over time. Conservative estimates of the influence of ozone on the variability (R²) of observed flow ranged from 7% in the area of lowest ozone exposure in West Virginia to 23% in the areas of highest exposure in Tennessee. Our results are supported by a controlled field study using free‐air concentration enrichment methodology which indicated progressive ozone‐induced loss of stomatal control over tree transpiration during the summer in mixed aspen‐birch stands. Despite the frequent assumption that ozone reduces tree water loss, our findings support increasing evidence that ozone at near ambient concentrations can reduce stomatal control of leaf transpiration, and increase water use. Increases in evapotranspiration and associated streamflow reductions in response to ambient ozone exposures are expected to episodically increase the frequency and severity of drought and affect flow‐dependent aquatic biota in forested watersheds. Regional and global models of hydrologic cycles and related ecosystem functions should consider potential interactions of ozone with climate under both current and future warmer and ozone‐enriched climatic conditions.     

A unifying explanation for variation in ozone sensitivity among woody plants

Tropospheric ozone is considered the most detrimental air pollutant for vegetation at the global scale, with negative consequences for both provisioning and climate regulating ecosystem services. In spite of recent developments in ozone exposure metrics, from a concentration‐based to a more physiologically relevant stomatal flux‐based index, large‐scale ozone risk assessment is still complicated by a large and unexplained variation in ozone sensitivity among tree species. Here, we explored whether the variation in ozone sensitivity among woody species can be linked to interspecific variation in leaf morphology. We found that ozone tolerance at the leaf level was closely linked to leaf dry mass per unit leaf area (LMA) and that whole‐tree biomass reductions were more strongly related to stomatal flux per unit leaf mass (r² = 0.56) than to stomatal flux per unit leaf area (r² = 0.42). Furthermore, the interspecific variation in slopes of ozone flux–response relationships was considerably lower when expressed on a leaf mass basis (coefficient of variation, CV = 36%) than when expressed on a leaf area basis (CV = 66%), and relationships for broadleaf and needle‐leaf species converged when using the mass‐based index. These results show that much of the variation in ozone sensitivity among woody plants can be explained by interspecific variation in LMA and that large‐scale ozone impact assessment could be greatly improved by considering this well‐known and easily measured leaf trait.     

Exposure to indoor fungi in different working environments: A comparative study

In this study an attempt was made to evaluate the qualitative and quantitative fungal burden (load) in five different working environments of South Assam (India) and the possible risks of indoor fungi to employees and stored products. Fungal concentrations in different working environments were studied using a Burkard personal petriplate sampler. The survey was done in five different working environments for one year. A total of 76 fungal types were recorded in the indoor air of South Assam during the survey period. The maximum fungal concentration (5,437.6 ± 145.3 CFU m⁻³ air) was recorded in the indoor air of medical wards, followed by the paper-processing industry (3,871.7 ± 93.4 CFU m⁻³ air). However the lowest concentration was observed in the indoor air of a bakery (1,796.8 ± 54.4 CFU m⁻³ air). The most dominant fungal genera were Aspergillus (34.2%) followed by Penicillium (17.8%), Geotrichum (7.0%) and the most dominant fungal species were Aspergillus fumigatus (2,650.4 CFU m⁻³ air) followed by Aspergillus flavus (1,388.2 CFU m⁻³ air), Geotrichum candidum (1,280.3 CFU m⁻³ air), Aspergillus niger (783.3 CFU m⁻³ air), and Penicillium aurantiovirens (774.0 CFU m⁻³ air). The fungal species viz., Aspergillus fumigatus, Penicillium aurantiovirens, Aspergillus flavus, Aspergillus niger, Geotrichum candidum, and Penicillium thomii, which were recorded well above threshold levels, may lead to adverse health hazards to indoor workers. Setting occupational exposure limits for indoor fungal spores as reference values is obligatory for prevention and control of adverse effects of indoor fungal exposure.     

