Biodegradation of potato slops from a rural distillery by thermophilic aerobic bacteria

Livestock manure may contain pathogenic organisms which pose a risk to the health of animals or humans if the manure is not adequately treated or disposed of. One possible treatment method is composting. However to ensure that pathogen destruction occurs, temperatures need to be sufficiently high throughout the heap to ensure that pathogens are inactivated. The temperature required to inactivate a marker organism, Escherichia coli 11943, has been investigated, and found to depend on substrate composition, moisture content and duration of incubation. Results show that temperatures in excess of 55 degrees C for 2 h are required for inactivation. Data are presented showing the levels of faecal coliforms in compost heaps where temperatures did not rise above mesophilic levels (35 degrees C where samples were taken).     

Inactivation of indicators and pathogens in cattle feedlot manures and compost as determined by molecular and culture assays

Accurate and conservative information about pathogen inactivation rates is needed as the basis for safe manure management on beef cattle feedlots. The survival of indicators and pathogens in faecal pen manure, stockpiled manure and manure compost was measured with autochthonous indicator bacteria (Escherichia coli, Clostridium perfringens, enterococci, total coliforms) and pathogens (Listeria monocytogenes, Campylobacter jejuni) using culture and/or real-time quantitative PCR (qPCR) methods. Additionally, the manures were incubated at 20, 37, 50 and 60 °C in microcosms to quantify the persistence of autochthonous microorganisms and selected process performance surrogates (Clostridium sporogenes, green fluorescent protein-labelled E. coli and L. monocytogenes). Estimated qPCR cell counts indicated that up to four orders of magnitude more target cells were present compared with the culturable counts. Corresponding T(90) estimates were up to sixfold higher. This study demonstrates the benefits of nucleic acid-based quantification of pathogen inactivation in cattle manures and concludes that the concurrent analysis of microorganisms by molecular and culture methods provides complementary value.     

Control of enteric pathogens in ready-to-eat vegetable crops in organic and 'low input' production systems: a HACCP-based approach

Risks from pathogens such as Salmonella, Yersinia, Campylobacter and Escherichia coli O157 have been identified as a particular concern for organic and 'low input' food production systems that rely on livestock manure as a nutrient source. Current data do not allow any solid conclusions to be drawn about the level of this risk, relative to conventional production systems. This review describes six Risk Reduction Points (RRPs) where risks from enteric pathogens can be reduced in ready-to-eat vegetables. Changes can be made to animal husbandry practices (RRP1) to reduce inoculum levels in manure. Outdoor livestock management (RRP2) can be optimized to eliminate the risk of faecal material entering irrigation water. Manure storage and processing (RRP3), soil management practices (RRP4) and timing of manure application (RRP5), can be adjusted to reduce the survival of pathogens originating from manure. During irrigation (RRP6), pathogen risks can be reduced by choosing a clean water source and minimizing the chances of faecal material splashing on to the crop. Although preventive measures at these RRPs can minimize enteric pathogen risk, zero risk can never be obtained for raw ready-to-eat vegetables. Good food hygiene practices at home are essential to reduce the incidence of food-borne illnesses.     

Changes in microbial community structure and function during vermicomposting of pig slurry

Most studies investigating the effects of earthworms on microorganisms have focused on the changes before and after vermicomposting rather than those that occur throughout the process. In the present study, we designed continuous feeding reactors in which new layers of pig slurry (1.5 and 3 kg) were added sequentially to form an age gradient inside the reactors in order to evaluate the impact of the earthworm species Eisenia fetida on microbial community structure and function. The activity of earthworms greatly reduced the bacterial and fungal biomass and microbial diversity relative to the control values. However, the pronounced presence of earthworms in the younger layers stimulated microbial activity and as such increased carbon mineralization probably due to the fact that the microorganisms may have been less resource-limited as a result of earthworm activity, as indicated by the ratio of monounsaturated to saturated PLFAs.     

