Impact of environmental factors on growth and satratoxin G production by strains of Stachybotrys chartarum

The black mould Stachybotrys chartarum and its mycotoxins have been linked to damp building-associated illnesses. The objective of this study was to determine the effects of water availability (water activity, aw) and temperature on growth and production of satratoxin G (SG) by a macrocyclic trichothecene-producing strain (IBT 7711) and non-producing strain (IBT 1495) of S. chartarum. Growth studies were carried out on potato dextrose agar modified with glycerol to 0.995-0.92 aw at 10-37 °C. Growth extension was measured and the cultures were extracted after 10 days and a competitive enzyme-linked immunosorbent assay (ELISA) method used to quantify the SG content. Growth was optimal at 25 to 30 °C at 0.995 aw, but this was modified to 0.98 aw at 30 °C for both strains (1.4- 1.6 mm/day, respectively). The ELISA method revealed that, in contrast to growth, SG production was maximal at 20 °C with highest production at 0.98 aw (approximately 250 μg/g mycelia). When water was freely available (0.995 aw), SG was maximally produced at 15 °C and decreased as temperature was increased. Interestingly, the strain classified as a non-toxigenic produced very low amounts of SG (<1.6 μg/g mycelia) that were maximal at 25 °C and 0.98 aw. Contour maps for growth and SG production were developed from these data sets. These data have shown, for the first time, that growth and SG production profiles are very different in relation to key environmental conditions in the indoor environment. This will be very useful in practically determining the risk from exposure to S. chartarum and its toxins in the built env

Characterisation of Stachybotrys chartarum from water damaged buildings

Fungal contaminated buildings and related adverse human health implications have long been a topical issue throughout the world and concern is mounting with regards to the presence of more toxigenic fungi found in buildings and the associated health risks. These risks are compounded when homes are affected by water damage as a result of water intrusion problems, in particular flooding. With the ever changing climate and unpredictable weather conditions the frequency of flash flooding has increased in recent years and is set to increase and subsequently more homes will inevitably be effected by mould contamination. The present study initially aimed to determine the types of fungi commonly detected in buildings in the United Kingdom with varied levels of water intrusion problems via a small survey using various sampling techniques and particularly aimed to determine the conditions by which growth of the toxigenic fungi Stachybotrys chartarum could occur. Penicillium, Cladosporium and Aspergillus species were the most commonly detected fungi in buildings with relatively moderate levels of water intrusion problems; Stacybotrys chartarum was only detected in building with more severe water intrusion problems. Cont/d.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Conditions of formation of ochratoxin A in drying, transport and in different commodities

Abstract The major species of fungi responsible for ochratoxin production (OTA) in a range of commodities are Penicillium verrucosum, Aspergillus ochraceus and Aspergillus section Nigri, especially A. carbonarius. P. verrucosum is particularly important in northern Europe where damp cooler conditions occur and where drying regimes need to be efficient and effective for preventing post-harvest contamination with OTA. A. ochraceus can infect cereals including barley, maize, coffee, cocoa and edible nuts. A. carbonarius has been identified as the key species responsible for OTA contamination of grapes, wine and vine fruits. Recent studies have identified the environmental regimes, especially of temperature and humidity, which are conducive to growth and OTA production by these species pre-and post-harvest and during transport. The optimum and marginal interacting conditions for growth and OTA contamination often vary considerably. This has to be borne in mind when effective preventative management strategies are being implemented. Recent studies with cereals have suggested that isolation frequency can be related to OTA contamination of cereals. A logistical model has been developed and identified that 1000 CFUs g À1 grain of P. verrucosum (CFUs) is the threshold limit at which the probability of exceeding the EU legislative limit of 5 mg kg À1 in cereal grain can be predicted under different storage regimes. Controlled atmospheres &gt;50% C0 2 is required to effectively prevent OTA accumulation in damp cereals. With regard to grapes, preharvest contamination with A. carbonarius has been shown to be a good indicator for regional risk in southern Europe from OTA contamination. The ecological conditions for optimum growth and OTA production have been shown to differ with the optima being 30-35 C and 15-25 C and 0.98-0.99 and 0.93-0.95 water activity, respectively. Studies on vine fruits (drying currants) suggest that OTA contamination and increase contamination levels occur during this drying process of 7-14 days. This will be influenced by prevailing weather conditions and drying rates. Minimizing OTA contamination in these and other commodities including coffee and cocoa require clear guidelines on safe moisture and temperature regimes pre-and post-harvest for the development of effective management strategies based on ecological criteria