Cloning and characterization of a chitinase gene <Emphasis Type="Italic">Lbchi31</Emphasis> from <Emphasis Type="Italic">Limonium bicolor</Emphasis> and identification of its biological activity

Chitinases are digestive enzymes that break down glycosidic bonds in chitin. In the current study, an endochitinase gene Lbchi31 was cloned from Limonium bicolor. The cDNA sequence of Lbchi31 was 1,107 bp in length, encoding 322 amino acid residues with a calculated molecular mass of 31.7 kDa. Clustal analysis showed that there was a highly conserved chitin-binding domains in Lbchi31 protein, containing four sulfide bridges. The Lbchi31 gene was inserted into the pPIC9 vector and transferred into yeast Pichia pastoris GS115 and KM71 for heterologous expression. The transformant harboring the Lbchi31 gene showed a clearly visible protein band with a molecular mass of more than 31 kDa in the SDS-PAGE gel, indicating that it had been translated in P. pastoris. Enzyme characterization showed that the optimal reaction condition for chitinase LbCHI31 activity was: 40°C, pH of 5.0 and 5 mmol l⁻¹ of Mn²⁺. The maximum enzyme activity was 0.88 U ml⁻¹ following exposure to the cell wall chitin of Valsa sordida. The LbCHI31 enzyme can efficiently degrade cell wall chitin of the phytopathogenic Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum, V. sordida, Septoria tritici and Phytophthora sojae, suggesting that it has the biocontrol function to fungal phytopathogen.     

In vivo exposure to ozone produces an increase in a 72-kDa heat shock protein in guinea pigs

Su, Wei Yi, and Terry Gordon. In vivo exposure to ozoneproduces an increase in a 72-kDa heat shock protein in guinea pigs.J. Appl. Physiol. 83(3): 707-711, 1997.Although several lines of evidence have suggested that oxidizingagents can induce heat shock proteins (HSPs) in vitro, little is knownabout the induction of HSPs during in vivo exposure to oxidants. Guinea pigs were exposed to ozone for 6 h and euthanized up to 72 h later. Proteins from lavage cells and lung tissue were characterized byimmunoblotting with 72- and 73/72-kDa HSP monoclonal antibodies. Although 73-kDa HSP was expressed constituitively in lung tissue, itwas not affected by ozone. In contrast, 72-kDa HSP was significantly increased in lavage cells and lung tissue of animals exposed to 0.4 and0.66 parts/million of ozone. Both heat treatment and arsenite induced72-kDa HSP in cultured alveolar macrophages. The increase in 72-kDa HSPin the lavage cell pellet peaked at 24 h after ozone, whereas theinflux of polymorphonuclear leukocytes peaked at 4 h. Examination ofthe induction of HSPs by ozone may provide clues to the development ofozone tolerance in humans and animals.

     

Production of indole-3-acetic acid by Thai native orchid-associated fungi

Thirteen endophytic fungi were isolated from roots of three orchid species, Spathoglottis affinis, Paphiopedelum bellatulum and Phaius tankervilleae. Of these, three fungal isolates produced high levels of indole-3-acetic acid (IAA) in culture medium supplemented with 2 mg/ml of L-tryptophan, and were selected for further analysis. Morphological characteristics and a phylogenetic analysis based on an alignment of internal transcribed spacer regions of nuclear rDNA indicated that the fungal isolates CMU-SLP 007 and CMU-NUT 013 belonged to family Tulasnellaceae, genus Tulasnella (the anamorphic genus Epulorhiza) and the fungal isolate CMU-AU 006 belonged to Colletotrichum gloeosporioides. These three fungal isolates produced maximum levels of IAA when grown in a culture medium supplemented with 4 mg/ml of L-tryptophan (C. gloeosporioides CMU-AU 006, 243.56 μg/ml and Tulasnella sp. CMU-SLP 007, 155.63 μg/ml) and 6 mg/ml of L-tryptophan (Tulasnella sp. CMU-NUT 013, 104.03 μg/ml). Thin layer chromatography revealed that all fungal IAA presented the same R_f value as the standard IAA. The biological activity of fungal IAA showed that it increased the length of stem forming roots and the number of roots of kidney bean (Phaseolus vulgaris), promoted seed germination, the length of roots and root to shoot ratio of corn (Zea mays) and increased the elongation of rice (Oryza sativa) coleoptiles when compared with all controls (water and culture medium treatments). In addition, the results of all biological activities using fungal IAA indicated that the quality of fungal IAA were similar to standard IAA.     

Mycogenesis of gold nanoparticles using a phytopathogen <Emphasis Type="Italic">Alternaria alternata</Emphasis>

The development of an eco-friendly and reliable process for the synthesis of gold nanomaterials (AuNPs) using microorganisms is gaining importance in the field of nanotechnology. In the present study, AuNPs have been synthesized by bio-reduction of chloroauric acid (HAuCl₄) using the fungal culture filtrate (FCF) of Alternaria alternata. The synthesis of the AuNPs was monitored by UV–visible spectroscopy. The particles thereby obtained were characterized by UV, dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Energy-dispersive X-ray study revealed the presence of gold in the nanoparticles. Fourier transform infrared spectroscopy confirmed the presence of a protein shell outside the nanoparticles which in turn also support their stabilization. Treatment of the fungal culture filtrate with aqueous Au⁺ ions produced AuNPs with an average particle size of 12 ± 5 nm. This proposed mechanistic principal might serve as a set of design rule for the synthesis of nanostructures with desired architecture and can be amenable for the large scale commercial production and technical applications.     