Identity of the downy mildew pathogens of basil, coleus, and sage with implications for quarantine measures

The downy mildew pathogen of basil (Ocimum spp.) has caused considerable damage throughout the past five years, and an end to the epidemics is not in sight. The downy mildew of coleus (Solenostemon spp.) is just emerging and here we report that it was very recently introduced into Germany. Although it has been recognised that these pathogens are a major threat, the identity of the pathogens is still unresolved, and so it is difficult to devise quarantine measures against them. Using morphological comparison and molecular phylogenetic reconstructions we confirmed in this study that the downy mildews of basil and coleus are unrelated to Peronospora lamii, which is a common pathogen of the weed Lamium purpureum. In addition, we conclude by the investigation of the type specimen of P. swingleii and downy mildew specimens on Salvia officinalis that the newly occurring pathogens are not identical to P. swingleii on Salvia reflexa. The taxonomy of the downy mildew pathogens of hosts from the Lamiaceae and, in particular, from the tribes Mentheae and Elsholtzieae, is discussed, and a new species is described to accommodate the downy mildew pathogen of basil and coleus, which is the first downy mildew pathogen known to be parasitic to hosts of the tribe Ocimeae.     

Shifts in microbial community,pathogenicity-related genes and antibiotic resistance genes during dairy manure piled up

The uncomposted faeces of dairy cow are usually stacked on cow breeding farms, dried under natural conditions and then used as cow bedding material or they may be continuously piled up. However, no information is available to evaluate variations in the human and animal pathogen genes and antibiotic resistance during the accumulation of fresh faeces of dairy cow to manure. Here, we present the metagenomic analysis of fresh faeces and manure from a dairy farm in Ning Xia, showing a unique enrichment of human and animal pathogen genes and antibiotic resistance genes (ARGs) in manure. We found that manure accumulation could significantly increase the diversity and abundance of the pathogenic constituents. Furthermore, pathogens from manure could spread to the plant environment and enphytotic pathogens could affect the yield and quality of crops during the use of manure as a fertilizer. Levels of virulence genes and ARGs increased with the enrichment of microbes and pathogens when faeces accumulated to manure. Accumulated manure was also the transfer station of ARGs to enrich the ARGs in the environment, indicating the ubiquitous presence of environmental antibiotic resistance genes. Our results demonstrate that manure accumulation and usage without effective manure management is an unreasonable approach that could enrich pathogenic microorganisms and ARGs in the environment. The manure metagenome structure allows us to appreciate the overall influence and interaction of animal waste on water, soil and other areas impacted by faecal accumulation and the factors that influence pathogen occurrence in products from dairy cows.     

Pathogenic effects of bacteria isolated from larvae of Hylesia metabus Crammer (Lepidoptera: Saturniidae)

Hylesia metabus larvae are susceptible to several pathogens indigenous to the area in which they are found. Some larvae show symptoms characteristic of bacterial infection; they become flaccid and lethargic, and show a marked loss of appetite. We isolated and identified 29 bacterial strains from live, dead and experimentally infected H. metabus larvae, and evaluated their pathogenic activity. The bacteria which caused mortality in the larvae were: Pseudomonas aeruginosa (60-93.3%), Proteus vulgaris (20%), Alcaligenes faecalis, Planococcus sp. and Bacillus megaterium (10%), at doses of 3-4 x 10(7). Although P. aeruginosa is a well-known insect pathogen, this is the first report of its pathogenic activity on H. metabus. The potential risk to humans and low virulence make it unlikely that P. aeruginosa could be used in an augmentative biological control programme. However its natural incidence may be enhanced using parasites and predators of H. metabus as carriers.     

Minor effects of two elicitors of insect and pathogen resistance on volatile emissions and parasitism of Spodoptera frugiperda in Mexican maize fields

Synthetic elicitors can be used to induce resistance in plants against pathogens and arthropod herbivores. Such compounds may also change the emission of herbivore-induced plant volatiles, which serve as important cues for parasitic wasps to locate their hosts. Therefore, the use of elicitors in the field may affect biological control of insect pests. To test this, we treated maize seedlings growing in a subtropical field in Mexico with methyl jasmonate (MeJA), an elicitor of defense responses against many insects, and benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), an elicitor of resistance against certain pathogens. Volatile emission, herbivore infestation, pathogen infection, and plant performance (growth and grain yield) of treated and untreated maize plants were measured. Application of BTH slightly reduced volatile emission in maize, while MeJA increased the emission compared to control treatments. Despite the apparent changes in volatile emissions, the elicitor application did not consistently affect infestation by Spodoptera frugiperda larvae, the main insect pest found on the maize seedlings, and had only marginal effects on parasitism rates. Similarly, there were no treatment effects on infestation by other herbivores and pathogens. Results for the six replications that stretched over one summer and one winter season were highly variable, with parasitism rates and the species composition of the parasitoids differing significantly between seasons. This variability, as well as the severe biotic and abiotic stresses on young seedlings might explain why we measured only slight effects of elicitor application on pest incidence and biological control in this specific field study. Indeed, an additional field experiment under milder and more standardized conditions revealed that BTH induced significant resistance against Bipolaris maydis, a major pathogen in the experimental maize fields. Similar affects can be expected for herbivory and parasitism rates.     

