Influence of straw types and nitrogen sources on mushroom composting emissions and compost productivity

The effects of different straw types and organic and inorganic nitrogen (N) sources on the chemical composition and odor concentration (OC) of mushroom composting emissions, compost parameters, and mushroom yield were examined using bench-scale and large-scale (windrows and aerated tunnels) composting systems. There were close correlations between the butanol or combined H₂S+dimethyl sulfide (DMS) concentration and OC of air samples taken from different composting ingredients (r=0.83 and 0.76–0.87, P<0.01, for log_e-transformed data). Differences in N availability, in terms of NH₃ and N losses during composting, were found between different N sources. Materials in which the N was less available (chipboard and digester wastes, cocoa shells, ammonium sulfate) produced lower mushroom yields than materials in which the N was more readily available (poultry manure, urea, brewers' grains, hop and molasses wastes, cocoa meal). Replacement of poultry manure with the other N sources at 50–100% or wheat straw with rape, bean, or linseed straw in aerated tunnel or windrow composts reduced the OC and emissions of odorous sulfur-containing compounds, but also reduced yield. Urea and cocoa meal may be suitable for “low odor” prewetting of straw, with addition of poultry manure immediately before aerated tunnel composting. Rape straw in compost reduces the formation of anaerobic zones and resulting odorous emissions, since it maintains its structure and porosity better than wheat straw. Journal of Industrial Microbiology & Biotechnology (2002) 29, 99–110 doi:10.1038/sj.jim.7000292 Received 08 January 2002/ Accepted in revised form 20 June 2002     

Characters of compost teas from different sources and their suppressive effect on fungal phytopathogens

Compost teas (CT) are fermented watery extracts of composted materials that are used to control plant diseases and on crop fertilization. In this work, aerated (ACT) and non-aerated compost teas (NCT) were obtained from four different composts: spent mushroom substrate compost, grape marc compost, greenhouse horticultural crop residues compost, and vermicompost. Physico-chemical and microbiological analysis were carried out to determine their properties. In vitro assays were performed to assess their suppressive effect on the mycelial growth of eight fungal phytopathogens. In vivo trials aimed to assess their effect on gummy stem blight (Didymella bryonae) and powdery mildew (Podosphaera fusca) in melon plants. Results showed that ACT and NCT filtrates inhibited the in vitro growth of all tested pathogens while autoclaved CT did not completely lose their inhibitory effect, and CT sterilized by microfiltration had no effect on the pathogen growth. The severity of powdery mildew was highly reduced by ACT and NCT from all sources, though in gummy stem blight assay only a delay in disease development was observed. In general, all compost teas showed a high level of microbial populations and nutrients. Results suggest that the efficacy of ACT and NCT firstly depend on the microbiota present in them. We consider compost teas from the four tested sources as a viable way to manage plant diseases and crop fertilization, throughout its integration in pest management programs and fertirrigation systems under different dilution rates.     

Induced resistance to Botrytis cinerea in Capsicum annuum by a Fusarium crude elicitor fraction,free of proteins

Fusarium oxysporum f. sp. lycopersici (FOL) induces resistance in pepper against the airborne pathogen Botrytis cinerea and the soil‐borne pathogen Verticillium dahliae. However, its practical use is limited due to its pathogenicity to other crops. In this study we tested several fractions of a heat‐sterilised crude FOL‐elicitor preparation to protect pepper against B. cinerea and V. dahliae. Only the protein‐free insoluble fraction of the preparation reduced B. cinerea infection. However, none of the fractions reduce V. dahliae symptoms. The insoluble protein‐free fraction induced expression of defence genes in the plant, namely a chitinase (CACHI2), a peroxidase (CAPO1), a sesquiterpene cyclase (CASC1) and a basic PR1 (CABPR1). Even though the CASC1 gene was not induced directly after treatment with the insoluble fraction in the leaves, it was induced after B. cinerea inoculation, showing a priming effect. The insoluble protein‐free FOL‐elicitor protected pepper against the airborne pathogen through a mechanism that involves induced responses in the plant, but different to the living FOL.     