Ecophysiology and production of the biocontrol agent Phlebiopsis gigantea

Heterobasidion annosum, the causative agent of the disease “root and butt rot” in conifers, is ubiquitous in the environment and causes severe financial losses to the forestry industry throughout the temperate zone. The normal route of infection is as basidiospores that land on the freshly cut stump surface during thinning operations, the colonisation of the stump providing sufficient inoculum for the fungal hyphae to invade healthy roots of adjoining trees. The most successful disease control measures involve depriving the pathogen the opportunity to become established in the food source of the fresh cut stump. Frequently killing the surface of the stump with a chemical treatment does this, but there is also some success with a biocontrol method. When the antagonist Phlebiopsis gigantea, a saprophyte, is inoculated onto the stump surface it rapidly invades the tissue thus preventing the pathogen access to the resource. Environmental studies have been carried out to assess the fitness of different isolates of the antagonist relative to the pathogen. Competitiveness was affected by environmental factors; water availability, osmotic/matric potentials, temperature, nutrition, and substrate. These indicate that the antagonist is not able to suppress the pathogen under all conditions. Generally, in wet warm conditions the antagonist is dominant, ID 10:2 antagonist:pathogen, but in drier, cooler conditions the pathogen is dominant, ID 2:10 on MEA. Interactions in situ on wood discs showed the pathogen was restricted to 0-2% of the treated portion and 2-10% of the un-treated surface at 25 ºC, but at 4 ºC it colonised 2-24% of the former and 34-57% the latter. Consideration needs to be given to possible field conditions at the time of application to maximise the establishment of the antagonist. Studies have been carried out to examine potential for liquid or solid substrate fermentation systems for optimising production of P.gigantea. Liquid culture studies were variable regardless of available nutrients and ecophysiological stresses imposed, producing a maximum of 6.5 log10 CFU ml -1 . However, temporal studies on solid substrate based on Pinus sylvestris sawdust gave 8 Log10 viable oidia g -1 in the best moisture content treatments. Scale up, to 200g substrate produced similar CFUs, however increasing to 400 g showed a reduction in viable oidia, due to lack of moisture equiibration. Analyses of the endogenous reserves to identify specific quality characteristics were inconclusive. Mycelial pellets and submerged conidia produced in fermentation had increased levels of glycerol and erythritol as aw was lowered, however this was not replicated by oidia produced in solid substrate fermentation. Preservation studies, in a fluidised bed reactor showed, the survival of PG21 spores at up to 60 ºC for 20 min. Studies were carried out to analyse volatile fingerprints of antagonist and pathogen isolates using an AlphaM.O.S. electronic nose. Volatile fingerprints showed clear grouping of antagonist and pathogen isolates, as distinct from each other. With some isolates, the fingerprints of interactions were co-incidental with the antagonist. It is suggested that this novel technique could be used as a rapid screening method for potential BCAs.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Exploitation of bioactive constituents of olive leaves, grape pomace, olive mills waste water and their application in phytoprotection

Pure plants extracts or/and essential oils show antifungal and antibacterial activity against a wide range of fungi and bacteria. Recently there has been increasing interest in the effects of natural compounds against important plant pathogens (fungi and bacteria). Although the antimicrobial activity of oleuropein, grape pomace (GPE) and olive mills waste water (OMWW) extracts have been studied widely, little research has been done on the in vitro and in vivo evaluation of these extracts efficiency against important plant diseases and postharvest treatments. The overall objectives of this study were firstly to extract and isolate from olive leaves (oleuropein), olive mills waste water and from grape pomace (winery by-products) natural compounds in order to be used for in vitro and in vivo experiments. In particular, all three natural extracts were found to restrain in vitro growth of a series of important bacterial and fungal pathogens, such as: Botrytis cinerea, the cause of grey mold disease, Alternaria alternata, causing leaf spots and moulds on several plant species, Fusarium oxysporum fsp melonis, causing Fusarium wilt of melon, a Rhizopus species (a genus causing fruit and vegetable decays), the crucifer pathogen Colletotrichum higginsianum, causing anthracnose leaf spot disease on several Brassica and Raphanus species and Phytophthora parasitica var. nicotianae, the causal agent of the black shank disease of tobacco. Bacterial strains including Clavibacter michiganensis spp. michiganensis, the cause of bacterial canker of tomato, Ralstonia solanacearum causing bacterial wilt in solanaceous plants, Pseudomonas syringae pv. tomato, the cause of bacterial speck on tomato and Arabidopsis and Xanthomonas campestris pv. vesicatoria causing the bacterial spot disease of pepper and tomato were tested. Oleuropein (semipure and pure) showed remarkable antibacterial activity. The minimal inhibitory concentration (MIC), at least of oleuropein was lower than 0.1%. MICs values for GPE and OMWW extract ranged from 0.1% to 0.2%. Moreover, these natural extracts were shown to inhibit and/or restrain spore germination of fungi in solid media, however grape pomace extract, was sufficiently effective to inhibit spore germination and germ tube of C. higginsianum and B. cinerea. Furthermore in vivo antibacterial activity of pure oleuropein and OMWW extract was assessed in greenhouse experiments, on Xanthomonas campestris pv. vesicatoria, the cause of bacterial spot of pepper plants and Pseudomonas syringae pv. tomato, the cause of bacterial speck of tomato plants, respectively. It seems that 0.1% pure oleuropein (98%) and 0.1% OMWW extract had a protective effect against bacterial spot and bacterial speck respectively, which is more obvious when oleuropein application started before infection. Besides endophytic growth of Phytophthora parasitica var. nicotianae, causal agent of the black shank disease of tobacco, on tobacco leaves by measuring its radial growth inside the infected tissue, was assessed. 0.1% GPE showed the most significant inhibition in all tobacco leaves treatments. The potential of postharvest treatment of table grapes with the grape pomace extract (GPE) to restrain grey mould (Botrytis cinerea) disease incidence and development was estimated. 5% GPE treatments produced the strongest inhibitory effect against B. cinerea incidence on grape berries and the time after treatment influenced the numbers of decayed berries. Finally the use of pure oleuropein as antibacterial in vase solution for cut flowers (carnation) was evaluated. Oleuropein showed strong antibacterial activity as vase solution and carnations vase life was more than doubled by using oleuropein 200ppm and 400ppm, compared with control (water).EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Pathogen responses in foods : underestimated ecophysiological factors