Reduction of indicator and pathogenic microorganisms by psychrophilic anaerobic digestion in swine slurries

The objective of this study was to evaluate the efficiency of a low temperature anaerobic treatment to reduce viable populations of indicator microorganisms (total coliforms, Escherichia coli) and the presence of selected pathogens (Salmonella, Yersinia enterocolitica, Cryptosporidium and Giardia) in swine slurries from different sources. Experiments were carried out in 40 l Sequencing Batch Reactors (SBRs). Experimental results indicated that anaerobic digestion of swine manure slurry at 20 degrees C for 20 days in an intermittently fed SBR: (1) reduced indigenous populations of total coliforms by 97.94-100%; (2) reduced indigenous populations of E. coli by 99.67-100%; (3) resulted in undetectable levels of indigenous strains of Salmonella, Cryptosporidium, and Giardia. It can be considered as a promising method for reducing indigenous indicator and pathogenic microorganisms populations in liquid swine manure slurries.     

Enterobacterial and viral decay experimental models for anaerobic digestion of piggery waste

Summary A laboratory study was conducted to determine effects of the continuous mesophilic anaerobic digestion of raw pig manure in two types of enteropathogenic microorganisms, bacterial and viral. Faecal coliforms (indigenous to pig manure) and coliphage f2 (ATCC 15766 B1) were used as a model for some indigenous enteropathogenic microorganisms. The study was completed with laboratory survival experiments in lagoon stabilization of raw pig manure, for both models. Experiments for f2 survival in cell-free synthetic medium were also carried out. The results show that the anaerobic digestion process is more effective in eliminating viral than bacterial particles. Some parameters related to the ultimate biogas yield and kinetics were also determined. Lagoon stabilization of raw pig manure provides a more suitable environment for the removal of faecal coliforms than does anaerobic digestion. Finally, it was concluded that volatile fatty acids appeared to be responsible for the elimination of faecal coliforms. The agent that causes f2 inactivation is not well identified, although in some cases it could be NH₃ that seems to act as a vircidal agent.Correspondence to: J. Mata-Alvarez     

温郁金内生真菌Chaetomium globosum L18对植物病原菌的抑菌谱及拮抗机理

通过体外培养法,研究了药用植物温郁金内生真菌Chaetomium globosum L18对几种常见的植物病原菌的抑菌谱及其拮抗机理。结果表明,Chaetomium globosum L18对多种植物病原真菌和细菌均有不同程度的抑制作用,具有较广的抑菌谱,但对不同植物病原菌的抑制作用具有显著性差异(P<0.05),抑制率最高可达到92.9%;抑菌机制结果显示,竞争作用和重寄生作用是其主要的拮抗机制之一;发酵产物抑制作用测定发现,内生真菌Chaetomium globosum L18能够分泌产生抗菌物质抑制病原菌菌丝的生长和孢子萌发,可引起病原菌菌丝菌丝膨大成串珠状,分枝增多,分枝顶端膨胀后细胞壁破裂,原生质外溢,产生溶菌作用;使分生孢子萌发畸形,萌发率降低。     

Diseases of spiny lobsters: a review

Spiny lobsters have few reported pathogens, parasites and symbionts. However, they do have a diverse fauna comprised of a pathogenic virus, several bacteria, protozoans, helminths and even symbiotic crustaceans. A few idiopathic syndromes have also been reported, but these appear correlated with lobsters held in poor conditions. Fungal and bacterial pathogens present significant threats for rearing spiny lobsters in aquaculture settings, but only one pathogen, Panulirus argus virus 1, is thought to have damaged a fishery for a spiny lobster. No doubt others will emerge as lobsters are brought into aquaculture setting and as fishing pressure intensifies with stocks become more susceptible to anthropogenic stressors.     