Presence of Transposons and Mycoviruses in Botrytis cinerea Isolates Collected from a German Grapevine Growing Region

Transposons and infection of fungal strains with mycoviruses can have significant effects on distinctive phenotypic traits of phytopathogenic fungi such as mycelial growth and sporulation, pathogenicity or fungicide resistance. Two transposable elements (TE), Boty and Flipper, are known to be associated with the ubiquitous fungus Botrytis cinerea. In addition, the presence of two types of ssRNAsRNA viruses, BVX and BVF, has been reported in B. cinerea. In this study, we assessed the genetic diversity of B. cinerea isolates, all sampled within a small‐sized German viticultural area (‘Rheingau’) by examining and classifying them according to the presence of TEs and mycoviruses. A subset of the isolates was further analysed with microsatellite markers to determine the origin of particular isolates with or without one or both mycoviruses. Virtually all isolates (98%) sampled in two different years (2008 and 2010) were screened positive for the presence of a transposon. Presence of one or both B. cinerea mycoviruses was confirmed for 37% of the analysed isolates sampled in 2010, representing the first record of B. cinerea mycoviruses in German isolates. Assignment on individual B. cinerea isolates to different genetic groups was independent of the presence or absence of a mycovirus or a transposable element, respectively. Furthermore, we found no correlation between the presence of either a mycovirus or a transposable element and different viticultural management practices, soil properties or levels of nitrogen fertilization applied to the respective vineyards. However, mycelial growth of B. cinerea strains containing mycovirus BVF was significantly reduced at lower temperatures.     

Suppressive effect of non-aerated compost teas on foliar fungal pathogens of tomato

Compost teas are fermented watery extracts of composted materials that are used for their ability to decrease plant disease. Non-aerated compost teas (NCT) prepared from five types of compost were tested for their ability to inhibit the growth of Alternaria solani, Botrytis cinerea, and Phytophthora infestans in vitro. Weekly applications of NCT were also used in greenhouse trials to assess their suppressive effect on powdery mildew (Oidium neolycopersici) and gray mold (B. cinerea) on tomato plants. All NCT significantly inhibited the mycelial growth of A. solani (37–66%), B. cinerea (57–75%), and P. infestans (100%), whereas sterilized teas did not inhibit growth of the tested pathogens. Although NCT failed to efficiently control powdery mildew, they were able to control tomato gray mold for up to 9 weeks in greenhouse experiments. Among the tested compost teas, NCT prepared from sheep manure compost consistently provided the highest inhibition of mycelial growth and the highest disease suppression, in particular of gray mold (>95% disease reduction). The overall relative efficacy of the various NCT did not correlate well with microbial communities or physico-chemical composition of the prepared NCT. Results also suggest that the presence of the microorganisms in the NCT is a prerequisite for inhibition.     

Effects of ozone treatment on the quality of kiwifruit during postharvest storage affected by Botrytis cinerea and Penicillium expansum

The objective was to reveal the effects of ozone treatment on quality maintenance and resistance to Botrytis cinerea and Penicillium expansum in kiwifruit during postharvest storage. Kiwifruits were treated with 79.44 ppm gaseous ozone for 1 hr once a day for 7 day at 0°C to determine the effects of ozone treatment on the quality and disease incidence caused by B. cinerea and P. expansum in vivo and the growth of B. cinerea and P. expansum in vitro. Ozone treatment significantly reduced the disease incidence of kiwifruit and inhibited the mycelial development and spore germination of B. cinerea and P. expansum. High levels of fruit firmness and titratable acidity were maintained in the ozone‐treated kiwifruit, and the activities of the defence‐related enzymes were remarkably enhanced. Therefore, ozone treatment may be an effective method to maintain the quality of kiwifruit and control its decay during postharvest storage.     

The Elongator complex‐associated protein DRL1 plays a positive role in immune responses against necrotrophic fungal pathogens in Arabidopsis

DEFORMED ROOT AND LEAVES1 (DRL1) is an Arabidopsis homologue of the yeast TOXIN TARGET4 (TOT4)/KILLER TOXIN‐INSENSITIVE12 (KTI12) protein that is physically associated with the RNA polymerase II‐interacting protein complex named Elongator. Mutations in DRL1 and Elongator lead to similar morphological and molecular phenotypes, suggesting that DRL1 and Elongator may functionally overlap in Arabidopsis. We have shown previously that Elongator plays an important role in both salicylic acid (SA)‐ and jasmonic acid (JA)/ethylene (ET)‐mediated defence responses. Here, we tested whether DRL1 also plays a similar role as Elongator in plant immune responses. Our results show that, although DRL1 partially contributes to SA‐induced cytotoxicity, it does not play a significant role in SA‐mediated expression of PATHOGENESIS‐RELATED genes and resistance to the virulent bacterial pathogen Pseudomonas syringae pv. maculicola ES4326. In contrast, DRL1 is required for JA/ET‐ and necrotrophic fungal pathogen Botrytis cinerea‐induced defence gene expression and for resistance to B. cinerea and Alternaria brassicicola. Furthermore, unlike the TOT4/KTI12 gene which, when overexpressed in yeast, confers zymocin resistance, a phenotype of the tot4/kti12 mutant, overexpression of DRL1 does not change B. cinerea‐induced defence gene expression and resistance to this pathogen. Finally, DRL1 contains an N‐terminal P‐loop and a C‐terminal calmodulin (CaM)‐binding domain and is a CaM‐binding protein. We demonstrate that both the P‐loop and the CaM‐binding domain are essential for the function of DRL1 in B. cinerea‐induced expression of PDF1.2 and ORA59, and in resistance to B. cinerea, suggesting that the function of DRL1 in plant immunity may be regulated by ATP/GTP and CaM binding.     