Effect of ozone on respiration of adult Sitophilus oryzae (L.), Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.)

The effect of ozone on the respiration of three species of adult stored-product Coleoptera was tested in an air-tight flask. Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst) adults were exposed to atmosphere containing 0.1, 0.2 or 0.4 μg/ml initial ozone at 23–25 °C and 50% r.h. Carbon dioxide (CO₂) production reflected the respiration rates of insects and was determined with a gas chromatograph (GC). The experiments showed that the effects of ozone on respiration had two distinct phases. Phase 1 involved a lower respiration rate of the adult stored-product Coleoptera under ozone atmosphere and reflected the need for insects to reduce ozone toxicity. After 1 h, CO₂ production of S. oryzae was 3.19, 2.63, 2.27 and 1.99 μl/mg for the ozone concentration of 0, 0.1, 0.2 and 0.4 μg/ml, respectively. The results also showed that there were decreases in the rate of respiration in R. dominica and T. castaneum with an increase in ozone concentration. During phase 2, respiration of S. oryzae, R. dominica, and T. castaneum adults treated with ozone increased as the ozone degraded to oxygen. After 7 h, the effect of ozone on CO₂ production, relative to the control, changed from a decrease to an increase. The findings in relation to control strategies were discussed.     

Enhancing plant disease suppression by Burkholderia vietnamiensis through chromosomal integration of Bacillus subtilis chitinase gene chi113

Burkholderia vietnamiensis P418 is a plant growth-promoting rhizobacteria. A chitinase gene from Bacillus subtilis was cloned and stably integrated into the chromosome of using the transposon delivery vector, pUTkm1. Chitinase activity was detected in recombinant P418-37 but not in wild type P418. Recombinant P418-37 retained the in vitro growth rate, N₂-fixation and phosphate and potassium-solubilizing characteristics of the wild type. P418-37 significantly (P < 0.05) increased in vitro inhibition of the plant pathogenic fungi Rhizoctonia solani, Fusarium oxysporum f.sp. vasinfectum, Rhizoctonia cerealis, Bipolaris sorokiniana, Verticillium dahliae and Gaeumannomyces graminis var. tritici compared with P418. In planta disease suppression assays indicated that P418-37 significantly (P < 0.05) enhanced suppression of wheat sheath blight (R. cerealis), cotton Fusarium wilt (F. oxysporium f.sp. vasinfectum) and tomato gray mould (Botrytis cinerea), relative to the wild type.     

Effects of the geometry of reinforcement on physical properties of sodium caseinate/TiO2 nanocomposite films for applications in food packaging

Plastic materials for food packaging are being replaced by biodegradable films based on biopolymers due to the adverse effects they have had on animal life and the environment. In this study, nanocomposite films containing 2.5 wt% sodium caseinate and 2 wt% glycerol were reinforced with 0.1 or 0.2 wt% nano TiO₂ prepared in two forms: spheres (P25) and tubes. The effects of nanoreinforcement geometry on mechanical, tensile, barrier, thermogravimetric, and optical properties, and distribution of nanoparticles were described. The interactions among film components were analyzed by Fourier transform infrared spectroscopy (FTIR). Addition of nanotubes significantly increased E' (341 wt%) and E" (395 wt%) moduli, the Young modulus E (660 wt%), the residual mass at 500°C (38 wt%), and color change (6.78) compared to control film. The compositional mapping studies showed that P25 nanoparticles were homogeneously distributed between the surfaces of the film while nanotubes were found on the bottom surface. The changes in position of the FTIR spectra signals as compared to pure protein signals indicated strong matrix/reinforcement interactions. In addition, the changes in intensity in 1100, 1033, and 1638 cm⁻¹ FTIR signals suggested formation of a protein/Tween 20 ester. The geometry of reinforcement was highly relevant regarding physical properties, showing nanotubes as being very successful for enhancing tensile properties.     