Evolution of the pathogen content during co-composting of winery and distillery wastes

The aim of this study was to monitor some microbial indicators and pathogen contents (sulphite reducers clostridia, total enterobacteriaceae, total coliforms, faecal coliforms (Escherichia coli), enterococci, Staphylococcus aureus and Salmonella spp.) throughout the co-composting of wastes from the winery and distillery industry with other organic residues, as well as the effect of the composting system used. Seven different piles using mixtures of winery-distillery wastes with other organic materials were prepared. P1 and P2 were made using grape stalk (GS), grape marc (GM), exhausted grape marc (EGM) and sewage sludge (SS), whereas in P3 and P4 were also used exhausted grape marc with cow manure (CW) and poultry manure (PM), respectively, using the Rutgers system. Additionally, P2 was watered with vinasse (V). The rest of piles (P5, P6 and P7) were prepared with grape marc, exhausted grape marc, cow manure and poultry manure, using the turning system. The effectiveness of the composting process to reduce the pathogen content was higher in the static aerated piles than in those elaborated with the turning. The relatively high temperatures (50-60 degrees C) reached in some of the piles produced a notable decrease in some microbial groups, such as total and faecal coliforms (E. coli), but the characteristics of the raw materials used notably influenced the pathogen contents of the end-product.     

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper

Background and Aims

Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots.

Methods

Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen.

Key Results

Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant.

Conclusions

The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.     

Removal of pathogen and indicator microorganisms from liquid swine manure in multi-step biological and chemical treatment

Concern has greatly increased about the potential for contamination of water, food, and air by pathogens present in manure. We evaluated pathogen reduction in liquid swine manure in a multi-stage treatment system where first the solids and liquid are separated with polymer, followed by biological nitrogen (N) removal using nitrification and denitrification, and then phosphorus (P) extraction through lime precipitation. Each step of the treatment system was analyzed for Salmonella and microbial indicators of fecal contamination (total coliforms, fecal coliforms, and enterococci). Before treatment, mean concentrations of Salmonella, total coliforms, fecal coliforms, and enterococci were 3.89, 6.79, 6.23 and 5.73 log(10) colony forming units (cfu)/ml, respectively. The flushed manure contained 10,590 mg/l TSS, 8270 mg/l COD, 688 mg/l TKN and 480 mg/l TP, which were reduced >98% by the treatment system. Results showed a consistent trend in reduction of pathogens and microbial indicators as a result of each step in the treatment system. Solid-liquid separation decreased their concentrations by 0.5-1 log(10). Additional biological N removal treatment with alternating anoxic and oxic conditions achieved a higher reduction with average removals of 2.4 log(10) for Salmonella and 4.1-4.5 log(10) for indicator microbes. Subsequent P treatment decreased concentration of Salmonella and pathogen indicators to undetectable level (<0.3 log(10) cfu/ml) due to elevated process pH (10.3). Our results indicate that nitrification/denitrification treatment after solids separation is very effective in reducing pathogens in liquid swine manure and that the phosphorus removal step via alkaline calcium precipitation produces a sanitized effluent which may be important for biosecurity reasons.     

Developmental modulation of immunity: changes within the feeding period of the fifth larval stage in the defence reactions of Manduca sexta to infection by Photorhabdus

In insect pathogen interactions, host developmental stage is among several factors that influence the induction of immune responses. Here, we show that the effectiveness of immune reactions to a pathogen can vary markedly within a single larval stage. Pre-wandering fifth-stage (day 5) larvae of the model lepidopteran insect Manduca sexta succumb faster to infection by the insect pathogenic bacterium Photorhabdus luminescens than newly ecdysed fifth-stage (day 0) caterpillars. The decrease in insect survival of the older larvae is associated with a reduction in both humoral and cellular defence reactions compared to less developed larvae. We present evidence that older fifth-stage larvae are less able to over-transcribe microbial pattern recognition protein and antibacterial effector genes in the fat body and hemocytes. Additionally, older larvae show reduced levels of phenoloxidase (PO) activity in the cell-free hemolymph plasma as well as a dramatic decrease in the number of circulating hemocytes, reduced ability to phagocytose bacteria and fewer melanotic nodules in the infected tissues. The decline in overall immune function of older fifth-stage larvae is reflected by higher bacterial growth in the hemolymph and increased colonization of Photorhabdus on the basal surface of the insect gut. We suggest that developmentally programmed variation in immune competence may have important implications for studies of ecological immunity.     