Some Characteristics of Red Light-induced Substance(s) against Botrytis cinerea Produced in Broad Bean Leaflets

The red light-induced antifungal substance(s) produced in broad bean was of relatively high molecular weight, water soluble, heat stable and fungi specific. Cellulose thin layer chromatography (TLC) of infection droplets of Botrytis cinerea or water droplets without spores of B. cinerea, recovered from inoculated broad bean leaflets kept under red light for 48 h, displayed inhibition zones at approximate Rf values of 0.0 and 0.6. Inhibition zones observed in cellulose TLC of water droplets were relatively faint compared to those of infection droplets. In a time-course study of accumulation of the antifungal substance(s), antifungal activity in both water and infection droplets recovered from red light irradiated broad bean leaflets occurred after 24 h irradiation. However, the antifungal activity in infection droplets was significantly higher than in water droplets. The antifungal substance(s) was less active against Botrytis fabae than B. cinerea.     

Pseudozyma aphidis activates reactive oxygen species production,programmed cell death and morphological alterations in the necrotrophic fungus Botrytis cinerea

Many types of yeast have been studied in the last few years as potential biocontrol agents against different phytopathogenic fungi. Their ability to control plant diseases is mainly through combined modes of action. Among them, antibiosis, competition for nutrients and niches, induction of systemic resistance in plants and mycoparasitism have been the most studied. In previous work, we have established that the epiphytic yeast Pseudozyma aphidis inhibits Botrytis cinerea through induced resistance and antibiosis. Here, we demonstrate that P. aphidis adheres to B. cinerea hyphae and competes with them for nutrients. We further show that the secreted antifungal compounds activate the production of reactive oxygen species and programmed cell death in B. cinerea mycelium. Finally, P. aphidis and its secreted compounds negatively affect B. cinerea hyphae, leading to morphological alterations, including hyphal curliness, vacuolization and branching, which presumably affects the colonization ability and infectivity of B. cinerea. This study demonstrates additional modes of action for P. aphidis and its antifungal compounds against the plant pathogen B. cinerea.     

First Report of Botrytis cinerea Pers. on Salicornia bigelovii Torr. in North‐West México

Grey mould has been detected on Salicornia bigelovii Torr plants in nursery and in the wild in north‐west Mexico. Sampling of the grey mould was performed in the state of Sonora, Mexico, of wild as well as cultivated S. bigelovii plants. The samples were isolated, and based on morphology, the species was identified as Botrytis cinerea Pers. Koch's postulates were fulfilled by pathogenicity tests carried out in plated petri dishes on branches from the 3‐month‐old potted S. bigelovii plants. To our knowledge, this is the first report of the isolation and identification of the fungal pathogen B. cinerea from S. bigelovii in the north‐west Mexico.     

Growth potential of faecal bacteria in simulated psychrophilic/mesophilic zones during composting of organic waste

Aim: This study investigated the growth potential of Salmonella serotype Typhimurium and faecal indicator organisms in compost materials and the correlation between bacterial growth potential and the physico‐chemical composition of the compost substrate and temperature. Methods and Results: Survival of Salm. Typhimurium, Enterococcus spp. and total coliforms at 14, 24 and 37°C was determined in material of different degrees of maturity collected from composting plants for household waste and manure. All three micro‐organisms showed the potential for growth in the material from active composts (Solvita index 4) but inactivation generally occurred over time in mature compost material (Solvita index 7–8). Conclusions: Salm. Typhimurium had the potential for growth in psychrophilic/mesophilic (P/M) zones of immature compost material and its growth potential correlated negatively with the maturity of the compost and the temperature within the simulated P/M zone. Significance and Impact of the Study: The risk of pathogen regrowth in P/M zones during organic waste composting further emphasizes the importance of good management practices and of avoiding P/M zones in combination with low compost maturity.     