Accurate prediction of the fate of microbial foodborne pathogens in foods is of great concern for anyone involved in the food chain. Factors that may influence microbial responses in foods and food environments, such as food structure and composition, microbial interactions and mode of growth were identified and assessed in the present study. The fate of Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7 was monitored both in and on teewurst, a raw spreadable sausage, at different storage temperatures. Regardless of the storage temperature and inoculation type, pathogen numbers decreased during storage. The increase of endogenous lactic acid bacteria and the concomitant reduction of pH mostly accounted for this reduction. The inactivation of all three pathogens inoculated into batter or onto slices varied considerably among trials possibly due to variations in the initial batch-to-batch levels of lactic acid microflora and the associated microbial interactions. The effect of structure, composition and microbial interactions on the growth kinetics of L. monocytogenes was evaluated in different growth substrates, including broth, agar, sterile meat blocks, naturally contaminated meat blocks and minced meat. The growth responses of L. monocytogenes were significantly different in the different growth media and food products tested. These differences were more pronounced at low temperatures. The validation of a model based on data from broth against the observed growth of the pathogen in the rest of the tested media showed that broth models may result in significant prediction errors. The potential for mono- or multi-strain cultures of Escherichia coli O157:H7 to attach and form biofilm in combinations of food-contact surfaces, growth substrates and storage temperatures was examined. The susceptibility of biofilms to sanitizers was also evaluated. Attachment and biofilm formation was strain dependent. The presence of food residues (liquid or solid) facilitated the attachment/transfer of E. coli O157:H7 on food-contact surfaces. At moderately cold temperatures culture broth was more conducive to subsequent growth. At chill temperatures the presence of natural microflora in liquid residues enhanced further attachment of the pathogen. Biofilms were less susceptible to sanitation treatments as compared to planktonic cells. Biofilm cells surviving sanitation were able to survive and present slight increases at refrigeration and abuse temperatures, respectively, in cross-contaminated ground meat. Acylated homoserine lactones (AHLs) and autoinducer-2 (AI-2) signalling molecules in the cell-free supernatants of Pseudomonas aeruginosa, Yersinia enterocolitica-like, Serratia proteamaculans and a mixture of two Yersinia enterocolitica strains were found to affect the growth kinetics of two Salmonella Enteritidis and S. Typhimurium strains, respectively. P. aeruginosa synthesized quorum sensing signals that accelerated the metabolic activity of Salmonella strains. All other quorated bacteria tested had a negative effect on both initiation of growth and metabolic activity. The effect seems to be strain and QS signal dependent.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

<i>Legionella</i> species: A potential problem associated with rain water harvesting systems?