Increased responsiveness in feeding behaviour of Caenorhabditis elegans after experimental coevolution with its microparasite Bacillus thuringiensis

Immune responses, either constitutive or induced, are costly. An alternative defence strategy may be based on behavioural responses. For example, avoidance behaviour reduces contact with pathogens and thus the risk of infection as well as the requirement of immune system activation. Similarly, if pathogens are taken up orally, preferential feeding of pathogen-free food may be advantageous. Behavioural defences have been found in many animals, including the nematode Caenorhabditis elegans. We here tested nematodes from a laboratory based evolution experiment which had either coevolved with their microparasite Bacillus thuringiensis (BT) or evolved under control conditions. After 48 generations, coevolved populations were more sensitive to food conditions: in comparison with the controls, they reduced feeding activity in the presence of pathogenic BT strains while at the same time increasing it in the presence of non-pathogenic strains. We conclude that host-parasite coevolution can drive changes in the behavioural responsiveness to bacterial microbes, potentially leading to an increased defence against pathogens.     

Quantification and kinetics of the decline in grass grub endopeptidase activity during initiation of amber disease

Amber disease in the grass grub (Costelytra zealandica White) (Coleoptera: Scarabaeidae), caused by strains of the bacteria Serratia entomophila or S. proteamaculans, is characterised by cessation of feeding and clearance of the midgut. Analysis of the midgut enzyme activity in diseased grass grub larvae showed that proteolytic activity was reduced to low levels. The endopeptidases, trypsin, elastase, and chymotrypsin, were all markedly reduced in activity whereas the exopeptidases (leucine-aminopeptidase and carboxypeptidase A and B) were much less affected. There was no effect on the non-proteolytic enzymes, esterase and alpha-amylase. Sequential analysis of enzyme levels in the gut during onset of disease showed that proteolytic activity dropped after cessation of feeding and preceded gut clearance. In starved, uninfected larvae enzyme activity levels remained high, indicating that decline in enzyme activity is not associated with absence of food and cessation of feeding, but with the onset of disease.     

The development of a qPCR assay to detect tick (Ixodida) DNA and its implementation for the study of tick-borne pathogen transmission

Polymerase chain reaction (PCR) analysis is regularly used to detect pathogens within arthropod vectors, but has also been applied to investigate vector DNA. This study details a novel highly sensitive quantitative PCR (qPCR) which detects and quantifies DNA from Ixodes ricinus, the European vector of Anaplasma phagocytophilum. By pairing this with a qPCR to detect A. phagocytophilum, valid comparisons of pathogen load can be made between different sized tick-tissue samples. These qPCRs were validated in I. ricinus that were fed A. phagocytophilum-infected blood using an artificial membrane feeder. Pathogens were detected in the tick haemolymph within 36 h, indicating that successful infection had taken place. This study illustrates the application of vector-targeted qPCRs to confirm and validate pathogen load in samples as part of investigations of vector-pathogen interactions.     

Species-specific differences in biomarker responses in two ecologically different earthworms exposed to the insecticide dimethoate

Earthworms ingest large amounts of soil and therefore are continuously exposed to contaminants through their alimentary surfaces. Additionally, several studies have shown that earthworm skin is a significant route of contaminant uptake as well. In order to determine effects of dimethoate, a broad-spectrum organophosphorous insecticide, two ecologically different earthworm species were used - Eisenia andrei and Octolasion lacteum. Although several studies used soil organisms to investigate the effects of dimethoate, none of these studies included investigations of dimethoate effects on biochemical biomarkers in earthworms. Earthworms were exposed to 0.001, 0.005, 0.01, 0.5 and 1 μg/cm(2) of dimethoate for 24 h, and the activities of acetylcholinesterase, carboxylesterase, catalase and efflux pump were measured. In both earthworm species dimethoate caused significant inhibition of acetylcholinesterase and carboxylesterase activities, however in E. andrei an hormetic effect was evident. Efflux pump activity was inhibited only in E. andrei, and catalase activity was significantly inhibited in both earthworm species. Additionally, responses of earthworm acetylcholinesterase, carboxylesterase and catalase activity to dimethoate were examined through in vitro experiments. Comparison of responses between E. andrei and O. lacteum has shown significant differences, and E. andrei has proved to be less susceptible to dimethoate exposure.