The growth potential of Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes in dairy manure‐based compost in a greenhouse setting under different seasons

Aim: The pathogen growth in dairy compost was studied in a greenhouse setting under different seasons. Methods and Results: The five‐strain mixtures of each Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes were inoculated separately into dry compost to yield c. 1 log CFU g^?1. After acclimation at room temperature, the inoculated compost was initially adjusted to moisture levels of 10–50% and then kept in a greenhouse under different seasons. The populations of all three pathogens increased by 2·1–3·9 log CFU g^?1 within 3 days in autoclaved compost with initial moisture content of at least 40%. Listeria monocytogenes multiplied up to 2·4 log CFU g^?1 in compost with initial moisture content of 30% and was detected up to 28 days for all seasons, whereas populations of both E. coli O157:H7 and Salmonella increased by c. 1 log in compost with initial moisture content of 30% during winter months only. No pathogen growth in nonautoclaved compost was detected. Conclusion: Bacterial species, temperature, light intensity and moisture content affected the growth potential and survival of pathogens in compost when the population of background microflora was low. Significance and Impact of the Study: Keeping compost as dry as possible and maintaining certain levels of background microflora may be critical to prevent the growth of pathogens.     

Inhibition of Botrytis cinerea by Epirodin: A Secondary Metabolite from New Zealand Isolates of Epicoccum nigrum

Many isolates of the saprophytic fungus Epicoccum nigrum produce yellow compounds that diffuse readily into culture media. Historically, two such compounds have been identified; flavipin and epirodin both reported to have antimicrobial properties. Preliminary studies on 280 New Zealand isolates of E. nigrum confirmed that all but two produced a yellow, intensely pigmented substance in sufficient amounts to inhibit the germination of Botrytis cinerea conidia. The compound produced by the inhibitory isolates is epirodin, a polyene antibiotic. Five representative E. nigrum isolates were selected for further investigation. Two of these produced relatively large amounts of epirodin and, in a diffusible metabolite assay, reduced germination of B. cinerea conidia by up to 94%. Another isolate produced a trace amount of epirodin and had no effect on the germination of B. cinerea conidia or on germ tube morphology. The two remaining isolates produced intermediate amounts of epirodin and were only moderately inhibitory to the germination of B. cinerea conidia and to germ tube morphology. In slide dual‐culture experiments, epirodin appeared to concentrate in conidia and mycelia of B. cinerea. In acid conditions, as on dual‐culture slides of E. nigrum and B. cinerea, the yellow‐coloured epirodin underwent a hypsochromic shift, changing colour to become red. The relationship between epirodin production and the suppression of Botrytis growth and development was further investigated using necrotic kiwifruit leaf discs. The E. nigrum isolate that produced the greatest amount of epirodin almost completely inhibited the growth and development of B. cinerea on the leaf discs. In contrast, the efficacy of E. nigrum isolates which produced less epirodin ranged from 78% to just 23%. This is the first report of epirodin production by New Zealand isolates of E. nigrum, and we conclude that isolates that produce high concentrations of epirodin may have potential for plant disease control.     

Changes in physical,chemical and microbial parameters during the composting of municipal sewage sludge

Changes in physical, chemical and microbial parameters were investigated during the composting of municipal sewage sludge. Raw sewage sludge (30% dry matter) was mixed with compost from sewage sludge (85% dry matter) in 3:1 ratio (v/v). The mixture was divided into 4 windrows which were composted under the same conditions except the turning factor. The turning was every 7, 10, 15 days and according to the temperature which must be (55–65°C) for windrow 1 (W1), windrow 2 (W2), windrow 3 (W3) and windrow 4 (W4), respectively. Water was added to adjust the moisture content (40–60%). The composting process consisted of 2 periods; fermentation (12 weeks) and maturation (4 weeks). The results showed that the temperature reached the maximum after 12 weeks for W1 and 11 weeks for W2, W3 and W4 and then decreased. The final compost was nearly odourless and black, especially in case of W4. The general trend indicates a decrease in organic matter, organic carbon and nitrogen (N), whereas ash, potassium (K) and phosphorus (P) increased and consequently C/K and C/P ratios decreased. There was a slight increase in C/N ratio. The pH increased and then decreased to near neutrality at the end. The mesophilic bacteria increased during the fermentation period and decreased after that, whereas the thermophilic ones increased with increasing of temperature, decreased after 2 weeks and increased again during the fermentation period and then decreased. The mesophilic and thermophilic fungi were present during the first week and disappeared after that. The final compost was pathogens-free as indicated by the counts of coliforms and Salmonella.     