In-vitro selection of Vitis vinifera `Chardonnay' with Elsinoe ampelina culture filtrate is accompanied by fungal resistance and enhanced secretion of chitinase

 Proembryogenic masses of grapevine (Vitis vinifera L.) `Chardonnay' (clone 02Ch) were exposed to the culture filtrate of Elsinoe ampelina (deBary) Shear, the causal agent of anthracnose disease. After four or five cycles of recurrent in-vitro selection with medium containing 40% fungal culture filtrate, putative resistant lines RC 1 and RC 2 respectively, were established. The selected lines inhibited the growth of E. ampelina and Fusarium oxysporium (Schlecht.) (isolated from watermelon) in a dual-culture assay and reduced the growth of mycelium on a conditioned-medium test, thus suggesting the involvement of extracellular compounds in resistance. Sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) gel electrophoresis of extracellular proteins from spent suspension-culture medium showed enhanced secretion of new proteins by selected lines. A 36-kDa protein was immunodetected by a chitinase antiserum. This chitinase continued to express constitutively in differentiated somatic embryos and also in the intercellular fluids of plants regenerated from the selected lines. Somatic embryos from selected lines grew uninhibitedly in a medium containing 40% fungal culture filtrate, whereas non-selected (control) somatic embryos became necrotic and died within a few days. Plants regenerated from selected lines exhibited resistance to infection by E. ampelina in both greenhouse tests and detached leaf bioassays. Results suggest that embryogenic cells can be selected for resistance following in-vitro selection, resulting in resistant plants. Whether or not resistant cells pre-existed in the original embryogenic culture or were induced by the selection pressure could not be determined. Received: 12 November 1999 / Accepted: 3 December 1999     

Novel Comparative Efficiency of Ozone and Gamma Sterilization on Fungal Deterioration of Archeological Painted Coffin,Saqqara Excavation,Egypt

An archeological wooden painted coffin was excavated in Tety tomb from Saqqara excavation. It belonged to the Ministry of Antiquities. This coffin was discovered in a bad state of conservation with many destroyed big and small pieces in Saqqara stores. Analyses and investigation study were performed on the ground layer of the coffin by X-ray diffraction (XRD), Energy dispersive X ray analysis (EDX) equipped with environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR). Results confirmed that the degradation factors affecting the wooden painted coffin are essentially attributed to direct effects of microbial phenomena, which have lead to many deterioration forms as: macro- and microcracks, hydrated salts, flaking, coloration, scaling and defoliation microbiological spots. Nine deteriorating fungal species were isolated from the painted and ground layers of the tested coffin. Fusarium moniliforme followed by Aspergillus flavus able to significantly solublize calcium salts as major components of the ground layer of archeological wooden coffin. Effect of ozone and Gamma sterilization on growth; lipid, tryptophan oxidation and protein, nucleic acid leakage in the most dominant toxigenic deteriorated fungal species were detected. No mycelial growth was observed at 4 ppm of ozone at all exposure times. As Gamma radiation dose increased over 250 Gy, the growth parameter gradually decreased to reach the lethal dose at 2000 Gy. The production of mycotoxins by the tested toxigenic fungi was completely disappeared under the exposure to 3 ppm and 90 min to ozone.     

Discordant susceptibility of inbred C57BL/6 versus outbred CD1 mice to experimental fungal sepsis

Individual susceptibility differences to fungal infection following invasive and/or immunosuppressive medical interventions are an important clinical issue. In order to explore immune response‐related factors that may be linked to fungal infection susceptibility, we have compared the response of inbred C57BL/6J and outbred CD1 mouse strains to different experimental models of fungal sepsis. The challenge of animals with the zymosan‐induced generalised inflammation model revealed poorer survival rates in C57BL/6J, consistent with lower Th1 cytokine interferon (IFN)‐γ serum levels, compared with CD1 mice. Likewise, ex vivo exposure of C57BL/6J splenocytes to zymosan but also bacterial lipopolisaccharide or lipoteichoic acid, resulted in lower IFN‐γ secretion compared with CD1 mice. C57BL/6J susceptibility could be reverted by rescue infusion of relative low IFN‐γ doses (0.2 μg/kg) either alone or in combination with the ß‐glucan‐binding CD5 protein (0.7 mg/kg) leading to improved post zymosan‐induced generalised inflammation survival. Similarly, low survival rates to systemic Candida albicans infection (2.86 × 10⁴ CFU/gr) were ameliorated by low‐dose IFN‐γ infusion in C57BL/6J but not CD1 mice. Our results highlight the importance of strain choice in experimental fungal infection models and provide a susceptibility rationale for more specific antifungal immunotherapy designs.