The risk of Legionella transmission from rain water harvesting (RWH)-fed water toilet flushing was investigated. Experiments monitored RWH tanks to determine Legionella spp. presence which was successfully isolated from three of four of RWH tanks (site 1: 3600 CFU/dm3 in February and 3600 CFU/dm3 in May; site 2: not detected; site 3: 3; site 4: 44,000 GU/dm3), and to determine whether toilets could generate aerosol droplets capable of harbouring bacteria. The concentrations of particles measuring 10 µm or less in diameter (PM10, capable of reaching the alveolar region of the lungs and causing disease) were monitored following flushes. Aerosols were detectable in an enclosed toilet cubicle (PM10 concentration increased in one experiment from 0.038 mg/m3 when t = 1–600 s to 0.057 mg/m3 when t = 600–800 s). Recovery of Lactobacillus plantarum (surrogate for Legionella) from a seeded toilet cistern (108 CFU ml/dm3) indicated that bacteria were expelled, as demonstrated by recovery on MRS plates placed around the toilet unit. Legionella could be dispersed via aerosols from a toilet flushed with water from an RWH system and the effect would be more pronounced in smaller, enclosed areas, but this is unlikely to pose a risk to human health

Making Sense of a New Transport System: An Ethnographic Study of the Cambridgeshire Guided Busway

An increase in public transport use has the potential to contribute to improving population health, and there is growing interest in innovative public transport systems. Yet how new public transport infrastructure is experienced and integrated (or not) into daily practice is little understood. We investigated how the Cambridgeshire Guided Busway, UK, was used and experienced in the weeks following its opening, using the method of participant observation (travelling on the busway and observing and talking to passengers) and drawing on Normalization Process Theory to interpret our data. Using excerpts of field notes to support our interpretations, we describe how the ease with which the new transport system could be integrated into existing daily routines was important in determining whether individuals would continue to use it. It emerged that there were two groups of passengers with different experiences and attitudes. Passengers who had previously travelled frequently on regular bus services did not perceive the new system to be an improvement; consequently, they were frustrated that it was differentiated from and not coherent with the regular system. In contrast, passengers who had previously travelled almost exclusively by car appraised the busway positively and perceived it to be a novel and superior form of travel. Our rich qualitative account highlights the varied and creative ways in which people learn to use new public transport and integrate it into their everyday lives. This has consequences for the introduction and promotion of future transport innovations. It is important to emphasise the novelty of new public transport, but also the ways in which its use can become ordinary and routine. Addressing these issues could help to promote uptake of other public transport interventions, which may contribute to increasing physical activity and improving population health. © 2013 Jones et al

Peak Running Speeds in Professional Male Football: Influence of Division and Playing Position

Well-established physical demands of competitive professional football facilitate prescription and monitoring of training. However, many factors influence these physical demands with implications for efficacious practice. Match-play data were analyzed over 2 seasons using global positioning systems technology, differentiating English Championship (33 matches) and League One (27 matches) demands. Playing position categorized wide and central defenders and midfielders and forwards. Peak running speeds defined the outcome measure, assessing the influence of the competition level and playing position across 1, 5, and 10-minute rolling average durations using a linear mixed model. Significant effects were detected for the competition level (F 1,324.5 = 5.44, p = 0.02) and playing position (F 4,328.3 = 89.90, p &lt; 0.001). League One matches demonstrated greater peak running speeds than Championship matches (mean difference = 2.72 m·min−1 [95% confidence intervals: 0.4, 5.0]). No difference was observed between central and wide midfielders (mean difference = 0.62 m·min−1 [95% confidence intervals: −3.1, 4.3]). Wide midfielders presented faster peak running speeds than forwards (mean difference = 18 m·min−1 [95% confidence intervals:14.1, 22.1], p &lt; 0.05), central defenders (mean difference = 25 m·min−1 [95% confidence intervals: 21.7, 29.8], p &lt; 0.05), and wide defenders (mean difference = 12 m·min−1 [95% confidence intervals: 8.2, 16.5], p &lt; 0.05). Interaction effects were found for division*position (F 4,328.3 = 2.57, p = 0.038) demonstrating greater running speeds in League One, except for central defenders. Wide midfielders presented greater peak 1-minute running speeds, whereas 5 and 10-minute peak running speeds were greatest in central midfielders. The sensitivity of peak running speeds to competition level and playing position has implications for training prescription, monitoring particularly when transitioning between competition levels, determining and monitoring positional training intensities, and objective targets for progressive overload during rehabilitation

Monitoring the succession of bacterial communities during storage of raw meat

Fresh meat is exposed to various factors which cause microbiological contamination during handling, processing, packaging and storage. Furthermore, the storage conditions applied may affect the microbial association of the product and consequently the spoilage process. Therefore, the purpose and importance of this study was to identify areas that should be addressed to monitor the succession of bacterial communities during storage of raw meat. The improvement of the microbiological quality and safety of meat was also studied. Cont/d.EThOS - Electronic Theses Online ServiceGBUnited Kingdo