Functional analysis of an extracellular catalase of Botrytis cinerea

There is evidence that the necrotrophic fungal pathogen Botrytis cinerea is exposed to oxidative processes within plant tissues. The pathogen itself also generates active oxygen species and H₂O₂ as pathogenicity factors. Our aim was to study how the pathogen may defend itself against cellular damage caused by the accumulation of H₂O₂ and the role of an extracellular catalase in its detoxification during the infection of tomato and bean plants by B. cinerea. Chloronaphthol staining followed by light microscopy showed that H₂O₂ accumulates in the infection zone in tomato and bean leaves. An extracellular catalase gene (denominated Bccat2) was cloned from B. cinerea. Exposure of mycelium to H₂O₂ in liquid culture resulted in increased Bccat2 mRNA levels in a concentration-dependent manner. Bccat2 mRNA was detected at early stages of tomato leaf infection, suggesting that B. cinerea experiences oxidative stress. Bccat2-deficient mutants were generated by transformation-mediated gene disruption. Mutants were more sensitive then the wild-type strain to H₂O₂in vitro, but they partly compensated for the absence of BcCAT2 by activating other protective mechanisms in the presence of H₂O₂. Bccat2-deficient mutants did not display a consistent reduction of virulence on bean and tomato leaves. Cerium chloride staining of infected leaf tissue for ultrastructural studies showed that Bccat2-deficient mutants were exposed to H₂O₂ comparably to the wild-type. The results suggest that B. cinerea is a robust pathogen adapted to growing in hostile oxidizing environments in host tissues.     

Antifungal Vapour‐phase Activity of a Combination of Allyl Isothiocyanate and Ethyl Isothiocyanate Against Botrytis cinerea and Penicillium expansum Infection on Apples

The potential use of allyl isothiocyanate (AITC) and ethyl isothiocyanate (EITC), singly and in combination, was tested in in vitro and in vivo trials for their effect on Penicillium expansum Link and Botrytis cinerea Persl. infection on apple when used as a fumigant. A 3 : 1 ratio of AITC : EITC was more efficient at reducing in vitro spore germination of P. expansum and B. cinerea than were other combinations or either AITC or EITC alone. The optimized combination showed the lowest EC₅₀ values, at 0.08 and 0.14 μg/ml air, for P. expansum conidial germination and mycelial growth, respectively, and 0.07 and 0.12 μg/ml air for B. cinerea conidial germination and mycelial growth, respectively. In in vivo trials, artificially infected apples were exposed for 4 days to an ITC‐enriched atmosphere. Among the ITCs tested, AITC, EITC and their combinations reduced incidence by more than 85% after 3–4 days of apple incubation at 20°C. Although further studies are necessary to evaluate any detrimental effects on apple quality, the evidence from this study supports the use of fumigation based on ITCs, and in particular a 3 : 1 combination of AITC and EITC, for control of postharvest mildew in apple fruit.     

Sensitivity to Fludioxonil of Botrytis cinerea Isolates from Tomato in Henan Province of China and Characterizations of Fludioxonil‐resistant Mutants

Grey mould, caused by Botrytis cinerea Pers ex Fr., is one of the most common diseases of tomato worldwide. Fludioxonil belongs to the phenylpyrrole fungicides, which have high activity against B. cinerea. The sensitivity of fludioxonil was evaluated on the basis of the level of inhibition of mycelium growth in 274 B. cinerea isolates collected from different locations (untreated with this fungicide) in Henan Province, China. The EC₅₀ values for fludioxonil ranged from 0.0033 to 0.0415 mg/l, and the average EC₅₀ values were 0.0156 ± 0.0078 mg/l. Three fludioxonil‐resistant mutants were obtained by subculturing fludioxonil‐sensitive wild‐type isolates on continuously increasing fludioxonil concentrations. For the cross‐resistance assay, fludioxonil revealed positive cross‐resistance with procymidone but did not reveal cross‐resistance with pyrimethanil, boscalid and trifloxystrobin. Mycelial growth, conidial production, hyphal dry weight and pathogenicity were diminished significantly between the fludioxonil‐resistant mutants and their sensitive wild‐type parental isolates. This study shows for the first time that fludioxonil‐resistant isolates of B. cinerea are still not present in Henan Province because this fungicide is an attractive and effective fungicide for chemical control. Recommendations can be made to growers to use fludioxonil to control grey mould and to consider the potential moderate resistance risk of using this fungicide.